LEIDSE GEOLOGISCHE MEDEDELINGEN, Deel 51, Aflevering 2, pp. 151-231, 16-11-1978
Biostratigraphy, palaeoecology and palaeogeography of the mainly marine Ager
Formation (Upper Paleocene — Lower Eocene) in the Tremp Basin, Central-South
Pyrenees, Spain
BY
Pieter A.M. Gaemers
Summary
with axial During the greater part of the Palaeogene the Tremp Basin was an area which underwent rapid subsidence as compared the
zone of the Pyrenees to the north, and the Ebro Massif to the south. As a result the sea occupied this area for a long time and
deposition of the Ager Formation took place during the Late Paleocene and Early Eocene in a bay forming an appendix of the Atlantic
Ocean. At the maximum of the transgression probably a connection with the Tethys existed. During this entire development the Tremp
subsidence. Basin was tectonically separated from the more southerly Ager Basin by the Montsech High which underwent much less
The southern side of the Tremp Basin, under the influence of this high, subsided less rapidly than the central part. This resulted in a
much considerably thinner succession along the southern side, consisting mainly of limestones, and a thicker pile in the central part
side of the basin for have been eroded. Where mainly built up of marls. Sediments deposited along the northern a greater part they
have been preserved, they are less limy than those along the southern side. The northern margin moved in the course of time in
northern or southern direction, in contrast to the stable Montsech High which formed a stationary southern margin.
The correlations within the formation are based on alveolinids and on lithostratigraphical characteristics. Hottinger’s alveolinid
has biozonation undergoes one modification which important consequences for the chronostratigraphy of the Mediterranean
Palaeogene. The .Fasciolites oblongus Zone namely does not appear to be a higher zone than the F. trempinus Zone, for F. oblongus
lived contemporaneously with F. corbaricus and F. trempinus; F. oblongus lived in deeper water than the latter two, which explains
that they are rarely found together in one sample. The occurrence of F. oblongus in the Ager Formation proves that the Ilerdian
coincides for with the the Paleocene-Eocene lie a large part Ypresian (Cuisian). Consequently usually accepted boundary comes to
within the Ilerdian, so that this stage cannot be maintained.
Data from all alveolinid have resulted in better of the evolution of this The number of species together a comprehension group.
and be smaller than has been From the of the alveolinids it be deduced that species lineages proves to thought. palaeoecology can
three possibilities were realized by the successive species of a lineage: (1) they remain restricted to some specific, shallow marine
environment their entire evolution, themselves but shallow marine environments and during (2) they adapt to many different, mainly
remain so during their further evolution, or (3) they migrate from shallow to deeper marine environments.
and characteristics. Fifteen facies types 51 subfacies types are distinguished on palaeontological and/or sedimentological Larger
foraminifera, other microfossils and various groups of macrofossils are used for this, together with sedimentary structures and
and lithology. A large variety of facies types from fluvial swamp deposits to marls of the deeper shelf occurs. Important facies types to
be mentioned and reefs and related facies and various marine facies. are lagoonal and tidal deposits, coral algal open
Apart from some minor fluctuations the sea gradually extended over a progressively larger area during the deposition of the lower
half of the Ager Formation becoming deeper at the same time. The relief of the sea bottom simultaneously became steeper. Half-way
through the formation the transgression reached its maximum, after which the sea again became shallower and the area occupied by it
smaller. The relief of the sea bottom then again was reduced. The maximum reef development occurred in the lower part of the F.
corbaricus Zone, and was most extensive along the southern side of the basin. In the upper half of the same biozone reef growth was
of clastic material. the half of the formation the of sand and more and more hampered due to important influxes In lower occurrence
silt is always local, whereas it is found nearly everywhere in the upper half. Most of this material came from NE, E and SE directions.
Basin situated at the northern of the of The fauna and the flora point to a tropical climate. The Tremp was margin tropics (zone
An marginal reef growth). The maximum depth of the sea in the area studied was between 100 and 150 m. important aid to the
determination of the sea depth of various facies is the occurrence of glauconite which cannot have been formed above ca. 50 m depth
in the Tremp Basin.
Samenvatting
Gedurende het Bekken dat snel daalde de axiale het grootste deel van het Paleogeen was van Tremp een gebied vergeleken met zone
van de Pyreneeën in het noorden en het Ebro-massief in het zuiden. Daardoor kon de zee dit gebied lange tijd in bezit nemen en
werden de mariene afzettingen van de Ager Formatie gevormd gedurende het Laat-Paleoceen en het Vroeg-Eoceen in een baai, die
een uitloper was van de Atlantische Oceaan. Tijdens het maximum van de transgressie is er waarschijnlijk een verbinding met de
deze struktureel het direkt Tethys geweest. Het Bekken van Tremp was tijdens gehele ontwikkeling geologisch gescheiden van ten
zuiden hiervan gelegen Bekken van Ager door het Montsech-hoog dat een veel geringere daling onderging. De zuidflank van het
dit minder snel dan het centrale Dit resulteerde in dunner Bekken van Tremp daalde onder invloed van hoog gedeelte. een aanzienlijk pakket sedimenten langs de zuidflank, voornamelijk bestaande uit kalken, en een veel dikker pakket van vnl. mergels in het centrale 152
gedeelte. De noordflank van het bekken is minder gespaard gebleven voor erosie en is, voor zover nog bewaard, minder kalkig
ontwikkeld dan de zuidflank. Bovendien verplaatste de noordelijke rand zich in de loop van de tijd in noordelijke of zuidelijke richting,
terwijl het Montsech-hoog, dat als zuidelijke rand fungeerde, zeer stabiel was.
De correlaties binnen de formatie berusten op alveolinen en lithostratigrafische kenmerken. De alveolinenbiozonering van Hottinger ondergaat één wijziging, die grote gevolgen heeft voor de chronostratigrafie van het mediterrane Paleogeen. De F. oblongus Zone
te boven de Zone. Fasciolites leefde met F. blijkt namelijk geen jongere zone zijn F. trempinus oblongus namelijk gelijktijdig
F. F. corbaricus en trempinus; oblongus kwam voor in een diepere faciës dan de twee laatste, waardoor ze meestal niet samen in één
monster gevonden worden. Het vóórkomen van F. oblongus in de Ager Formatie bewijst dat het Ilerdien voor een groot deel het
Eoceen Yprésien (Cuisien) overlapt. Hierdoor komt de gewoonlijk gehanteerde grens tussen Paleoceen en in het Ilerdien te liggen,
kan worden. zodat deze etage niet gehandhaafd
Het Alle gegevens van de gevonden alveolinensoorten te zamen maken een beter begrip van de evolutie van deze groep mogelijk. aantal soorten en evolutielijnen blijkt geringer te zijn dan vroeger werd gedacht. Uit de paleoecologie van de alveolinen is af te leiden, dat de opeenvolgende soorten van een evolutielijn een drietal mogelijkheden ter beschikking staat: (1) zij blijven gedurende de gehele evolutie beperkt tot enkele specifieke ondiep-marienemilieus, (2) zij passen zich aan vele mariene, vnl. ondiepe milieus aan en blijven dat gedurende de verdere evolutie, ofwel (3) zij verhuizen van ondiepe naar dieper mariene milieus.
worden 15 51 onderscheiden kenmerken. Er faciëstypen en subfaciëstypen op grond van paleontologische en/of sedimentologische
Grootforaminiferen, andere microfossielen en diverse groepen macrofossielen worden hiervoor gebruikt naast sedimentaire strukturen
scala variërend rivier- de shelf en de lithologie. Een groot van faciëstypen van en moerasafzettingen tot mergelafzettingen van diepere
is aanwezig. Hiervan kunnen als belangrijke faciëstypen genoemd worden: lagunaire en getijde-afzettingen, koraal- en algenriffen en genetisch verwante faciës, en diverse open-mariene faciës.
Kleine schommelingen daargelaten strekte de zee zich tijdens de afzetting van de onderste helft van de Ager Formatie geleidelijk aan
de over een steeds groter gebied uit en werd bovendien steeds dieper. De zeebodemtopografie werd hierbij steeds steiler. Halverwege afzetting van de formatie bereikte de transgressie haar hoogtepunt, waarna de zee weer ondieper werd en een steeds kleiner areaal besloeg. De zeebodemtopografie werd toen weer afgevlakt. De maximale rifontwikkeling vond plaats in het onderste deel van de F. corbaricus Zone, en was het meest uitgestrekt langs de zuidflank van het bekken. In de bovenste helft van dezelfde biozone werd
rifgroei steeds moeilijker door belangrijke toevoer van klastisch materiaal. In de onderste helft van de formatie is het vóórkomen van zand en silt steeds plaatselijk, terwijl in de bovenste helft vrijwel overal siliciklastisch materiaal gevonden wordt. De aanvoer van dit materiaal kwam vooral uit NE, E en SE richtingen.
De fauna en flora wijzen op een tropisch klimaat. Het Bekken van Tremp heeft zich aan de noordelijke rand van de tropen
100 à 150 bevonden (zone van marginale rifgroei). De maximale diepte van de zee in het onderzochte gebied is m geweest. Een
faciës dat het belangrijk hulpmiddel bij het bepalen van de zeediepte van diverse is het vóórkomen van glauconiet, in Bekken van
Tremp niet boven de ca. 50 m-dieptelijn gevormd kan zijn.
Contents
I. Introduction 153 Basin 166
I. Geological situation of the Tremp Basin and 2.1. Nannoplankton 166
historical geology of the south-central Pyrenees 153 2.2. Planktonic foraminifera 168
2. Geographical situation of the area studied 154 2J.Ostracods 168
154 2.4. Fish 3. Previous work on the Tremp area remains 168
Tectonic 154 3. Correlations with other 4. complications stratotypes 168
5. classification of the sediments 156 4. The Paleocene-Eocene ]69 Petrographic .... boundary
6. Methods and techniques used 156 5. Concluding remarks 170
7. Storage of samples and additional data 156
8. Acknowledgements 156 V. Facies descriptions and interpretations 171
1. Introduction 171
II. About the evolution of alveolinids 157 2. Diagenesis 171
1. General view 157 3. The different facies and subfacies types 172
2. Evolution of the alveolinids of the Tremp Basin 157 3.1. Facies I. Continental deposits 172
3.2. Facies II. Lagoonal deposits 172
III. Palaeoecology of alveolinids and other larger fora- 3.3. Facies III. Beach and barrier 174 deposits ..
minifera 159 3.4. Facies IV. Tidal deposits (IVa-d) and
I. General fora- shallow with palaeoecological notes on larger deposits scour
minifera 159 and too! marks (IVe) 175
V. 2. Recent alveolinids 160 3.5. Facies Deposits with sand waves and
3. Fossil alveolinids 161 other large sedimentary struc-
4. Palaeoecology of the fossil alveolinids in the tures 177
Basin 161 Tremp 3.6. Facies VI. Shallow marine deposits con-
5. General palaeoecological trends within the al- taining imperforate foraminife-
veolinid lineages 163 ral associations (carbonate
6. Problems in correlation due to facies changes 164 platform) 179
3.7. Facies VII. Back-reef deposits 180
IV. Biostratigraphy and chronostratigraphy 165 3.8. Fades VIII. Reefs 181
I. Zonation on the basis of alveolinids 165 3.9. Facies IX. Calcarenitic deposits, strongly
2. Other biostratigraphic data from the Tremp influenced by tidal currents. 153
in between and arounds reefs 183 1.4. Mode of construction of the facies and
3.10. Facies X. Reef-breccia limestones (fore- the isopach maps 1%
2. of the successive reef deposits sensu strido) 183 Palaeogeography phases 1%
3.11. Facies XI. Deposits consisting mainly of 2.1. Fasciolites cucumiformis Zone 196
2.2. Fasciolites Zone pure limestones with mixed ellipsoidalis 198
imperforate-perforate forami- 2.3. Fasciolites moussoulensis Zone 200
2.4. Lower of corbaricus nifera associations 184 part Fasciolites Zone 200
3.12. Facies XII. Deposits consisting mainly of 2.5. Upper part of Fasciolites corbaricus Zone 202
clayey limestones and marls 2.6. Fasciolites trempinus Zone 204
with mixed imperforate-perfo-
VII. rate foraminifera associations 185 General palaeoecological and palaeogeographical
3.13. Facies XIII. Fore-reef detrital limestones picture 205
fore-reef 188 1. Introduction 205 (deeper deposits) ...
3.14. Facies XIV. Deposits of marls, impure 2. Sedimentation rates and duration of the diffe-
intervals 205 limestones and some sand- rent
3. Currents stones containing perforate 206
foraminifera associations 189 4. Climatological evidence 207 ....
3.15. Facies XV. Deposits containinga!Turritella 5. Autochthonous glauconite, an important expe-
dient in reconstructions community 192 palaeoecological 207
6. Other temperature/depth data 208
7. Tectonics as cause for the existence of the Pa-
VI. Palaeogeography of the successive phases as de- laeogene Tremp Basin 209
fined by the alveolinid biozones 193
1. General remarks 193 References 210
1.1. Introduction 193
1.2. Evidence for erosion in the hinterland 194 .... Plates I to VIII 216
1.3. Remarks concerningthe horizontal sections
(Enclosures 2 and 3) 195 Enclosures I to 6 (in back flap)
CHAPTER I
INTRODUCTION
GEOLOGICAL SITUATION OF THE TREMP BA- with the deposition of many turbidites, mudflow
SIN AND HISTORICAL GEOLOGY OF THE sediments and olistostromes in the Vallcarga Formation
SOUTH-CENTRAL PYRENEES (van Hoorn, 1970). Turbidites were also deposited during
the Maastrichtian (Arén Formation), thus demonstrating
The Tremp Basin, together with the Ager Basin, forms continuing instability. Nearshore calcarenites and eolian
the easternmost part of the Palaeogene of the southern quartz sandstones overlying this formation provide
situated Pyrenean marginal trough. This trough is evidence of a distinct regression (Ghibaudo et al., 1973;
between the axial zone (consisting of Palaeozoic rocks Ghibaudo et al., 1974; Mutti et al., 1975). This complex
folded and cleaved by the Variscan orogeny) in the is followed by the Tremp Formation (Upper
north, and the Ebro Basin with Oligo-Miocene deposits Maastrichtian-Thanetian; in earlier literature the term
in the south. The Ebro area was indeed characterized by Garumnian is used for this interval) which consists
a distinct positive topography during most of the mainly of reddish-brown mudstones. sandstones and
did into basin Palaeogene. The Ebro Block not change a conglomerates of fluvial origin. To the west these
before the main phase of the Alpine orogeny of the deposits change into shallow marine deposits. Between
Pyrenees (Pyrenean phase). the Esera River and the Noguera Ribagorzana River
A short survey of the lithostratigraphic development of there is a frequent interfingering of marine and fluvial
the post-Variscan deposits in the south-central Pyrenees deposits. East of the latter river there was little marine
has been given by Mey et al. (1968). The sequence starts influence whereas in the valley of the Isàbena River five
with the largely fluvial molassic deposits of Late important ingressions have been found (Kooter, 1970).
Carboniferous and Permian age in combination with A large transgression which supplied the deposits of
important volcanic deposits (Nagtegaal, 1969). An the Ager Formation (Sparnacian-Ypresian) was followed
unconformity separates these Palaeozoic rocks from the by the deltaic complex of the Montahana Group
Triassic which is developed in Germanic facies. The (Ypresian-Lutetian). This interval included two phases Triassic is followed by marine Jurassic and Cretaceous of expansion of the sea, each followed by a regression.
sediments which consist of limestones and marls The extended'farther mainly sea never east than the villages of and some dolomite. They were formed under rather Roda de Isàbena and Castigaleu (Nijman & Nio, 1975).
stable conditions. An angular unconformity separates these deposits from
This picture changes rather abruptly in the Santonian the Upper Eocene Campodarbe Group which contains 154
and deltaic fluvial deposits. A more distinct angular Of the above-mentioned authors only Ferrer et al.
main unconformity, representing the phase of the (1971, 1973) and Luterbacher (1973) attempted an
Pyrenean folding, separates these deposits from the environmental analysis of the marine Palaeogene
Collegats Formation (uppermost Upper Eocene-Oligo- deposits in the Tremp Basin.
cene), which consists of a thick sequence of continental
conglomerates near the source area changing into more TECTONIC COMPLICATIONS
finely grained fluvial sediments farther to the south.
These are the demolition of the The idea that of products rising Pyre- large parts the Pyrenees are
nean orogene. allochthonous is not new. Dalloni (1910, 1930) already
supposed that an important displacement to the south
had taken place. Jacob & Fallot (1914) and Jacob et al. GEOGRAPHICAL SITUATION OF THE AREA (1927) on the other hand believed in a large (thrust) STUDIED movement to the north. Misch (1934) however preferred
an entirely autochthonous interpretation. Seguret (1970) The Ager Formation in the Tremp Basin has been breathed life into again new the allochthonous concept. investigated from Campo in the northwest and Benabarre He supposed that two large nappes slid across the in the west to Sant Salvador de Tolo in the east. The autochthonous rocks and across each other. Most later of this is situated in western part area the province of investigators have accepted his theory with only minor the in the of Lérida Huesca, eastern part province changes and amplifications (see Garrido & Rios, 1972; (Enclosure 1; Fig. 1). Garrido, 1973; Saenz de Santa Maria, 1976).
- Everywhere north of the line Campo Arén - Tremp A drilled deep boring by the Spanish oil company - Sant Salvador de Tolo the formation has disappeared Auxini in February 1975, provided new insights into the due to erosion; the same is true in the Sierra del tectonics of the south-central Pyrenees. This boring Montsech south of the Tremp Basin. (Isona no. 1 -bis) is situated 9.5 km east and slightly South of the Montsech mountains another, smaller north of Isona. It pierced a 3592 m thick Mesozoic basin This is Palaeogene occurs. the Ager Basin which succession of Upper Cretaceous to Triassic sediments; studied J. was by Rosell's group (Universidad Autònoma below this are Upper Eocene (Priabonian) marls and de Barcelona). Already several studies have been with thickness of least This evaporites a at 722 m. boring published on this basin, sometimes dealing with the thus shows the existence of a nappe thrust over Tremp Basin as well (Villalta & Roseli, 1963; Crusafont autochthonous sediments of Eocene Late age. This et al., 1968; Ferrer et al., 1971, 1973; Roseli, 1973; that in disproves previous ideas no large nappe exists the Stevens, 1973; Mutti et al.. 1973, 1974; Ghibaudo, 1976; southern Pyrenees (Gaemers, 1974), or that the entire Llompart. 1977). For literature on the western south-central Pyrenean unit (unite sud-pyrénéenne continuation of the Tremp Basin the reader is referred to centrale) was thrust during the deposition of the middle the papers by Soler & Puigdefàbregas (1970, 1972), part of the Upper Eocene (Seguret, 1970). Rupke (1972): Puigdefàbregas (1975) and Puigdefàbregas The Priabonian deposits under the thrust plane prove et al. (1975). that gravitational sliding of the south-central Pyrenean
unit did not occur before the latest Late Eocene.
PREVIOUS WORK ON THE TREMP AREA According to the ideas of Seguret (1970) the Cotiella
formed nappe a whole with the south-central Pyrenean
For a time the south-central have been unit. In this the thrust of the Cotiella long Pyrenees a case, plane nappe of subject interest to geologists. Earlier investigations should have originated at the same time as the thrust emphasized the regional features; stratigraphy and plane of the entire tectonic unit. Since the sliding of the tectonics were broadly outlined, often accompanied by Cotiella massif occurred simultaneously with the eloborate Vidal palaeontological inventories, e.g. (1875), deposition of a thick Eocene marl sequence, the exact
of this Carez (1881), Dalloni (1910, 1930), Misch (1934), Selzer age event can be ascertained. Near Foradada the
(1934), Almela & Rios (1947), Alastrué et al. (1957) and overthrust of the Cotiella massif dies out (Gaemers,
(1959). The of this kind Mangin most recent study is the 1974) and changes eastwards into an angular
& publication by Garrido Rios (1972). unconformity, which continues at least to the south of
In the course of time more specialized studies Merli (a small village northwest of La Puebla de Roda) in appeared, often of limited geographical or stratigraphical the marls of the Ager Formation; these marls are of scope, e.g. Hottinger (1960, 1962), Hottinger & Schaub Ypresian age (PI. 1, Fig. 2). It follows that the overthrust
of (I960), de Renzi (1965, 1968, 1975), Crusafont et al. the Cotiella massif is also of Ypresian age; it is
(1966, 1968), Plaziat & de Renzi (1968), Luterbacher therefore much older than the Late Eocene thrusting of
(1969. 1973), Kruit & Brouwer (1971), Mutti et al. (1972), the south-central Pyrenean unit, from which it is evident Ferrer et al. (1971, 1973), Gaemers (1974), le Calvez that the two thrust planes are different and independent
(1975) and Plaziat (1975). Tectonic publications are phenomena. Therefore there is no reason to doubt that mentioned in the following section, studies dealing with the Cotiella sliding and the rotary movement of this
and of local biostratigraphical chronostratigraphical correlations sliding were only importance as explained by in IV. Chapter Gaemers (1974). Furthermore it would now appear likely 155
sections. measured
the
of location
with studied
area
the
of
map Geological
1.
Fig. 156
south-central unit his that Seguret's Pyrenean and were sampled. If a stratum was rich in macrofossils, a
Gavarnie nappe constitute only one large nappe. small collection of the latter was often made and
sometimes also loose fossils were collected. The weight
PETROGRAPHIC CLASSIFICATION OF THE of all rock samples and fossils collected amounted to
SEDIMENTS about 1500 kg.
In addition to about 1400 thin sections several polished
In the stratigraphic sections the carbonates are classified surfaces were studied if the structures were larger than a according to Dunham's (1962) system. Accordingly the normal thin section. Sometimes staining of the samples
is used for mudfree calciclastic with Alizarine Red-S in order name grainstone was necessary to
sediments. Dunham maintains that a calcarenite should distinguish between calcite an dolomite. Many marl
if it contains be called a packstone more than \% mud. samples were treated with a diluted hydrogen peroxide
Experience has shown that this \% boundary is too solution so that they could be sifted more easily. The strict, for only a few limestones meet this definition of microfaunas and macrofaunas in the residues could then grainstones. Therefore the 5% boundary suggested by be studied. van de Graaff (1971, p. 163) is used. The most frequent groups of larger benthonic
In the terminology of Folk (1959, 1962) the limestones foraminifera were counted in the thin sections. The occurring in the area of the present study nearly all counts were always made in or recalculated for a
2 to belong the biospar(rud)ites (calcarenites and standard area of 6 cm . calcirudites) and biomicr(ud)ites. In rare cases they can In the stratigraphic sections the widths of the bars
indicate be classified as intraspar(rud)ites. According to Folk's the quantities of foraminifera in the accessory classification the diversity of the carbonates is therefore samples. Unintentionally the bars of the individual rather limited. In the discussion of the several facies and alveolinid species have different widths in some sections. subfacies types (Chapter V) Folk's system is used for the This has no significance in this case; for these short foraminifera the of lithologic descriptions. presence a bar means only the
A of in substantial part of the sediments in the Tremp Basin presence the species the accessory sample without is a mixture of two or more of the following rock types: saying anything about the number of individuals. dolomite, limestone, clay, silt, sand, gravel and boulders.
Dolomite, gravel and boulders are rare; nevertheless STORAGE OF SAMPLES AND ADDITIONAL DATA there is a large number of possible varieties and gradations between the other rock types. This some- The rock samples, residues, thin sections, fossils and times identification makes and classification difficult. some sedimentary structures collected and studied were
deposited in the collection of the Rijksmuseum van
METHODS AND TECHNIQUES USED Geologie en Mineralogie, Hooglandse Kerkgracht 17,
Leiden. In order to make the collection as compact as
The outcrop area of the Ager Formation as shown in possible the hard rock samples were sawn into slices
Fig. 1, was checked in the field in many places. Large about 1-2 cm thick.
the relevant sheets of the parts were mapped on Mapa Additional data (mainly unpublished sections) were de Espana, scale 1:50.000. The marked topography deposited in the same museum and in the files of the
these does of and indicated on maps not always agree Department Stratigraphy Palaeontology, sufficiently with reality, for example in the Geologisch en Mineralogisch Instituut, University of neighbourhood of section G. The outcrop area between Leiden.
Campo and Serraduy (NE of La Puebla de Roda) is
The based chiefly on the maps of van Eden (1967, 1970). ACKNOWLEDGEMENTS
Ager Formation on the southern side of the basin and on the northern side between Serraduy and Tendruy (small I am indebted to the Comisión Nacional de Geologia village NW of Tremp) was mapped in its entirety by the (Madrid) for their permission to study the marine author with the help of aerial photographs and field Palaeogene of the Tremp Basin.
to the who work; there are no essential differences between these I am very grateful following persons of parts of the map and those made by Garrido & Rios assisted me with their special knowledge various types
(1972). of fossils: Dr. J. Roman (Muséum National d'Histoire
Most sections were measured on a scale of 1:100 or Naturelle, Paris) studied echinoids from the Tremp
Dr. R. Shell 1:200. Thick, monotonous sequences were recorded on a Basin, the late Lagaaij (Koninklijke
K. scale of 1:500 whereas some detailed sections with a Exploratie en Produktie Laboratorium, S. E. P. L.,
thin strata measured scale and Dr. G. C. Cadée Instituut succession of many were on a Rijswijk) (Nederlands of 1:50. The data were noted in the field on check lists in voor Onderzoek der Zee, Texel) identified some
and useful order to save time and to standardize data collection. important bryozoan genera, provided
Sampling was intensive, usually in proportion to the information about the ecology of these animals, Mrs. S.
S. identified details within each section. Hard rock samples (mainly E. van Heck (K. E. P. L., Rijswijk)
limestones and sandstones) as well as soft rock samples nannoplanktonfrom selected samples for biostratigraphic
(mainly marls) were collected, although not all marls correlations, Mr. A. W. Janssen (Rijksmuseum van 157
with the students who Geologie en Mineralogie, Leiden) helped younger (called 'meelopers') assisted me
identification of the molluscs, and Mr. M. van den Bosch during the field work: Messrs. F. M. Blom, W. E.
Leiden) Busser, R. W. J. M. van der Ham, P. M. A. (Rijksmuseum van Geologie en Mineralogie,
sharks F. G. M. identified some remains of and rays. Haseldonckx, J. de Nijs, M. Th. Otten, F. J.
I wish to thank Dr. J. van der Land and Mr. J. de Reuver and W. M. Wiemer.
Walenkamp (both of the Rijksmuseum van Natuurlijke I am grateful to Messrs. K. A. Hakkert. J. J. J.
Historie, Leiden) for their assistance in finding ecologie Bergenhenegouwen, T. van Hinte and M. L. Brittijn who
the drew the and Messrs. W. C. information about the worm Ditrupa and crinoid many figures enclosures,
Rhizocrinus, respectively. Laurijssen, H. Schiet and W. A. M. Devilée who
1 am thankful to Mr. L. Villalobos (Departamento de handled the photography, Messrs. H. C. de Graaf, J.
and and J. thin Investigaciones Petrolfferas, Madrid) Empresa Schipper Schuilenburg who prepared many
Auxiliar de la Industria, S.A. (Auxini, Madrid) for their sections. Mrs. D. S. de Laaf and Ms. G. Klunder who
willingness to furnish well log data from the Tremp typed large parts of the manuscript, and Mrs. G. P.
Basin. Bieger-Smith who corrected the English text.
It is a special pleasure for me to be able to thank the
CHAPTER II
ABOUT THE EVOLUTION OF ALVEOLINIDS
VIEW GENERAL Younger alveolinids are Borelis which is known from
Late Eocene times to the present day, Bullalveolina
The oldest known representatives of the Alveolinidae which is only known from the Oligocene, and
family are small, globular species of the genus Alveolinella which is known f.-'jm the Miocene to recent.
Praealveolina which occur in the Lower Cenomanian. The latter is In genus probably a descendant of Borelis.
strata The of younger Praealveolina gradually evolves into origin these three genera which seem to form a
with and fusiform uncertain. species larger more shells: moreover natural group is Usually they are presumed to
other viz. three genera, Cisalveolina, Ovalveolina and have miliolid ancestors because both the microspheric
and Multispirina, appear which may have evolved from megalospheric generations of Borelis have a milioline
In in Praealveolina. the Turonian this latter genus again is nepionic stage contrast to most of the older alveolinids
the only representative of the family. Subalveolina, which have a planispiral megalospheric stage (Smout. occurring in the Santonian and Lower Campanian, will 1963).
have evolved from Praealveolina and is the latest
of this EVOLUTION OF THE representative Cretaceous group. These THE ALVEOLINIDS OF
Cretaceous alveolinids form as a whole a distinct natural TREMP BASIN
unit.
Except for aberrant of local occurrence some genera Hottinger's monograph of 1962 on the Palaeogene
such as Pseudedomia Henson, Smout emend., no alveolinids of the Mediterranean area is an indispensable alveolinids have been found in the higher part of the publication for the study of the alveolinids of the Tremp
Campanian and in the Maastrichtian. From Danian and Basin. An important improvement of Hottinger's work
Montian alveolinids unknown with to earlier deal with deposits are completely up regard publications which the to now. It is therefore highly unlikely that the same group of foraminifera is the use of standard
Palaeogene alveolinids evolved directly from the magnifications in the photographs of the species: Cretaceous species. Moreover the Palaeogene forms ten-fold, twenty-fold and forty-fold. This is especially differ from the Cretaceous in for species that they have a important the alveolinids. for the size is one of the strongly developed postseptal canal and alternating most essential characteristics for the identification. chamberlets (Smout, 1963). Thus it is much more if likely However, the successive species of a lineage increase that the Paleo-Eocene forms from miliolid in size, arose a considerably it often happens that they are not ancestor. Fasciolites has been found from the all at Thanetian pictured the same standard magnification. As a
to and including the Biarritzian (Middle Paleo- result the up phyletic relationships between some species or cene-Late Eocene). All alveolinids from the Tremp groups of species are obscured. For example the species
Basin belong to this genus which can be subdivided into Fasciolites (Microfasciolites) boscii shown by Hottinger two viz. Fasciolites and at subgenera, Microfasciolites (see a twenty-fold magnification was not identified as a
alveolinids Gaemers, 1978). The evolution of these starts member of the subgenus Microfasciolites (syn.: with small, globular forms which evolve into gradually Glomalveolina) the species of which are usually shown and Thus the always larger more elongated species. at a forty-fold magnification. of general evolution of these alveolinids is highly In a previous publication the pattern (Gaemers. 1978) present similar to that of the Cretaceous forms. author tried to assemble the species from the Palaeogene 158
of the Basin in natural Tremp groups which are as
extensive as possible. This arrangement with the addition of data of younger alveolinids collected from the
literature provides a more elaborate scheme of the
evolutionary development of some Palaeogene
alveolinids (Fig. 2). One of the most important
discoveries is the bifurcation of the lineage of F.
ellipsoidalis after F. moussoulensis. In fact in the Tremp
Basin transitional forms have been found not only
between F. moussoulensis and F. corbaricus but also
between the former species and F. oblongus (Gaemers,
1978, pi. 2, figs. 5, 6). These forms are intermediate with
respect to their elongation index, the size of the
chamberlets and the coiling. The chamberlets of F.
oblongus are generally smaller than those of F.
moussoulensis. The characteristics of the spirals of the latter species remain much more uniform during growth
than those of F. oblongus which show two different
ontogenetic stages: a younger, more elongated stage with
thickened and distinctly poles, an older, more compact
stage with tightly coiled spirals.
Parallel developments are obvious in all lineages. In
the of time the size the course average of proloculus of
megalospheric forms increases. We have to keep in mind
that the variability of this characteristic is pronounced in
most species. The sizes of the proloculus for successive
species of a lineage tend therefore to show considerable
which overlap. Species are not or only slightly
flosculinized increase in size, and the elongation index increases simultaneously. Highly flosculinized species
generally increase in size only (see for example the
F. F. sequence globulus globosus F. triestinus).
Moreover the number of chambers in a corresponding
coil increases in the course of the evolution of the
lineages. Finally the difference in size between the
microspheric and megalospheric generations always
increases as the of the development lineage progresses.
Although other characteristics can be affected by more
accidental changes, the course of evolution seems to be
fixed to a considerable degree. This does not mean
however that the evolution of the alveolinids is
completely determined beforehand. One cannot predict the future of a lineage entirely, because not only internal
processes but also external, environmental circumstances
influence the of evolution. The internal course processes in each individual animal and in the species as a whole
transmitted as by propagation seem always to follow the
same path. Once a lineage has started, it has to obey the laws of the internal processes. The above-mentioned
parallel developments express the realization of these
processes. Apart from the degree of flosculinization the
only important difference found in the development of
the various lineages is the rate at which the changes take
Fig. 2. Evolutionary lineages of the majority of the alveolinids
occurring in the Tremp Basin. The connections between F.
varians and F. decipiens, and between F. schwageri and F.
distefanoi, which have been drawn as bifurcations, only signify
a gradual transition between these species. 159
in place. Probably population size is an important factor Katagenetic developments, recorded for many animal
this respect (see Chapter III). groups such as bryozoans, gastropods, cephalopods and
Naturally animals tend to adapt themselves to the bony fishes (Gaemers, 1976), are not known from the
environment if conditions the lifetime of alveolinids. change during Only progressive sequences have been the lineage to which the species belong. This adaptation observed and it is unlikely that retrograde tendencies wil which be discovered can lead to new features however are in the future. It appears that among
the basic form determined the alveolinids (and most foraminifera) size superimposed upon by probably among internal For instance the of alveolinids increase and increase of processes. poles elongation once started continue
to unchecked until can be pointed truncated. Microspheric forms of F. a lineage has reached the maximum size
ellipsoidalis have fairly pointed poles, micro- and at which point it becomes extinct. From the available
megalospheric forms of F. moussoulensis have truncated data it cannot yet be determined whether rejuvenation by of poles; those of F. corbaricus and megalospheric forms of means neogenesis (Gaemers, 1976) occurs in this
- has been F. ellipsoidalis have realized the intermediate possibility group as found for the codfishes (Gaemers,
of rounded poles. The simultaneous increase in the size 1976). If not, new lineages of alveolinids can only arise
of the and of the entire the increase from the Miliolidae. Miliolidae proloculus test, plus are an example of
in the elongation index during the evolution take place foraminifera in which size increase seems to be checked.
irrespective of changes in the shape of the poles. The Perhaps the alveolinids have surpassed a certain
splitting of a lineage into two (or more) branches, which threshold and the miliolids have not or not yet.
Thus evolution is called cladogenesis, is a matter of environmental the of the alveolinids seems to differ in
conditions animal (in casu a geographical or ecological some respects from that of higher groups. Many
still have separation) and cannot therefore be deduced from the questions to be solved before their evolution
internal will be clear. processes, which are guided by genetic completely
principles.
CHAPTER III
PALAEOECOLOGY OF ALVEOLINIDS AND OTHER LARGER FORAMINIFERA
GENERAL PALAEOECOLOGICAL NOTES ON limited area like the Tremp Basin. A second important
LARGER FORAMINIFERA environmental factor for the distribution of the benthonic
foraminifera associations is the kind of sediment
foraminifera in for Although larger are used many cases deposited.
and biostratigraphic purposes, have therefore been In order to unravel the influences of depth and bottom
studied for few taxonomically many years, only a sediment it is important to find a sequence which shows
palaeontologists have concerned themselves with the gradually changing foraminifera associations while the
fossils. is due palaeoecology of these Perhaps this partly sediment remains much the same. This is the case in
the of the of section to scanty knowledge ecology many groups P and therefore this section can be used as a key of recent foraminifera. section.
A division of associations of into three main groups The sequence consists of pure limestones with
foraminifera is well-known for larger many Palaeogene occasionally more or less sandy beds. The lower part in deposits and can also be applied the Tremp Basin, but contains imperforate foraminifera associations, which more detailed information cannot be obtained from the lived in a shallow marine, fairly protected environment, literature. These groups of associations are the judging from the entire faunal and floral composition. The middle contains following: part mainly mixed per-
I. The imperforate foraminifera associations, composed forate-imperforate foraminifera associations which of Miliolidae, Alveolinidae and least Orbitolites, or at lived in somewhat deeper, more open marine one or two of these groups. environments. An important exception is noted in the
2. foraminifera The mixed perforate-imperforate asso- upper part of this interval where an imperforate ciations, in which species of the imperforate associa- association predominates. Here the perforate elements tions found with Nummulites and/or have are usually together practically disappeared. Temporarily the sea
Operculina. became shallower, and reefs and fore-reef deposits could
3. associations. in- In The perforate foraminifera These be formed. the upper part of section P perforate clude Nummulites, Assilina and Operculina, Discocy- associations are present which are indicative of deeper clina. Miliolids in can still play an important role these shelf waters; this is evident from the occurrence of associations. glauconite and from the entire faunal and floral
In a general way these foraminiferaassociations tell us composition. Discocyclina and Nummulites are the most something water depth the latter about and temperature; numerous genera here. Higher in this part of the section is to closely related the depth when we consider a Nummulites generally decreases in number in contrast to 160
Discocyclina which becomes more abundant. From this glauconite. Fore-reef deposits in the broad sense and
contain numbers of these fossils. and also from other data of the Tremp Basin it can be deep reefs fairly large concluded that Discocyclina on the whole lived in deeper
water than Nummulites. RECENT ALVEOLINIDS
not restricted to Most larger foraminifera are one type of sediment, but they always have clear preferences. We Little is known about the ecology of recent alveolinids have mind that of each and other foraminifera. The data to keep in more species genus of many larger sparse
not all are involved and that necessarily occupied the available about the life habits of recent alveolinids
of Three same ecological niche. The following therefore is only a chiefly concern the depth the sea. recent general impression of the main ecological requirements alveolinid species are known from the Indo-Pacific
Borelis for some of the genera of larger foraminifera common in region, viz. Alveolinella quoyi (d'Orbigny), melo the Tremp Basin. Fichtel & Moll) and Borelis schlumbergeri (Reichel); A.
Orbitolites preferred a shallow marine environment quoyi is the species most often recorded. which was protected against wave and tide actions; they According to Brady (1884) Alveolinella quoyi "most
in limestone Therefore the affects shallow water of the coral reefs, and becomes appear pure deposits. the back-reef environment was most favourable. Orbitolites rare at depths greater than 54 fathoms" (97 metres). He also occurs in limestones with a low sand or clay observed this species for example in the coral reefs of
This 72 At content. genus was probably epiphytic like its Honolulu (Hawaii) at a depth of m. Funafuti recent counterpart Sorites (Hottinger, 1973). It is mainly Chapman (1899) found this species at depths of 90 to associated with numbers of miliolids and Cushman found around the large 109 m. (1914) A. quoyi alveolinids. Hawaiian Islands in waters about 113 metres deep. In
Nummulites is most abundant in limestones and 1921 he observed this species in the seas around the sandstones. In areas of extensive clay deposition it is Philippines, where it is most abundant at depths between usually rare. Sometimes large numbers of nummulite 18 and 70 m; one occurrence was recorded at the
An specimens are found in marls. explanation for this extreme depth of 582 m. Cushman (1933) mentions could be that such marls were deposited at a much lower typical specimens of this species in Mokaujar rate Nummulites lived than most other marls. generally Anchorage, Fiji, at a depth of 13 fathoms (23.5 m).
15-50 recorded in moderately deep shelf waters (ca. m). When an Hofker (1930) a range of 9 tot 45 metres for important influx of sand entered the basin, these different stations in the Malayan Archipelago, whereas le
to foraminifera seem have replaced the alveolinid Roy (1938) found a Dendritina-Alveolinella community elements in the shallow environment. Nummulites could in a protected shoal facies ranging in depth from 7 to 26 also live in deeper waters if mainly calcium carbonate metres (Peper Bay, west coast of Java, Indonesia). Other and/or sand deposition took place instead of clay authors who have found Alveolinella in reefs, back reef commonly found at these depths. zones, reef flat channels and/or tropical lagoons are
Operculina is observed chiefly in limestones and Gardiner (1906), Newell (1956), Cole (1957), Maxwell et marls. It could only persist when the sand content was al. (1961), Bandy (1964), Maxwell & Swinchatt (1970) low. numbers of this be found Typically large genus can and Chevalier (1973) (literature compiled by Ghose, in moderately deep shelf waters, like the nummulites. 1977).
limestones Assilina occurs mainly in marls and marly The occurrence of A. quoyi in bottom samples from that on the average were deposited at greater depths deeper water surrounding oceanic islands can be than those in which operculines are frequent. Assilines explained by transportation of shells from shallower
Alveolinella and also are not normally sand or pure carbonate dwellers. regions (Cushman, 1910).
Glauconite can often be found together with assilines Orbitolites are considered by many authors to be when the sedimentation rate was sufficiently low (in characteristic constituents of a shallow marine marly limestones). environment of the tropics in and around reefs where the
Of Discocyclina two distinctly different forms occur in water is clear. the Tremp Basin. One has markedly flattened discs and Borelis melo has been recorded off the Hawaiian
central the part is only slightly elevated. This form is Islands and near Ceylon (Brady, 1884). The limited
mainly found in marls; it can also be found in marly and amount of data does not justify an ecological
sometimes somewhat sandy glauconite-rich limestones interpretation. intercalated as thin layers in the marls. These The type material of Borelis schlumbergeri, described
Neoalveolina discocyclines often occur together with assilines but by Reichel (1937) as pygmaea generally they live in deeper waters. In fact, marls with schlumbergeri, comes from Mayotte Island and Nossibé an abundance of discocyclines represent the deepest Island, northwest of Madagascar. Unfortunately no environment in the studied than indications area (probably more depth or other data are known. Specimens
100 m). The other form is characterized by inflated discs that can be included in the same species had already with a thickened been found earlier Möbius and markedly central part. It can be found by (1880) Egger (1893). in limestones limestones which Möbius observed shells white carbonate pure or sandy are empty in a mud associated with reef development. This form also only at the bottom of the channel between the coastal reef lived in deeper waters, and is usually associated with and the Fouquets dam reef of the Isle of Mauritius. 161
live Egger found his alveolinids in samples taken at depths of in a brackish environment in contrast to miliolids,
since B.137 m and 411 m to the west of Mauritius. Finally alveolinids never occur in deposits which can be
schlumbergeri was recorded by Hanzawa (1948) as being interpreted as definitely brackish (Hottinger, 1960). This in from of south of is in with present a sample a depth 82 m, accordance the data of recent species, which Tarama-jima (Ryukyu Islands, Japan). From these data it have only been recorded from water of normal salinity.
seems probable that B. schlumbergeri lives in somewhat Hottinger's description of the habitat indeed applies to
deeper water than A. quoyi, although we have to the majority of the alveolinids in the Tremp area, but exist. remember that currents may have transported empty exceptions It is certainly not true that alveolinids
shells to deeper waters. are always restricted ecologically to protected shelf
for areas, as Hottinger (1973, p. 443) stated, although
FOSSIL ALVEOLINIDS many species his view is applicable. Thanks to a detailed
study of the facies of the marine deposits in the Tremp
The fossil alveolinids listed in Table in it is I seem general to Basin, now possible to consider the palaeoecology
occupy the same ecological niches as their recent of the different species and thus to obtain more precise
descendants. According to Hottinger (1960) fossil information on this subject than ever before.
alveolinids flourished within only narrow facies ranges; PALAEOECOLOGY OF THE FOSSIL ALVEO- fossil biocoenoses occur only in lime-rich deposits,
which often contain LINIDS IN THE TREMP BASIN numerous other porcellaneous
foraminifera (mainly Miliolidae and Orbitolites) as well
1 as many calcareous algae; alveolinids apparently could Table shows the distribution of all important alveolinid
live shallow bottoms which in detritus the different on sea were poor species over (sub)facies types as compiled
For (Hottinger, 1960, p. 271). Alveolinids evidently could not for the Tremp Basin. three reasons however, this
Facies
a b c d d a c e *> <* f b led e a a b a e a b e a b b d bel a c Name of species I I I I I '| I I I I ! I I I I I I I I I I I I I I I I | | II HI IV IV IV IV | | | | | | IV VI VI VI VI VI VI Vll|Vllt VIII VIII IX IX X X XI XI XI XI XII XII XII XIII XIII XIV XIV XV F.(M.) lepidulus group of F.(M.) pilulus
F.(M.) lepidulus F.(M.) minutulus
F.(M.) subtilis F.(M.) boscii F.(M.) agerensis
Lineage F.(M.) boscii
F.(F.) cucumiformis F. (F) cucumiformis
F.(F.) tumidus »• ••
Lineage "* ■■- F.(F.) ruetimeyeri •• —
F.(F.) ellipsoidalis - F. — — ••• F.(F.) oblongus (F.) moussoulensis •• •• ■
corbaricus • F. (F.) •• ■•" ■-•
F.(F.) -——^-^^^^^—■ I Lineage trempinus H F.(F.) oblongus
F.(F.) dolioliformis — F.(F.) subpyrenaicus •• ••• ...
•• F.(F.) subpyrenaicus ••• •• •• waim ■- •
Lineage F.(F.) fornasinii
F.(F.) F.(F.) decipiens varians F.(F.) decipiens Lineage F.(F.) schwageri F.(F.) globulus F.(F.) globosus
•• •• i •• — ... F.(F.) globosus ...
Lineage us F.(F.) triestin •• ...
F.(F.) a vellanus
F.(F.) pasticillatus F.(F.) pasticillatus
F.(F.) leupoldi Lineage F.(F.) parvus
F.(F.) canavarii F.(F.) laxus
Lineage F.(F.) canavarii
— rare ì
common s in Basin _ the Tremp
— abundant J
be facies •■ to expected in this outside the Tremp Basin, not found in the Tremp Basin
transported from other, adjacent facies
Table 1. Ecologic distribution of the alveolinids occurring in the Tremp Basin. Subfacies IIc: lagoonal deposits; facies III: beach and barrier subfacies deposits; IVa-c: shallow tidal deposits; subfacies IVd, d’: deeper tidal deposits; facies VI: shallow marine deposits with imperforate foraminifera associations; facies VII: back-reef deposits; subfacies VIIIb: Lithothamnium ridges; subfacies VIIIc, d: coral-algal reefs and coral reefs; subfacies VIIIe: deeper coral reefs; subfacies IXa: off-reef shoal limestones; subfacies IXb: reef channel limestones; subfacies Xa: shallow fore-reef deposits; subfacies Xb: fore-reef facies XI: limestones with deeper deposits; pure mixed imperforate-perforate foraminifera associations; facies XII: clayey limestones and marls with mixed imperforate-perforate foraminifera facies XIII: fore-reef detrital facies associations; limestones; XIV: marls and impure limestones with perforate foraminifera associations; facies XV: marls with Turritella community. 162
much chance of this for which table must be used cautiously. In the first place some finding species the
F. F.species appeared to be rare in the area, notably (M.) biozone is named. The rarity of (F.) tumidus in facies XI subtilis, F. (F.) tumidus and F. (F.) laxus. It is however however is a good indication that F. (F.) cucumi-
distribution also in this facies. The latter probable that their palaeoecological was formis was scarce species
more extensive than indicated by the few specimens as well as F. (F.) ruetimeyeri could endure a consider-
found. able influx of sand. The few of F. Secondly many species will not have been specimens (F.) tumidus observed in all environments in which they lived, were found in pure limestones, but it is highly
that this restricted to these because strata representative for these environments are unlikely species was sedi-
not exposed in the Tremp Basin in all stratigraphic ments and could not tolerate sand. It is striking that all
intervals. F. (F.) subpyrenaicus for instance could not be three species of this lineage seldom occur in large
found in lagoonal deposits because the lagoonal numbers in rock samples.
environment is not represented in the existing outcrops Typically both F. (F.) ellipsoidalis and F. (F.)
of this A corbaricus inhabit the clean calcareous bottoms of facies of the stratigraphic range species. special
symbol is used in the table to indicate that it is highly VI and XI, and occur in the neighbourhood of reefs.
likely that a species lived in more environments, as Probably F. (F.) trempinus had the same mode of life as
deduced from the known facies distribution of that these species. Reefs however are unknown in the
of F. species, and from the distribution of the most closely exposures the (F.) trempinus Zone in the Tremp
allied species. Thirdly it is not always possible to know Basin; for this reason the autochthonous occurrence of
whether the occurrence of a species in a (sub)facies was F. (F.) trempinus in reefs cannot yet be verified. The
distribution of caused by transportation from other (sub)facies or not. F. (F.) moussoulensis is more extensive.
F. F. Examples are the presence of (F.) ellipsoidalis, This species could also live under muddier bottom
(F.) laxus and F. (F.) canavarii in facies IX. conditions. F. (F.) oblongus had the geatest tolerance for
sand of all alveolinids in the Basin. Notwithstanding the above-mentioned restrictions a lot Tremp It can be
of information is available. In the following the separate found in large numbers in calcareous sandstones rich in
species will be discussed first, and then the trends within quartz sand. However, it is not restricted to such
In the lineages will be considered. sediments: it also occurs in pure limestones. the
F. (M.) lepidulus occurs in all imperforate and mixed glauconitic sands of the Cuisian in the Paris Basin this
perforate-imperforate foraminifera associations. Pure species is the only alveolinid. Apparently it is the only
carbonate was preferred by this species but it could species that could survive such bottom conditions. In the
southern endure some sand or mud in the sediment. Pyrenees F. (F.) oblongus nearly always
The palaeoecological distributions of F. (M.) pilulus indicates deeper (and also colder) water. Usually it is found in and F. (M.) minutulus are somewhat less extensive than glauconite-rich deposits, although it is not as
accurate indicator of conditions that of F. (M.) lepidulus. F. (M.) minutulus shows some an deep water as F. (M.)
tolerance for sand. F. (M.) pilulus on the other hand boscii.
limestones. There to be difference between the seems to be restricted mainly to pure seems a striking
In the F. (M.) boscii lineage F. (M.) subtilis represents occurrence of F. (F.) oblongus in the Paris Basin and in
the species which lived in the shallowest water. It is only the Tremp Basin. Whereas this species lived in relatively
foraminifera associations. known to occur in imperforate deep and cold water (usually 50 metres or more) in the
Its successor F. (M.) agerensis belonged to the typical Tremp Basin, it occurs in the Paris Basin in deposits
mixed perforate-imperforate foraminifera associations, which are supposed to have been formed under much
If this is which lived in somewhat deeper waters than the shallower conditions. true, there are two
imperforate foraminifera associations. Surely this species possibilities which perhaps are not mutually exclusive.
influx F. could tolerate a small amount of mud in the carbonate Firstly the sand may have been so large that
sediment, judging from its common occurrence in all (F.) oblongus and the nummulites superseded the other
subfacies of facies XII. F. (M.) boscii lived in even alveolinids completely. Secondly the temperature of the
in fact alveolinid which surface of the in the Paris Basin have deeper seas and it is the species layers sea may
lived in the deepest water in the Tremp Basin. It never been lower than in the Tremp Basin. This is highly
since Paris occurs above the zone in which glauconite was formed likely, the Basin is situated farther north than
(see also Chapter VII, section 5) in contrast to the other the Tremp Basin. Moreover, the communication of the
species which also lived in relatively deep waters; it is Paris Basin with the North Sea was much larger than the
therefore reliable indicator of the Atlantic which a a fairly deep sea. narrow seaway to Ocean indirectly
Apparently it could tolerate the sand and mud in the connected it with the Tethys region.
calcareous of mainly sediment quite well. Certainly the most successful group alveolinids in
It is likely that the three members of the F. (F.) the Tremp Basin, as far as distribution is concerned, is cucumiformis lineage found in the Tremp Basin lived the F. (F.) subpyrenaicus lineage. The three species under the conditions, for all in the known from this in same they occur lineage are all abundant a large
imperforate foraminifera associations (facies VI). variety of facies and subfacies. Numerous F. (F.)
Unfortunately the mixed perforate-imperforate fora- dolioliformis specimens lived in normal saline lagoons
environments minifera associations (facies XI) are poorly represented up to and including the with mixed
in the F. (F.) cucumiformis Zone, so that there was not perforate-imperforate foraminifera associations. This 163
species could tolerate some mud and sand but preferred foraminifera associations. There is some preference for
conditions clean carbonate sediments. The same life the latter associations (facies XI). This is suggested
hold for F. (F.) subpyrenaicus and F. (F.) fornasinii, mainly by the fact that dwarf forms of this species are
in in facies VI in facies XI. although both species have not yet been recorded a more common than In many
lagoonal environment because there are no deposits of cases dwarf forms have been found in the same samples
this milieu in the Tremp Basin from the time when as specimens of normal size. Transitional forms are also
these species existed. Moreover, F. (F.) fornasinii has a known. It can be concluded that the size is ecologically
better tolerance for sand than the other two species of determined. Therefore there is no reason to separate
the lineage. these specimens into two species as Hottinger (1962) has
The species of the F. (F.) decipiens lineage which done: he described the dwarf form as a new species, Alveolina rotundata. F. laxus is occur in the Tremp Basin are most abundant in the Although (F.) very
imperforate foraminifera associations, but F. (F.) scarce in the Tremp Basin, it seems highly likely that it facies decipiens and F. (F.) schwageri also occur in occurred in the same as F. (F.) canavarii and that
considerable numbers in the mixed perforate-imperforate it had the same preference for facies XI. F. (F.)
foraminifera associations. It is not certain whether F. canavarii tolerated sand and mud admixtures in the
limestone well. Once it found in a marl. (F.) varians occurred in facies XI or not. All species of quite was even
The tolerance of F. less. this lineage could endure only small percentages of sand (F.) laxus was probably
or mud in a carbonate environment. It is interesting to
note that F. (F.) schwageri is extremely abundant in GENERAL PALAEOECOLOGICAL TRENDS WITH-
various shallow marine limestones of facies VI, whereas IN THE ALVEOLINID LINEAGES
F. (F.) varians and generally also F. (F.) decipiens are shallow marine limestones of facies contain definitely more rare in this facies. It is striking that F. The VI by
(F.) schwageri does not become abundant until F. (F.) far the largest numbers of alveolinids in the Tremp
subpyrenaicus has disappeared in the higher parts of the Basin, followed by the somewhat deeper-water
XI. F. (F.) corbaricus Zone. This suggests that F. (F.) limestones of facies The Middle Paleocene ancestors
dolioliformis and F. (F.) subpyrenaicus were important of these alveolinids also lived in shallow marine
competitors with respect to the members of the F. (F.) environments where calcium carbonate was deposited.
decipiens lineage, in contrast to F. (F.) fornasinii. Thus most descendants remained faithful to the mode of
The F. (F.) globosus lineage is characterized by its life of their forerunners.
in the Three with different behaviour very low tolerance for detrital particles sediment, groups ecological can
the lowest compared with all other alveolinid lineages. be distinguished in the investigated lineages, as they
F. in the Basin. Of this group (F.) globulus is still the least restrictive appear Tremp
it is in I. alveolinids which abundant in species in this respect: known to occur lagoonal Barely specialized were
limestones of XI. F. facies their entire evolution. This sediments up to and including facies many during group
(F.) triestinus, the youngest member of the lineage in the includes the F. (F.) subpyrenaicus lineage and also the F. Tremp Basin, seems as a rule to have lived in slightly species (M.) lepidulus. It is striking that these
which must have occurred deeper water, although it has not been found in a deeper alveolinids, as large environment than facies XI. populations, show low rates of evolution.
The F. (F.) pasticillatus lineage starts with F. (F.) 2. More specialized alveolinids which did not markedly avellanus which occurs almost exclusively in imperforate change their mode of life during their evolution. The
F. associations. Its descendant F. (F.) pasticillatus on the sequence (F.) ellipsoidalis F. (F.) trempinus, the F.
mixed the F. other hand is a characteristic species of the (F.) cucumiformis lineage, (F.) decipiens lineage,
perforate-imperforate foraminifera associations. This the F. (F.) globosus lineage and the F. (F.) canavarii
and when to this While the F. species is rare in pure imperforate associations lineage belong group. (F.)
it resemble Alveolina is characteristic of the shallow does occur the specimens closely cucumiformis lineage
marine facies VI, conditions for the F. sp. aff. pasticillata shown by Hottinger (1962, I, p. 91, optimum (F.)
fig. 46b). This form is characterized by thicker, canavarii lineage were those of facies XI. Normally the of this have somewhat more irregular coils with chamberlets which lineages group moderately high to high rates
exists of evolution. are larger than normal. F. (F.) leupoldi exclusively
in mixed perforate-imperforate foraminiferaassociations. 3. More specialized alveolinids which markedly changed
It in the their mode of life their evolution. This can even be found rather frequently during group glauconite-bearing limestones of facies XIII. This species consists of the F. (F.) ellipsoidalis F. (F.) oblongus
F. shows tolerance F. boscii and F. as well as (F.) pasticillatus a good sequence, the (M.) lineage the (F.)
mud. On the F. the These three from for whole (F.) parvus occupies same pasticillatus lineage. lineages changed marine palaeoecological niche as F. (F.) leupoldi, although it a shallow to a deeper habitat. The F. (F.)
the least in this seems to be somewhat less sensitive to the depth of the pasticillatus lineage changed respect.
most sea since it can be found in imperforate foraminifera The striking change in depth is found for the F. associations. (M.) boscii lineage, but the difference with respect to the
F. F. (F.) canavarii is a common species in limestones of sequence of (F.) ellipsoidalis F. (F.) oblongus is not the imperforate and the mixed perforate-imperforate great. The position of F. (F.) moussoulensis at the 164
the F. have beginning of two sequences leading to (F.) species (which are usually clearly elongated) should and is lived trempinus F. (F.) oblongus rather peculiar. On the in more clayey or sandy sediments. The above
one hand it occupies the niche of the ecologically discussion on the palaeoecology of the different
F. while other alveolinid stationary (F.) trempinus branch, on the species proves that such a stringent
hand it is also found in an intermediate position in the relationship between shape and mode of life does not
ecologically shifting F. (F.) oblongus branch. exist. It is however indeed likely that the more elongated
is worth that those which forms had It mentioning species an advantage over the spherical forms in
occupied the most aberrant palaeoecological niches of all environments with distinct current action because they
alveolinid species, viz. F. (M.) boscii and F. (F.) could not roll in all directions. In quiet environments all
oblongus, had the largest tolerance for sand. This alveolinid forms are on an equal par.
accidental tolerance cannot be an phenomenon. As both
species lived in deeper, and thus darker, water it is PROBLEMS IN CORRELATION DUE TO FACIES
probable that their food consisted for the greater part of CHANGES
minute living animals and/or dead animals rather than
the more vegetable diet of most foraminifera which The optimum development of alveolinids occurred in
mainly consists of diatoms, filamentous algae and other shallow marine calcium carbonate environments. They
small plant material (Myers, 1943; Lipps & Valentine, are scarce or absent in other shallow marine sediments in marine 1970). Considerable amounts of sand supplied to an and deeper deposits except for some especially
environment largely hinders the settlement of plants. adapted species. Therefore it is difficult or even
It is remarkable that the species which lived in deeper impossible to establish the biozonation of these latter
water had low rates of evolution in comparison with deposits by means of alveolinids. Sediments of the
their ancestors who lived in shallow water. For two southern side of the Tremp Basin are mainly in
reasons it is likely that the populations of F. (M.) bos cii limestone facies. Here the alveolinids occur in sufficient
F. of numbers in and (F.) oblongus were larger than those most most layers to permit reliable biostratigraphic
other alveolinids: in appropriate facies in the Tremp correlations.
Basin they occur in large numbers (there was no With the help of samples containing shallow and
with and alveolinids competition related species) they are common deeper living the deeper facies where F. (M.)
in areas such as the Paris Basin where no other boscii and F. (F.) oblongus are present could be
F. correlated with the shallow alveolinids occur. Therefore it may be assumed that stratigraphically carbonate
(M.) boscii and F. (F.) oblongus were more facies where most alveolinid species lived. Naturally one
of that cosmopolitan species than most other alveolinids. This is the groups must be allochthonous in case, but in with of when it be shown that it is accordance the results the investigations of can only an allochthony of
Boucot (1975a, b: 1977), who studied about 2000 genera space and not of time the available data can be used for
and subgenera of brachiopods. rudistids and correlations without reservation.
scleractinians. He found that cosmopolitan taxa have far On the northern side of the basin however, marls and
Thus larger stratigraphic ranges than endemic taxa. there sandstones predominate, especially in the upper part of is inverse correlation the a highly between the area occupied Ager Formation. In that area therefore we must use by a taxon and its evolutionary rate, which suggests that other fossil groups if accurate correlations are to be population size is the first order correlative of obtained. Another, less safe approach is to look for evolutionary rate. important sedimentary events which affected larger parts
For This author agrees with Boucot that population size is of the basin. example, a sudden sand influx which
if in a very important, not the most important, factor presumably occurred simultaneously in many sections of
the of evolution. size the basin be determining rate Population can used as a stratigraphic marker. The however, does not depend only on the extent of the area stratigraphical position of facies fairly close to those certain the alveolinids occupied by a species as suggested by Boucot, containing can also be determined with but also the number of individuals unit surface the of allochthonous on per help specimens. Here again it is essential and on the number of (sub)facies that this species to be able to show that these fossils are inhabits. alveolinids F. allochthonous with The barely specialized of the (F.) respect to space, not with respect to
which in subpyrenaicus lineage occur many (sub)facies time or to both time and space. are good examples in this respect. Experience indicates that only a few alveolinids have
Finally it has to be remarked that the simple been reworked from older deposits. Reworking does
between the and the relationship the shape of test occur, for instance in highly condensed sequences. The sediment which best in the alveolinids lived cannot be given example is section G; there we find alveolinids from by rule as (1962, different biozones a general implied by Hottinger p. 22). together in one sample. Most sections
He states that the spherical forms are typical of pure represent a practically continuous sedimentation, or limestones, and that the oval and more elongated forms sedimentation alternating with non-deposition without inhabited detritai facies. more If this were true, the clearly defined erosion. Each alveolinid association in
alveolinids (which primitive are spherical) should have these sections contains species which belong to the same lived in sediment, pure carbonate and most evolved biozone. 165
CHAPTER IV
BIOSTRATIGRAPHY AND CHRONOSTRATIGRAPHY
ZONATION ON THE BASIS OF ALVEOLINIDS mixed with autochthonous specimens. This has only
been encountered in a few cases (e.g. in samples 43a and
The vertical range of the alveolinid species, the 43b of section X). Unfortunately the direct ancestor of
taxonomy of which has been dealt with in Gaemers F. ellipsoidalis is not known; for this reason there is no
(1978), allows the establishment of alveolinid biozones in better alternative for the F. cucumiformis and F.
most stratigraphic sections, and provides biostratigraphic ellipsoidalis Zones. sections correlations of these as a base for the Many misunderstandings and incorrect biostratigraphic
the reconstruction of the history of Tremp Basin. correlations have arisen as a result of the establishment
The results of this previous study (Gaemers, 1978) of the F. oblongus Zone by Hottinger (I960) above the
deviate from those obtained by Hottinger (I960, 1962) in F. trempinus Zone and the 'Niveau de Coudures'. It is
and the of the unfortunate because the between many respects, as a consequence position particularly boundary
Ilerdian stage which was defined by Hottinger & Schaub Ilerdian and Cuisian was placed by Hottinger and
(1960) has to be re-examined. Schaub (I960) between the F. trempinus and F. oblongus
Biozonation on the basis of alveolinids. as established Zones. Between these two biozones is the 'Niveau de
contains biozones which Coudures'; by Hottinger (1960), many however this new zone which was introduced
correspond to relatively short intervals of time. During by Hottinger (I960) is not a separate entity since the
that F. F. my previous investigations however, it was found species oblongus and ruetimeyeri, occurring in this
have the relationships between alveolinid species had to be zone, a large stratigraphic range. Furthermore it is
worked out in more detail. Many successive biozones highly unlikely that F. coudurensis is a species in its own
introduced defined discussions of the former by Hottinger (I960) are not by right (see two species and of F.
successive species of one and the same lineage so that canavarii, Gaemers, 1978). Presumably the 'Niveau de
uncertainties are introduced into the biostratigraphic Coudures' is part of the F. trempinus Zone (Gaemers,
divisions. This is seen in particular in the transitions 1974).
F. F. In the Basin F. between the cucumiformis Zone and the Tremp oblongus is very abundant; it
F. ellipsoidalis Zone, the trempinus Zone and the F. has been found in the same stratigraphic horizons as F.
oblongus Zone, the F. oblongus Zone and the F. corbaricus and F. trempinus. From this it is evident that
dainellii Zone, and finally the F. dainelii Zone and the the F. oblongus Zone coincides with the F. corbaricus
F. violae Zone. In these cases difficulties can be and F. trempinus Zones together. It is more accurate to
because is small maintain the F. Zone in F. expected, theoretically the chance very oblongus addition to the
will be and Zones than that that a species boundary in one lineage placed at corbaricus F. trempinus to say the
F. precisely the same level where a species boundary is oblongus Zone does not exist (Gaemers. 1974), for in
in another There is almost either where F. corbaricus and F. placed lineage. always regions trempinus are
absent, for the Paris a certain overlap or a time gap. as instance in Basin, a less detailed
At present in fact it is customary in nearly all age determination is still possible using F. oblongus. F. corbaricus biostratigraphic research to use the most frequently and F. trempinus are of course to be
F. fossils occurring species with a presumably short stratigraphic preferred to oblongus as zone because they
the between the detailed range, without considering relationships permit a more age determination.
guide fossils which characterize successive biozones. In The occurrence of F. oblongus together with F.
F. my opinion the only reliable, watertight approach for corbaricus and trempinus has considerable impact on
is the biostratigraphy the use of evolutionary sequences of the chronostratigraphic concepts of Palaeogene in the
within interconnected Mediterranean and F. marks the species an area. Certainly many area beyond. oblongus problems in stratigraphy can be solved by such an Lower Cuisian; it occurs in the type section of the approach. Cuisian at Cuise-la-Motte, France. There is general
that the The best method is to use many lineages, especially in agreement among stratigraphers Cuisian stage is
to view of the fact that all lineages are finite (see Gaemers, be included in the Eocene, and lies in the lowermost
that the role zonation At 1976) so for purposes of one part of that series. least a part of the F. corbaricus lineage has later to be taken over by another lineage. Zone and/or the F. trempinus Zone of the Ilerdian stage,
Another advantage of using more than one lineage in established by Hottinger & Schaub (I960) in the Tremp biostratigraphy is that there is better control, thus Basin, can now be correlated with the Cuisian of the mistakes are made less easily. Paris Basin and are thus to be considered as Eocene.
As F. far as the cucumiformis and F. ellipsoidalis The presence of other Lower Eocene alveolinids in the serious is Zones are concerned no problems exist. It a F. corbaricus and F. trempinus Zones of the Tremp well-known fact that within the Basin Basin also this Tremp typical supports assumption. These species are of specimens F. cucumiformis do not or only rare- F. ruetimeyeri, F. fornasinii and F. schwageri. Even F.
occur with F. unless boscii in ly together ellipsoidalis, (M.) occurs these zones. This species, which stratigraphically older, reworked alveolinids have been formerly was only known to occur in the Lutetian, 166
Thus differences with to the correlations of evidently has a large stratigraphical range. The respect considerable overlap occurs in Hottinger's system of Kapellos & Schaub (1973, 1975) are: alveolinid zonation. 1. the major portion of the F. corbaricus Zone correlates
M. Fortunately no real problems arise concerning the F. with the tribrachiatus Zone,
Zone. F. F. does correlate with the D. dainellii rugosus, the descendant of 2. the F. trempinus Zone not
which lies above binodosus trempinus, occurs in this biozone just Zone,
Zone. F. F. 3. F. the F. trempinus oblongus is an ancestor of the upper part of the trempinus Zone correlates difference in the of lodoensis Zone, violae. There is a distinct elongation with the lower part the D.
F. much 4. F. D. binodosus Zone index of the two species, violae being longer oblongus ranges from the up to
lodoensis Zone. than F. oblongus. An intermediate form therefore can be and including the lower part of the D.
has expected in the F. dainellii Zone, which however not Unfortunately the Campo section does not offer many
F. these yet been found in the fossil record (see Fig. 2). opportunities to verify ideas, as alveolinids are dainellii belongs to a group of highly flosculinized, almost absent in the stratigraphic interval involved. Only
ovoid alveolinids and member F. the of this spherical to slightly is a of oblongus occurs at some levels, but range a different lineage than F. oblongus and F. trempinus. species is too extensive to allow a precise correlation.
between the F. F. alveolinid zonation for section Nevertheless a zone trempinus (cq. The given the Campo by oblongus) Zone and the F. violae Zone could be justified von Hillebrandt (1965) and Kapellos & Schaub (1973,
the evolution of the the on the basis of the data on lineages 1975) is therefore largely conjectural except of F. trempinus and F. oblongus. lowermost part of the section.
Although I disagree with some of Hottinger's The Tremp section along the road from Tremp to alveolinid zonations, most of his zones are still valid and Puente de Montanana offers better opportunities for the of great value for biostratigraphy. His biozonation based correlation of nannoplankton and alveolinid biozo-
is It which on members of the ellipsoidalis group particularly nations. is important to see species were effective, since evolution proceeds faster in this lineage found by Kapellos & Schaub in their Discoaster
alveolinids. binodosus than in any of the other common groups of Zone. Most species also occur in the
Therefore the most detailed division of the Upper Marthasterites tribrachiatus Zone, namely Zygodiscus
Paleocene and Lower Eocene on the basis of alveolinids adamas, Micrantholithus attenuatus. Braarudosphaera will be established using the successive evolutionary bigelowi, Discoaster binodosus. Neococcolithes dubius,
of this Most of alveolinid radians and Marthasterites tribrachiatus. stages group. Hottinger's zones Sphenolithus in the Upper Paleocene and Lower Eocene are accepted, Only two species, namely Heliolithus kleinpelli and
All biozones from F. Discoaster in the although there were too many. mohleri, do not occur so high ellipsoidalis up to and including F. trempinus are valid succession. According to Perch-Nielsen (in Caro et al., because they are based on species of an evolutionary 1975) the former species does not occur above the lineage. Discoaster multiradiatus Zone and the latter cannot
even be found above the Discoaster nobilis Zone ( =
Heliolithus riedeli Zone). Perhaps the specimens of these
reworked. it be OTHER BIOSTRATIGRAPHIC DATA FROM THE two species were Moreover cannot seen
TREMP BASIN from the publication of Kapellos & Schaub (1973) which
part of the substantial portion of the section identified as
Recent investigations in the fields of nannoplankton, the D. binodosus Zone contained these two species.
The lower of the F. corbaricus Zone still planktonic foraminifera and ostracods have provided part
in to the D. binodosus Zone more data for age determinations. corresponds my opinion
(Tab. 2). Therefore at least part of that portion of the
Nannoplankton Tremp section identified as the D. binodosus Zone by the D. Wilcoxon (1973) and Kapellos & Schaub (1973, 1975) Kapellos & Schaub will indeed correspond to
studied the nannoplankton floras from the Campo and binodosus Zone. On the basis of the data given by remains that Tremp sections. Their nannoplankton zones are based Kapellos & Schaub however it quite likely a
is D. Zone in the on assemblages of species. This customary in considerable part of their binodosus
M. biostratigraphic work with these fossils, because most Tremp section belongs to the tribrachiatus Zone.
have That the lower of the F. corbaricus Zone can be species a large stratigraphic range. part
This be Until correlated with the D. binodosus Zone is proven by the approach may not sufficiently accurate. base it is known exactly when the species appeared and occurrence ofF. corbaricus ca. 550 m above the of
in the section disappeared, uncertainties will continue to exist. As the the F. cucumiformis Zone Campo (von
Hillebrandt, for to & Schaub number of investigated species increases, more precision 1965), according Kapellos will be attained. Wilcoxon for instance distinguished (1973) the D. binodosus Zone extends from ca. 285 m to
Zone. fewer biozones in the Tremp section than Kapellos & ca. 880 m above the base of the F. cucumiformis
Schaub. In the Tremp section a correlation of the F. trempinus
If biozones with the Zone with the D. lodoensis Zone has not been we compare the nannoplankton revised alveolinid zonation, the most probable confirmed. The stratigraphically youngest nannoflora far correlation is that shown in Table 2. discovered so (Kapellos & Schaub, 1973) belongs to 167
the M. tribrachiatus Zone. The top of the F. trempinus indicated by the marine succession in the Tremp section,
Zone therefore in the a which has been earlier (Gaemers, very probably is missing Tremp possibility suggested seetion. This idea is supported by the fact that marine 1974). development within the Tremp Basin becomes much The Cuisian of the Paris Basin comprises only the
towards the of the M. tribrachiatus Zone and the lower thicker and more complete west. F. upper part
D. oblongus has been found in strata which are much part of the lodoensis Zone with certainty (Kapellos &
in the section than the strata in the Schaub, 1973, 1975). This does not imply that the range younger Campo
is that F. of F. vicinity of Tremp. Thus it very probable oblongus covers only this interval. The type
short time trempinus also extends higher stratigraphically than is section of the Cuisian represents only a very
Von this publication Martini, 1970 Berggren, 1969 Premoli Silva Hillebrandt, stratigraphic range
& 1973 1965 of Bolli, some stages
1960 F. violae Discoaster sublodoensis Schaub,
middle Globorotalia
Acarinina Globorotalia caucasica &
F. dainellii densa pentacamerata Globorotalia
palmerae? Acarinina, Discoaster aspensis Hottinger —? >^ lodoensis
Globorotalia Globorotalia Globorotalia
aragonensis aragonensis aragonensis F. trempinus llerdian
Globorotalia
formosa Globorotalia EOCENE Globorotalia formosa formosa Acarinina Marthasterites 1880 oblongus formosa tribrachiatus angulosa lower 1880 Dollfus,
F. corbaricus Fasciolites Globorotalia Dollfus, Cuisian subbotinae?/ Globorotalia Globorotalia
Pseudohastigerina subbotinae lensiformis
wilcoxensis Discoaster
binodosus Sparnacian
?
I
Globorotalia Globorotalia F. moussoulensis Globorotalia subbotinae 1873 1849 Marthasterites velascoensis/ edgari Globorotalia subbotinae marginodentata contortus — F. ellipsoidalis
Globorotalia Globorotalia Globorotalia Renevier, upper Dumont, velascoensis velascoensis velascoensis
; F. cucumiformis Discoaster PALEOCENE multiradiatus Ypresian F. (M) levis Thanetian Globorotalia Globorotalia Globorotalia
Heliotithus pseudomenardji pseudomenardii pseudomenardii middle F. primaevus riedeli "■
alveolinids nannoplankton planktonic foraminifera
taxon-range-zones (partly lineage- concurrent-range-zones
zones)
Table 2. Correlations of biozonations of alveolinids, nannoplankton and planktonic foraminifera, and the stratigraphic range of some important stages. 168
interval (Bignot & Moorkens, 1975), whereas the range All things considered planktonic foraminifera from the
of F. oblongus is definitely much greater. This species Tremp Basin can be of little help for the solution of the is fossil. of therefore a rather poor guide The absence biostratigraphic problems.
the D. binodosus Zone in the Cuisian of the Paris Basin
only means that the Eocene was non-marine there at that Ostracods
time, so that F. oblongus obviously could not have lived Investigations of the ostracod faunas in the Tremp Basin
there at that time. It can be concluded that the have been carried out by Ducasse (1972), Tambareau &
nannoplankton data given by Kapellos & Schaub do not Villane (1974), Tambareau (1975) and Carbonnel (1975).
contradict the revised alveolinid zonation. The Thanetian-Ilerdianboundary seems to be very sharp
because make first the many species their appearance in Planktonic foraminifera Lower Ilerdian (Tambareau, 1975). The relationship have studied Different investigators already planktonic between Ilerdian and Cuisian as indicated by the
foraminifera in the Tremp Basin, viz. Gartner & Hay ostracods is however not yet clear enough because of the
(1962). von Hillebrandt (1965, 1975), Luterbacher (1969) limited number of sections studied.
and Ferrer et al. (1973). An interpretation of these data
Fish remains is a difficult task, because nearly all authors who study
and planktonic foraminifera use a different biozonation, and Shark ray teeth are very scarce in the Tremp Basin.
for has in shark teeth found is because the terminology many species changed Although some were only one
the course of time for taxonomie reasons. In this study preserved well enough for a species identification. This
the zonation of Premoli Silva & Bolli (1973) as described is a large tooth of Lamna obliqua (Agassiz. 1843) found
in Caro et al. (1975) is followed. near Sant Adria in a loose piece of limestone (coll. ROM
Another difficulty is the fact that the planktonic 175 888). This sample undoubtedly belongs to the upper foraminifera in sections of the Basin most Tremp could part of the Ager Formation, as no younger marine
not be isolated from the samples. However, in the centre Tertiary strata occur in the area around Sant Adria. The
and the northern the is part of Tremp Basin where marls most probable age Early Eocene (Ypresian) as the
predominate sufficient specimens could be collected at species occurred predominantly during this interval; in
certain horizons. The southern part of the basin is rare cases it can be found in the Upper Paleocene
mainly developed in limestone facies. In thin sections (Casier, 1946; Arambourg, 1952). planktonic foraminifera are not rare but they could not Sample J-26 (section at Guardia de Tremp) from the F.
be the For identified at species level. this purpose loose moussoulensis Zone has yielded a complete tooth plate
from the specimens are necessary. the middle part of jaw of Myliobatis cf. striatus
The Tremp section again is the section which has been Buckland. 1837 (coll. RGM 175 889), Up to now M.
studied the most. Gartner & Hay (1962) have identified striatus is only known to occur in the Eocene
Globorotalia pseudomenardii, but this finding is (Ypresian). Large ray teeth, including those of M.
contradicted by later investigators. This identification striatus, have not yet been mentioned from the Upper
must be based on a mistake which resulted in an age Paleocene. On the basis of the alveolinids however, a
Von which was too old. Hillebrandt (1965), Luterbacher Late Paleocene age is most likely for the F.
(1969) and Ferrer et al. (1973) mention planktonic moussoulensis biozone; sample J-26 however occurs in
foraminifera, G. subbotinae from its belonging to the Zone, upper part.
a rather limited stratigraphic interval which corresponds
with the lower part of the F. corbaricus Zone. CORRELATIONS WITH OTHER STRATOTYPES
In the Sant Adria and Aren sections the G. subbotinae
Zone could also be demonstrated (Luterbacher, 1969; Several authors have already tried to find the
Ferrer et al., 1973), but a correlation with the alveolinid relationships between the Palaeogene stages defined in
zones is not possible because alveolinids are lacking in western Europe. For this study the investigations of
these The intervals in either section. proven range of the Moorkens (1973), Kapellos & Schaub (1973. 1975), Caro
G. subbotinae Zone must be greater here, perhaps et al. (1975) and Bignot & Moorkens (1975) are the most extending somewhat further back in time than in the important.
Tremp section. Most problems in the determination of the
Von Hillebrandt (1965) has studied the Campo section biostratigraphic relationships between the stratotypes are
where planktonic foraminifera are more abundant. In caused by the differences in palaeontological contents.
spite of this it is still difficult to delineate the biozones The type section of the Ilerdian is rich in nummulites
and precisely. Very probably the boundary between the G. and assilines, but poor in alveolinids planktonic
and G. subbotinae Zones (this is the foraminifera. Calcareous edgari boundary nannoplankton occurs in between the G. subbotinae - G. marginodentata Zone sufficient numbers. Fortunately numerous alveolinids can and the G. lensiformis Zone of von Hillebrandt) is be found in most horizons of the sections south of the
situated close to where the top of the F. moussoulensis Tremp section, where Hottinger (1969, 1962) was able to
Zone can be expected (but again alveolinids are lacking). establish a substantial part of his alveolinid zonation.
This is indicated the fact that Globorotalia In the Sands of section by aequa Cuise-la-Motte, the type of the
this and G. and disappears at point lensiformis appears. Cuisian, alveolinids nummulites abound, but the 169
is restricted. G. Zone and it correlates with number of species of both groups very pseudomenard ii probably
There is a reasonable number of species of calcareous the Thanetian (Bignot & Moorkens, 1975).
but nannoplankton an age determination based on
planktonic foraminifera is difficult. From the occurrence THE PALEOCENE-EOCENE BOUNDARY
of Globorotalia formosa gracilis. G. marginodentata, G.
and G. wilcoxensis - to the definition of (1874) the subbotinae ex. gr. esnaensis, According Schimper
de independently identified by many authors (see Bignot & Paleocene contains the 'Sables Bracheux, Travertin
conclusions be derived. ancien de Sézanne', and et Grès du Soissonnais' Moorkens, 1975), no precise can 'Lignite
The G. subbotinae Zone as well as the G. formosa which represent the Thanetian and the Sparnacian.
Zone has Therefore the has include formosa received consideration. It is not very Paleocene to these stages in
likely that the G. aragonensis Zone is represented any case, and the upper boundary of the Paleocene has
(Bignot & Moorkens, 1975). The stratotype of the to be drawn above the Sparnacian (Hottinger, Lehmann
Cuisian undoubtedly contains nannoplankton of the M. & Schaub, 1964). Obviously difficulties will arise
tribrachiatus Zone (Kapellos & Schaub, 1973, 1975). because the Sparnacian has not been defined by (purely)
When the data of alveolinids, planktonic foraminifera marine deposits, but it is wise to respect the original
and calcareous nannoplankton are considered together, definition of the Paleocene as far as possible in order to
the Cuisian corresponds partly with the uppermost part avoid unnecessary confusion. Therefore the division of
of the Ilerdian (Tab. 2). Blondeau et al. (1965) who place the Sparnacian within
the the Moreover that The stratolype of Ypresian includes the Yper Clay Ypresian has to be rejected. the fact
and the Sands of Mons-en-Pévèle. Nummulites the Sparnacian and the Cuisian of the Paris Basin fall in
planulatus is very frequent in these deposits, but the same sedimentary cycle cannot be used as a valid since alveolinids are absent. With the aid of nannoplankton the argument, transgressions and regressions may not
and M. tribrachiatus Zone could be demonstrated by many occur simultaneously throughout the whole world,
the Paris Basin is authors. In borings taken at Ooigem and Kallo the D. only a small, unimportant basin on a
of world-wide scale. binodosus Zone was demonstrated in the lower part
the Yper Clay: at Kallo the D. lodoensis Zone was found When the Paleocene-Eocene boundary as accepted by
in the uppermost part of the Sands of Mons-en-Pévèle specialists of planktonic foraminifera and calcareous
(Bignot & Moorkens. 1975). The assemblage of nannoplankton is considered, rather close agreement
which is the exists planktonic foraminifera. practically same as among most investigators. Nannoplankton
Cuisian, in draw this between the that present in the type section of the occurs specialists usually boundary M.
the and D. while most of the Sands of Mons-en-Pévèle and upper part contortus Zone the binodosus Zone, many
of foraminifera of the Yper Clay (Bignot & Moorkens, 1975). When all specialists planktonic use the
data are taken into consideration there is no doubt that Pseudohastigerina datum proposed by Berggren (1964, 1971) which is defined the Ypresian and the Ilerdian overlap one another by the first appearance of
considerably (Tab. 2). Pseudohastigerina wilcoxensis (Cushman & Ponton).
The Sparnacian, defined by Dollfus (1880) in the Paris Unfortunately this species has not yet been found in the
but from all available data it Basin, consists mainly of lagoonal-lacustrine fresh-water Tremp Basin, appears likely
and brackish deposits: only the top contains some very that the above-mentioned boundaries of nannoplankton
shallow marine deposits (Plaziat, 1975). A direct and plantonic foraminifera nearly coincide with the
is difficult F. and the F. comparison with other areas therefore very boundary between the moussoulensis
corbaricus Zones and it would be better to develop a new stage with a new (Tab. 2). These boundaries do not
of marine contradict the definition of the Paleocene stratotype consisting of a sequence open by Schimper.
deposits to replace the Sparnacian. Certainly the In consequence the Paleocene-Eocene boundary, as it is
at Sparnacian corresponds with a part of the Early Ilerdian. generally recognized present, distinctly lies in the
The stratigraphic position of the Thanet Beds with Ilerdian (Tab. 2).
Cyprina morrisi, the stratotype of the Thanetian, is still If the Paleocene-Eocene boundary is shifted to the
determine of the base of the llerdian, the Eocene will difficult to because most planktonic enlarged occupy a
and reworked time foraminifera nannoplankton are from span which is no longer in proper proportion to that of the shortened Paleocene; Upper Cretaceous rocks and lower parts of the furthermore little or nothing riedeli will Paleocene. The discovery of Heliolithus by be left in the Upper Paleocene so that the
Thanetian Thanetian. which is BramJette & Sullivan (1961) suggests that the universally regarded as Middle belongs to the biozone of the same name (Bignot & Paleocene, would automatically become Upper
Moorkens. 1975). Paleocene (Curry. 1975).
The Landenian, defined in 1839, and There is however at by Dumont present no good reason for emended by him in 1849, unfortunately contains only few shifting the Paleocene-Eocene boundary. The Ilerdian in
of the of planktonic microfossils. The scarce findings sense Hottinger & Schaub (1960) consists of a
the make to planktonic foraminifera in 'Tuffeau de Lincent' lower part which belongs the Upper Paleocene and an
determination of the which it difficult to come to an explicit upper part belongs to the Lower Eocene. Since a
This stratigraphic position. stage probably belongs to the lower-rank stratigraphic unit (stage) may not belong to 170
two internationally accepted higher units (series), the of an Internationa] Guide to Stratigraphic Classification,
Ilerdian be international cannot accepted as an stage Terminology and Usage (1972) was the predecessor of
The unless the series boundaries are changed. attempt to this publication. In many cases boundary stratotypes the Paleocene-Hocene adapt boundary to the original must be redefined for the existing stratotypes in order to
of concept the Ilerdian stage, which was proposed by fix the boundaries exactly. These boundary stratotypes
Pomerol at the special session 'Le contenu de I'llerdien ought to lie within an interval with continuous marine
et sa dans le on 18 November 1974 in place Paleogene' sedimentation. One of the greatest sources of confusion
Paris (Pomerol, 1975), must be rejected. The concept of namely lies in the fact that geologists have established
the Ilerdian is based on a succession of stage essentially stage boundaries on facies changes. As a result it is
cannot be zones of larger foraminifera, which recognized impossible to tell whether or not marine biozones which
world-wide scale on a (Luterbacher, 1975). Relative age border on non-marine sediments are genuine range zones
determinations in this area based on planktonic or assemblage zones. In other words: do these zones
foraminifera are difficult, and correlations at good with terminate the facies boundary or not. It is much more these fossils are even impossible. It is therefore to be likely that these biozones are more extensive than their
that of the session Paris in the rock regretted many participants at apparent range sequence.
to were tempted choose a Paleocene-Eocene boundary Schaub (1968) compares the relationship between a
at the base or at the of the Ilerdian top (Anonymous, stage and its stratotype with the relationship between a
1975). species and its type specimen (holotype, lectotype, A considerable exists between the gap stratotypes of neotype). He maintains that the holotype and the the and the Cuisian Sparnacian (Tab. 2). Stratigraph- stratotype do not serve to define the species or the stage
ically the base of the Cuisian is situated in its but fix distinctly higher entirety, to them. It is of course impossible than the base of the For Ypresian. these reasons and for one specimen or one section to include all properties
also because of the superposition of the Cuisian on of the species or stage. Every species nevertheless has
essentially non-marine deposists, the Cuisian does not been fixed in time by evolutionary development. It is well-defined series provide a boundary as proposed by necessary to know when the precursors and the Hay (1969). successors appeared so that the exact time interval The base of the Ypresian approximates the Paleo- within which a species existed can be determined. Only
cene-Eocene boundary the best (Bignot & Moorkens. when this has been established can a reliable
1975). Therefore it would be an contribution be important biostratigraphy set up. Similarly it is necessary to
toward an international if know stratigraphic scheme this where stage boundaries are situated, otherwise
base could be established well-defined In by a boundary hopeless confusion among geologists will result. this
The Ypresian of Dumont (1849) is to be the stratotype. sense comparison between a stage and a species can
preferred to the Cuisian of Dollfus (1880) because of be continued. Schaub states that this is not necessary priority, its usefulness (the section of the because, greater type according to him, a stratotype does not serve to
Cuisian comprises only a very small interval), the define the entire time interval of the stage but only to fix that it is free of greater certainty ambiguities and its it in cases of doubt. This idea must be rejected, since for greater suitability wide-spread application. proceeding from this principle means in fact that cases of
doubt will continue to exist because then not all time
CONCLUDING REMARKS intervals will be established officially. According to the
recommendations of the ISSC, boundary stratotypes
For want of clear, international decisions have on stratigraphic to be designated together with the unit stratotypes. boundaries and from It is that stratotypes (apart some good however not necessary they occur in the same exceptions), many ambiguities have permeated the locality. stratigraphic literature resulting in considerable confusion The Ilerdian cannot be considered as an international and many contradictions. If all available stratotypes of stage, in spite of Schaub's designation (1969) of the the localities it type are considered, is seen that large Campo section as parastratotype. because hiatuses or overlaps often exist between stages. A 1. it is highly probable that the F. trempinus Zone continuous stratigraphic classification system covering all continues above the marine deposits of the Tremp
be obtained geological history cannot in this way. section; F. trempinus has not been found in the Campo
Therefore were in many stages subsequently enlarged section, although marine sedimentation continued for a order to reach balanced This has led to much time in a system. many longer the Campo area than farther to the different most concepts about stages, none of which has east. an official status unless an 2. the internationally accepted F. oblongus Zone is not a zone lying above the
has been reached. Ilerdian but is of it. agreement a part
In order to avoid confusion and it is vagueness 3. planktonic foraminifera are too scarce in the entire essential that in the future every stratigrapher follows area, insofar as the possible recommendations of the 4. there is considerable overlap with the Ypresian, International Subcommission Classifica- on Stratigraphic 5. overlap with the Cuisian is highly probable. tion (ISSC), which are given in the International Strat- 6. the Paleocene-Eocene boundary as originally defined igraphic Guide (editor: Hedberg, 1976). The Summary lies within this stage. 171
On of the fact that the is not between It is account Sparnacian a gap the Thanetian and the Ypresian.
suitable alternative, a should be established however suitable new stage not really as a stage as suggested by between Thanetian the and the Ypresian. This stage has Gaemers (1974), because not enough data are available
to be defined on the basis of nannoplankton and on the planktonic foraminifera, and because no marine
foraminifera of known planktonic evolutionary de- deposits occur below the F. cucumiformis Zone in the
velopment. It would of course be useful if benthonic province of Lerida.
foraminifera were also present, but this is nor a Nevertheless the Tremp area will always be an The is find for necessity. difficulty to a suitable area which important area Palaeogene stratigraphy because this
contains a continuous sequence of marine sediments and region has the great advantage that there is a continuous
also meets these requirements. marine sedimentation around the Paleocene-Eocene
The lower part of the Ilerdian occupies most of the boundary.
CHAPTER V
FACIES DESCRIPTIONS AND INTERPRETATIONS
INTRODUCTION communities after species which are characteristic and
common there. Worms, molluscs and echinoderms are
Fifteen fades and 51 subfacies have been distinguished the most important groups for distinguishing the different
fossil communities on lithologic and sedimentary features, and (see also Toulemont. 1972).
content. Field observations were coupled with the study Molluscs and echinoids usually fossilize easily.
of thin sections. whereas only the few worms with calcareous or
In most facies large benthonic foraminifera are arenaceous tubes have parts which fossilize: ophiuroids
The and data numerous. qualitative quantitative on these and other starfishes only occur as fossils in very
to reconstruct the and fossils furnish a good opportunity exceptional cases. For the definition description of
general framework so that the mutual relationships fossil communities, which always contain fewer species between different facies will become clear than the communities, therefore the types to a original living we must
and large extent. Specific fossils which are characteristic of a rely upon those molluscs echinoids. supplemented
of with subfacies usually belong to a larger or smaller group other fossilized groups. which form the
the macroscopic fossils which are often recognizable in the autochthonous part of thanatocoenosis. Consequently
field. The frequency of the larger macrofossils is such fossil communities will of necessity sometimes be named
in thin section after other animal than their that they will not appear a and only rarely groups recent counterparts.
This the in an arbitrarily taken sample. The presence of these could imply that boundaries between fossil
be important fossils therefore usually can only communities will not coincide with those of the
the ascertained in field. The smaller characteristic corresponding original communities, so that the space
macrofossils occur frequently, but not always, in thin occupied by fossil and recent communities is not always
is needed sections; usually a magnifying glass to comparable.
recognize them with certainty in the field. Some facies Communities always grade into each other. The
few fossils, the absence of types contain no or only a or mainly only sharp boundaries makes it difficult for
then and remains of allochthonous organisms; lithological ecologists as well as palaeoecologists to set up a good
form basis of division. especially sedimentary characteristics the Each organism has its own distribution which
an identification. normally does not coincide with that of others nor with
The successful ecological concept of biocoenosis. the chosen community boundaries. For these reasons we
introduced Möbius in be used in have in mind by 1877, cannot to keep that these boundaries are arbitrary. palaeontology. Only a part of the biocoenosis is Boundaries can best be drawn there where marked
for do in faunal and/or preserved in the sediment, many organisms not changes floral composition occur. The
leave fossil remains or are transported to other determinationof boundaries is often even more difficult
in in environments: moreover alien elements can be added by palaeoecology than ecology because the
transportation after death; therefore the term allochthonous elements tend to obscure the differences
thanatocoenosis is used in palaeontology to indicate all between communities.
in the fossils present the sediment at a particular location
(Brouwer. 1967). DIAGENESIS
A biocoenosis is a community of organisms which
other form a dynamic equilibrium with each and with the The state of preservation of fossilized parts depends environment. (1950) and Petersen (1913. 1915), Caspers highly on the kind of material of which the fossil
Thorson (1957, 1958) were the pioneers in the study of consists. Aragonite has usually been greatly affected by communities shelf From the the animal on the bottom. early diagenesis in the Tremp Basin; often it has even
it has to beginning been common practice name dissolved completely. This explains the occurrence of 172
and external and the Here many internal moulds calcite pollen floras of the Ager Formation. elements from
Taxodiaceae, replacement of many coral colonies, as well as of many coastal swamps predominate: Nyssaceae,
molluscs. Consequently the fossils consisting of calcite Sabal and Myricaceae (fresh water coastal swamp
and than are often easier to collect to identify aragonitic dwellers) and Nypa (brackish water mangrove swamp
ones, so that the occurrence of calcific fossils is easily dweller). Pollen grains of coastal swamp plants are much
in overemphasized. more numerous the Ager Formation than those of
Another of is Therefore it is that example early diagenesis seen in the mangrove swamp plants. likely the
much skeletons of nummulitid foraminifera (Assilina, fresh water swamps occupied larger areas than the
and Some the Operculina Nummulites) which have been replaced brackish swamps. of swamp deposits are
to different degrees by chert. Neither other foraminifera certainly of brackish origin: this is the case for example nor other fossils nor the surrounding sediment were when Cerithidae are present. The floral elements indicate
the of small climate. affected. The process starts with formation a tropical
globules of chert which consist of radial fibres. These This subfacies is present in sections H, H'. I, I' and S
globules preferably originate in the thickest parts of the
walls of the shells. By growth and increase in number Subfacies lb. Fluvial deposits. - These deposits consist
and than half the they can merge replace more of original of grey to dark grey quartzose sandstones and
amount of calcite material. Eventually the cavities conglomerates with channels; fossils are scarce; mainly between the walls be filled with In Microcodium may chert. this way a fragments and remains of higher plants are
continuous piece of chert is formed inside the shell, found. Clay galls frequently occur.
whereas the outer of the skeleton remain In parts This subfacies is present in only two places. section unaffected (PI. 3-5). This S 5, Figs. I, replacement always (sample 149) a variety of sedimentary structures was
F. occurs in impure limestones of the corbaricus Zone found. Clearly symmetrical wave ripples indicate a
around the in upper boundary of the glauconite formation, deposition shallow water, whereas rain prints prove
mainly in subfacies XlVa, but also in subfacies XI Ila that the area dried out temporarily. The base of section and Xllb c, and c, and XIa when they are associated H' consists of coarser sediments in which current action
with subfacies XlVa. It is most frequent in sections O dominated (mega cross-bedding and small-scale and L. cross-bedding, parallel lamination).
This early diagenesi* probably followed the pattern These deposits have only been found in the F.
which is as the main for the formation postulated process cucumiformis Zone. They are associated with lagoonal of and deep-sea chert: in situ dissolution of biogenous opal swamp deposits.
with silica reprecipitated inorganically as authigenic disordered alpha-cristobalite (Weaver & Wise, 1974; Facies II. Lagoonal deposits
Keene & Kastner, 1974). This material in turn A of with gradually large variety lagoonal deposits a highly
to form Most content the recrystallizes chalcedony. probably the variable fossil occurs in Tremp Basin. To a
is biogenous opal supplied by diatoms (Weaver & Wise, large extent this is a reflection of different salinities. In
1974), which dissolve than radiolarians the described more rapidly or exposures here they are limited to the F. other siliceous fossils such as sponge spicules. cucumiformis Zone and the F. trempinus Zone.
Subfacies Ila. Deposits containing a Serratocerithium
THE DIFFERENT FACIES AND SUBFACIES - These community. are dark clays and marls containing
TYPES Cerithidae. Sedimentary structures are lacking. The best
of I' exposure this subfacies is section (F. cucumiformis
Facies I. Continental deposits A fauna in Zone). gastropod rich individuals but poor in Sediments this facies belonging to are always very poor species is present. Most numerous are the cerithids of in fossils. Fossils characteristic of environments with the genus Batillaria represented by several species, normal marine This facies is salinity are always lacking. including B. (Vicinocerithium) goniophora (Deshayes), only known to occur in the F. cucumiformis Zone. and Serratocerithium. Furthermore another cerithid,
Tympanotonos, has been found in small numbers
Subfacies la. Coastal deposits. - These deposits with other swamp together some gastropods such as Volutilithes, consist of dark gray marls, mudstones and (some) Pyrazus, Sycostoma and Ampullella semipatula siltstones without stratification and are irregularly (Deshayes).
mottled with rust-brown In some places (section spots. I') Nowadays cerithids dominate in quiet lagoons which calcium carbonate concretions occur. In rare instances are connected with the sea, and in sheltered shallow
some such as of the euryhaline organisms, gastropods bays in the tropics and subtropics where the salinity is
Cerithidae family, can be found. usually higher or lower than in the open sea. For two
The rust-brown are due to differential spots reasons a higher salinity is very probable for the cerithid oxidation-reduction caused oxidation of processes by community in the Tremp Basin. Firstly the subfacies is
Coleman al. plant roots. et (1970) describe recent clays associated with the dolomites and dolomitic limestones with the same characteristics in Malaysian mangrove of subfacies He. Secondly the warm climate gave rise to Haseldonckx (1972a and b, has studied swamps. 1973) considerable evaporation from the lagoons. This 173
of the subfacies thus can be interpreted as a hypersaline conditions that differ in some respects from those
lagoonal environment. Crassostrea community. The Cubitostrea community it is This subfacies has been found in the F. cucumiformis often consists of only a few species. In these cases
Zone of sections H' and I'. likely that the salinity deviated from that of normal sea
water. Apparently Cubitostrea could also live in sea
Subfacies lib. Deposits containing Crassostrea and water of normal salinity, for it has also been found in in species. communities. - less restricted communities which richer Cubitostrea The dark grey clays and are subfacies Ila and lib in marls contain Ostreidae. These deposits are most Transitions between occur
which and cerithids are of characteristic when the oysters are extremely abundant. oysters nearly equal
locations in F. abundance (section N, F. Zone). These This is the case in several the trempinus trempinus
Zone. sediments are often sandy. Subfacies Mb has been found
Zone I' In this zone the species Cubitostrea multicostata in the F. cucumiformis of sections H, H' and of sections N and O (Deshayes, 1832) occurs. The specimens of this species and in the F. trempinus Zone (at
other locations loose closely resemble those from the type locality of the only oysters were collected).
Cuisian (Cuise-la-Motte, Paris Basin). The exterior Although oysters can inhabit an enormous variety of ornamentation of the valves, the outline of the valves facies and subfacies, the association of the and the hinge are similar. The French specimens above-mentioned marls, which contain oysters almost
however have a shallower, larger and more protracted exclusively, with other lagoonal deposits leaves no doubt
Mb. muscle scar, which is situated farther towards the umbo. as to the lagoonal conditions of subfacies
Often the soft sediments of the F. trempinus Zone are covered with weathering layers; then only loose Subfacies Ile. Deposits containing only imperforate
to dark in which - consist of specimens of Cubitostrea shells can be found, foraminifera. These deposits grey contain Miliolidae. case the two valves are frequently still joined together. grey marls and limestones and many
and Orbitolites. Other fossils Serpulid worms are sometimes encrusted on the inner often Alveolinidae rarely found in the F. and outer surfaces of the thick valves. are scarce. This subfacies has only been
sections I, S and Z. Another area where large quantities of oysters can be cucumiformis Zone of H, I', found is immediately to the east of section I'. Here a If only Miliolidae are present there may have been
from marls rich in cerithids to deviation from the normal salinity of the sea. sudden change occurs some open normal if of the other of marls with many large specimens of Crussostrea angusta The salinity was one groups miliolids. This (Deshayes). In the section itself oysters are usually scarce foraminifera occurred together with the
of and small. Unfortunately the degree of exposure of these subfacies represents the seawardmost development
have found in environments in the Basin. Transitions marls is poor, so that the oysters not been lagoonal Tremp
from the marls, subfacies lib. d, f and have been found. situ; the oysters however must come to g because they have been found on the steep slopes of an
ostracods. - In isolated small hill consisting entirely of marls. The outer Subfacies lid. Deposits containing many of limestones and surfaces of the shells were often perforated by clionid these deposits consisting grey (silty)
sedimentation. At least marls, Ostracoda The next most numerous sponges suggesting low rates of predominate.
marls be crowded with is that of the small benthonic foraminifera. Some some layers of these must group
for clusters and stalk of Characeae (fresh water oysters, many of oysters that grew together oogonids fragments washed into these Other have been collected. Nevertheless oyster reefs of either green algae) have been deposits.
fossils This subfacies has been Crassostrea or Cubitostrea have not been encountered. are scarce. only
F. Zone of section Z The study of the ecology of recent oysters has encountered in the cucumiformis Association with dolomites of revealed that "iCrassostrea seems to be the most (sample 365a, 366).
subfacies He that hypersaline conditions euryhaline oyster genus" (Stenzel, 1971, p. N1038) suggests whereas "(Ostrea is polyhaline to euhaline and less existed. euryhaline than Crassostrea (Stenzel, 1971, p. N1039).
in the Subfacies lie. Dolomitic deposits. - These deposits The occurrence of many specimens of Crassostrea consist of dolomites and immediate neighbourhood of the Serratocerithium light grey occasionally sandy or
limestones. The dolomites community suggests that these animals also lived under clayey and dolomitic pure are with uniform sizes hypersaline conditions. Recent specimens of Crassostrea microcrystalline (crystals strikingly between 10-20 um) and mottled by small burrows. At virginicaand C. rhizophorae however do not live in sea ca. 40 level in the F. cucumiformis Zone of section Z, water with a salinity of more than pro mille; they one
where most of this subfacies chert has even prefer distinctly lower salinities (Stenzel, 1971). It deposits occur, Fossils Evidence of is therefore probable that the Serratocerithium and developed. are rare. slumping which the dolomites must have Crassostrea communities flourished under slightly suggests a slope upon subfacies is also in section hypersaline conditions. been deposited. The present
I there is one thin It has been For the Cubitostrea community a reliable estimate of I'; in section layer. only
found in the F. Zone. the salinity is difficult because no recent representatives cucumiformis No In it be The dolomites can be as primary. of Cubitostrea are known. any case may interpreted transmutation have been found and the supposed that the Cubitostrea community lived under phenomena 174
dolomite is always restricted to specific, distinct layers. under fresh water conditions if other fossils are absent.
A is associated with the high pH commonly precipitation If miliolids are present they were formed in lagoons
of magnesian carbonates (Peterson & von der Borch, which were at least brackish.
These authors discovered modern 1965). have inorganic This subfacies occurs in many sections (sections H,
deposition of chert in a lagoonal environment H', I, I', R. S, T and U), but is always limited to the F.
comparable with subfacies He. They found considerable cucumiformis Zone.
fluctuations in the pH, which in the lagoon can easily
exceed 10 during active photosynthesis by Ruppia Facies III. Beach and barrier deposits
Linnaeus while maritimabeneath the surface of the Only a few layers within the Tremp Basin can be
sediment it can be as low as 6.5 due to rotting plant assigned to this facies.
remains. Detrital quartz grains can dissolve in high pH
and solutions low Mollusc-rich - reprecipitate during water levels as a Subfacies Illa. beach deposits. Grey and
result of the reduction in pH and the higher brown quartzose sandstones, conglomeratic sandstones
concentrations of brine. and with conglomerates many molluscs make up this
The energy necessary to transform the quartz into subfacies. They sometimes occur at the base of the F.
is radiation. Zone opal-cristobalite supplied by solar A warm cucumiformis or at the top of the F. trempinus hot climate is inferred. or Like Peterson & von der Zone. The top of section X contains the best example of
Borch this author found detrital grains with this subfacies. Here rich mollusc quartz a assemblage can be caused corrosion. Halos of found in irregular shapes by which pelecypods dominate markedly over
fine-grained silica and carbonate surrounding the grains gastropods; it includes single valves of members of the
are sometimes clear. Undoubtedly the grains and very quartz Veneridae Solenidae families, oysters, mussels and
furnished the material for most of the chert. The chert in Nassarius-like gastropods. The molluscs and also the
subfacies He was formed predominantly in and all shallow around other fossils present are marine elements
fossils (foraminifera and siliceous Sometimes it which to the coast. All sponges). can live close fossils are
which developed as pseudomorphs of gypsum crystals, allochthonous. The majority of the valves of the
with the formation of dolomite, indicate together an pelecypods are oriented with their convex side upward.
evaporine hypersaline environment. The orientation of these fossils as well as the
the composition of mollusc fauna indicates a normal
Subfacies llf Deposits containing many fragments of beach environment.
Microcodium. - These deposits consist of grey Other occurrences of this subfacies are near the bases
sandstones, siltstones and limestones and contain of sections R. S and U.
Microcodium fragments. Other fossils are rare. The
sandstones of and consist mainly poorly sorted often Subfacies Mb. Beach and barrier deposits. - These
angular grains. This well-sorted quartz suggests transportation over deposits consist of grey quartzose sandstones
a short and distance. calcarenites with parallel ( =horizontal) lamination
Microcodium is a fresh water of which the (PI. 3, Some alga, Fig. 3). small current ripples are associated
precise systematic position is still unknown (Bodelle & with the horizontal lamination, which is disturbed by
Campredon. 1968). In the Ager Formation this alga has burrow activity in some places. Low-angle cross-bedding been always transported and fragmented, but in the has also been observed. The fossils (mainly foraminifera)
Formation it be found in situ. It is are underlying Tremp can fragmented or at least rounded. The parallel uncertain whether the fragments of Microcodium in the lamination is clearly visible thanks to the alternation of
Formation from Ager originate partly algae that lived thin layers of coarse, more fossiliferous material, and
the simultaneously in hinterland or whether more they all have finer, inorganic material (mainly quartz grains). been reworked from the Formation. The This subfacies Tremp occurs in the F. cuc umiformis Zone of
occurrence of Upper Cretaceous pebbles in the F. sections S and H. and at the top of the F. corbaricus cucumiformis Zone, suggests that at least some of the Zone of sections A, B and M.
Microcodium fragments have been eroded from the These deposits evidently represent a high-energy Tremp Formation. The lack of marine fossils and the environment. The palaeogeographic and stratigraphic between other subfacies stratigraphic position make it positions with respect to other subfacies indicate a
highly probable that subfacies I If is lagoonal. normal beach environment for deposits in the F. This subfacies is in present sections I', S, T, U and Y cucumiformis Zone, and a barrier environment for those and is known only to occur in the F. cucumiformis Zone. in the F. corbaricus Zone. The latter deposits alternate
Transitions exist to subfacies lig. with mottled muddy sandstones, which are less
well-sorted. The boundaries between them are sharp. A
remains Subfacies Hg. Deposits containing many of land comparison with the shore-face storm deposits described
plants. - These dark marls Kumar deposits are mainly grey and by & Sanders (1976) seems obvious. Only the
some limestones which sometimes basal grey are sandy. gravel which they interpret as lag gravel formed
Remains of land plants are characteristic storm constituents of during maximum intensity is absent in the area these deposits. Sometimes of Characeae but fragments are studied, this may be due to the lack of coarse present. These sediments have been material. may deposited The burrow-mottled sediments were deposited 175
seaward of the wave base during fair weather. The M and O. In the F. trempinus Zone these sediments are
laminated sandstones are presumed to have been closely associated with lagoonal deposits (mainly
deposited under storm conditions. subfacies lib). They can be considered as small marine
ingressions into the lagoons. In the F. cucumiformis
Subfacies lllc. Evaporine beach deposits (Pt. 6, figs. I, Zone subfacies IVa can also be associated with lagoonal
2). - These deposits are represented by a light brown deposits but usually it occurs together with subfacies
biomicritic limestone (packstone) which contains IVb and facies VI. Essentially all deposits of subfacies
and IVa formed under tidal conditions. bird's-eyes pseudomorphs of gypsum crystals (PI. 6, were
Figs. I, 2). This subfacies was encountered only once,
Shallow tidal namely in the F. cucumiformis Zone of section P (sample Subfacies IVb. deposits containing a
P5). The limestone consists mainly of imperforate community somewhat richer in species. - These deposits
and but and foraminifera (miliolids, alveolinids Orbitolites) consist of light grey grey biosparitic (and less
from some other foraminifera occur as well. Apart commonly biomicritic) calcarenites (grainstones and
siltstones foraminifera fossils are scarce. Irregular spots of sparry packstones) as well as quartzose sandstones,
calcite (bird's-eyes) lie together at specific levels. Some and clays with imperforate foraminifera and
the of the spots, especially larger ones, have several megacross-bedding. Usually the bedding is planar. of and small-scale sharp and straight boundaries (PI. 6, Fig. 1). They can be Herringbones large cross-bedding,
recognized as former crystals, which have been replaced which are frequently encountered, are proof of ebb and by smaller calcite crystals. The shapes of the different flood currents. Clay galls are common, especially in the
the F. Zone. sections through such crystals indicate gypsum as trempinus original material. Channels, shallow as well as deeper ones, are also
in this limestone that this often in this subfacies but into The structures prove deposit seen they rarely cut
was formed under supratidal and evaporitic conditions. deposits of other (sub)facies. Vertical burrows usually
and At Bird's-eyes gypsum crystals nowadays are both dominate over horizontal ones. one place a nice
formed in the supratidal zone of the Persian Gulf (Curtis grazing trail has been found (PI. 3. Fig. 5.). Parallel
and et al., 1963; Illing et al., 1965; Lucia, 1972). lamination, fining upwards, low-angle mega-
cross-bedding are observed much less frequently. A
Facies IV. Tidal deposits (IVa-d) and shallow deposits large variety of transported fossils is present, mainly
tool marks foraminifera, with scour and (IVe) pelecypods (mainly oysters), gastropods,
has Except for subfacies IVe the division of this facies echinoids, ostracods and crabs; different groups of
been made chiefly on the basis of associations of large calcareous algae and bryozoans as well as remains of land fishes minor benthonic foraminifera. In most cases this provides a plants, worms and are constituents
satisfactory classification, but sometimes it is somewhat transported from adjacent environments. artificial. This subfacies is the most wide-spread of all tidal
Tidal influences are of course not limited to subfacies deposits. It has been found in the F. cucumiformis Zone
of sections B, C, E, F, F', G, I', IVa-d, but they are clearly visible here due to the type A, H', I, J, K, L, M, of sediment (mostly sandy or silty) and/or the N, O, T and Y. It is present in the F. ellipsoidalis Zone
sedimentary structures that are present. Other of sections B, F, G, N, P and Z, in the F. moussoulensis
(sub)facies where tidal action played an important role Zone of sections G and N, in the F. corbaricus Zone of are facies III, V, VI, IX, X and XI and subfacies Villa sections B, G, L, M and N, and in the F. trempinus and b. Zone of sections A, B, C, E, G, J, K, L, M, N and O.
Transitions to subfacies VIb, d and e occur frequently.
of fossils from Subfacies IVu. Shallow tidal deposits containing a Most the transported probably come these community with few species. - This subfacies is subfacies. Facies VI and subfacies IVa, and to a lesser
subfacies associated with IVb characterized by light to dark grey calcareous quartzose degree lib, are subfacies sandstones, siltstones and in rare instances which is a distinct tidal environment with more
connections with subfacies conglomerates with only a few fossil remains (chiefly the open sea than IVa. oyster fragments and remains of land plants). The layers usually appear as planar beds. The most common Subfacies IVc. Wadden-like tidal deposits. - These
and consist dark sedimentary structures are small-scale cross-bedding deposits of grey to grey quartzose megacross-bedding (both also as herringbones), and sandstones, quartz-bearing calcarenites, siltstones. marls horizontal and vertical burrows. Other structures, i.e. and conglomerates. Characteristic structures are flaser and linsen structures, clay galls, small channels, channels cut into the underlying sediments which often different load coasts and Ophiomorpha burrows are less frequent. have a lithology (pi. 2, Figs. 2, 3, 4). Clay galls
form the of channels. In rare cases transported gastropods, other pelecypods, frequently lag these Other ostracods and echinoid remains can be seen; they are important sedimentary structures are small-scale and nearly always fragmented. megacross-bedding as well as flaser and linsen structures
This subfacies has been found in the F. cucumiformis (PI. 1, Fig. 1). Horizontal lamination is rarely seen. Horizontal and vertical burrows Zone of sections C, E, F, G, H, H', [', J, K, M and O, are numerous; several and in the F. trempinus Zone of sections A, B, G, J, K, bedding planes have been penetrated by many kinds of 176
horizontal burrows of varying diameters. Many of the found in thin sections, mainly from section B. The radial animals which inhabited these burrows fed also on partitions which serve as internal supports are clearly
remains of which often visible. this is the Eoscutum doncieuxi imperforate foraminifera, the are Probably species in Ilerdian concentrated in the burrows. Fragments of land plants (Lambert), which was found the regressive
in the French and described are common; some bedding planes are strewn with them. deposits Pyrenees by
Minute fragments of the fresh water algae Microcodium Crochet et al. (1976). In the Tremp Basin it also occurs
The recent are numerous in many layers. These fossils were in the regressive sequence. Echinocyamus
transported from other, neighbouring environments pusillus lives in fine and medium-grained, well-sorted remains of various together with the less common sands. Off the coast of Brittany it occurs chiefly at foraminifera, fragments of echinoids. pelecypods depths between 20 and 70 m (Toulemont, 1972). When
(notably oysters), ostracods, gastropods, dasycladaceans, the coast is somewhat protected and hence the water
this be found at much etc. Some oysters are probably autochthonous. less turbulent species can also
Burrowing animals clearly thrived in this environment. shallower depths. It is therefore not a good depth
All sedimentary and palaeontological evidence favours indicator.
wadden-like environment for this subfacies, which is Subfacies IVd occurs predominantly in the F.
b. most closely related to subfacies IVa and corbaricus Zone; it occurs in sections A, B, C, D, E, G,
The most typical and extensive development of J, K, L, M, N, O, U and X. In the F. ellipsoidalis Zone it in sections D, in subfacies IVc occurs in the F. cucumiformis Zone of occurs E and X', the F.
in sections and and in the section X. The only other section where it can be found moussoulensis Zone D E, F.
Zone in sections B, N and O. is section W. Here, in the same biozone, coarse trempinus E, J, K,
this XI conglomerates form part of the tidal sequence. They Usually subfacies is associated with facies
with subfacies In instances it is consist of more or less angular, poorly sorted pebbles, (chiefly XIa). rare cobbles and boulders. The largest boulder measured is a associated with facies XIII and XIV (in sections L, N
sandstone boulder 60 and in F. Zone of cm long. Size sorting of the and O). Its presence the cucumiformis
section X 21a, is rather Here grains suggest a very short transport. Therefore these (sample b) peculiar. a conglomerates are probably the demolished remnants of slightly quartz-bearing biosparitic calcarenite with a
fossil rich in which have a cliff in the immediateneighbourhood. assemblage extremely species
been washed together from various shallow and deeper
tidal - Subfacies IVd. Deeper deposits. Light grey to (sub)facies lies intercalated between the shallow water
of subfacies Vic and d and IVc. It be grey calcarenites, quartzose sandstones and siltstones deposits can
are the constituents of this subfacies. The calcarenites interpreted as a small but rather violent marine
this are sometimes white; sandstones and siltstones rich in ingression. The erosive base of this layer supports black rock-derived material are dark grey. The most conclusion (PI. 2, Fig. 1). frequently occurring sedimentary structures are planar The sedimentary structures in particular help to
large and small-scale cross-bedding and trough determine the environment of this subfacies. Especially
megacross-bedding (both megacross-bedding types often the herringbones indicate that it has strongly been
burrows it occur as herringbones). Vertical and horizontal influenced by tidal currents. On the basis of the fossils
that these sediments are numerous. Many beds contain clay galls. Less can be demonstrated were
frequently vertical, and sometimes horizontal, deposited in a somewhat deeper sea than the previously
Ophiomorpha burrows, made by Callianassa lobsters mentioned subfacies of facies IV. The trough-shaped
have been found, chiefly east of the Noguera Pallaresa megacross-bedding was formed by lunate megaripples.
in River; furthermore horizontal lamination, flat shallow The presence of many of these structures proves that
velocities of channels, and channels with rounded profiles, low-angle many places the the sea currents were high
megacross-bedding, small-scale current ripples, flaser (Reineck & Singh, 1973, p. 35). and linsen structures, and load casts are seen
occasionally. The most abundant fossils are oysters, Subfacies IVa" . Deeper tidal deposits with large
many of which are juvenile specimens, other pelecypods, channels. - This subfacies is a special case of subfacies
IVd; it echinoid remains, serpulid worms. gastropods, consists of light to dark grey, more or less ostracods. and remains of crabs and land plants. Usually quartz-bearing calcarenites at the top of the F. corba-
the fossils are fragmented. Occasionally many other ritus Zone and the base of the F. trempinus Zone in
various calcareous section E. Channels which the of fossils are present, for example algae are largest the whole and bryozoans, foraminifera and corals. These fossils are Ager Formation extend many metres down into older
nearly always fragmented and allochthonous. Among the deposits. This is partly due to the relatively low rates of
frequent fossils many molluscs (especially the oysters), sedimentation and subsidence in this area, but it is also
crabs, serpulids and some echinids are probably the result of the special position in the palaeogeographic
autochthonous. Burrowing animals without hard skeletal setting (see Chapter VI). In spite of these large
parts flourished in this environment. structures, these deposits fit well within the tidal
of subfacies A typical inhabitant of this environment is a small complex IVd.
fibulariid sea urchin that resembles the recent species The fossil Echinocyamus pusillus. species has been Subfacies IVe. Shallow deposits with scour and tool 177
marks. - that These deposits eonsist of dark grey, more or therefore these sediments were deposited in a
less silty marls alternating with grey and dark grey marine environment not more than some metres deep.
sandstones and siltstones. The base of the sandstones
and siltstones into the marls. with sand and other always cuts erosively Many Facies V. Deposits waves large
interesting scour marks can be observed together with sedimentary structures
which tool marks and other structures, i.e. parallel lamination Sand waves are giant ripples are about IO m high.
and load casts: occasionally small-scale cross-bedding Sometimes they can reach a height of 20 m. Their and horizontal burrows are also seen. Fossils are absent wavelength is several hundred metres. Two types can be
in Basin: except for some transported remains of land plants, distinguished the Tremp one consists
some foraminiferaand oyster fragments. exclusively of bioclastic material, the other mainly of
Within the wide variety of scour marks present we can non-calcareous detrital grains. distinguish flute marks (PI. 3, Figs. I, 2), longitudinal
marks, flute rill furrows and ridges, pillow-like scour and Subfacies Va. Sand waves consisting of bioclasts
marks (terminology according to Reineck & Singh, 1973). (mainly imperforate foraminifera). - This subfacies is
Slightly meandering flute rill marks can change into characterized by white biocalcirudites to biocalcarenites
normal flute marks. These structures can differ in size: (grainstones) with giant-sized megacross-bedding. Only
small-scale (widths expressed in mm) and larger scale one such giant ripple has been found in the Tremp
(widths in Associated with these expressed cm). scour Basin. It occurs in the F. ellipsoidalis Zone of section X
marks are different types of tool marks. Most numerous immediately N of Serraduy, where it is excellently
which formed 100 are slide marks: long, straight grooves are exposed over a length of about metres along the by the continuous dragging of objects in the direction of eastern side of the Isàbena River (PI. 2, Fig. I). slide marks the current along the sea bottom. Narrow Perpendicular to the river bank is a small valley where it
formed small cut be in cross-section (width sharply into the soft sediment; therefore they are also western side of the Isàbena River valley nor the northern 5 of called groove marks. Wider slide marks (up to cm or side the small valley contains remnants of this large of more) made by larger objects usually have a more sedimentary phenomenon. The greatest height the beds there rounded profile (PI, 3, Fig. 2). In some may giant ripple in the outcrop is 10 m. In the Isàbena River small be much be many prod marks; they can as as 1 cm valley the thickness gradually decreases towards the long and 1 to 2 mm wide. In addition some bounce south. In the small valley the sand wave wedges out marks with widths of up to about I cm have been rapidly towards the east (PI. 2, Fig. 2). A horizontally observed. All scour and tool marks have been preserved layered lag deposit, which increases upwards in fineness as moulds the lower surface of lithified sands and indicated fossils on as by the (samples 41 and 42), forms the silts. base of the sand wave in the Isàbena River valley. In the The measured orientation of the flute marks varies small valley the giant ripple cuts directly into the from 190° to 256°, thus indicating that the direction of the underlying wadden-like deposits. In both places there is individual current was approximately S to WSW. In beds a distinct angular unconformity. however, the directions of the and tool marks The has been built of alveolinids scour giant ripple up mainly do than 30 normally not vary more degrees. In and miliolids. In addition there are often fragments of the difference be than 45°. colonies of Lithothamnium exceptional cases may more the red algae and corals, as Often the slide marks run parallel to the scour marks. well as broken and rounded molluscs. As would be siltstones The alternation of marls and sandstones or expected the fineness of the bioclasts increases upwards: with scour and tool marks allows no other interpretation large alveolinids and large fragments of other fossils than that moved the occasional small turbidity currents occur at the base of the sand wave whereas at top downwards along a palaeoslope which was the site of a only miliolids and small alveolinids can be found. normally quiet sedimentation of marls. Otherwise the From the apparent gradual change in the slope of the marked and sudden changes in current velocities cannot cross-bedding of the giant ripple from S to N along the is clear direct be explained. Unfortunately there no Isàbena River it can be inferred that the direction of the evidence of a turbidite origin of the sandstones and maximum in slope the sand wave turns. This is siltstones. None of these beds is built up of a distinct confirmed by the orientations of the dips. In the turbidite is indistinct, if the sequence; fining upwards pres- southern and central part of exposure the ent at all. Probably this is due to the fact that most beds orientations measured almost were exactly eastwards, in are thin and are composed of small grains. the norhern part (in fact the central portion of the giant These sediments can not have been deposited in deep ripple) the direction measured was southeasterly. Thus water, because they lie intercalated between shallow the crest of the giant ripple was not straight but lunate. marine and sheltered deposits (tidal deposits deposits). The main current direction was from NW to SE. The of numerous Thalassinoides burrows in The of the presence depth sea must have been at least as great of the tidal sediments is additional of some proof a as the height of the ripple: 10 m or more. Vertical and shallow sublittoral environment 1975, 17). The lateral facies in (Frey, p. changes the Ager Formation near oldest turbidite were in fact formed on that deposits directly Serraduy make it improbable the giant ripple was marls with an bed. We have formed 30 lagoonal oyster to accept at a depth of more than m. The entire 178 tabular of sequence of which this structure forms a part is clearly megacross-beddings highly variable transgressive. The lunate ripple is underlain by thicknesses and irregular bases due to scouring and the wadden-like deposits superposed strata indicate processes. The megasets were deposited on a horizontal bottom a gradually deepening sea. This agrees well with the or only slightly sloping sea (see Nio, 1976, figs. sand the North 7a and 7a and development of recent ridges in southern 5a, and b 8; in figs. b only the upper marked C Sea, which is mainly transgressive during the Holocene sequence belongs to this type). (Jelgersma, 1961; Hageman, 1969). An important The second complex (called type b here) is difference however can be found in the orientation of the characterized by its regular features. The thicknesses of that main crest compared with of the current. The crest the preserved parts of the megacross-beddings vary of the of the giant ripple Serraduy was approximately much less. The boundaries between megasets are perpendicular to the currents, whereas the recent sand remarkably straight and not horizontal (in other words: in the North Sea lie or less the ridges more parallel to they do not run parallel to the base and top of the main current. The enormous size of the lunate ripple complex) but slope upwards or downwards with dips of that the velocities It 7a and proves current were very high. can up to 15° (see Nio, 1976, figs. b; only the lower (see only be a high order phenomenon Folk, 1976). sequence marked C belongs to this type). Judging from the photographs no essential differences Vb. Sand and other Subfacies waves large sedimentary can be seen between the formation of the post-sand structures (mainly with perforate foraminifera). - Light wave facies and that of the initial sandwave facies calcareous sandstones and 4a In the grey to grey quartzose figured by Nio (1976, figs. and b). the case of bioclastic calcarenites make this initial facies (grainstones) up sand wave one would expect a general size is Giant subfacies. The grain coarse to medium. increase in the current velocities and consequently an and cross-bedding megacross-bedding are the most increase in the thicknesses of the megasets. In the characteristic structures. Tabular megacross-bedding post-sand wave facies one would expect exactly the predominates markedly over trough megacross-bedding. opposite. burrows Long vertical escape which often run through Sometimes a lateral change from giant ripples (facies entire occur in the an megaset frequently megaripples. B2 of Nio) into Nio's post-sand wave facies C occurs Horizontal burrows The of both are frequent. presence (see Nijman & Nio, 1975, fig. 15a). There are also of burrows that sedimentation types demonstrates rapid transitional zones between types a and b of facies C (see alternated with non-deposition or slow sedimentation. Nijman & Nio, 1975, figs. 15a. b). It is however The burrows are the only sure proof of the existence of remarkable that most sedimentary structures described remains of autochthonous animals. Other organisms are as sand waves persist over long distances (see Nijman & all allochthonous. benthonic for- practically Large Nio, 1975, figs. 14a, b). The gentle slopes on which the aminifera, especially nummulites and discocyclines, megasets of type b of facies C were deposited sometimes Furthermore mollusc and echinoid are numerous. dip in a direction which is opposite to that of the fragments and fragments of cyclostomatous and underlying giant ripple (to the right in fig. 15b, Nijman & cheilostomatous bryozoans (e.g. Biflustra) occur. The Nio, 1975); together with the gentle slopes often of and decrease presence many discocyclines Biflustra specimens continuing for hundreds of metres without a in that this subfacies in proves developed relatively deep the steepness of the slopes, this is a strong argument in than subfacies Va. water, any case distinctly deeper against a post-sand wave filling of the lower parts Megacross-bedding sometimes changes vertically and between the crests of sand waves. laterally into small-scale cross-bedding (see Nio, 1976, There is another reason for not believing that Nijman this of alternation show & Nio's fig. 4a). Beds containing type post-sand wave facies originated as a deposit structures and convolute of said many clay galls. Loading on a slope the giant ripples, slope leading to a bedding point to rapid burial of unconsolidated rocks marked reduction in the current velocities after the with loose packing. The thickest sand wave sequence formation of the giant sets. Sedimentation of the upward lies on a convolute bedding at least 1.50 m thick (see and downward sloping megacross-beddings certainly Nio, 1976, fig. 4b). occurred under high-energy conditions, otherwise the This subfacies has been found in the F. of the sets to be only heights up 1.50 m cannot explained. Nio corbaricus Zone of section X, Zone and the F. trempinus (1976) on the other hand assumes distinctly lower current La in the immediate vicinity of the village Puebla de velocities for these deposits. His main argument is his Nio Roda. A more detailed description is presented by observation that the current directions are highly sand (1976) who distinguished an initial wave facies, a variable. The spread of the measurements of the sand which wave facies and a post-sand wave facies, cross-beddings was not less than 150° (the extremes all been have included in our subfacies Vb. being 180° (S) and 330° (NNW). Some critical remarks however in order are concerning These data can perhaps be explained by using a quite Nio's threefold division. From the photographs in his different sedimentary model. If the directions of the it is clear that the so-called publication post-sand wave megacross-beddings were randomly oriented within the facies (marked consists of two different C) sedimentary sediment body, as would be expected had relatively which must have in different complexes, originated two low-energy conditions prevailed, no distinct regular ways. The first (called type a here) consists mainly of structure could have been formed. Since the structure of 179 the type b complex is regular and simple, the only numerous in this subfacies. Imperforate and rotaliid possible solution is that all current directions played a foraminifera and fragments of echinoids, including their in also specific role a large-scale sedimentary process. This is spines, are common. The presence of large numbers of these fossils in this subfacies in the case for instance when sand ridges are formed in an and their scarcity environment governed by tidally induced currents. Sand neighbouring areas suggest that they are autochthonous. ridges lie with their crests roughly parallel to the Remains of land plants, and fragments of crabs, and and Other maximum current can grow by lateral and vertical pelecypods some gastropods often occur. accretion. On one side the sediment is transported up the fossils are scarce. slope by one tidal current and on the other side it is Transitions to subfacies VId and e and the tidal transported down the slope by the opposite tidal current. deposits of subfacies IVb frequently occur. In most limestones, the influence inferred In such a sedimentary regime differences of 150° of currents can be between the current directions can easily occur. from the texture of the limestones and the rounding of of many the fossils. Micritisation caused by algal boring Facies VI. Shallow murine deposits containing through the outer coils of alveolinids and other imperforate foraminiferal associations (carbonate foraminifera is often seen, suggesting low rates of platform) deposition and interrupted sedimentation. This facies is wide-spread in the basin, occurring in all This subfacies represents a shallow marine, mainly sections. Six subfacies can be distinguished by their rather high-energy environment less restricted than different fossil content. Transitions between these subfacies Via. It is most widely distributed in the F. subfacies frequently occur, especially between subfacies cucumiformis Zone and F. ellipsoidalis Zone. Vic. d and e. The facies occurs predominantly in the F. F. Vic. cucumiformis Zone and is well represented in the Subfacies Deposits containing a Pseudomiltha Zone and the F. Zone. - These of ellipsoidalis trempinus community. deposits consist grey to dark grey, sometimes light grey, biomicritic limestones Subfacies Vla. Deposits containing almost exclusively (packstones), argillaceous limestones and marls, and are foraminifera. - These deposits consist of light grey to usually nodular or irregularly bedded. Sometimes a small biomicritic limestones grey (packstones), which are amount of sand has been mixed into the sediment. Large sometimes sandy or silty, and grey to dark grey marls. shells of Pseudomiltha corbarica (Leymerie) (PI. 4. Fig. Horizontal burrows frequently occur, and vertical 7) in position of life, i.e. burrowed vertically into the The fauna consists almost burrows are not rare. sediment, are the characteristic fossils of these deposits of alveolinids, miliolids and Orbitolites. The (for detailed exclusively a description see Plaziat, 1972, p. 33). Most remaining faunal elements are mainly other foraminifera numerous are the imperforate foraminifera. In addition to and fragments of oysters and echinoids, and in rare rotaliid and valvulinid foraminifera there are echinoid instances fragments of gastropods, bryozoans and other fragments, oysters, other pelecypods, gastropods, pelecypods. Allochthonous fragments of land plants are ostracods. and remains of land plants. In the typical common in the marls. Fragments of calcareous algae are deposits of this subfacies however, P. corbarica In scarce. predominates markedly over the other molluscs. many On the northern side of the basin the deposits are cases dasycladaceans (green algae) occur together with associated with quiet deposits of other subfacies of facies this species, so that many gradual transitions to VI. to On the southern side of the basin they seem have subfacies Vie can be found. Horizontal and vertical been under conditions. Here deposited higher energy burrows are common. Inorganic sedimentary structures they are usually associated with the tidal deposits of are rare. Geopetal structures are perhaps most frequent. Vic subfacies IVb. Sometimes they gradually pass into the Sometimes subfacies passes into the tidal deposits deposits of the latter subfacies. of subfacies IVb. In that case P. corbarica lived on Subfacies Via can be interpreted as a shallow marine mud-free bottoms consisting of bioclasts. Some restricted environment. It has been found almost small-scale cross-bedding and flaser and linsen structures exclusively in the F. cucumiformis Zone. may then also occur. The typical deposits however, never show evidence of currents and have been VIb. and this Subfacies Deposits containing many oysters deposited in a quiet environment. Thus subfacies echinoids. - These deposits consist of light grey to grey represents a protected shallow marine environment, biomicritic, sometimes biosparitic, limestones with a although it is not lagoonal as suggested by Ferrer et al. variable quartz sand content. The limestones are mainly (1973), for fauna and flora indicate normal salinities. packstones as well as some grainstones and It occurs in the F. cucumiformis Zone and the F. wackestones. The limestones F. Occasionally they are silty. ellipsoidalis Zone of many sections. In the Zone it is are often nodular. Some grey marls can also be included moussoulensis rare. in this subfacies. Horizontal and vertical burrows are Small-scale be VJd. common. cross-bedding or clay galls may Subfacies Deposits containing a rich mollusc encountered in rare cases. assemblage (PI. 5, Fig. 2). - These deposits consist of the characteristic fossils. Sometimes biomicritic Oysters are light grey to grey limestones (packstones) and clusters can be found, especially in the marls; they are grey to dark grey marls; sometimes they contain small 180 remains as those found in subfacies VId. but quantities of sand, silt or clay. These deposits are same can of be from the latter the of the characterized by a rich mollusc assemblage distinguished by presence pelecypods and gastropods. All fossils occurring in the gastropod Velates schmiedeli and/or the cheilostome Pseudomiltha corbarica former subfacies, except P. corbarica, can be found in bryozoan Beisselina. Sometimes also subfacies VId. On the whole the fauna and flora of this occurs. Vlf is localized almost the subfacies are indeed more varied: serpulid worms, Subfacies exclusively on in Basin. Its widest Acicularia (a green alga) and some corals also occur southern side of the Tremp distribution is in the F. Zone. this subfacies. There are often dasycladaceans and the geographical ellipsoidalis transitions exist codiacean alga Halimeda, so that to Vie, d and e combined. - A fossil subfacies Vie. Usually there is no evidence of currents, Subfacies community but occasionally biosparitic limestones (grainstones) extraordinarily rich in species occurs in the F. trempinus the composed of allochthonous fossils suggest current Zone of sections A, B, C, K, N and O. In slightly activity. sandy, grey to dark grey nodular limestones (packstones) marine the molluscs in are This subfacies can be interpreted as a shallow particular represented by many of families. of the environment more open marine than the previously species many Species following in families common: Cardiidae, Carditidae, described subfacies but still rather protected. It occurs pelecypod are the F. cucumiformis Zone of nearly all sections. It is Mytilidae, Lucinidae (among others Pseudomiltha) and two common in the F. ellipsoidalis Zone and much rarer in Ostreidae. The valves are almost always still joined of the families of Cerithidae the higher zones. together. Species gastropod and Volutidae frequently occur, as well as Globularia aff. sigaretina, Ancilla, and Rimella. the Subfacies Vie. Deposits containing many green algae Seraphs Among to megafossils large sea urchins (PI. 6. Fig. 3). - These deposits consist of grey dark there are many furthermore smaller echinoids, crabs, grey biomicritic limestones (packstones) and . larls which (Conoclypus): contain and brain corals not In thin are sometimes sandy or silty. They many serpulid worms are rare. sections multitude of of different remains of green algae, viz. dasycladaceans (including a fragments Neomeris and Belzungia), and the codiacean Halimeda, dasycladaceans can be observed together with many extensive submarine meadows, foraminifera, ostracods and bryozoans. which may have formed brown and flora, together with and other green algae of which no These limestones with a rich fauna and individuals, traces remain. Belzungia is known from the Danian of representing numerous species were which the French Pyrenees and the lower Lutetian of Libya deposited in a shallow marine environment was flow and Kgypt (Pfender & Massieux, 1966; Massieux, 1966). protected against strong tidal currents although the In the F. trempinus Zone the internodes of the of sea water was suffient to provide enough food and A is the most udoteacean green alga Ovulites are common (PI. 6, Fig. oxygen. sheltered bay therefore probable environment for these 3). Sometimes they are extremely abundant and deposits. dominate over all other fossils. These algae are also known to occur in the Sparnacian of the French Facies VII. Buck-reef deposits Pyrenees (Deloffre, 1970) and the Ypresian of the As a rule sediments are assigned to this facies when the is northern part of the Corbières region (Massieux, 1965). relationship with reefs in the immediate neighbourhood evident from field observations and when there is Ovulites is closely related to the recent genus Penicillus. no A striking fossil which often accompanies Ovulites in the evidence of strong currents. The connection with reefs Basin is small calcareous the in the field is if reef debris Tremp a sponge resembling seen especially important no for in that there no field genus Barroisia. occurs, case are specific or of known microfacies characteristics of this subfacies. Recent species Neomeris are only to occur foraminifera association consists of in the littoral zone and the uppermost part of the The mainly restricted elements (alveolinids, miliolids and infralittoral zone (0-10 m depth) and are to imperforate do fall below 20 °C Orbitolites) but some nummulites also be seas where the isocrymes not may present. (Konishi & Epis, 1962). At present Penicillus also lives We have to remember that deposits assigned to other back-reef in warm, shallow marine environments and the same is facies may also have been formed in a for subfacies Vic, e and f. and true of Ovuli tes. environment, example subfacies Xlb and d. direct between these This subfacies usually occurs in combination with A relationship subfacies and the reefs has however not been discovered subfacies Vic or d and it has therefore roughly the same geographical, stratigraphical and ecological distribution. during the field work. Subfacies VIf Deposits containing Velates and/or Subfacies Vila. Back-reef deposits without reef debris. - Beis sometimes white, selina. Light to dark grey biomicritic limestones These are light grey to grey, dirty biomicritic limestones with (packstones), which are sometimes sandy, silty or (packstones). occasionally Foraminifera abundant fossils. clayey, and grey to dark grey marls make up this intraclasts. are the most well subfacies. It represents the transition between the five Skeletal parts of echinoids as as gastropods, foregoing subfacies and facies XI, and is characterized pelecypods, ostracods and fragments of the fragile red by a fossil assemblage rich in species. It includes the alga Lithoporella are encountered frequently. Less 181 Acicularia remains existence of such reefs. be discovered common are dasycladaceans, and of the They can only crabs, serpulids and various bryozoans. The spaces by field observations. Unfortunately these reefs are not in contrast to the massive between the fossils are mainly filled with lime mud, and easily visible in outcrops there is not much fragmentation of the fossils; obviously Lithothamnium reefs. Their most characteristic aspect is the sediments were deposited in a low-energy that their bedding is irregular or nodular (PI. 1, Figs. 3, environment. 4, 6). The large and small knobs represent coral Association with reefs (facies VIII), off-reef shoal colonies. Their bedding planes, if discemable at all, are with (PI. The different of limestones (subfacies IXa), or back-reef deposits usually undulating 1, Figs. 3). types reef debris (subfacies Vllb), suggest a back-reef coral reefs and coral-algal reefs are characterized by environment: otherwise these deposits would have been different species of corals which unfortunately could not incorporated in facies VI or XI. They occur in the F. be identified because a coral specialist could not be moussoulensis Zone of sections C and P, and in the F. found. corbaricus Zone of sections C, G and Q. Recent coral reefs as a rule lack a massive framework of coral colonies. Apart from the large structures - reefs stricto such channels Subfacies Vllb. Back-reef deposits with reef debris. between the sensu as and This subfacies consists of light grey to grey biomicritic lagoons, there are cavities and interspaces between the colonies smaller which filled with limestones (packstones and some wackestones) usually on a much scale, are without sand grains or intraclasts. Some burrows occur. lime mud and sand containing small skeletons The same fossils as in subfacies Vila can be found (foraminifera, molluscs, etc.) (Maxwell, 1968). If we although fauna and flora are more varied. Fragments of could observe such recent reefs in cross-section they colonies of corals and/or the red alga Lithothamnium are would resemble the fossil coral reefs of the area studied. often abundant suggesting the close proximity of reefs. The difficulty involved in recognizing fossil reefs is the the The components of this material reflect the composition evident from literature. Only a few of reefs on of the reefs. Most fossils however are not fragmented, the northern side of the Tremp Basin have been environment. identified Garrido & Rios (1972). In the which indicates a low-energy by publications Transitions to subfacies IXa and XIa occur. The of Ferrer et al. (1971) and Ferrer et al. (1973), which back-reef deposits often change laterally into reefs and focus on the marine Palaeogene deposits of the Tremp off-reef shoal limestones. In the F. corbaricus Zone Basin, reefs are not mentionedat all. side of subfacies VIlb occurs along the entire southern the Tremp Basin. Moreover this subfacies is present in Subfacies Villa. Patch reefs on shallow platforms. - F. Zone This subfacies the moussoulensis of sections C, G and P. includes light grey to grey boundstones Along the northern side of the basin it has only been and biomicritic limestones (packstones) and is found in the F. corbaricus Zone of section X'. The reef characterized by a fauna and flora rich in species and debris in F. individuals. colonies the trempinus Zone of section O is the only Coral are abundant whereby indication of reef growth during that interval. hemispherical and platy forms predominate. They are Small reefs often patch on a shallow platform of alveolinid encrusted by Lithothamnium. Various groups of not to limestones, do give rise well-developed fore-reefand foraminifera, including Reophax and sessile types, occur back-reef other deposits which can be distinguished from together with the three imperforate groups. Remains of platform sediments. This is the case in theF. cucumiformis oysters, other pelecypods, including boring species Zoneof sections J, K and L, and in theF. ellipsoidalis Zone gastropods, ostracods, echinoids, crabs, worms and of sections indicate animal L, N, O and P. some bryozoans a rich community. In addition to the red algae (Lithothamnium and VIII. the Facies Reefs Lithoporella) green algae are also well-represented Many geologists only consider a limestone body a reef by Dasycladaceae, Halimeda and Acicularia. when it is composed entirely of boundstones. In this These reefs are always associated with limestones concept animal and/or algal colonies grow on top of one which contain pure associations of imperforate small, both in and another continuously without leaving much space for foraminifera. They are always extent detritai lime sediment. The only reefs in the Tremp in thickness. The absence of undeniable fore-reef Basin that answer this requirement are the algal ridges deposits with distinct palaeoslopes is characteristic. The of reefs that (subfacies VIlib) which were formed by the coralline red limited size and the position these prove Lithothamnium. interstitial between the reefs, which often have the alga The space they are patch developed on colonies is minimal. reef flat behind the algal ridge or which were otherwise In the various fossil coral reefs or coral-algal reefs a protected against strong wave and current actions. lot of interspace can exist between the colonies so that They have been found in the F. cucumiformis Zone of no horizontally and vertically continuous boundstone sections J and L, in the F. ellipsoidalis Zone of section is formed. The interspaces contain packstones, N, in the F. moussoulensis Zone of section P, and in the wackestones or grainstones, and if a sample is taken F. corbaricus Zone of section Q. only from this part of the reef, it is impossible to make the correct environmental interpretation. Nor can one Subfacies VlUb. Lithothamnium ridges. - These ridges small consist of boundstones and contain thin section through a coral or algal colony prove light grey tightly 182 clustered Lithothamnium colonies which have a roughly Examples of subfacies Ville have been found in the F. spherical shape and are usually 0.5-2 cm across (PI. 4, corbaricus Zone of sections A, B, M and P. Fig. 4). The scarce interstitial spaces are filled with lime mud (sometimes marl) in which small allochthonous Subfaeies Mild. Coral reefs {PI, I. Figs. 3. 4). - The fossil occur. to the reefs consist of and fragments They belong following light grey to dark grey boundstones groups: foraminifera. gastropods, pelecypods, Corallina, biomicritic limestones (packstones and wackestones) Lithoporella, ostracods, echinoids, crabs, bryozoans and with a fauna and flora rich in species and individuals. corals. The red alga Lithothamnium forms the bulk of The accompanying foraminifera association of these the volume of reefs: which lived in reefs some worms and their surrounding rocks is usually a mixed calcareous tubes (Haliotus-like worms and others) as imperforate-perforate one (alveolinids, miliolids and sessile foraminifera lived Orbitolites well as on and in the algal with some nummulites and an occasional colonies. Sometimes autochthonous corals also occur. transported discocycline). Hemispherical coral colonies Other autochthonous organisms are lacking: thus this (among others brain corals) predominate over the subfacies is in poor species. branching types. The largest colony observed had a distinct with In In some places a slope dips of up to 30° diameter of 70 cm (sample C37). one case (section X') observed can be on the seaward side of the algal reefs platy corals occur which are embedded in a marl. Sessile (PI. 5). At one (about 50 m east of foraminifera abundant. I, Fig. locality sample are Boring pelecypods can locality A29 of section A) it could be demonstrated that frequently be found in the coral colonies (PI. 3. Fig. 4). fossil after its formation and animals a algal ridge emerged Many lived between the corals: large oysters and remained so for some time. Its top is covered by a thin other pelecypods (the valves are still often joined reddish weathering layer which is clear evidence of this together), gastropods (sometimes Velates), solitary event that must have been caused a tectonic echinoids, ostracods. different of by slight corals, groups uplift. This residual sediment contains small crystals of bryozoans, serpulid and Haliotus-like worms, crabs and which environment. gypsum, indicate an evaporitic fish remains. Red algae, i.e. encrustations of Several small fissures in the algal ridge were formed by Lithothamnium and Lithoporella, and the internodes of subaerial solution (karst). Corallina as well as green algae (dasycladaceans and The recent counterparts of the Lithothamnium reefs Halimeda) also occur. are the algal ridges (Lithothamnium ridges) which form These reefs flourished where wave action was not the most exposed parts of modern reef complexes (see very strong, thus usually in water at least several metres These for instance Maxwell, 1968; Adey & Burke, 1976). deep. Their distribution is the greatest in the F. algal ridges develop best where the breakers have their corbaricus Zone where they have been found in sections This is the greatest strength. generally case on the A, B, C, K, N and X'. In addition they occur in the F. windward side of islands. These algae (and also certain cucumiformis Zone of section H' and in the F. vermetid gastropods) form the only organic framework moussoulensis Zone of section X'. capable of resisting the strongest oceanic breakers because of their compact construction. The algal ridges Subfaeies Ville. Coral reefs of deeper water. - These formed than several below are no more metres the reefs consist of dark grey boundstones and biomicritic level. ebb tide lie limestones In high-tide During large portions can (packstones); they may contain glauconite. above the water-level. the reef flat addition They protect against to many hemispherical coral colonies, branching action. strong wave types are also relatively abundant. Encrustations by Lithothamnium have been found in the F. Lithothamnium ridges and borings by pelecypods are common. of sections L in F. ellipsoidalis Zone and W, and the Foraminifera, ostracods, oysters, pectinids, Spondylus corbaricus Zone of sections A, P, Q and X'. and other pelecypods, Velates and other gastropods. Porocidaris and other echinoids, solitary corals, crabs Ville. - In and Subfacies Coral-algal reefs. these grey to some bryozoans lived between the coral colonies. dark biomicritic than grey boundstones and limestones Sponges seem to be more common in the shallower (packstones and wackestones), coral and algal colonies reefs. The foraminifera association of the reef and both appear in about equal proportions. A well-exposed the lateral and vertical adjacent sediments contain more example has been found about 50 m east of sample perforate than imperforate elements. Nummulites, locality A29a (section A; see PI. 1, Fig. 6). These reefs Operculina, Assilina and Discocyclina occur. The transition between represent the the algal ridges presence of these foraminifera together with F. (M.) (subfacies Vlllb) and the coral reefs of subfacies VHId. boscii suggests a depth of at least 40-70 metres. Many Their therefore is colonies presence indicative of intermediate fragile branching coral prove that quiet depths and wave strength. The faunal and floral conditions prevailed. composition of these reefs is also intermediate, and for The only places where this reef type has been this one is referred to the descriptions of subfacies Vlllb identified with certainty is in the F. corbaricus Zone of and d. In this connection it should be mentionedthat the sections J and L. Transitions to the shallower reefs of coral is almost exclusively hemispherical and that subfacies VIHd have all been incorporated in the latter subfacies; encrusting bryozoans are relatively common. they are characterized by the occurrence of some glauconite and discocyclines. 183 Facies IX. of white sometimes Calcarenitic deposits, strongly influenced by deposits consist to light grey, grey, tidal currents, in between and around reefs biomieritic limestones (packstones) and biosparitic The of the deposits two subfacies distinguished are very limestones (grainstones). The only sedimentary similar. The off-reef shoal limestones are more often structures observed are channels and vertical burrows. sparine and have a greater variety of sedimentary The same groups of fossils occur as in the off-reef shoal structures than the reef channels. Differences between limestones. The fragments of the coral and the fossil contents of the two subfacies are usually only Lithothamnium colonies in particular are larger in the in off-reef shoals. quantitative: as a rule Corallina and Lithoporella (PI. 7, channels than the An important reason for the Fig. 2) are more frequent in the off-reef limestones, this is certainly that reef debris in the channels whereas massive and branching corals, Lithothamnium, travelled a shorter distance with respect to the source. dasycladaceans. Halimeda and Acicularia, sessile Imperforate or mixed imperforate-perforate foraminifera foraminifera and encrusting calcareous tubes of worms associations can occur, depending upon the depth at in the reef (Haliotus and others) are more frequent which the reef channels lie. channels. Moreover fragmentation of the fossils is more Reef channels are found most frequently in the F. pronounced in the off-reef limestones which indicates a corbaricus Zone, in sections C, K, M, N, P, Q and X'. for the in the latter Furthermore in the F. Zone of longer average transport particles they occur ellipsoidalis In W F. moussoulensis subfacies. many cases an unambiguous identification section and in the Zone of sections of these subfacies is possible with the help of the vertical B and P. and lateral facies changes. Facies X. Reef-breccia limestones (fore-reef deposits Subfacies lXa. Off-reef shoal limestones {PI. 7, Fig. 2). - scusa stricto) This subfacies consists of white to light grey, sometimes These deposits for the most part are composed of coral limestones and biomicritic colonies and/or colonies of red The remainder grey, biosparitic (grainstones) algae. limestones (packstones). which occasionally contain consists of other floral and faunal elements derived from sand intraclasts. The communities. If of of the some and in rare instances some the reef the degree exposure most frequent sedimentary structures are shallow and rocks is sufficient these limestones can be recognized in somewhat deeper channels and vertical burrows. the field by the distinct palaeoslopes which dip towards Furthermore horizontal burrows, small-scale and the centre of the basin (PI. I, Fig. 5). Sometimes megacross-bedding (both sometimes as herringbones) and channels have developed. These limestones are highly fining upwards of the fossil debris can be seen. Often resistant and therefore they often form perpendicular micritisation of the exterior of fossils (mainly walls which are not accessible without special equipment foraminifera) caused by boring algae is found, indicating and experience. The same indeed applies to many reef In low sedimentation rates. Most fossils are fragmented. exposures. addition to the above-mentioned fossils the following As there is a gradual transition from shallow to deeper groups are also frequently encountered: foraminifera. reefs, only an arbitrary subdivision of the fore-reef ostracods. echinoids. oysters, other pelecypods, Velates, deposits can be made. The foraminifera association and other of cheilostomatous the between sediments gastropods, many types stratigraphic position adjacent bryozoans, crabs, solitary corals, serpulid worms, fish furnish the most conclusive indications. Distinct fore-reef remains (rarely), the red alga Distichoplax biserialis and deposits are absent when there are patch reefs on the remains of land plants. shallow platform (reef flat). the which these Depending upon depth at deposits were formed the foraminifera association will be entirely Subfacies Xa. Shallow fore-reef deposits (PI. 7, Fig. I). imperforate or mixed imperforate-perforate. Usually the - These deposits consist of white to light grey, imperforate elements predominate. Nummulites is often sometimes grey, biomicritic limestones (packstones). abundant. Operculina, Assilina and Discocyclina are Biosparitic limestones (grainstones) are much less Glauconite is usually much more rare. common. usually absent. Depending upon Foraminifera and encrusting and articulate coralline the reefs from which the debris has derived, fragments of Lithothamnium algae form the bulk of the volume of these limestones. colonies or coral colonies or both are This with the observations of Forman & foraminifera agrees present. Imperforate always predominate 619 Schlanger (1957. p. and pi. 4) on the Tertiary markedly over the perforate elements; often they are the limestones of Louisiana and Guam, which also have only large benthonic foraminifera present. The frequently fossil been interpreted as off-reef shoal limestones. observed micritisation of the fragments caused by indicates in the Off-reef shoals are most frequent in the F. corbaricus boring algae interruptions enlargement or M and Zone, i.e. in sections A, B, C, D, E, G, J, K, L, shifting of the fore-reefarea. All fossil groups mentioned N. They are furthermore found in the F. cucumiformis under subfacies Vlllb, c and d can be expected. Zone of sections E, K and V, in the F. ellipsoidalis Zone These fore-reef deposits often change laterally into of section X and in the F. moussoulensis Zone of off-reef shoal limestones. Subfacies Xa has been found in sections G. K. P and W. the F. cucumiformis Zone of sections H' and V, in the F. ellipsoidalis Zone of section W, in the F. Subfacies IXb. Reef channel limestones. - These moussoulensis Zone of section X', in the F. corbaricus 184 of sections B, M. N, and X', in F. Zone A, K, P and the scarce. In some places megacross-bedding (sometimes as trempinus Zone of section J. herringbones) and channels are clear indications of strong currents in this subfacies. Such deposits are Subfacies Xb. Deeper fore-reef deposits. - These transitions to the tidal environment (subfacies IVb and Where these deposits consist of light grey to grey biomicritic d). structures are missing the presence of limestones (packstones) in which glauconite often many small fossil fragments and the usually small occurs. These deposits are composed of the debris of quantities of lime mud between the fossils are often for environment. shallow and deeper reefs, and all of the organisms suggestive a high-energy mentioned for these subfacies can be expected. Perforate In addition to foraminifera, oyster fragments and/or foraminifera echinoid usually predominate over the imperforate. fragments predominate in the thin sections. Alveolinids (with the exception of some specimens of F. Whole shells of oysters and irregular echinoids are (M.) boscii), most miliolids and Orbitolites usually show common. Entire skeletons of the sea urchins Conoclypus rounding by transportation and are thus obviously sp. and Opissaster aff. minor Lambert have been found. allochthonous - in contrast to the perforate foraminifera, The cheilostomatous Beisselina is the most frequently Other fossils of which nummulites are generally the most numerous. occurring bryozoan. are generally much In order of decreasing importance discocyclines, less common. Of these in particular the for- aminifer operculines and assilines can also be found. Reophax and sessile foraminifera are worth Sometimes these deposits contain the cheilostomatous mentioning. Carditidae, Cardiidae, Pectinidae and those bryozoan Biflustra, in which case they grade into Crassatella sometimes occur; the two valves may still be subfacies Transitions of XIlib. to subfacies XIIIc are joined together. Furthermore other pelecypods, also seen; these fore-reef deposits contain numerous gastropods, ostracods, crabs, various cheilostomatous corals thick spines of regular echinoids (section A). The deeper bryozoans, (chiefly colonies), serpulid worms, fore-reef associated with various Lithothamnium, deposits are always the Lithoporella, Corallina, Halimeda, subfacies of facies XIII and XIV. They have only been Acicularia, dasycladaceans and remains of land plants found in the F. corbaricus Zone in the sections A, I, K, are found, chiefly as fragments. L and Y. Subfacies XIa is usually associateci with subfacies IXa, facies VI, VII and XII and subfacies XlVa. Transitions Fades XI. consistin limestones to Deposits fi mainly ofpure exist subfacies IXa, Xlla, b and e, VIb, Vllb, XlVa with mixed imperforate—perforate foraminifera and b and XlIIb. associations (PI. 6. Fig. 4) This facies is in the Basin. All Xlb. Pseudo- widespread Tremp Subfacies Deposits containing a subfacies of facies XI have been found in all alveolinid miltha-Velates community (closely allied to sub- biozones. The various subfacies of this facies in - occur facies Vic). These deposits consist of light to dark F. the cucumiformis Zone in sections along the northern grey biomicritic limestones (packstones) which are often side of the basin, whereas they are nearly absent along nodular. Some clayey limestones and marls belong to the southern side in this biozone. The opposite is the this subfacies. The joint occurrence of Pseudomiltha case in the F. trempinus Zone. In general it is true of all corbarica (Leymerie) (usually in position of life) and subfacies that they have developed more extensively Velates schmiedeli Chemnitz is characteristic for these the southern side than the northern side of These molluscs along along deposits. and oysters occur in the basin. considerable numbers. Carditidae, Cardiidae, Pectinidae Subfacies Xla, b, and d show resemblances often c many (the two valves are still joined together) and with subfacies VIb, c, d and e, respectively. In addition Turritella are much more rare. Sometimes entire the differences in the foraminifera associations Ditremaster to the skeletons of the echinoids sp. and subfacies of facies XI always contain additional faunal Amblypygus sp. ex gr. dilatatus Agassiz have been elements compared with the resembling subfacies of found. Fragments of echinoids as well as various facies VI. foraminifera and ostracods are common. Other fossils Horizontal and vertical burrows occur in all subfacies. which often occur as fragments are other pelecypods and Nummulites are the most common perforate gastropods, various cheilostomatous bryozoans, some foraminifera, followed by Operculina; Discocyclina and cyclostomatous bryozoans, crabs, coral colonies, Assilina are rare. Transitions between the subfacies are serpulid worms, Lithothamnium, Lithoporella, frequently observed. Halimeda, Acicularia, dasycladaceans and remains of land plants. The rare occurrence of terebratulid Xla. and Subfacies Deposits containing many oysters brachiopods and of spines of the regular echinoid echinoids (closely allied to subfacies VIb). - These Porocidaris indicates a transition to subfacies Xlla or b. deposits consist of light grey to grey, sometimes dark Subfacies Xlb is often associated with the latter two biomicritic limestones grey, (packstones) and more rarely subfacies, with facies VI, and also with subfacies IXa biosparitic limestones (grainstones); they are sometimes and IVd. Some sandy or silty. marls have also been included in The absence of sedimentary structures formed by this subfacies. The limestones are sometimes nodular. currents, the presence of pelecypods in situ and the kind of sediment indicative environment. Sedimentary structures, except burrows, are usually are of a low-energy 185 subfacies is the means of Subfacies XIc. Deposits contamini; a rich mollusc other principal distinguishing assemblage (closely allied to subfacies Vici). - These both subfacies. of the sections, which alternate deposits consist of light to dark grey, sometimes slightly The unexposed parts with the limestones of facies XI, mainly sandy biomicritic limestones (packstones) which may be probably are rich mollusc fauna; marls and limestones and are interpreted as nodular. They are characterized by a marly of facies XII. especially gastropods are abundant. The families the belonging to Volutidae, Cardiidae, Ostreidae and Pectinidae could be XIla. a identified with certainty as well as the genus Clavilithes Subfacies Deposits containing Spondylus dark - consist of and' the species Bicorbula vidali (Cossmann). Brain community. These deposits grey to sometimes biomicritic limestones corals sometimes occur in situ. In one place a specimen grey, light grey, of the large irregular echinoid Conoclypus was found. (packstones) which are usually irregularly bedded and limestones often Except for Pseudomiltha, Velates and the specifically sometimes nodular. These are clayey. mentioned echinoids of the previous subfacies all fossil Some marls also belong to this subfacies. Nummulites be found in subfacies XIc. and/or are the most numerous groups of subfacies Xlb can operculines usually Moreover solitary corals, other brachiopods and other perforate foraminifera, miliolids are always the most Alveolinids. Orbitolites and worms occasionally occur. numerous imperforate ones. field The lack of cross-bedding and other sedimentary especially assilines are less common. In the the kind of and most Of the structures formed by currents as well as pelecypods gastropods are conspicuous. environment for subfacies the Leymerie sediment suggest a low-energy epifauna pelecypods Spondylus eocenus the subfacies (PI. 8), Chamidae. Pectinidae, and XIc. It may be associated with same as 4, Fig. oysters Mytilus valves subfacies Xlb. are the most important representatives. The two still The are nearly always joined together. following gastropods are epifaunal: Cypraeidae (? Gisortia), Subfacies Xhl. Deposits containing many green algae Xenophora, Clavilithes and Rostellaria; the same mode (closely alliedto subfacies Vie). - These deposits consist of life can be presumed for their fossil relatives; these biomicritic limestones of grey to dark grey (packstones) fossils are however less common. Other pelecypods this which are often nodular. Some marls also belong to present are mainly shallow burrowers like Cardiidae, Halimeda and subfacies. The green algae dasycladaceans Carditidae, Lucinidae, Crassatella and Fimbria. Other are abundant. Entire skeletons of the echinoid Opissaster Naticidae, Ancilla and Rimella. gastropods are Seraphs, aff. minor, molluscs of the families Carditidae and Brain corals and boring pelecypods are rare. Volutidae. and brain corals have been found and surely in this Terebratulid brachiopods are more frequent belong with certainty to the autochthonous fauna. subfacies than in other subfacies. Small radially ribbed Usually this subfacies occurs in association with echinoids brachiopods are rare. Regular and irregular subfacies Xlb or XIc. were abundant. This can be deduced from the occurrence of many loose plates and spines (including Facies Entire skeletons XII. Deposits consisting mainly of clayey those of Porocidaris; see PI. 4, Fig. 9). limestones and marls with mixed imperforate—perforate of sea urchins are as a rule rare and belong mostly to foraminifera associations Maretia aragonensis Cotteau and Ditremaster cf. alarici The subfacies of this facies can be divided into two (Tallavignes) (PI. 4, Fig. 2). Other fossils occurring in and groups. One group comprises subfacies Xlla, b c, this subfacies are various foraminifera (including sessile which are characterized by abundant and varied faunas. ones), ostracods, different types of cheilostomatous The other group, represented by subfacies XIId, has a bryozoans (vinculariiform and adeoniform, sometimes A considerable of the rather poor fauna. proportion also lunulitiform types) and some cyclostomatous fauna of the first group consists of epifaunal elements. bryozoans (including Entalophora), fragments of crabs, horizontal and The only sedimentary structures are various serpulid worms, some solitary corals, some vertical burrows. All types of transition between these massive and branching coral colonies, fish remains (rare) subfacies exist. Even the fossils for which the and pieces of dasycladaceans and Halimeda. The in bed. communities are named may occur together one foraminifer Reophax. fragments of Lithothamnium and Nevertheless the subfacies can usually be distinguished Lithoporella. and remains of land plants can all be fairly easily. Fossils, which are mainly restricted to these considered allochthonous. subfacies and which therefore are characteristic for Transitions to subfacies XIa, b, c and d, and subfacies of the In Pseudomiltha corbarica them, are the Chamidae, many representatives Vic, d and f exist. that case Pectinidae, Eutrephoceras aff. lamarcki and a and/or Velates schmiedeli are often found together with terebratulid brachiopod (Terebratula montolearensis the above-mentioned fauna and flora. In some places Leymerie). The cheilostomatous bryozoan Beisselina is where an impoverished Spondylus community lived in not restricted to subfacies Xlla, b and c, but is most more agitated water (for instance in section N) the numerous there, from which it may be concluded that it bryozoans are nearly or completely absent in the lived there under optimum conditions. limestones which in such a case are light grey and Subfacies Xlld does not differ essentially from without clay. Transitions to subfacies XHIb and XlVb XV subfacies XlVd. The stratigraphical position between and facies can also be seen. Then glauconite may be 186 and Conocrinus internodes present, Biflustra fragments, usually the only perforate foraminifera. Miliolids are or Turritella may be found. In these apparently deeper always the most numerous imperforate foraminifera. Lunulites water deposits the lunulitiform bryozoan is Alveolinids and Orbitolites are less common. Echinoids in often abundant, whereas this species is absent are abundant, in their number of individuals as well as in shallower environments. their number of species. Most specimens are preserved The Spondylus community with its many epifaunal as complete skeletons (without spines). Schizaster aff. elements lived in areas where the sedimentation rate was vilanovai Cotteau (PI. 4, Fig. 3), Linthia hovelacquei low. The presence of fossil fragments and the usually Cotteau (PI. 4, Fig. I), Maretia aragonensis Cotteau and make high concentrations of the fossils it probable that Ditremaster gregoirei Cotteau are the most common some erosion occurred. Living species of the families of species. Other irregular echinoids found are Trachyaster the Spondylidae, Chamidae and Ostreidae are cemented aff. raulini Cotteau, Schizaster aff. biarritzensis by secreted shell material to a hard substratum (Moore, (d'Archiac), Conoclypus cf. cotteaui Lambert and 1970). This be firm bottom the 1969; Stanley, can a or Conoclypus marginatus Desor. Complete skeletons of skeleton of another organism. The valves of our fossil regular echinoids are rare. This is also the case in other of the Chamidae environments species Spondylidae and are unequal and might be due to the differences in the but not as asymmetrical as those of many recent mode of life of irregular and regular echinoids: regular representatives of these families. Nevertheless a similar echinoids always belong to the epifauna and irregular mode of life is highly likely for these species. The long ones usually to the infauna. Three regular echinoid spines of Spondylus eocenus were useful as a protection species have been found, viz. Rhabdocidaris aff. pouechi against predators (for instance fishes), like those of Cotteau, Thylechinus pegoti Cotteau, and Porosoma recent species. rousseli (Cotteau). It is not impossible that the loose In the majority of the cases the Spondylus community spines identified as Porocidaris seratta d'Archiac (PI. 4, lived under quiet conditions, i.e. was not disturbed by Fig. 9) belong to the same species as the complete waves The various of skeletons (without which or strong currents. types spines) have been identified as bryozoans which surely are definitely autochthonous Rhabdocidaris aff. pouechi. this. This subfacies molluscs form prove therefore represents an Many part of this community, i.e. environment below wave base, with the possible Pectinidae. Cardiidae, Chamidae, Ostreidae, Crassatella, of the Naticidae, Rimella others. In exception impoverished Spondylus community of and many contrast to section N. The minimum of this subfacies subfacies Xlla the depth was gastropods are clearly in the minority at therefore least ca. 15 m. The lower limit is less easily compared with the pelecypods. Other fossils that occur fix. If the conditions of solid various to a sea bottom, low are foraminifera, ostracods, different types of and sedimentation rate low energy are fulfilled, the cheilostomatous bryozoans (vinculariiform and adeoniform Spondylus community can be expected in a considerable types) and cyclostomatous bryozoans, crabs, of the various part photic zone. serpulid worms, sponges, some solitary corals The abundance of and the and species presence of the massive coral colonies, fish remains (rare) and large shells of the free-swimming nautiloid Eutrephoceras fragments of Halimeda and dascycladaceans. The aff. lamarcki indicate conditions. foraminifer (Deshayes) open sea Reophax as well as fragments of The presence of shells of this nautiloid mainly in this Lithothamnium, Lithoporella, Corallina, Acicularia and subfacies and in subfacies Xllb and is due land c probably to plants are rare; where encountered they represent the transitional position of facies XII between the allochthonous elements. shallower marls. An limestones and the deeper The empty exceptionally well-preserved fauna which can be shells probably stranded here, as facies XII often seems considered as a variant of the Schizaster - Linthia - to have acted as a threshold between the Ditremaster the open sea community can be seen fairly high up in and shallow environments the water realm. F. corbaricus Zone of section X, immediately west of Subfacies Xlla is found in association with subfacies the village La Puebla de Roda. Here the irregular Xllb and XIa, b. and d, XlVb and and facies XV. echinoids Ditremaster cf. and c. c c nux (Desor), Brissopsis sp. The distribution of this subfacies is in the F. largest Isopneustes sp. occur. Many pelecypods have been moussoulensis found: Zone where it occurs in sections A, B, I, large oysters, Pectinidae (including Chlamys), J, L, M and O. It is also found in the F. Chamidae, ellipsoidalis Limidae and Mytilidae (all epifaunal Zone of sections F, J, K, O, U and V, in the F. elements) as well as Musculinae (semi-infaunal). The Zone of section U, in the F. corbaricus of cucumiformis presence sponges consisting of funnel-shaped cups on Zone of sections I. J. M. N, U, X and X', and in the F. relatively thin stems, and of complete skeletons of crabs trempinus Zone of section K and east of section X. of the species Xanthopsis dufouri, with pincers and articulate legs still attached, indicates quiet conditions Subfacies Xllb. Deposits containing a. Schizaster - during deposition. Association with subfacies XlVb and Linthia - Ditremaster community. - These deposits c suggests that this variant of the community lived in consist of dark biomicritic limestones grey to grey rather deep water. and (packstones some wackestones), which are The Schizaster - Linthia - Ditremaster community nodular, irregularly bedded or dark grey marls and in lived under about the same conditions as the Spondylus and rare instances siltstones. Nummulites operculines are community. The sedimentation rate was somewhat 187 foraminifera. "The ideal biotope for the higher, and no significant erosion took place, as can be fragments or of echinoid skeletons lunulitiform is therefore a small particle (quartz seen from the presence complete Bryozoa and the smaller proportion of cemented pelecypods. and/or carbonate sand) bottom. They never occur on a with those of the bottom of and are never found Other environmental conditions agree consisting entirely clay latter subfacies. Many of the echinoid species listed for encrusting rocks, large pebbles, piles, larger shells, or 1963, 181). this subfacies probably also occurred in adjacent other such large objects" (Lagaaij, p. environments. There however they will be difficult to Therefore it is understandable that lunulitiform of the locate because there is less chance that they will have bryozoans are usually absent in the marls typical Turritella facies. substrate is in been preserved as complete skeletons and because they The particle incorporated the that the adult is free of the were probably less common. Thus originally the contrast colony, so colony to sediment. can a shallow burial in the with other (sub)facies was probably less than it seems They escape be now. sediment by crawling upwards. All other bryozoans to hard substratum. Lunulitiform Transitions to subfacies XIa, b, c and d and subfacies remain attached a where other XlVa of Pseudomiltha therefore inhabit areas exist. The presence and/or bryozoans can Velates indicates the transition to subfacies Xlb, that of bryozoans cannot live. The minimum depth at which the larvae of lunulitiform Ditrupa to subfacies XlVa. Subfacies Xllb may be colonies associated with subfacies Xlla and c, XIa, b, c and d, bryozoans can settle and develop into adult on the of the water turbulence at the and with subfacies XlVa, b and c. In the latter case depends degree bottom, i.e. the level of the base and the glauconite may be present. upon wave strength of bottom the larvae cannot settle on a Subfacies XIlb occurs in the F. ellipsoidalis Zone of currents; bottom tend sections F, H, J, K and V, in the F. moussoulensis Zone where the sand grains to shift under the of sections F, J, K, L. O, V and X, in the F. corbaricus influence of water movement (Lagaaij, 1963, p. 187). thus Zone of sections F, J, M, O, V and X. and in the F. The Patallophyllia community lived in a trempinus Zone of section J. low-energy environment below wave base. The sedimentation rate was usually higher than that in the environment of the - Linthia - Ditremaster Subfacies Xllc. Deposits Containing a Patallophyllia Schizaster relatively low. The - but still average community. These deposits consist of dark grey marls community, was two limestones depth was probably than that of the and grey to dark grey biomicritie (packstones) greater subfacies, the maximum will which are sometimes slightly sandy. The limestones preceding although depth nummulites not have differed much from that of these subfacies. usually show irregular bedding. As a rule are There often transitions to facies XV. in which the most abundant perforate elements, but occasionally are Turritella well are numerous. operculines, assilines or discocyclines may predominate. as as Patallophyllia foraminifera. Transitions to facies XI and subfacies XlVa and b also Miliolids are the most frequent imperforate associated with The characteristic fossil is the solitary coral exist. Subfacies XIIc may have been facies XV and with subfacies Xlla, b and d. XIa. b, c Patallophyllia (PI. 4, Figs. 5, 6). Various molluscs occur, including pelecypods of the Cardiidae, Carditidae, and d, XlVb and c and Ville. Ostreidae and Teredinidae families and Crassatella (the Subfacies XIIc occurs in the F. ellipsoidalis Zone of sections U and V, in the F. moussoulensis two valves are often still joined together); Naticidae, F, H', J, of sections in the corbaricus Turritella, Sigmesalia aff. duvali (Rouault) and Rimella Zone F, I, R and U, and F. fossils in Zone of sections F, H, I, J, M, O, R, U and X. are common gastropods. Other this subfacies are various foraminifera, ostracods, echinoids (Schizaster of the Subfacies Xlld. containing a fauna poor in sp.; Porocidaris spines; in general fragments Deposits skeletons), various cheilostomatous bryozoans species. - These deposits consist of dark grey marls and biomicritic limestones (adeoniform, vinculariiform and lunulitiform types) and some clayey (packstones and wackestones). Nummulites the most abundant cyclostomatous bryozoans, other solitary corals, some are crab remains, foraminifera, miliolids the most abundant coral colonies, various serpulid worms, perforate Furthermore small radially ribbed brachiopods, fish remains (rare) and imperforate ones. Orbitolites, Operculina, fragments of Halimeda and dasycladaceans. Al- Assilina and Discocyclina can occur. Oysters are Litho- in addition lochthonous elements are fragments of probably the most common pelecypods; thamnium, driftwood containing Teredinidae (boring pele- Carditidae and occasionally Limidae have been found; often still cypods) and other remains of land plants. the two valves are joined together. Other less fossils other foraminifera, Lunulites bugei Reguant is a common fossil in common are gastropods, ostracods, echinoids adeoniform, subfacies XIIc, just as in subfacies Xlld, XlVa, b and c. (mainly fragments), vinculariiform and sometimes lunulitiform cheilo- It belongs to the lunulitiform bryozoans, which have a stomatous bryozoans, cyclostomatous bryozoans, peculiar mode of life and hence are of special ecological and in instances The interest. Lagaaij (1963) studied these bryozoans serpulid worms rare scaphopods. extensively, especially the species Cupuladria number of species is always small. canariensis (Busk) which is known from the Miocene to These sediments show the greatest affinity with the other subfaeies of facies XII. The conditions under the present. The larvae settle on small, solid particles, small fossil which these formed about for instance on coarse quartz grains, pellets, deposits were were probably 188 the same as those for the Patallophyllia community. This facies is confined to the F. corbaricus Zone. Transitions are known to subfacies Xlb and XlVb. % Subfacies Xlld occurs in association with facies XI and Subfacies Xllla. Deposits containing a community of subfacies Xllb and e. Subfacies Xlld occurs in the F. various cheilostomatous and cyclostomatous bryozoans H' and - cucumiformis Zone of sections S. in the F. (PI. 7, Fig. 4). These deposits consist of light grey to ellipsoidalis Zone of sections H, I and J, and in the F. grey biomicritic and biosparitic limestones (packstones and moussoulensis and F. corbaricus Zones of sections I and J. grainstones), which are sometimes slightly sandy. Large benthonic foraminifera and cheilostomatous and Facies XIII. Fore-reef detrital limestones (deeper cyclostomatous bryozoans predominate in this subfacies, the vinculariiform fore-reef deposits) among which types are most These deposits consist of an accumulation of shells numerous (chiefly Idmonea s.l.), followed by the in benthonic adeoniform (Beisselina). Sometimes which are general broken. Remains of large types some foraminifera, echinoids, bryozoans and red algae fragments of Biflustra are present. Terebratulid dominate, although their mutual proportions can differ brachiopods and small, radially ribbed brachiopods occur this subfacies of Porocidaris markedly. For reason three can be commonly. Spines are scarce. Fragments of massive and distinguished which gradually merge into one another. branching coral colonies, Acicularia, and the foraminifer allochthonous. The faunal and floral composition of this facies is usually Reophax are They are more diverse than that of the fore-reef detrital limestones derived from the reefs, just like many fragments of red from Louisiana and Guam described by Forman & algae. Schlanger (1957), who found assemblages in which large Many Lithothamnium colonies however will have been benthonic foraminifera predominated substantially over autochthonous and they contributed to the formation of a all firm bottom which the other groups. sea upon bryozoans could attach The broken fossils have usually retained their angular themselves. The many vinculariiform bryozoans indicate edges, which indicates that they were transported over that it was a quiet sea and that the depth of the sea was considerable (Stach. & Gautier, short distances only. This can also be deduced from the 1936; Lagaaij 1965). The usually sudden transitions to other facies. The latter two authors only found high percentages of these below of is characteristic fossils of facies XIII are usually found in bryozoans a depth 120 m. It impossible to much smaller quantities in adjacent environments, suppose that little or no current action occurred. The suggesting that they actually lived on the fore-reef composition of the fauna and flora makes it highly likely that continuous existed which did slopes, although it is extremely difficult to find any currents not change fossils in position of life. Without doubt this was due to much in direction. Strong currents would jeopardize the the low sedimentation rate, coupled with some current many fragile epifaunal organisms too much. Low current action. The most common sedimentary structures are velocities must have prevailed (less than about channels and megacross-bedding; vertical and horizontal 20 cm/sec; see Schopf, 1969, table I). Transitions to facies subfacies burrows also occur. The frequent occurrence of occur X and XIIIc and glauconite indicates that these deposits were formed in XlVa. Subfacies XHIa has been found in association fairly deep water (Chapter VII, section 5). It occurs as with subfacies XIIIc, Xb, VHId and e. IXa and XlVa corbaricus sand grains and as filling in fossils. and d. It occurs in the F. Zone of sections J, and X'. Nummulites are usually the dominant group of K. L, M, N, O, P, Q The most extensive perforate foraminifera. Miliolids are frequent and development of this subfacies occurs in section P. alveolinids, especially F. (F.) oblongus, are often common. Where the sea was deeper Discocyclina predominates. Operculina, Assilina and Orbitolites are Subfacies Xlllb. Deposits containing a Biflustra less rule distinct mixed - usually important. Thus as a a community (PI. 7, Fig. 3). These deposits consist of imperforate-perforate foraminifera association occurs, light grey to grey biosparitic and biomicritic limestones even though these deposits were formed in relatively (grainstones and packstones), which sometimes are The foraminifera could live here deep water. imperforate sandy. If the sand contains numerous black rock-derived at greater depths than usual because the sediment grains, the limestones are dark grey. Large benthonic consists mainly of pure limestones without clay. foraminifera, the cheilostomatous bryozoan Biflustra and Most fossils can be found in all three subfacies: the echinoid fragments predominate in this subfacies. red algae Lithothamnium, Lithoporella, Corallina and Biflustra fans can form complete tapestries on bedding Halimeda when washed The Distichoplax biserialis, the green algae and planes, they are together. upper layer dasycladaceans, foraminifera (including sessile ones), of zoecia of the flat lying fans is often partly filled with ostracods, various cheilostomatous and cyclostomatous lime mud, thus forming clear-cut geopetal structures (PI. bryozoans, irregular and regular echinoids, oysters 7, Fig. 3). The lower layer seems to have been much (chiefly juvenile specimens), Pectinidae, boring and other more difficult to fill. It was usually free of sediment at valves and with pelecypods (the two often still joined together), first became filled later clear sparry calcite. When the is mud gastropods, serpulid worms (including Haliotus) and upper layer filled entirely with lime and fragments of crabs and corals (solitary ones and the lower layer is still entirely free of sediment, as colonies). frequently happens, the geopetal structures can easily be 189 the of this misinterpreted, for one is inclined to think that the filled echinoids seem to have preferred quieter parts subfacies. layer is the lower one. of in this Other bryozoans are of minor importance. Molluscs The absence or rare presence bryozoans to are more abundant than in subfacies XMIa and c. subfacies can often be attributed the very sandy the limestones. the Fragments of massive coral colonies and red algae, nature of many of Probably sedimentation rate and the Acicularia, dasycladaceans and Reophax are debris from was commonly too high animals to be able to adjacent reefs. currents were too strong for these This subfacies formed at the as the This subfacies often contains more grainstones than settle. same depths subfacies XMIa. In these grainstones in particular the two preceding subfacies. Transitions to subfacies XHIa facies be Subfacies fossil fragments are more rounded: this indicates a more and b and XIVa and X can seen. has been found in association with subfacies Xllla agitated environment, which was probably on the XIIIc than that of subfacies and b, IXa and b, XlVa and d, Xb and VHId and e. and average somewhat shallower Xllla. sometimes with subfacies IVd. It occurs in the F. of corbaricus Zone I. P and Biflustra belongs to the eschariform type bryozoans. of sections J, K, L, M, N. O, most typical development of this subfacies Stach (1936, p. 62) wrote: "This type is adapted for life Q. The at at 10 It occurs in section Q and the most extensive occurrence in sublittoral zones depths of least fathoms. ... L extend but not to the littoral has been found in sections K. and O. may to deeper water, zone". limestones The species Biflustra savartii which is known from the Facies XIV. Deposits of marls, impure and sandstones foraminifera Eocene to the present, nowadays has a tropical some containing perforate of least associations distribution and lives at a depth at 100 m The foraminiferaassociations of these called (Lagaaij. 1952, p. 19, 20). According to Schopf (1969) deposits are recent eschariform bryozoans occur in environments perforate foraminifera associations, although miliolids alveolinids not in subfacies with moderate current velocities and a low rate of commonly occur and are rare miliolids and of the sedimentation. The sedimentary characteristics of XlVa and c. Many of the some subfacies XHIa confirm that the fossil Biflustra lived alveolinids have been transported from shallower under environments and the autochthonous alveolinids are similar circumstances. Schopf (1969, p. 243) in flustriform limited to a few water wrongly incorporated Biflustra the group, deep species. The autochthonous elements of all subfacies include which consists of bryozoans with chitinous, very flexible foraminifera, small skeletons adapted to littoral environments. the following fossils: large benthonic Transitions occur to subfacies IXa, XIIIc and XlVa. benthonic ones (more rare than in shallower deposits), Subfacies XIlib has been found in association with ostracods, echinoid fragments (including Porocidaris subfacies IXa. XIIIc, XlVa and d, and sometimes with spines), gastropods and pelecypods (including Ostrea and cyclo- subfacies IVd. It occurs in the F. corbaricus Zone of Turritella). serpulid worms, crab fragments, Idmonea and the sections A, I. J. K, L, M, N. O and Q. The most typical stomatous bryozoans (chiefly s.l.) cheilostomatous Beisselina. Planktonic and most extensive development of this subfacies occurs bryozoan in sections L and M. foraminifera and remains of lands plants, both allochthonous fossils, can be found in all subfacies. Horizontal and vertical burrows the Subfacies XIIIc. Deposits containing a community of are usually only - These consist of structures in these sediments. Glauconite occurs as many irregular echinoids. deposits in fossils and sand when the light grey to grey biomicritic and biosparitic limestones filling as grains, of (packstones and grainstones), which are often sandy. sedimentation rate was low. The presence glauconite indicates that the formation of this facies took in The sand frequently contains many black rock-derived place rather water (see This grains which give the limestones a dark grey colour. deep Chapter VII). authigenic Large benthonic foraminifera and echinoid fragments mineral is however often absent because of a sedimentation rate which predominate over all other fossils and even the echinoid was too high. Unfortunately in this not all deposits belonging to facies XIV can be assigned fragments can be less numerous; that case subfacies approximates the fore-reef detrital limestones with certainty to one of the four subfacies because the of Forman & Schlanger (1957). It is not easy to find ecological guide fossils are sometimes rare. whole skeletons of echinoids and therefore species of XlVa. a identification is difficult; only one complete skeleton Subfacies Deposits containing Ditrupa i.e. the schizasterid (PI. 8, Fig. I). - These deposits consist of an irregular echinoid has been found, community to dark biomicritic Linthia sp. ex gr. aragonensis Cotteau, Although the light grey grey sandy, silty or clayey to echinoids have never been found in situ and are nearly limestones (packstones), grey dark grey marls which always broken, they must have lived in large numbers in are often silty and some grey sandstones. The limestones sometimes the fossils in these this environment, for the fragments are usually more are partly sparitic; are Moreover numerous here than in adjacent (sub)facies. The number limestones frequently rounded. of echinoid fragments is roughly inversely proportionate sedimentary structures such as channels and here; these to the rounding of the fossil fragments. Thus the megacross-bedding are more common 190 - - deposits were subjected to relatively strong current glebifex Amphiura filiformis Amphiura chiajei action. subcommunity (Toulemont, 1972). Picard (1965) found The fauna consists of a limited number of this off the usually species French coast near Marseille at depths Nummulites in limestones species. predominate the ranging between 32 and 78 m, and occasionally between which contain rounded fossil 105 and many angular or fragments 1 13 m. Finally, Pérès (1959) records living structure. and consequently have a coarse-grained specimens at depths ranging between 91 and 210 m in the and In Operculines discocyclines are generally common. waters around Corsica and the sea between Tunisia and marls and limestones with a micritic matrix and Malta. As far this more as author knows a modern analogue of fewer fossil fragments the assilines In these the abundant of Dit found in predominate. occurrence r upa the Tremp latter deposits operculines and discocyclines are common Basin exists only in the northern part of the present well. The as large benthonic foraminifera are practically North Sea. Large masses of Ditrupa also occurred in the far the abundant of all fossils. Sands of always by most The Kattendijk which were deposited in the Early characteristic worm Ditrupa with its slightly and Pliocene North Sea in the neighbourhood of Antwerp bent tubes regularly consisting of two distinct layers, a (Belgium). calcitic and an (PI. 8, is Like all other aragonitic one Fig. 1), usually serpulid worms Ditrupa is a suspension numerous to be it differs not sufficiently present in thin sections; the feeder; however in that it is encrusted on a species is Ditrupa plana (J. Sowerby). In the hard substrate. Instead the tubes are loose and rise coarse-grained, nummulite-dominated limestones the above the soft sediment bottom. Off the coast of concentration of the tubes of is and Ditrupa greater because Brittany this species lives on in very fine to of the lower sedimentation rate of these sediments. medium-grained sand bottoms (grain diameters between Sometimes they may also have been washed together. 0.05 and 0.5 mm) with a highly variable pelitic content Other fossils which regularly occur are echinoid (Toulemont, 1972). The sediments in which Picard (1965) fragments, and different found described pelecypods, gastropods species Ditrupa are as heterogeneous, that is to of and serpulid worms. Vinculariiform, adeoniform say sediments with sand, silt and clay mixed together. In lunulitiform have been found. It is not both bryozoans likely areas Ditrupa occurs only in the transitional zones that they are all autochthonous. between domains containing mainly sand or clay One whole specimen of the regular echinoid deposits. Rhabdocidaris aff. pouechi Cotteau has been found. These data agree well with those of the Ditrupa Other autochthonous fossils are the pelecypods of the community in the Tremp Basin. The sediments in which Carditidae, Veneridae, Arcidae, Pectinidae Cardiidae, Ditrupa has been found here are usually also and Musculinae, and Crassatella. Except for the heterogeneous and also represent the transition between of the Musculinae which is representative a semi-infaunal the more sandy and the more clayey areas. The tidal element, and the usually epifaunal Pectinidae, all are difference in the Mediterranean Sea is small, that of the infaunal pelecypods which lived in the uppermost part of Atlantic Ocean near Brittany is certainly greater. Ditrupa the sediment. inhabits always places where the tide-induced currents Other fossils, which occur mainly as fragments, are are weak or absent and therefore it can live at shallower allochthonous and definitely came mainly from reefs; depths in the Mediterranean Sea. Sedimentary and these of massive and coral are fragments branching palaeontological evidence proves that the tidal influences colonies, Lithothamnium, Corallina, in Lithoporella, were strong the Tremp Basin, so that the depth at Distichoplax biserialis, Acicularia, dasycladaceans, which the lived Ditrupa community was certainly as sessile foraminifera, and radiolarians. Reophax They great as that in Brittany. a small of to represent only proportion the total number of Transitions occur subfacies XHIb and c, XlVb, the fossils. Xllb and c and IXa, and facies XI and XV. Subfacies At present the distribution of the genus Ditrupa is XlVa has been found mainly in association with known to be world-wide in to tropical temperate subfacies XlVb and c and facies XIII. It is also latitudes. recent The species Ditrupa arietina (O. F. associated with subfacies Xllb and c, XIa and IXa, and Muller) is known to occur in the northern part of the facies XV. Its widest distribution is in the F. corbaricus North Sea, the the Skagerrak, Cattegat, the Channel and Zone: it occurs in sections F, H, I, J, L, M, O, P, Q, U, the Öresund northern (Hartmann-Schröder, 1971), and V, X and X', it also is seen in the F. moussoulensis the Atlantic Mediterranean near and coasts of France Zone of sections F, V, Y, and Z, and the F. ellipsoidalis and Lo V. Spain (Toulemont, 1972, Picard, 1965; Rioja y Zone of section Bianco, 1931), as well as in the Atlantic Ocean, the Mediterranean Sea, the Red Sea, the Andaman Sea (at Subfacies XlVb. Deposits containing a Conocrinus 785 fathoms) and around the Philippine Islands (Fauvel, community (PI. 8, Figs. 2, 3). - These deposits consist of 1953). Recent Ditrupa sp. has also been off the to dark marls and reported grey grey dark grey to light grey 71 fathoms Japanese coast at (Cheng, 1974). The Euro- clayey, silty and sandy biomicritic limestones finds better documented pean are and are usually in shal- (packstones). The most abundant large benthonic lower water. Off the coast of D. has Brittany arietina foraminifera are assilines, operculines and discocyclines. been found at 60 depths ranging between and 85 m in the Nummulites are rare. The abundance of cheilostomatous Astrorhiza limicola community and in the Maldane is There bryozoans striking. are many specimens of 191 and should many species of the vinculariiform. adeoniform that the fossil Conocrinus have lived at such great lunulitiform types. Cyclostomatous bryozoans are also depths in the Tremp Basin: the abundance of large seen (chiefly the vinculariiform Idmonea s.l.). The loose benthonic foraminifera proves that it must have lived in doncieuxi the The Conocrinus often internodes of the sea lily Conocrinus Roux, photic zone. community in alternates with the which contains 1978 are often sufficiently numerous to appear thin Ditrupa community molluscs which sections. Whole skeletons of these animals have never many are normally confined to the photic Thus the lived been found. Small radially ribbed brachiopods are zone. Conocrinus community certainly at with those of the common, terebratulids are much more scarce. Among depths comparable Ditrupa community. the pelecypods the pectinids must be mentioned. The It is therefore impossible for this sea lily to have lived in worm Spirorbis has also been found. Radiolarians are really shallow waters. allochthonous such broken rare elements. The only way in which concentrations of As a rule the bryozoans are abundant in those beds and rounded fossils could have been formed at these containing large concentrations of fossils. In these depths is through severe storms or temporarily strong of fossils has been The fine sediment then usually thin layers the majority the currents. particles are washed broken the and and/or rounded. These deposits contrast with the away to deeper parts of basin a lag deposit which more commonly occurring marls in fragmentation consisting of the coarser fossil fragments is left. is not as pronounced. The nature of these fine sediments The most frequent transitions are those to facies XV. and the fauna indicates that the currents were usually There are also transitions to subfacies XlVa and c and weak. XI la and e. Subfacies XI Vb has been found in A recent relative of the fossil Conocrinus is association with these same facies and subfacies. It Rhizocrinus in the corbaricus of sections lofotensis M. Sars, 1864*. This species is occurs F. Zone H, U, X characterized by its small and fragile stem and calyx. and X', in the F. moussoulensis Zone of sections R, U in The internodes of the stem are obviously more slender and Z, and the F. ellipsoidalis Zone of section U. It is than those of the fossil species. The recent animals fall striking that it has only been found on the northern side apart easily and the same may be presumed for the fossil of the Tremp Basin. Conocrinus. Therefore it is not strange that a complete fossil skeleton or at least a major portion of one has Subfacies XIVc. Deposits containing a mollusc-rich never been found, although they were somewhat more community (PI. 8, Fig. 4). - These deposits consist of dark robust. The recent species lives together in large grey to grey, often silty marls and grey to dark numbers; the fossil species must have had the same grey, sometimes light grey, biomicritic limestones gregarious way of life, otherwise the abundance of (packstones, rarely wackestones) which can be silty, skeletal parts of these sea lilies remains unexplained. R. clayey and sometimes sandy. The most abundant large benthonic foraminifera assilines lofotensis prefers to live on a firm mud bottom where it are and operculines. Molluscs the anchors itself with its cirrhi; extra attachment points are Discocyclines may also be common. are furnished by empty shells, spines of sea urchins, etc. most important group of organisms. There are usually (Sars, 1868). High sedimentation rates cannot therefore numerous species. The number of specimens is rather It assumed that the be endured. may be fossil variable. Probably this subfacies can be subdivided into Conocrinus made the subenvironments after same demands on its environment. more a more detailed study, since The recent species lives at considerable depths. It has different mollusc assemblages seem to occur. The been found by Sars off the Lofoten Islands (Norway) at pelecypods are the most varied. The following families depths ranging between 100 and 300 fathoms. It is also and genera have been identified: Carditidae, Cardiidae, known Veneridae, to occur in deep waters in the tropics, since it Musculinae, Nuculidae, Arcidae, Pectinidae. has been found before the coasts of Surinam and British Ostrea (many juvenile specimens), Crassatella, Guyana on muddy bottoms at depths of ca. 500-600 m Pholadomya and Thyasira. The two valves are often still (J. Walenkamp, pers. comm.). It is however not possible joined together. Gastropods are represented by Turridae, Turritella, Buccinacea, Sigmesalia aff. duvali (Rouault) and Athleta (? Volutispina). Many other unidentified species of pelecypods and gastropods also occur. The *) After completing the text I found a picture of an internode of scaphopod Dentalium is occasionally Conocrinus doncieuxi in Roux, 1978a (pi. 2, fig. 2) which is seen. Other fossils vinculariiform and lunulitiform evidently the same species that I have found in the Tremp are bryozoans, the Basin. This new species will be described in Roux (1978b). solitary coral Trochocyathus, Spirorbis and other Roux described new species belonging to the (1976) two recent serpulid worms, small radially ribbed brachiopods, Conocrinus, viz. C. and C. which genus cherbonnieri cabiochi, sponges and fish remains (rare). Fragments of massive occurred at depths of about 300-500 m and about 2000 m, coral colonies are scarce and are undoubtedly respectively. Therefore the depth range of Conocrinus is allochthonous. considerable (see also Roux & Montenat, 1977). The two Nuculacea are discriminating bottom sediment feeders recent species of Conocrinus and the recent Rhizocrinus (Stanley, 1970; Boekschoten, 1963). Most of the other lofotensis seem to live under about the same ecological are feeders. Carditidae circumstances. Probably the genera Conocrinus and pelecypods suspension, Cardiidae, to Rhizocrinus are synonymous (Roux, 1976): if so, then the name and Veneridae are largely restricted bottoms which Conocrinus deserves priority because it is the older one. belong to the photic zone. This can be due to their 192 dependence on a sufficient supply of phytoplankton This facies consist of grey to dark grey, in rare instances and limestones (Boekschoten, 1963; Yonge, 1928). Thyasira is a light grey, marls biomicritic (packstones). pelecypod which usually lives in deeper waters; it is a The marls are often silty and the limestones are mainly The characteristic element of many deep-sea clay bottoms at clayey and/or silty. marls predominate markedly limestones in this facies. present, but it has also been found before the Rhone over the They are generally delta in water 20 m deep by van Straaten (1960). The much thicker than the limestones. The most frequent structures horizontal followed depth to which light penetrates sea water depends highly are burrows, by load the of the water, and this is structures. Vertical burrows is upon transparency are rare, as determined mainly by the concentration of the suspended cross-bedding. A perforate foraminifera association material. It is highly unlikely that light penetrated occurs in which assilines and operculines are the most beyond about 150 m, in view of the large accumulations abundant elements. Discocyclines are much scarcer and in the northern of the basin. nummulites of clay part occur only occasionally. Miliolids are the In some marls small thin-shelled pelecypods and only imperforate elements. The characteristic gastropods are the only molluscs. These beds were fossil of subfacies XV is the probably deposited at considerably higher rates than gastropod Turritella trempina Carez, which can be those containing the larger, thicker-shelled molluscs. replaced by Turritella figolina Carez (see de Renzi, Rapidly deposited clay is much softer and contains much 1968). The latter species can be distinguished from the more water between the clay particles than slowly former by its sharper, more protruding carina. The deposited clay. Small thin-shelled molluscs do not sink number of specimens found is highly variable. These into the muddy bottom as easily as the larger species do gastropods occur in such quantities in some beds that (Stanley, 1970). Therefore although the sediments are they lie piled up one on top of the other; the remaining is then filled with marl and mainly marls, which barely differ from one another interspace other, smaller have the lithologically. their sedimentation rate may varied fossils. On other hand the number of turritellids can greatly. be so small that the marls in question are easily confused Transitions occur to facies XV and subfacies XlVb with marls of other facies, like those of subfacies XlVb and d and XIIc. Subfacies XIVc has been found in and c. Thus gradual transitions to these subfacies exist, association with facies XV, subfacies XlVa, XHIa and c, and also to subfacies XIIc. Xlb and sometimes with subfacies IVd. Its widest The most typical fossil assemblage which causes the distribution is in the F. corbaricus Zone in sections H, I, least confusion with other assemblages of other facies is L, N, 0, U, X and Y. It also occurs in the F. a fauna with few species which contains in addition to moussoulensis Zone of sections H, H', R, U and Y, in Turritella some gastropods and pelecypods, foraminifera, the ostracods, remains F. ellipsoidalis Zone of sections H and H', and in the serpulids and of irregular sea urchins. F. trempinus Zone of section X. Other assemblages in the Tremp Basin which belong to facies XV have a richer fauna. In addition to the faunal XIVcl. in elements mentioned Subfacies Deposits containing a fauna poor already the following fossils may species. - These deposits consist of dark grey and grey also be included in this assemblage: bryozoans marls and biomicritic limestones some (packstones), (especially Lunulites, but also some Beisselina, and which are often silty and sometimes sandy, and some fragile vinculariiform types), the solitary coral sandstones with clay galls. Assilines and operculines are Trochocyathus, small radially ribbed brachiopods, the most benthonic foraminifera. and important large sponges, regular sea urchins the worm Spirorbis. and also Nummulites discocyclines may occur. Oysters, Special groups of molluscs that should be mentioned are of which many are juveniles, are probably the most Sigmesalia aff. duvali, Naticidae and Strombidae common molluscs in this subfacies. Sometimes they are (gastropods) and Carditidae, Mytilidae, Nuculanidae and clearly found in situ. Furthermore some Turritella, Crassatella (pelecypods). Allochthonous elements are Carditidae and few other shark a pelecypods and gastropods teeth (rare), boring pelecypods of the Teredinidae be may present. Bryozoans, terebratulid brachiopods and family and remains of land plants. fish Lithothamnium remains are rare. Fragments of and Various recent turritellids can endure high coral colonies be allochthonous elements. sedimentation The can only rates. most comprehensive ecological The circumstances were far from favourable in this study on a Turritella species has been written by this from Sartenaer subfacies; can be concluded the fact that the (1959). Sartenaer, and also van Straaten (I960) fauna and is poor in species. The only possible reason for Picard (1965). found large quantities of living this be sedimentation can that the rate was too high. specimens of Turritella tricarinata communis Risso quite Transitions occur to subfacies XIVe. and XIIc. This close to the mouth of the Rhone River, where other subfacies XV and is associated with facies subfacies molluscs are very rare or even absent. It can occur in XlVa and IVd. It in the corbaricus occurs F. Zone of large numbers there because it does not need to compete sections I, J, K, L, O, U and V, in the F. ellipsoidalis with other organisms. This Turritella species is well Zone and/or F. moussoulensis H to Zone of sections and adapted environments in which fine sediments are H', and in the F. Zone of section X. also trempinus rapidly deposited (see van Straaten, 1970, p. 112). Small tentacles the along mantle margin ensure that only Facies XV. Deposits containing a Turrilella community desirable sediment particles can intrude into the mouth. 193 burial under new of water 1959; van 1960). In the The species can also easily escape (Sartenaer, Straaten, the sediment Basin with its tidal sediment by crawling upwards to new Tremp stronger and current actions T. surface (Sartenaer, 1959; van Straaten, 1960). Turritellids the upper limit for the occurrence of numerous and T. A are infaunal deposit feeders; this mode of feeding is trempina figolina was certainly much lower. of filter minimum of 20 m reasonable. common to only a few groups gastropods; they depth seems The and eat sifted deepest recent occurrence of Turritella is 210 m by a process of ciliary feeding finely bottom sediments (Cox, 1960). T. tricarinata communis, (Pérès & Picard, 1958). Van Straaten (1960) found T. like other tricarinata communis in water a deposit feeder turritellids, thus lives in a more than 120 m deep molluscs before the Rhone delta, but it is abundant special ecological niche not open to other or no longer macro-invertebrates; it requires large quantities of finely below 50 m. According to Sartenaer (1959) a dramatic decrease in the number of of this grained bottom material and cannot withstand too much specimens species turbulence in the water (Sartenaer, 1959, van Straaten, occurs at about 35 m in the Gulf of Fos. This Turritella I960). prefers to live in the biocoenosis of the coastal is For these reasons it is not accidental that Turritella terrigenous mud, which shows a striking decrease in those where number of 85 most abundant in parts of the Tremp Basin specimens of all organisms below m the thickest and most finely grained sediment masses (Picard, 1965). developed. Therefore there is no reason to doubt that The lower limit for the occurrence of numerous T. the above-mentioned fossil species lived under the same trempina and T. figolina must also be lower in the tricarinata Basin than in the Mediterranean. The sedimentary conditions as the recent T. Tremp present in which communis. In other facies other turritellid species deposits these species are abundant and/or the demand another of fauna exhibits the thus the sometimes occur. These species type highest diversity are shallowest environment. Such turritellids are also known to exist members of this facies. The deepest members lives fauna, today. T. triplicata (Brocchi) for instance also along display an impoverished qualitatively as well as the French Mediterranean coast, but prefers sandier quantitatively whereby the turritellids are also much environments (see Picard. 1965). more rare. indicates lower Turritella and associated The richer assemblage a distinctly Frequently Patallophyllia are than with the transition sedimentation rate that presumed for the poor one another. Such a community forms assemblage. Nevertheless this sedimentation rate is to subfacies XIIc. Facies XV is found mostly in nearly always still much too high for the formation of association with this subfacies or subfacies XIVc and b. glauconite, since this mineral is seldom found. Occasionally it is associated with subfacies XlVa and d, The depth at wich this facies developed is rather Xlla and XIa. It has been found only in the northern and central of the basin. It in the F. variable. The upper limit is determined by the wave base parts occurs ellipsoidalis where F. and by strong currents. In the Mediterranean Sea Zone and moussoulensis Zone of sections H, H', R and F. tidal and current actions are limited T. tricarinata and U, in the corbaricus Zone of sections H, I. R, U and X. communis can be found in large numbers in up to IO m CHAPTER VI PALAEOGEOGRAPHY OF THE SUCCESSIVE PHASES AS DEFINED BY THE ALVEOLINID BIOZONES GENERAL REMARKS covered by beaches, lagoons and sheltered bays, leaving comparatively little space for open marine environments. This interpretation cannot be maintained when the Introduction ecology of recent representatives of important fossil One of attempt to reconstruct palaeogeographic maps the species is taken into account. Ferrer et al. were led to Basin has this Ferrer al. (1971) shallow, Tremp preceded study. et assume so many protected environments on published an isopach map for the entire Formation, account of the of bars built Ager presumed presence up of and facies maps covering mainly the same stratigraphic nummulite shells. Such bars would have acted as intervals in used the maps of the present publication. barriers protecting the sheltered marine environment. No was made in the draw an The found attempt present study to present author has not however any evidence for the entire formation isopach map because not enough that the nummulite accumulations encountered have data the of the formation formed submarine concerning upper part were ridges. These accumulations always available. Nevertheless results make it clear that in sediment bodies in which our occur planar no sedimentary Ferrer's isopach map is based on too few data. structures have been observed. with the of None of the various reef Compared my interpretation interpretation types which do occur were identified the facies presented by Ferrer et al. is generally that of a by Ferrer et al. Independently Gaemers (1971) much shallower basin. In their and Garrido & Rios opinion large areas were (1972) discovered the reefs on the 194 in amounts in northern side of the basin. The reefs on the southern occur as sand grains and pebbles large the side were first mentionedby Gaemers (1974). deposits formed during those times (pers. comm. P. J. C. Nagtegaal). Thus it is not necessary that Lower Evidence for erosion in the hinterland Carboniferous sediments were eroded in the Early Conglomerates have been found chiefly in the F. Tertiary. It is indeed probable that the Triassic Bunter cucumiformis Zone. In the Tremp Basin they always furnished this material. The radiolarite fragments also have a polymict composition. Most frequent are pebbles occur in some Cretaceous deposits, but there they are and cobbles of sandstones, limestones and white quartz. too scarce to be an important supply for the Ager The sandstones and limestones can often be identified by Formation. means of their fossil content as originating from the Arén Muscovite occurs in many sandy deposits of the Ager Formation from the Formation. Other Formation, the of biotite and or Tremp frequent occurrence At the F. Cretaceous pebbles also occur. least some erosion of muscovite flakes in upper part of the corbaricus the Tremp Formation must have taken place. This Zone and the F. trempinus Zone on the northern side of the basin is often and formation contains many conglomerates which include worth mentioning. They are large fresh. Biotite is not numerous pebbles from older formations. On the basis of always appear especially very that the conglomerates therefore it cannot be proven resistant to weathering and it is therefore inconceivable deposits older than the Tremp Formation furnished the that this mica was involved in more than one coarse material for the Ager Formation. sedimentation cycle. During Early Eocene times the the The sand fraction which occurs in many beds in biotite must have been eroded from the northern to northeastern hinterland, biotite absent area studied consists predominantly of black rock being on the particles; under the microscope lighter and darker areas southern side of the basin. The biotite and much of the and white spots are visible in these particles. Often these muscovite can only have originated from the axial zone that the colour of of the where These old black grains are so numerous the Pyrenees many granites occur. sandstones have been becomes grey to very dark grey. Sometimes intrusive rocks must therefore exposed at these rock fragments reach the size of fine gravel; in one least in some places during the Early Eocene. case distinct radiolarians were observed in such a Moreover the occurrence of mica suggests that fragment. These particles therefore can only come from "winnowing and/or by-passing are not being carried out Carboniferous black radiolarites which et al., 1968, The the Lower are efficiently" (Doyle p. 381). large highly resistant to weathering. These radiolarites had quantities of mica in the upper half of the Ager however already been attacked by erosion during Late Formation on the northern side of the basin indicate that Carboniferous, Permian and Early Triassic times, and much mica was supplied, and little mica was washed - A Aren I - Isona Ag - Ager PM - Puente de Montanina B - Benabarre PR - la Puebla de Roda C - Campo T - Tremp - G Graus ST - San Salvador de Tolo v facies l-ll of and deposits rivers, swamps lagoons o beaches and barriers, shallow tidal and shallow ,, lll-IVa,b,c,e deposits turbidites • IVd deeper tidal ,, deposits Va sand waves mainly with imperforate foraminifera = Vb sand waves etc. with foraminifera „ mainly perforate » VI shallow marine with foraminifera „ deposits imperforate » Vll-VIII-IXb-X back-reef, reefs, reef channels and fore-reef „ + IXa off-reef shoals „ - XI limestones with and foraminifera ,, pure imperforate perforate XII marls and limestones with and i „ clayey imperforate perforate foraminifera XIII fore-reef detrital limestones (pure limestones of the deeper fore-reef) ° XlVa marls and limestones with ,, deeper impure Ditrupa community ■ XlVb.cd other marls and limestones with perforate foraminifera „ deeper impure - XV marls and limestones with Turritella „ clayey community - slumping of facies XIV * turbidites isopachs in metres uninterrupted isopachs: best known isopachs dashed isopachs: extra polated isopachs Legend for Figures 3-12. 195 From this it be concluded away (Doyle et al., 1968). can the large quantities of clay in the Ager Formation was that resedimentation was unimportant and the furnished by Upper Cretaceous rocks. Moreover this sedimentation rate was relatively high. conclusion makes it more probable that coarser material of interval contributed The study of the nannoplankton has revealed that 90% the same also directly to the or more of the specimens were reworked from the sediments of the Ager Formation. Cretaceous. Most of this material originates from the Upper Cretaceous (all stages are represented), and some Remarks concerning the horizontal sections (Enclosures of it even comes from the Albian and pre-Albian. It is 2 and 3) One therefore not unreasonable to suppose that the bulk of horizontal section connects the measured vertical 3. of the F. Zone. Continuous line: northern line of the Basin for the lower of Fig. Isopach map cucumiformis heavy coast Tremp part the dashed line: southern line of Basin for the lower of the dashed-dotted zone. Heavy hypothetical coast the Tremp part zone. Heavy line: northern coast line of the Tremp Basin for the middle part of the zone. All coast lines mark the maximum extension of the land for the relevant time interval. Legend on p. 194. 4. Facies of the F. Zone. 194 Fig. map cucumiformis Legend on p. 196 the southern side of the basin indicate the and sections along (Enclosure maps to more important more rapid 2. Two smaller horizontal sections are nearly facies changes so that the distributionof the predominant the perpendicular to first one, running in a north-south facies types or groups of facies types becomes more direction (Enclosure 3). Data along the northern side did obvious, thus designating the general palaeogeographical not suffice to make a horizontal section. It is to be noted trends. that the measured sections as a rule tend to represent a basinward towards - The of more development the top. This is Isopach maps (Figs. 3, 5, 7, 9, 12). thicknesses L This the biozones have particularly the case in sections X, H, and O. been measured as accurately as explains the relatively thick development of the F. possible. If no or not enough alveolinids occurred in the relevant interval thickness estimated with corbaricus and F. trempinus Zones in sections L and O the was the aid of The with respect to the thicknesses in adjacent sections in palaeoecological and lithologica] data. extent of the horizontal section of Enclosure 2. Also the seemingly each biozone in a section can be indicated by a line on large and unexpected facies changes in these biozones the map. For all sections the centre of these lines between sections L and O and the adjacent sections can representing the relevant biozone have been plotted on the the with thickness of be explained by same phenomenon. map a dot. The measured the biozone is given in metres at each point. Continuous Mode of construction of the facies and the isopach maps isopachs were drawn whenever the density of data A palinspastic reconstruction is not necessary because allowed the reconstruction of sufficiently accurate the Tremp Basin has not suffered considerable isopachs. Dashed lines were used for those parts of the of is available shortening. Usually the dip the strata less than basin where insufficient or no data were but 15-20°. The area with the steepest dips lies between where an extrapolation could be made by taking into Campo and Merli where the base of the Ager Formation account the general palaeogeographicalpicture. dips to the south at an angle of 45°; near Merli even THE steeper dips of about 60° occur locally.The younger PALAEOGEOGRAPHY OF SUCCESSIVE deposits of the formation immediately south of this zone PHASES already dip much less. A slight N-S shortening persevered throughout the Fasciolites cucumiformis Zone (Figs. 3, 4) deposition of the Ager Formation. Due to this, the In most of the Tremp Basin the Ager Formation lies shortening is somewhat greater for the lower biozones directly on the fluvial red beds of the Tremp Formation. than for the upper ones. This shortening is connected The latter sediments consist mainly of sand and clay with the fact that the basin subsided more rapidly along deposited in the channels of meandering rivers and the the long axis than along the borders (see also Chapter backlands, respectively. From this it can be concluded 7. In VII, section that the landscape had a very low relief. the western-most part of the basin the marine sediments of - The symbols used the Devotas Formation (Kooter, 1970) underlie the first for the different facies and subfacies types are closely strata of the Ager Formation; they always indicate spaced where the Ager Formation crops out. The extremely shallow water conditions, thus confirming the configuration of the facies symbols in that area is presence of a low relief. it is primarily based upon the distribution of the facies in the Therefore quite understandable that the individual sections. The extent of each biozone in a transgression which led to the deposition of the marine section can be indicated by a line on the map. The sediments of the Ager Formation rapidly advanced centre of these lines representing the relevant biozone eastwards over most of the area studied. With the degree be the The facies have of attainable difference in can plotted on map. symbols biostratigraphic accuracy no been grouped around these centres in proportion to the time can be found between the beginning of the each In this the the importance of facies represented. way many transgression in eastern part of area. An clusters of facies symbols appear on the map which are important land area was situated north of the connected with one another by filling the interspaces northern outcrop area. Thanks to the intercalation of with continental between marine in a gradually changing symbol pattern. In a reliable deposits deposits a number be drawn for way this can only be done for rapid facies changes if the of sections, shore lines could the clusters lie close together. No attempt has been made to lower and middle parts of the F. cucumiformis Zone fill the 4). In the of this interval there interspaces between separate clusters if a too (Fig. upper part was again large distance between the clusters did not allow a a marked transgression (although not as extensive as in reliable the which interpretation. beginning) extended beyond the outcrop area. A the shore the wide spacing is used outside the outcrop area where Probably then existing line was for most no data could be collected. Only the presumably most part already beyond the area covered by the map. important facies types and the supposed general trend The land immediately north of the line Campo - Gurp have been indicated in such areas. must have had a somewhat more marked relief than that The result is set of of line - Sant This a palaeogeographic maps showing a north the Gurp Salvador de Tolo. can qualitative as well as quantitative picture of the facies. be deduced from the influx of coarser siliciclastic Continuous lines have heavy been used on the facies material which is especially pronounced in sections W 197 W H nature and X. In section poorly rounded boulders up to near Tendruy a siliciclastic influx of a different 60 has cm in diameter occur, which can only have been been found which can in no way be connected with transported over short distances. It is presumed that the the earlier influx at the base of the F. cucumiformis coarse conglomerate in which these boulders occur Zone. In section H the largest and coarsest siliciclastic from cliff of of influx in half of biozone. In originated a conglomerates the Tremp occurs the upper the other Formation situated immediately north of the section. A sections along the northern side of the basin than those limited influx of siliciclastic material more was noted in already mentioned some sand and silt occur but they are sections S and T. Here pebbles are never more than of lesser importance. In summary, there are at least four addition influx of 10 cm across. In an coarse fluvial separate sources of siliciclastic material lying not far to material was found in section H' near Gurp (diameter of the north or northeast of the northern side of the basin. the pebbles: up to 13 cm). Not far to the south in section On the southern side an extensive, continuous area of 5. of the F. Zone. 194. Fig. Isopach map ellipsoidalis Legend on p. Fig. 6. Facies of the F. Zone. 194 map ellipsoidalis Legend on p. 198 but in is siliciclastic influx is situated to the east of the Selles over the sedimentary filling, some cases nullified sedimentation. barrage lake (Noguera Pallaresa River): sections A to G or surpassed by a pronounced to this thickest and the The best of the latter situation be found in belong area. The development example can coarsest material occur in sections G and E; to the west that part of section H where very shallow deposits the influence of the detrital influx diminishes gradually. overlie turbiditic sediments with scour and tool marks at K Section represents a special case. Whereas the their base. The average SW direction of the currents scoured out siliciclastics of the former area must have originated which the flute marks is practically from a source to the east, the conglomerate in section K perpendicular to the shore lines and points towards the centre of the basin. This fits well within the can only have come from a source somewhere in the general south. The sections north and west of section K namely palaeogeographic picture. contain no or hardly any siliciclastics; the adjacent to the contain sections east only more finely grained sediments. The conglomerate in section K thus points to Fasciolites ellipsoidalis Zone (Figs. 5, 6) a supply from the Montsech High. The sea clearly extended over a larger area during this I West of Tremp and in sections and I' fine-grained interval than during the former one. The area where swamp and lagoonal deposits dominate. Thin dolomitic shallow marine deposits have been found is less beds indicate evaporitic conditions. The general trend of extensive, and continental deposits are absent in the For the isopachs (Fig. 3) suggests that the swamps and outcrop area. this reason shore lines cannot be covered a east of these localities drawn. lagoons large area (Fig. Probably they lie outside the map area for the 4). This is in accordance with the accepted picture of larger part (Fig. 5). E-W elements, viz. roughly running palaeomorphological Shallow marine deposits occur in a zone from Campo the northern of the Basin the Montsech northeast of La edge Tremp and to Puebla de Roda, and in a zone threshold which forms the southern edge of the basin. parallel to and directly north of the Montsech. The from two where siliciclastic sediments of demonstrable Apart areas influx of siliciclastic material is much more tidal origin prevail (N of La Pucbla de Roda and S of restricted than that of the F. cucumiformis Zone. The Sant Salvador de Tolo) and the area W and SW of area of the main occurrence of this material is situated Tremp where mainly swamps and lagoons occur, shallow south of Sant Salvador de Tolo. Here tidal deposits marine limestones along the southern side, and shallow predominate (Fig. 6). Section G contains the coarsest marine limestones marls side and along the northern sediments, including some conglomerates. The of the basin dominatein the These associations of benthonic outcrop area. deposits larger foraminifera prove that belong for the most part to facies VI. They can change the tidal deposits of section G were formed in shallow into carbonates of subfacies IVb, and those of gradually so that no water, the more northerly sections D be E sharp boundary between these two facies can drawn. and in somewhat deeper water. The occurrence of Only locally did some small patch reefs develop on this some sand and silt in sections A, B, C and F can be carbonate location (N of it attributed platform. At one Benabarre) to the same source as that in the tidal deposits E can be proven that temporarily this shallow platform was of sections D, and G. The source area must have been slightly above the high-tide level under evaporitic situated not far to the south or southeast of section G. conditions, because gypsum pseudomorphs have been The pure quartz sands consisting mainly of rounded and found. This suggests the existence of a series of low well-rounded grains in section Z south of Campo on the islands, of foraminiferal other hand consisting sands, and lying in can only have come from a northern source of of older the prolongation a peninsula: outcrops area. sediments have furnished the In on the peninsula may the northern shallow area many biosparites and K. material for the conglomerate of section This rather biosparrudities with megacross-bedding occur in the shore line is dashed The hypothetical indicated by a line (Fig. lower part of the biozone. presence of these 3). The which is main fault in the Montsech, an upthrust deposits proves that this area was heavily exposed to fault, however caused an important N-S shortening currents and tides. The most impressive sediment body between the Tremp and Ager Basins which has not been developed under high current velocities is the giant taken into the lunate of account on map. ripple section X at Serraduy; this 10 m high would to to have built Normally one expect isopachs run parallel megacross-bedding must been up by a current the shorelines. This is the with not case our flowing towards the SE (see Chapter V, section 3.5). A reconstructed northern shore lines which the smaller cut megacross-bedding in the more westerly section isopachs clearly. This is due to the fact that whenever X' indicates a current with a NE direction. The subsidence was pronounced the sedimentation rate was occurrence of massive Lithothamnium ridges east of even higher at some places, so that continental deposits Serraduy in section W is compatible with this picture, for were formed during shorter or longer intervals. The such ridges offer good resistance to strong wave and differences in the rates of subsidence are primarily current movements, and in fact need such an extreme controlled by tectonics; the filling of the basin with environment. sediments is determined thus the largely by the relief During deposition of the upper part of the biozone In formed. the Tremp Basin the subsidence is a largely quieter conditions prevailed in the northern shallow area synsedimentary phenomenon which usually predominates mainly because the basin deepened somewhat in this 199 region. Here the pelecypod Pseudomiltha is often cases small Lithothamnium reefs occur. Only in sections encountered in life position. A, C and K can a distinct deepening of the basin be The southern shallow zone is characterized for the inferred from the deposits in the upper part of the horizontal and vertical alternation of biozone. most part by a more sheltered biomicrites (Pseudomiltha often occurs in Bordering on the above-mentioned shallow marine biomicrites and which is wide in which mixed situ) and more exposed biosparites areas a 6-10 km zone obviously were influenced by tidal currents. No sharp imperforate-perforate foraminifera associations dominate boundaries can be drawn between these sediment types. (facies XI and XII, see Fig. 6). The most frequently On this more or less protected carbonate platform some occurring, distinct communities in this zone are those of small patch reefs were built by coral colonies. In rare Spondylus and Patallophyllia. Subfacies XIa and XIc are Fig. 7. Isopach map of the F. moussoulensis Zone. Legend on p. 194. Fig. 8. Facies of the F. Zone. map moussoulensis Legend on p. 194. 200 of the Pallaresa River. The role. This in important east Noguera most principal zone turn passes into an area - - dominated the Turritella extensive development of the Schizaster Linthia by community which occurs in Ditremaster community has been found in section K, the central part of the basin. This community and the Halimeda-rich whereas the deposits of subfacies Xld are Patallophyllia community are often united to one larger by far the most extensive in sections I and F. It is community. remarkable that the latter subfacies occurs near the only The southern shallow zone is bordered by a 6-10 km striking anomaly in the isopach pattern (Figs. 5, 6). The wide zone where mixed imperforate-perforate for- aminifera associations biozone here is represented by a thicker succession. The dominate. This area can be of Halimeda divided into two occurrence many specimens of suggests parts: a somewhat shallower southern that a local depression existed and that the bottom was part in which more limestones have been deposited, and well-protected against currents, for this alga flourishes in a somewhat deeper northern part with more marly conditions. Therefore it be assumed that sedimentation. In the sheltered can southern part off-reef shoal limestones and reefs dominant in the subsidence was even more rapid than deposition at this are westernmost place. and easternmost parts (sections G and P); in sections A The Turritella community dominated in the centre of and B and sections K up to and including section O the the basin where the highest sedimentation rates occurred. Spondylus and Pseudomiltha - Velates communities - the Schizaster - This facies (XV) is rare outside the 40 m isopach (see are important; Linthia Ditremaster Figs. 5, 6). community is common as well. In the northern part the The most important facies boundaries (Fig. 6) do not Patallophyllia community is more significant, forming deviate much from the general isopach pattern (Fig. 5). the transition to the central area with its Turritella marls. This latter facies where Probably the isobaths also followed the isopachs rather rarely occurs the zone is 35 m closely. For this reason the palaeogeography of the F. thick or less. ellipsoidalis Zone is less complicated than that of the F. In summary the northern side of the basin shows an cucumiformis Zone. Compared with the latter biozone important development of facies XIV, whereas facies XI the southern side. This the transgression advanced mainly towards the and XII are well-developed along that the of the basin not situated northeast. Certainly the submarine relief was somewhat means deepest part was than the of the in the centre where the thickest occurs (Fig. more pronounced during deposition sequence preceding biozone. 7), but farther towards the north. The relief of the sea bottom was therefore much steeper on the northern side Fasciolites moussoulensis Zone (Figs. 7, 8) of the basin than on the southern side. On the whole the submarine relief indeed in The sea again advanced during this interval, although it was more pronounced than the F. Zone. facies boundaries made much less progress than during the preceding ellipsoidalis Important intervals. Shallow marine areas occupy somewhat less follow the isopachs fairly well. The most striking deviation is the of the 40 space in the outcrop area than those of the former protrusion m isopach near La F. biozones. The northern shallow area directly north of section The presence of fossils characteristic of facies Puebla de Roda tends to become somewhat isolated. The XIV. viz. tubes of Ditrupa and internodes of strata the southern shallow area has shifted a little towards the Conocrinus, in several of this section suggests south over its entire length. continued existence of the local depression mentioned The only part of the basin where sand has been found for the preceding biozone. is in the southeast. The highest concentration of sand in corbaricus occurs section E, directly south of Sant Salvador de Lower part of Fasciolites Zone (Figs. 9, 10) Tolo. Smaller quantities have been found in sections D, The F. corbaricus Zone corresponds to a much longer F and G. This distribution points to an eastern episode in which much thicker sediments were deposited provenance for these siliciclastics. The direction of the than in the underlying biozones (see Chapter VII, section supply of this material has therefore changed compared 2). It is necessary to split this zone into two parts of with that of the preceding biozone. Apart from some thin approximately equal thicknesses because many important silt beds the sediments consist of limestones and marls. palaeogeographical changes took place. Even one half of Reef development increased somewhat in the western the F. corbaricus Zone lasted much longer than one of part of the basin. Section X' contains a coral reef with the three older biozones (see Chapter VII), so that more encrusting coralline algae, and in section P another coral palaeogeographical changes took place; in point of fact it reef has been found. They must have grown in deeper would necessitate more than the one facies map given and quieter water than Lithothamnium reefs. The reefs (Fig. 10) to represent the development of the basin in as only occur where the zone is 20 m thick or less. much detail as in Figs. 4, 6 and 8, successively. The symmetry which existed to-a large extent in the During the first half of this long interval the trans- F. ellipsoidalis Zone between the northern and the gression again gainedground, in particular not long after the southern sides of the basin has almost disappeared. start of this interval, followed by a certain equilibrium subsidence and of basin. Along the northern shallow zone there is only a narrow between the the filling the strip in which facies XI and XII predominate (not In the northern area where shallow marine carbonate indicated the sedimentation occurred these carbonates restricted on the map. Fig. 8). This is bounded to are to XIV the base of the lower of F. corbaricus It south by a wider zone where facies plays the part the Zone. 201 Lithothamnium sides and of the consists of two areas which perhaps were connected ridge. On three (W, S E) where the Formation shallow carbonate a relief must have with one another in the north Ager area pronounced sediments which has now disappeared by erosion. The larger area is existed, because the of facies XIV were situated NW of La Puebla de Roda; the approximate deposited in distinctly deeper water lie close by, maximum extension is indicated by the heavy line interfingering with the shallower deposits. The of this It is of limestones terminated immediately north village (Fig. 10). deposition pure suddenly, the It remarkable that a shallowing development occurred changing into muddy sediments of deeper facies. culminating in reef development near the top of this follows that a rapid subsidence of this area occurred at This is the of the that moment. limestone sequence. just opposite general trend of deepening of the basin. The local and The smaller northern area with limestone deposition short of about 5 km the very shallowing even led to the formation a covers an area long extending along 9. 194 Fig. Isopach map of the F. corbaricus Zone. Legend on p. of the lower F. corbaricus Fig. 10. Facies map part of the Zone. Legend on p. 194. 202 outcrop area immediately west of Arén. Because it west. The bioclastic fore-reef detrital limestones of for section P existed an even shorter time and because of its small contain a significant percentage of pure quartz thickness in thick it could not be marked sand. In section this a sequence, Q sand occurs in smaller quantities adequately on the facies map. Here also there is a in the same deposits. The source area must have been situated in shallowing sequence with a coral reef on top, followed the west or southwest. A southern origin is out abruptly by deeper marls. ruled because the reefs are located there, a northern entire The northern shallow area thus was origin because of the deeper, muddier sediments in that characterized by a marked instability and this realm direction, and an eastern origin because the sand differs in shifted far towards the north. The isopach pattern on the composition from that in the east and also because northern side of the basin (Fig. 9) also indicates that this almost no sand occurs between sections O and B. part of the basin had lost its stability: thick successions Palaeocurrent measurements of megacross-beddings in were deposited pointing to rapid subsidence. sections A, E and K are concentrated in the sector In contrast, the southern area with shallow marine between the south and northwest. These cross-beddings carbonate deposition was mainly stationary. Many reefs were formed by ebb- and flood-currents. NW to NN>V flourished here; they form a continuous belt at least ebb-current directions were determined in section O. 50 km long and several km wide situated on the northern The nearly easterly direction measured in section P the Montsech Thus the side of threshold (Fig. 10). lower suggests a current parallel to the reef belt and agrees corbaricus with the western part of the F. Zone is characterized by the provenance of the sand in the same most exuberant and most extensive reef growth in the section. of reefs In the of Tremp Basin. Many types developed in this belt. greater part the area the deeper-water In the there of facies XIV dominate. This westernmost part (section P) are deposits means that the Lithothamnium ridges and coral-algal reefs. These reef basin as a whole was deeper than during the preceding types are dominant up to the Noguera Ribagorzana intervals. In the centre of the basin (around Arén) the River. Coral reefs become more important towards the Turritella marls are the most important facies. Probably dominate east. They almost everywhere east of this the basin here was even somewhat deeper. The deepest river. The lies only exception is section A where a part of the basin on the western border of the area Lithothamnium ridge and coral-algal reefs occur. Ap- studied, where turbidites occur. This is the region of the the breakers forceful lower of the parently were more or more part shelf and of the continental slope which effective here than else the eastern forms the transition to the oceanic everywhere along deep sea. South of of the reef belt due to the shallowness of the part sea Campo are large slumps and olistoliths (Gaemers, 1974, section A. The Lithothamnium near ridge was even figs. 2, 3). The olistoliths consist of shallow marine above level for time V, section sea some (see Chapter 3, limestones with an abundant fauna and flora; they are The western 8). dominance of algal reefs in the part of often reef limestones. Their source area was situated the belt be can explained by a combination of factors, only some km towards the northeast, from which it is viz. the shallowness of the and the evident sea greater exposure that very steep palaeoslopes existed here. to surf action than farther In eastwards. The latter cir- summary, the palaeogeography of the Tremp Basin cumstance resulted from the lack of probably sheltering in this interval is characterized by a rather deep shelf shallow areas farther towards the west. Moreover the bordered by high, steep reefs. During the later half of the relief of the sea bottom was stronger in the west than in interval the western part of the basin subsided so the east as shown the westward out of by rapid wedging markedly that the narrow elongated bay changed into a the strip where the mixed fora- imperforate-perforate more open, funnel-shaped sea with its widest opening minifera associations predominate (Fig. 10). There the directed towards the ocean. reef complex borders directly on the deeper facies (XIII and XIV). Upper part of Fasciolites corbaricus Zone (Figs. 9 and In and the eastern middle parts of the basin the reef 11) belt could maintain its the entire interval. The of this interval position during beginning is marked by an important In the western part near Benabarre the reef complex change in the supply of sediment. Sudden influxes of makes for the fore-reef sand took definitely way deeper detrital place practically simultaneously in numerous limestones This that this of the locations where thus far (facies XIII). means part no or very little sand had been reef belt shifted towards the south in the time interval deposited. Notwithstanding various interruptions this embracing the upper half of the lower part of the F. influx continued until the end of the deposition of the corbaricus Zone. Formation, and in Ager even continued younger In the entire interval treated in this section the continental deposits which followed. occurrence of sand is limited to the S of There two mainly area are separate areas one of which is situated Sant Salvador de Tolo. The around largest influx of sand occurs section H, northwest of Tremp where large in section E, with smaller but still of sand appreciable quantities quantities occur, indicating that the sand must in sections D and G. To west the a rapid decrease have derived from at least two sources. reduced the sand to almost in sections B In portion nothing the northwest, between Merli and Arén, is an area and C. This sand distribution indicates a from the which must have received much sand supply from a northern or east. Another where sand area occurs is situated in the northeastern source. Perhaps the complicated Turbón 203 structure north of the Basin is the sediment Tremp connected with these deposits thick sequences occur which this material. In supply of detrital the lower part of the belong to facies XIV. An important transgression during interval of sand. La that are the largest accumulations Near space of time as suggested by Nio (1976) is certainly Puebla de Roda the most obvious structures developed out of the question. Nio highly underestimated the at that time are giant cross-beddings. These structures. depths at which the underlying beds were formed. well as of as megacross-beddings forming parts large Subsidence and deposition near La Puebla de Roda sediment bodies, probably originated in an environment remained in fairly close equilibrium during the interval with tide-induced currents the of strong, (see Chapter V, corresponding with upper part the F. corbaricus section the formation of these 3.5). During large Zone. Probably even a regressive tendency existed: this sediment bodies the sea must have been rather deep can be deduced from the large sediment bodies migrating metres at (many tens of least), since below and above basin-inwards in the course of time. This is in 11, Facies of the F. 194. Fig. map upper part of the corbaricus Zone. Legend on p. Fig. 12. Isopach map of the F. trempinus Zone. Legend on p. 194 204 trend sufficient and food. The second consists of accordance with the regressive in all other oxygen group measured sections. limestones with cross-beddings and channels formed by number of in In the southeast there is another area with a large sand strong tidal currents. The species these limestones is fossils identified often influx. Although it is continuous, two separate sources limited, and the are Transitions between must be responsible for the sand supply. This is evident allochthonous. the two groups from the grain size distribution and the differences in the occur. amounts of sand in the area. One source can be All transitions can be found from pure carbonate tidal D and E where and siliciclastic tidal postulated east of sections larger deposits up to including pure sections. The calcareous tidal dominate in quantities of sand occur than in the adjacent deposits. more deposits siliciclastic Four other sections, viz. J, K, A and B, contain more the lower half of the interval, and the more sand As southern side of and coarser than the immediately adjacent areas. ones in the upper half. a rule on the south most This sand can only have come from the or the basin of the measured megacross-beddings were south-east. formed by ebb-tide currents. The only exception is Reefs could not flourish along the northern side of the section A where more flood-tide directions were basin because the sedimentation rate was too high. measured. the the northern side of the basin in thick Along southern side coral reefs could grow only On particular, sand siliciclastic which indicate during the time when no or almost no was supplied. sequences were deposited an from north north-east. Important reef growth occurred in a belt at least 20 km important influx of sand the or long. The probable continuation of this reef belt west of Much smaller quantities of sand occur on the southern this from section N unfortunately cannot be demonstrated because side of the basin. Probably sand came a source in in view of the size distribution in of erosion of the Ager Formation or coverage by the southeast, grain thickest reef is of a much younger sediments. The development that area. Deposition clay played more located near Sant Esteve de la Sarga (section N) and important role in this part of the basin. in the of the can be attributed to the favourable combination of slight The prevailing regressive trend deposits subsidence and limited sand supply. F. trempinus Zone can be demonstrated by the the of this The deepest part of the basin undoubtedly was differences between the lower and upper parts turbidites of the lower situated in the west where were deposited. biozone. During the deposition part open Apart from the sandy deposits discussed above, chiefly marine conditions prevailed, whereas tidal deposits were marls and XIV XV in the when silts of facies XII. and were more important upper part lagoonal deposited outside the shallow marine zone where environments covered large areas. in the calcium carbonate deposition dominated. Three different areas can be distinguished palaeogeography of the Tremp Basin during the Fasciolites trempinus Zone (Fig. 12) deposition of the F. trempinus Zone. South of the heavy The regression which started in the preceding interval dashed line in Fig. 12 only shallow marine and lagoonal contain continued during the deposition of the F. trempinus deposits occur. The marine sediments only Zone. Before the end of this interval continuing imperforate foraminifera associations. North of the sedimentation led to the filling of the shallow sea in the dashed line mixed imperforate-perforate foraminifera which greater part of the basin. Only in the westernmost part of associations also occur (facies XI and XII) the area near the Esera River did marine sedimentation indicates that temporarily a somewhat deeper sea continue. existed. From about the Isàbena River towards the west The influx of clastic material was considerable so that is the third area where the sea was even deeper when and almost limestones could first of the F. Zone pure pure barely develop. the beds trempinus were deposited. They are only observed in the lower half of the F. In this area facies XIV also occurs. The transition from continental conditions took later in that trempinus Zone, except for one bed in section B in the marine to place The upper half of the exposed part of this zone. The most area than in the more easterly regions. boundary and the important occurrence of these limestones is on the between the marine Ager Formation mainly southern side of the basin, west of the Noguera Pallaresa fluvial Montahana Group east of the Isàbena River can River. In this area there is some indication that several be considered as isochronous, because the sea withdrew small from this entire coral reefs existed. In sections J and O a thin very rapidly area. F. fore-reef and a back-reef deposit were found. On account of the poor degree of exposure of the in it is to make The limestones can be divided into two groups. The trempinus Zone many places, impossible for the first consists of nodular limestones deposited in a quiet, as accurate a facies map as other biozones. The contain because not sheltered environment. These sediments isopach map is only fragmentary enough thicknesses available for this predominantly a large number of autochthonous species measurements of total are from which it is evident that (weak) currents provided biozone. 205 CHAPTER VII GENERAL PALAEOECOLOGICAL AND PALAEOGEOGRAPHICAL PICTURE INTRODUCTION for the deposition of the entire Ager Formation east of the Isabena River. The aim of this investigation is a reconstruction of the The thicknesses of the successive biozones (see Late Paleocene-Early Eocene Tremp Basin. Much has Enclosures 2 and 3) already suggest that the time already been said about the conditions of deposition in intervals represented by these zones are of unequal the discussions of the different (sub)facies types. In this length. Convincing support of the idea that considerable discuss main features differences must have existed be obtained chapter an attempt is made to the really can and to estimate the different parameters as accurately as from the distribution of the Turritella facies. The factors Turritella in this facies possible. Unfortunately nearly all important species occurring needs a rather which combine to produce the environment can only be high sedimentation rate in order to compete with other determined in an indirect manner, such as temperature, organisms so that they are not replaced by them. When depth, salinity, pH, oxygen content, current and wave the distribution of the Turritella facies in a certain actions, light intensity, clearness of the water, etc. Fossil biozone is compared with the isopach pattern of that faunal and floral elements can provide fairly detailed and biozone, an isopach can be found which represents the accurate information about most of these factors. critical boundary outside of which the rate of sedimentation not for Sedimentary structures are an important aid in was sufficiently high the Turritella determining other factors (for example, directions of species to live. The minimum sedimentation rate currents). necessary for the occurrence of Turritella remained the All of in these factors are interrelated different same supposing the way of life of this Turritella species remain of manners, some more directly than others. A problem in to unchanged during the deposition the entire this respect is that often no simple, unambiguous Ager Formation. If the critical boundaries for the relationship exists between an organism and its Turritella facies lie at different isopachs in the different environment. biozones it For example, the depth at which an animal thus can only mean that the biozones lives is often dependent on the temperature. In that case comprise time intervals of unequal lengths: and this is in have such we an equation with two unknowns, depth and a manner that the lengths of the time intervals are temperature. Resolution is only possible if we can also proportional to the thicknesses of the biozones at the obtain data from other organisms. The total fossil critical boundary. environment with its multitude of unknown factors Comparison of the data collected in the facies and the naturally demands even more data before it is isopach maps of the F. ellipsoidalis Zone (Figs. 5, 6) sufficiently known. Detailed studies, such as the work of shows that the Turritella facies is restricted to the areas the of the lunulitiform where 40 Lagaaij (1963) on ecology the isopachs only rarely surpass values of m. In the F. moussoulensis bryozoan Cupuladria canariensis, are of great help in Zone the critical boundary of this determining the relationships between the different facies is at the 35 m isopach (Figs. 7, 8), but a factors. Thus it is evident from Lagaaij's study for markedly different value is found for the F. corbaricus example that the maximum depth at which this bryozoan Zone, namely ca. 250 m (Figs. 9. 10. II). For other facies similar occurs is determined mainly by the temperature of the types differences are noted when the F. bottom water. corbaricus Zone is compared with the F. ellipsoidalis or Most the F. moussoulensis Zone. Thus facies types of the area studied contain a large it can be concluded that the F. corbaricus variety of species so that a reasonably accurate idea of Zone lasted 6 to 7 times longer than the environmental factors can be obtained. Facies with a each of the other two biozones. This well scarcity of fossils can then be interpolated fairly agrees quite with the average thicknesses of with these biozones. Therefore the thicknesses of all precisely once the relationships the highly average individual biozones have been fossiliferous facies are known from a regional study. The taken as a measure of the of the time intervals entire reconstruction moreover will become even more length represented by these biozones. estimate reliable if different independent data are mutually A simplified which approximates the measured thicknesses is F. corroborative (Brouwer. 1967. p. 88, 89). satisfactorily that the Zone far it is trempinus (as as represented in the eastern SEDIMENTATION RATES DURATION OF of the basin) would about AND part represent the same of time THE DIFFERENT INTERVALS amount as the three lowest biozones together, whereas the F. corbaricus Zone would represent an interval which On the basis of the correlations between the zones based lasted twice as long as that of the F. Zone. The time intervals on nannoplankton and planktonic foraminifera, and trempinus represented by the benthonic foraminifera as given in Tab. 2. and F. cucumiformis Zone, the F. ellipsoidalis Zone and the comparison of the biozonation of planktonic foraminifera F. moussoulensis Zone would not differ markedly from with the time scale in table 52.40 (1971), one another. The time interval of the F. Berggren's a ellipsoidalis about 5 Zone time interval of millions years can be deduced probably was slightly longer than that of the F. 206 distribution of the sedimentation 3.16 and 3.56 moussoulensis Zone judging from the rates are cm/thousand years, Turritella facies. This facies is restricted mainly to the respectively, which are low (1-10 cm/thousand years is 40 considered area where the isopachs surpass values of m for the the range for low rates of sedimentation: see former and 35 m for the latter biozone. The time Schopf, 1969). intervals of the F. cucumiformis Zone and the F. The highest sedimentation rates can be expected in the Turritella ellipsoidalis Zone probably were about equally long. facies which generally occurs in the thickest From the above the duration of the intervals of all sections. The most continuous formation of deposits of this facies is in individual biozones can be estimated. For the F. type the F. ellipsoidalis Zone of section cucumiformis and F. ellipsoidalis Zones a value of H' at Gurp. The estimated thickness of this interval is F. Zone 60 Some thin 430 000 years is found, for the moussoulensis about m. intercalations of more slowly for the F. corbaricus Zone 2.5 million sediments however also 380 000 years, deposited are present. The and for the F. Zone in the eastern thickness of a continuous of the years trempinus part completely sequence basin 1.25 Turritella facies would therefore of the million years. certainly have been The preceding results can be used to estimate the greater and can be estimated at about 80 m. A rate of sedimentation 18.5 mean rates of sedimentation as well as more specific of about cm/thousand years can be rates for different facies. calculated from this. This is a moderate rate (10-100 The thinnest sequence found in the basin is section G, cm/thousand years is considered the range for moderate rates of ca. 3.5 km south of Sant Salvador de Tolo. The sedimentation: see Schopf, 1969). from the base of the F. Zone to The conclusion drawn is that the of sequence cucumiformis rates sedimentation the top of the F. corbaricus Zone measures 59.40 m. The in the Tremp Basin were never really of time for this interval is 3.75 millions The estimated space high. transparency of the sea water may therefore of years. The mean rate of sedimentation which can be have been good to very good in most places so that light estimated from this is the low value of 1.58 cm/thousand could penetrate down to great depths of at least 100-150 years. Cross-bedded strata in this section prove that m. often much higher rates must have existed. From this it hiatuses in this CURRENTS can be concluded that many occur sequence; this idea is supported by the occurrence of channels the In the northern 0 and 40° many at different horizons, which at same hemisphere, between latitude, time indicates considerable erosion. the atmospheric and oceanic circulations follow a in the Basin the due The thickest sequences Tremp are clockwise pattern to the Coriolis force which is Tendruy-Sant Adria section (section H) and the Tremp generated by the rotation of the earth. Such a pattern section (several km west of Tremp). The latter section must also have existed in the Atlantic Ocean during the has been described by Luterbacher (1973) and by Ferrer Palaeogene. Since the Tremp Basin is an east-west thickness of has basin with wide et al. (1973); both give a 900 m. It running a opening to the Atlantic Ocean appeared that the thicknesses of all sections which were in the west, it is highly probable that it was a part of this measured the A again during present study are always oceanic circulation pattern. consequence of this is that found to be smaller than those given by Ferrer et al. The a sea current from (north)west to (south)east would have thickness of the Tremp section comprising the entire entered the basin along its northern side, and would have Ager Formation is therefore estimated to be about left the basin along its southern side running in the 800 m. The mean rate of sedimentation for this section opposite direction. thus The of amounts to 16 cm/thousand years in that case, ten strength this current however could impossibly times be as rapid as the rate of section G. Hiatuses caused great. In any case it would not be able to form erosion by non-deposition or are hardly to be expected megacross-beddings or giant cross-beddings on the sea in the Tremp section because the strata generally bottom. By far the greater part of these structures will changed gradually. therefore have been formed by tidal currents. For the of sedimentation rates of Measurements of the directions of the estimation the mega ripples along specific facies types or the rate necessary for the the southern side of the basin reveal that ebb-tide formation currents this of glauconite, it is necessary to find sequences are overrepresented here; supports the idea in which that facies is of a E-W current which intensified the type present as continuously as roughly running F. Zone possible. The upper part of the corbaricus in influence of the ebb-tides. sections for The above-mentioned K and N is most suitable in this respect outline seems to be the most glauconite. The duration of this interval was about 1.25 probable model in the event that the basin only opened million years. Glauconite-bearing deposits predominate to the Atlantic Ocean. From the palaeogeographical of reconstruction of the F. Zone it markedly in these sections, and the remaining parts cucumiformis appears the sections consist mainly of reefs and related certain that this situation did exist during that interval. sediments which also developed at comparably low rates The same geographical situation must have existed at of sedimentation (in reefs least the of some deeper glauconite occurs during upper part the F. trempinus Zone. in F. situ). The thicknesses of the upper part of the For the interjacent interval nothing can be said with corbaricus Zone are 39.50 m and 44.50 m for sections K certainty because the sea extended too far beyond the and N, respectively. The calculated estimations of the outcrop area of the Ager Formation. It is however 207 probable that during at least a part of this interval, Lees & Buller (1972) these are called the chlorozoan and namely at the time of maximum transgression, a the foramol associations, respectively. Hermatypic corals connection with the Tethys (Mediterranean Sea) existed, and calcareous algae (for instance Halimeda) are because not far to the east, in the Sierra del Cadi and in abundant in the coral-algal facies whereas brachiopods, of the also and barnacles In the the vicinity of Oliana, deposits same age bryozoans are scarce. developed under clearly marine conditions. During that bryozoan-algal facies the opposite holds. Red algae and time the Tremp Basin would have formed part of a strait foraminifera are about equally abundant in both facies, between the Atlantic Ocean and the Tethys, by which and molluscs are somewhat more important in the Spain was isolated from the western European continent. bryozoan-algal facies (Schlanger & Konishi, 1975, fig. This is a much more complicated palaeogeographical 2a; Lees & Buller, 1972, fig. 1). situation, it is difficult in how far the facies in and therefore to say Generally coral-algal the area studied and in which respect the current pattern differed from represents the shallower, warmer waters and the facies the above-mentioned model. The only thing that can be bryozoan-algal the deeper, colder waters. This said is that there is a greater likelyhood of higher current can easily be explained by the well-known dependence of velocities in the event that the Tremp Basin was part of hermatypic corals on intense sunlight and relatively water such a connecting seaway. high temperatures (Wells, 1957). In tropical areas characterized by the vigorous growth of coral and algal CLIMATOLOGICAL EVIDENCE reefs bryozoans are abundant at depths of several tens of metres (Maxwell et al., 1961; Maxwell, 1968). In higher times situated the latitudes inhabit shallower During Eocene the Pyrenees were on bryozoans can depths because thirtieth degree of northern latitude (Smith et al., 1973, of the lack of competition of reef corals. At It is not accidental that reef in the text-fig. 6, map I). present this would mean a location growth Tremp on the extreme margin of the tropics. On a world-wide Basin was most extensive during the time that submarine relief scale the Paleocene-Eocene climate was on the average was most pronounced. In the present-day marginal and clearly warmer than it is now, for no extremely cold reef growth zone, coral algal reefs can grow only on climates existed at that time. A wider tropic belt must relief elements that clearly rise above their surroundings. in have hemmed the equator, and the other climatic belts On the weakly sloping parts between the must have shifted towards the poles. Therefore the area bryozoan-algal facies dominates (Carrigy & Fairbridge, 1954; Maxwell et al., 1961; van Andel & Veevers, 1965; studied was definitely located within the tropics. The Maxwell, coral reefs and the thick and compact Lithothamnium 1968). ridges are the most striking witnesses of such AUTOCHTHONOUS GLAUCONITE, AN IMPOR- climatological conditions. EXPEDIENT IN PALAEOECOLOGICAL Nevertheless the Tremp Basin must have been in the TANT RECONSTRUCTIONS zone of marginal reef growth as defined by Schlanger & Konishi (1975), judging from the composition of the encountered fauna and flora. This is due mainly to the The authigenic mineral glauconite can be formed in with fact that the Tremp Basin was connected with the water a pH slightly higher than 7, under mildly if turbulence and sedimentation eastern part of the Atlantic Ocean. At tropical latitudes reducing conditions, rates are not too The suitable the eastern sides of the oceans are generally colder than high. temperature range the western sides (Lees & Buller, 1972); these regional for the formation of this mineral is fairly limited. circulation the minimum is about 15 °C and differences can be explained by the oceanic Probably temperature 20 As which in its turn is influenced by the rotation of the the maximum °C. a result the depth interval in in which be formed is also rather limited. In earth on the climate. Reef growth was relatively weak glauconite can the Tremp Basin, although reefs and related facies temperate seas glauconite originates mainly at depths of about 30 m. In it is formed covered large areas during some episodes. The tropical areas at much greater The of autochthonous production of coral was low so that the reefs could not depths. deepest occurrence would be 250-500 m above-mentioned contribute much material to deeper facies. As a result glauconite (all the production of indigenous material in deeper water data from McRae, 1972; Buurman, 1973). The statement and colonies of that the maximum is not was not obscured by transported coral algal Kohier (1977) depth 800 m is because the will not be and the shells of other reef inhabitants as would happen very likely required temperature reached at that under circum- when vigorous reef growth occurred (Schlanger & easily depth present A stances. Konishi, 1975, fig. 4). fortunate consequence is that much Within such limited area as the Tremp Basin where many facies types can be distinguished more a uniform climatic conditions be assumed to have sharply and clearly than in the zone of optimum reef can growth. The specific character of the deeper facies existed we may proceed from the assumption that the basin the limit for autochthonous bordering on the reefs thus is clearly evident in the throughout upper Tremp Basin. glauconite remained approximately the same. Along the side of the basin this limit was probably A peculiarity of the area studied is that typical northern & somewhat because of the influence of the current coral-algal as well as bryozoan-algal facies (Schlanger higher Whenever Konishi, 1975) have been found. In the terminology of entering from the Atlantic Ocean. the 208 that the water in sedimentation rate was not too high during most of the This means temperatures of the sea the of basin will formation of the marine sediments of a certain section, shallow and protected parts the easily have reached value of 30 °C. Near beaches and in then the parts with autochthonous glauconite of such a lagoons conditions section must have been formed in deeper waters and the where evaporitic prevailed, even higher be parts without this mineral in shallower waters (the lower temperatures can expected. with recent for instance limit of the occurrence of glauconite will never have Corresponding examples (see le facies with foraminifera been reached in the area studied, except perhaps in the Roy, 1938) imperforate - extreme western part mainly west of the Esera River). associations (viz. subfacies IVa, b, e; Va; Vla-f; Vila, Vllla-c and Sometimes glauconite was transported to shallower b; IXb) are indicative of the shallowest and waters. Then it was often more or less oxidized. The warmest parts of the sea (depths of 0-25 or 30 m). In most obvious example of allochthonous glauconite has fact subfacies IVa-c, Vila, b and VIIIa-e are generally F. X been found in the cucumiformis Zone of section confined to the upper part of this range, whereas subfacies Va is limited the lower of this (samples 21a, 21b). Here a glauconitiferous layer strictly to part and containing many transported fossils from a large variety range. As a rule coral reefs (subfacies VHId) off-reef of marine environments lies between shallow marine shoal limestones (subfacies IXa) will also have developed with foraminifera associations above of often contain deposits imperforate depths 25-30 m. although they a (facies VI). The glauconite of this layer is largely mixed perforate-imperforate foraminifera association. The elements oxidized into a brown-coloured mineral. perforate here are usually allochthonous. In the tropical part of the present eastern Atlantic Mixed perforate-imperforate foraminifera associations (facies XI and XII) in Ocean (between latitudes 10° N and 10 °S) temperatures occur deeper waters, although a of 20 °C usually prevail at depths of 50-100 m (Corcoran considerable overlap with the preceding association exists. Le (1938) for instance found - & Mahnken, 1969; Voigt et al., 1969). Above 50 m Roy an Operculina at than higher temperatures exist, so that no glauconite can be Ozawaia community depths greater 18 m. formed there. The Tremp Basin was situated at a more Differences in environmental protection are the cause of latitude it of strait this Perforate elements inhabit northern but because was part a or a overlap. can shallower Atlantic Ocean it will the in the than in less sheltered narrow appendix to the upon depths open sea more or environments, whole have been warmer than the open ocean at the and the opposite is true for the elements, such as alveolinids same latitude due to its more sheltered position. imperforate most and Orbitolites. Therefore the minimum depth of the occurrence of The lower boundary of the mixed glauconite can be estimated at about 50 m. perforate-imperforate foraminifera association generally Facies XIII and XIV nearly always developed below coincides with the upper limit of the occurrence of this critical boundary. Facies XV can occur above as glauconite, namely ca. 50 m. Only in rare instances somewhat be well as below this depth; this can only be deduced from greater depths can assumed. indirect sources, for the rate of sedimentation of the The perforate foraminifera associations (facies XIII, Turritella marls was too rapid for the formation of XIV and part of facies XV) consequently inhabited sea in bottoms 50 glauconite. The presence or absence of glauconite at depths greater than m as already described. thin, intercalated layers which were deposited slowly The recent bryozoan species Biflustra savartii determination reefs make a depth possible. Some is known to live below ca. 100 m; subfacies XIlib is (subfacies Ville) must have flourished in waters deeper characterized by a Biflustra community. Subfacies XHIa 50 from the of than about m, judging presence contains the most diverse bryozoan fauna of the Tremp autochthonous glauconite which colours parts of the Basin; according to Schopf (1969) nowadays the largest skeletons of many corals. The regular occurrence of this numbers of species of bryozoans occur between depths mineral and the accompanying faunal elements in of 50-100 metres. Therefore a maximum depth of about subfacies Vb of formation of about 40-50 be for suggest a depth 100 m can supposed subfacies XHIa and XHIb on m for this subfacies with its giant cross-beddings. Facies the grounds of the bryozoans. Subfacies XIIIc is XI and XII sometimes developed within the depth range generally so closely connected with the other two that it in of this mineral but generally they developed shallower must have been limited to the same depth interval. The autochthonous and various water. All other facies never contain presence of large benthonic foraminifera at to glauconite and developed depths of less than 50 groups of molluscs which are limited the photic zone metres. suggests that the sea in the area studied was rarely than about deeper 100-150 m. The temperature certainly OTHER TEMPERATURE/DEPTH DATA was not below 15 °C at the normal maximum depths, since glauconite always occurred whenever the rate of foraminifera In most facies types large benthonic sedimentation was sufficiently low. predominate. At present the tropics are the only area A three-dimensional model can be drawn in which the distribution where this is the case. This together with the position of the various (sub)facies types with respect to of and occurrence coral reefs, algal reefs, calcareous green one another with respect to the depth of the sea is of in the As algae and many other tropical groups organisms given (Fig. 13). many subfacies as possible are Tremp Basin make only one conclusion possible, namely included in this block diagram (only subfacies IVe, Va that this area was situated in the tropical climate zone. and Vb are not represented), so that the true 209 followed the of The smaller Basin, relationships are somewhat strained: the relative spaces to Bay Biscay. Ager occupied by the subfacies were sometimes larger in fact having an axis parallel to that of the Tremp Basin, can subfacies be considered similar basin which the than depicted here. Many moreover have only a joins large structure. been found in a limited stratigraphic range. Fig. 13 The basins are separated by the Montsech therefore is a theoretical diagram, for which data threshold. North of the Tremp Basin is a positive area, concerning the development of the entire Tremp Basin and north of that the southern French marginal trough. were used. The latter two units also have an east-west directed It has been attempted to indicate the most frequently axis. occurring relationships between the different (sub)facies In cross-section therefore the picture is that of an types, but it should be remembered that one subfacies in accordeon-like structure on which smaller undulations outside nature often also bordered on other subfacies. The may have been superposed the Tremp Basin. model thicknesses of various subfacies shown in the The direction of this structure agrees completely with estimated direction of force have been made to agree with the the the greatest compressional due to sedimentation rates of these subfacies. the collision of Africa and Europe between which Spain was pinched. During the formation of the Ager Formation the TECTONICS AS CAUSE FOR THE EXISTENCE OF compression was apparent partly as the slow but THE PALAEOGENE TREMP BASIN persistent deepening of the Tremp Basin which was the greatest near the axis of the basin. As a result some N-S It be asked the Basin existed and of basin this may why Tremp why shortening the occurred; when could no it has the shape it actually has. longer happen (in the course of the Eocene) the other The Basin of Tremp forms the easternmost part a possibility of shortening, namely nappe formation, took large east-west trending basin structure which can be place. between the different (sub)facies Fig. 13. Three-dimensional model in which the most frequently occurring relationships types are with the estimated sedimentation of these subfacies. shown. The thicknesses of various subfacies have been made to agree rates 210 REFERENCES Adey, W. H. & Burke, R., 1976. Holocene bioherms (algal artikel van S. G. McRae, Glauconite, Earth Sci. Rev., 8, pp. ridges and bank-barrier reefs) of the eastern Caribbean. Geol. 1972). Meded. Werkgr. Tert. Kwart. Geol., 10/3, Soc. America 87, 95-109. 79-86. Bull., pp. pp. Alastrué, E., Almela, A. & Rios, J. M., 1957. Explicación al Y. foraminifères mapa geològico de la provincia de Huesca, escala 1:200.000. Calvez, le, 1975. Repartition des dans les Inst. Geol. Minerò Esp., Madrid, 253 pp., 2 maps. différents facies de l'Ilerdien de la region de Tremp. Bull. al Soc. Géol. Almela, A. & Rios, J. M., 1947. Explicación mapa geologico France, (7) 17/2, pp. 191-194. 1975. Les ostracodes de l'Ilerdien de la provincia de Lérida, escala 1:200.000. Inst. Geol. Carbonnel, G., (Eocène inférieur) Minerò Esp., Madrid, 193 pp. du bassin de Tremp (Espagne): stratotype et & Submarine avoisinantes. Rev. 37-50. Andel, T. H. van Veevers, J. J., 1965. coupes Esp. Micropal., 7/1, pp. morphology of the Sahul shelf, northwestern Australia. Geol. Carez, L., 1881. Etudes de terrains crétacés et tertiaires du America 695-700. nord de Librairie 323 Soc. Bull., 76, pp. l'Espagne. Savy, Paris, pp. Anonymous, 1975. Propositions (Séance spécialisée du 18 Caro, Y., Luterbacher, H.-P., Perch-Nielsen, K., novembre 1974 sur "Le contenu de l'Ilerdien et sa place Premoli-Silva, I., Riedel, W. R. & Sanfilippo, A., 1975. dans le Paleogene"). Bull. Soc. Géol. France, (7) 17/2, 223 Zonations à l'aide de microfossiles du Paleocène supérieur et de l'Eocène inférieur. Bull. Soc. Géol. pp. France, (7) 17/2, pp. Arambourg. C 1952. Les vertébrés fossiles des gisements des 125-147. phosphates (Maroc - Algerie - Tunisie). Protectorat de la Carrigy, M. A. & Fairbridge, R. W., 1954. Recent République francaise au Maroc, Direction de la production sedimentation, physiography and structure of the continental industrielle et des mines, Division des mines et de la shelves of Western Australia. Jour. Roy. Soc. West. geologie. Service géologique. Notes et Mémoires, 92, 372 pp. Australia, 38, pp. 65-95. Casier, E., 1946. La faune ichthyologique de l'Yprésien de la O. 1964. General correlation of foraminiferal Mém. Mus. hist. 104, 267 Bandy, L., Belgique. roy. nat. Belg., pp. structure with environment. In: J. Imbrie & N. Newell Caspers, H., 1950. Die Lebensgemeinschaft der Helgolander Austerbank. wiss. (eds.). Approaches to paleoecology. John Wiley, New York, Helgol. Meeresunters., 3, pp. 120-169. Chapman, F., 1899. On some new and Foraminifera pp. 75-90. interesting W. from the Funafuti Ellice Islands. Linn. Berggren, A., 1964. Paleocene - Lower Eocene Atoll, Jour. Soc, biostratigraphy of Luxor and nearby Western Desert. Petr. Zool., 28, pp. 1-32. Explor. Soc. Libya, 6th Ann. Field Conf., pp. 149-176. Cheng, Y. M., 1974. Paleocurrent direction of the Taliao The Formation indicated -, 1971. Tertiary boundaries and correlations. In: (Lower Miocene) by Ditrupa sp. M. W. micropalaeontology of the oceans (ed. B. Funnel & R. (Serpulidae) shells. Acta Geol. Taiwanica, 17, pp. 13-22. Riedel). At the University Press, Cambridge, pp. 693-809. Chevalier, J. P., 1973. Coral reefs of New Caledonia. In: O. A. Bignot, G., 1975. Extraits de la discussion qui suivit la Jones & R. Endean (eds.). Biology and geology of coral reefs, I, Geology I. Academic Press. New York, presentation des communications sur "Le contenu de pp. 143-167. l'Ilerdien et sa place dans le Paleogene". Bull. Soc. Géol. Cole, W. S., 1957. Larger Foraminifera from Eniwetok Atoll 17/2, 218-221. drill holes. U. S. Geol. Surv. Prof. Pap., 260-V, 743-784 France, (7) pp. pp. J. S. & W. 1970. - & Position relative du de Coleman, M.. Gagliano, Smith, G., Moorkens, Th., 1975. stratotype M., à Sedimentation in tide delta. In: Deltaic l'Ilerdien et de plusieurs autres étages par rapport quelques a Malaysian high sedimentation. Modern and ancient (ed. J. P. microbiozonations. Buil. Soc. Géol. France, (7) 17/2, pp. Morgan). 208-212. Special Pubi., Soc. Econ. Paleontol. & Mineral., 15, pp. Blondeau, A., Cavelier, C, Feugueur, L. & Pomerol, C., 1965. 185-197. & Mahnken. of Stratigraphie du Paleogene du Bassin de Paris en relation Corcoran, E. F. C. V. W., 1969. Productivity the Atlantic Ocean. of the avec les bassins avoisinants. Buil. Soc. Géol. France, (7) 7/2, tropical Proceedings symposium 200-221. on the oceanography and fisheries resources of the tropical pp. Bodelle, J. & Campredon, R., 1968. Les formations à Atlantic, Abidjan. Ivory Coast, 20-28 October 1966, Unesco, Microcodium dans les Alpes-Maritimes franco-italiennes et FAO & OAU, pp. 57-67. L. 1960. General characteristics of In: les Basses-Alpes, leur importance paléogéographique. Mém. Cox, R., Gastropoda. B. Treatise on Invertebrate I, Mollusca (ed. R. R. G. M., 68, pp. 453-471. Paleontology, 1 C. Moore), 185-1169. Boekschoten, G. J., 1963. Paleoecological notes on the Septaria pp. Clay (Oligocene) of the eastern Netherlands. Proc. Koninkl. Crochet, B., Tambareau, Y. & Villane, J., 1976. Modalités de la ilerdienne l'Aude. Les à Ned. Akad. 66/5, 280-295. regression entre l'Ariège et plages Wetensch., (B) pp. Boucot, A. J., 1975a. Evolution and extinction rate controls. Eoscutum doncieuxi (Lambert). C. R. somm. Soc. Géol. France, 1976/2, 35-37. Elsevier, Amsterdam, 427 pp. pp. -, 1975b. Standing diversity of fossil groups in successive Crusafont, M., Renzi, M. de, & Clavell, E., 1966. Un corte intervals of geologic time viewed in the light of changing estratigràfico del Garumniense - Paleoceno - Eoceno en la levels of del Isàbena. Acta Geol. provincialism. Jour. Paleontol., 49/6, pp. 1105-1 111. cuenca preaxial Hisp., 1/5, pp. 1977. Rates of evolution and number of 22-24. -, descriptive terms. Jour. 4I4--415. M. & 1968. Les Paleontol., 51/2, pp. Crusafont, M., Renzi, de, Clavell, E., grands Brady, H. B., 1884. Report on the Foraminifera dredged by H. traits d'une coupure Crétacé - Paleocène - Eocène au sud M. S. 'Challenger' during the years 1873-1876. Rep. Voy des Pyrenees (Isàbena). Mém. B. R. G. M., 58, pp. 591-596. 2 115 Challenger Zool., 9, 814 pp., maps, pis., London. Crusafont, M., Roseli, J., Golpe, J. M. & Renzi. M. de, 1968. Brouwer. A.. 1967. General palaeontology. Oliver & Boyd, Le Paleogene de la vallèe d'Ager et ses rapports avec celui Edinburgh & London. 216 pp. de la Conca de Tremp (Pyrenees de la province de Lérida, Buurman, P., 1973. Glauconiet (een samenvatting van het Espagne). Mém. B. R. G. M., 58, pp. 583-589. 211 Curry, D., 1975. The status of the Ilerdian and its relation to Gaemers, P. A. M., 1971. Een paleo-ecologische studie van de - the Palaeocene - Eocene boundary. Bull. Soc. Géol. France, Cadi en de Roda Formatie (Boven-Paleoceen (7) 17/2, p. 222. Onder-Eoceen) in het oostelijk deel van de provincie Huesca Curtis, R., Evans, G., Kinsman, D. J. J. & Shearman, D. J., (deels in de provincie Lérida) in Spanje. Unpublished 1963. Association of dolomite and in the master's 5 5 82 12 anhydrite recent thesis, 60 pp., figs., 1 tab., maps, photos, sediments of the Persian Gulf. 197, 679-680. sections. Nature, pp. J. 1917. A of the Foraminifera of the 1974. A on Lower Cushman, A., monograph -, study Tertiary stratigraphy, paleogeography North Pacific Ocean. Part 6. Miliolidae. Bull. U. S. Nat. and tectonics in the Spanish Pyrenees. Kon. Nederl. Akad. 108 Wetensch., Mus., 71, pp. (B) 77/3, pp. 246-258. -, 1933. The Foraminifera of the tropical Pacific collections of -, 1976. New concepts in the evolution of the Gadidae the 1899-1900. Part 2: to their Albatross, Lagenidae (Vertebrata, Pisces), based on otoliths. Meded. Werkgr. U. Nat. Alveolinellidae. Bull. S. Mus., 161, pp. 1-79. Ten. Kwart. Geol., 13/1, pp. 3-32. 1978. of the alveolinids of -, Systematics the Tremp Basin, M., 1910. Etude des de south-central Leidse Geol. Dalloni, géologique Pyrenees l'Aragon Pyrenees, Spain. Meded., 51, pp. Ann. Fac. Sci. Marseille, 19, 444 pp. 103-129. -, 1930. Etude géologique des Pyrenees catalanes. Ann. Fac Gardiner, J. S., 1906. The fauna and geography of the Maldive Sci. 373 Marseille, 26, pp. and Laccadive Archipelagos, II/6. Lagoon deposits I. Deloffre, R., 1970. Niveau à algues dans le Sparnacien de la General account. Cambridge, pp. 581-583. de - et Garrido 1973. region Piagne (Petites-Pyrénées Haute-Garonne) Megias, A., Estudio geològico y relación entre Neomeris observations sur Ie genre Lamouroux, 1816. Buil. tectónica y sedimentación del Secundario y Terciario de la Centre Rech. Pau - SNPA, 4/2, pp. 353-379. veniente meridional Pirinaica en su zona central (provincias Doyle, L. J., Cleary, W. J. & Pilkey, D. H., 1968. Mica: its de Huesca y Lérida). PhD thesis. University ofGranada, 395 use in Marine Geol., 51 9 of enclos. determining shelf-depositional regimes. pp.. figs., sets (incl. sections, maps, etc.). 6, pp. 381-389. - & Rios Aragües, L. M.. 1972. Sintesis geològica del Secundario Terciario entre los Ducasse, O., 1972. Ostracodes de la coupe de Campo (Prov. y rios Cinca y Segre (Pirineo Huesca, Espagne). Rev. Esp. Micropal., Madrid, num. extr., Central de la vertiente sur de Huesca pirinaica, provincias y 273-289. Bol. Geol. Minerò, 1-47. pp. Lérida). 83/1, pp. Dunham, R. J., 1962. Classification of carbonate rocks Gartner, S. & Hay, W. W., 1962. Planktonic Foraminifera from In: Classification of the Ilerdian. Eel. Geol. 553-572. according to depositional texture. type Helv., 55/2, pp. carbonate rocks - A symposium (ed. W. E. Ham). Mem. Ghibaudo, G.. 1976. Depositi di barra di foce nel Paleogene Ass. Boll. Amer. Petr. Geol., 1, pp. 108-121. della Valle di Ager (Provincia di Lérida, Spagna). Soc. Geol. Ita!., 94/6, pp. 2131-2154. Eden, J. G. van, 1967. Het Eoceen in het bekken van Tremp -.Morelli, E., Mutti, E., Obrador, A., Pons, J. M., Unpublished master's thesis, Leiden. Ramasco, M. & Roseli, J., 1973. Osservazioni Reconnaissance of deltaic environment in the Middle -, 1970. sedimentologiche preliminari sulle Arenarie di Aren Eocene of the south-central Geol. Pyrenees, Spain. (Cretacico superiore) tra Isona e il Rio Noguera Ribagorzana Mijnbouw, 49/2, pp. 145-157. (Prepirenei spagnoli). Boi. Soc. Geol. Ital., 92, pp. 529-540. C. E., 1893. Foraminiferen aus Egger, Meeresgrundproben. -, Mutti, E. & Roseli. J., 1974. Le spiagge fossili delle Arenarie gelothet von 1874 bis 1878 von S. M. Sch. Gazelle. Abh. k di Aren (Cretacico superiore) nella valle Noguera bay. Akad. Wiss. 2 CI., 18/2, pp. 195^158. Ribagorzana (Pirenei centro-meridionali, provincia di Lérida e Huesca, Spagna). Mem. Soc. Geol. Hai., 13, pp. 497-537. Fauvel. P., 1953. The fauna of India including Pakistan, Ghose, B. K., 1977. Paleoecology of the Cenozoic reefal Annelida, - Ceylon, Burma and Malaya. Polychaeta. The foraminifers and algae a brief review. Palaeogeogr., Indian Press, Ltd., Allahabad, 507 pp. Palaeoclimat., Palaeoecol., 22/3, pp. 231-256. Ferrer, J., Luterbacher, H. P., Mutti, E. & Roseli, J., 1971. El Graaff, W. J. E. van de, 1971. Three Upper Carboniferous, Paleogeno marino de la region de Tremp (Cataluna). I limestone-rich, high-destructive, delta systems with Congreso Hispano-Luso-Americano Geol. Econ., sección 1. submarine fan deposits, Cantabrian Mountains, Spain. Leidse 2, 813-827. Geol. 157-235. Geologia, pp. Meded., 46, pp. Ferrer, J., Calvez, J. le, Luterbacher, H. P. & Premoli Silva, I., 1973. Contribution à l'étude des foraminifères ilerdiens de Hageman, B. P., 1969. Development of the western part of the la Hist. region de Tremp (Catalogne). Mém. Mus. Nat. Nat., Netherlands during the Holocene. Geol. Mijnbouw, 48, pp. nouveau série, (C) 29, pp. 1-107. 373-388. Folk, R. L., 1959. Practical petrographic classification of Hanzawa, S., 1948. A comparative study of the fossil limestones. Amer. Ass. Petr. Geol. 1-38. foraminiferal fauna of the Limestone and the Bull., 43, pp. Ryukyu recent fauna of Islands. 1962. Spectral subdivision of limestone types. In: the Ryukyu Rept. Comm. Treat. Marine A W. E. Classification of carbonate rocks - symposium (ed. Ecol. Paleoecol., 7, pp. 77-88. Die Tierwelt Ham). Mem. Amer. Ass. Petr. Geol., 1, pp. 62-84. Hartmann-Schröder, G., 1971. Deutschlands und 1976. Rollers and in streams and der Meeresteile nach ihren Merkmalen und -, ripples sand, sky: rhythmic angrenzenden alteration of transverse longitudinal vortices in three orders. nach ihrer Lebensweise. 58. Annelida, Borstenwürmer, Sedimentology, 23/5, pp. 649-668. Polychaeta. Gustav Fischer Verlag, Jena, 594 pp. 1957. P. M. Forman, McL. J. & Schlanger, S. O., Tertiary reef and Haseldonckx, A., 1972a. Palynologie van paleogene Jour. associated limestone facies from Louisiana and Guam. afzettingen tussen de Rio Segre en de Rio Esera, Zuidelijke 81 Geology, 65/6, pp. 611-627. Pyreneeën, Spanje. Unpublished master's thesis. Leiden, Frey, R. W. (ed.), 1975. The study of trace fossils. Springer pp., 9 figs., 20 tab. in a Verlag, Berlin, Heidelberg, New York, 562 pp. -, 1972b. The presence of Nypa palms Europe: solved problem. Geol. Mijnbouw, 51/6, pp. 645-650. 212 1973. The of some Palaeogene deposits between im Palaogen der Pyrenàen. Ecl. Geol. Helv., 66/3, pp -, palynology 687-737. the Rio Esera and the Rio Segre, Southern Pyrenees, Spain. 145-165. - & 1975. L'Ilerdien dans les dans les Leidse Geol. Meded., 49, pp. -, Alpes, Pyrenees et en Hay, W. W., 1964. Utilisation stratigraphique des disco- Crimée. Correlation de zones à grands foraminifères et à astéridés la zonation Paleocène Buil. Soc. Géol. France, 17/2, pour du et de l'Eocène nannoplancton. (7) pp. inférieur. Mem. B. R. G. M., 28, pp. 885-889. 148-161. 1969. On boundaries between the Paleocene, Kauffman, E. G.. 1969. Form, function and evolution. In: -, defining R. Part N. Mollusca Eocene and Oligocene. Mém. B. G. M., 69, pp. 197-200. Treatise on invertebrate paleontology. 1. 6, Hedberg, H. D. (ed.), 1972. International Subcommission on Bivalvia (ed. R. C. Moore). Geol. Soc. America, Inc. & Stratigraphic Classification (ISSC). (a) Introduction to an Univ. Kansas, pp. N129-N205. international guide to stratigraphic classification, termino- Keene, J. B. & Kastner, M.. 1974. Clays and formation of logy, and usage; (b) Summary of an international guide to deep-sea chert. Nature, 249, pp. 754-755. stratigraphic classification, terminology, and usage. Lethaia, Kohier, E. E., 1977. Zum Stand der Glaukonitforschung - eine Zbl. Geol. Palàontol., Teil I, 5/3, pp. 283-323. Bibliographic 1976/5,6, pp. 1976. International Guide. A to 974-1017. -, (ed.) Stratigraphic guide stratigraphic classification, terminology, and procedure. Konishi, K. & Epis, R. C, 1962. Some early Cretaceous from Cochise Arizona. Wiley, New York, London, Sydney, Toronto, 200 pp. calcareous algae County. Hillebrandt. A. von, 1965. Foraminiferen-Stratigraphie im Micropaleontology,8/1, pp. 67-76. Sedimentologie en van de Alttertiàr von Zumaya (Provinz Guipiizcoa, NW-Spanien) und Kooter, C. M., 1970. stratigrafie Devotas ein Vergleich mit anderen Tethys-Gebieten. Bayer. Akad. Formatie van Tremp en de Formatie. Unpublished Wissensch., Math. Naturwiss. K.I., Abhandl., N. F., 123, 62 master's thesis, Leiden. 67 pp., 35 figs., 7 end., 6 sections, 7 detail sect., 64 pp. photos. Correlation les biozones de foraminifères Kruit. C. & Brouwer, J., 1971. sobre la -, 1975. entre grands Investigaciones et de foraminifères planctoniques de lTlerdien. Buil. Soc. geologia sedimentaria de la cuenca sur pirenaica. I Congr. Géol. 162-167. Geol. France, (7) 17/2, pp. Hispano-Luso-Americano Econ., Madrid-Lisboa, 1971, 213-224. Hofker, J., 1930. The Foraminifera of the Siboga Expedition. secc. 2, pp. Brill. Kumar. N. & J. E., 1976. Characteristics of shoreface Part 2. Siboga-Expeditie IVa. Leiden, 92 pp. Sanders, modern and ancient Jour. Sed. Hoorn, B. van, 1970. Sedimentology and paleogeography of an storm deposits: examples. Upper Cretaceous turbidite basin in the south-central Petr.,46/1, pp. 145-162. Pyrenees, Spain. Leidse Geol. Meded., 45, pp. 73-154. Low Hottinger, L., 1960. Über paleocaene und eocaene Alveolinen. Lagaaij, R., 1952. The Pliocene Bryozoa of the Countries and their marine the North Sea Ecl. Geol. Helv., 53/1, pp. 265-284. bearing on the stratigraphy of Mcdcd. Gcol. (C) 233 -, 1962. Recherches sur les Alvéolines du Paleocène et de region. Stichting, 5/5, pp. Schweiz. Palaontol. 1963. canariensis (Busk) - Portrait of a l'Eocène. Abh., 75/76, 243 pp. -, Cupuladria 172-217. 1963. Les alvéolines d'un bryozoan. Palaeontology, 6/1, pp. -, paléogènes. exemple genre - from marine polyphylétique. In: Evolutionary trends in foraminifera. A & Gautier. Y. V.. 1965. Bryozoan assemblages I. M. sediments of France. collection of papers dedicated to van der Vlerk on the the Rhone delta, Micropaleontology. R. 39-58. occasion of his 70th birthday (eds. G. H. von 11/1, pp. Koenigswald et al.), pp. 298-314. Lees, A. & Buller, A. T., 1972. Modern temperate-water and 1973. shelf carbonate sediments contrasted. Mar. -, Selected Paleogene larger Foraminifera. In: Atlas of warm-water Paleobiogeography (ed. A. Hallam). Elsevier, Amsterdam, Geol., 13, pp. M67-M73. London, New 443-452. Lipps, J. H. & Valentine, J. W., 1970. The role of York, pp. Lehmann, R. & Schaub, H., 1964. Données actuelles sur Foraminifera in the trophic structure of marine communities. -, B. la biostratigraphie du nummulitique méditerranéen. Mém. Lethaia, 3, pp. 279-286. R. G. 610-652. 1977. de la fauna de moluseos M., 28, pp. Llompart, C, Paleoecologia & Schaub, H., I960. Zur des Paleocaens ilerdienses en un de la Vail Lleida). -, Stufeneinteilung sector d'Ager (prov. und des der Stuf Ilerdien und Thesis. Univ. Autón. Barcelona, Public. Geol.. 7, 1-249. Eocaens. Einführung en pp. Biarritzien. Eel. Geol. Helv., 53/1, pp. 453-479. Lucia, F. J., 1972. Recognition of evaporite-carbonate shoreline sedimentation. In: Recognition of ancient sedimentary Soc. Illing. L. V., Wells, A. J. & Taylor, J. C. M., 1965 environments (eds. J. K. Rigby & W. K. Hamblin). Penecontemporary dolomite in the Persian Gulf. In Econ. Paleont. Mineralogists. Spec. Pubi.. 16. pp. 160-191. Dolomitization and limestone diagenesis - a symposium. Soc Luterbacher. H. P.. 1969. Remarques sur la position Econ. Paleont. 89-111. de la Formation (Pyrenees Mineralogists, Spec. Pubi., 13, pp. stratigraphique d'Ager Méridionales). Mém. B. R. G. M.. 69. pp. 225-232. du Jacob, Ch. & Fallot, P., 1914. La nappe de charriage -, 1973. La sección tipo del piso Ilerdiensc. I3th Coloq. Europ Madrid. 113-140. Montsech, en Catalogne. C. R. Acad. Sci., 150. p. 1222. Micropaleont., Espana, pp. 1975. sur "The status of the Ilerdian and its Jacob, Ch., Fallot. P.. Astre, G. & Ciry, R.. 1927. -, Remarques relation to the Palaeocene-Eocene Dennis Observations tectoniques sur le versant meridional des boundary" par Bull. Soc. Géol. France. (7) 222. Pyrenees centrales et orientales. C. R. XIV Congr. Int. Curry. 17/2. p. Geol.. Madrid. 2, pp. 335-412. 1961. le Jelgersma, S., Holocene sea level changes in the Mangin, J.-Ph., 1959. Données nouvelles sur Nummulitique Netherlands. Meded. Geol. Bull. Soc. Géol. France, (7) 16-30. Stichting, (C) 6/7, 101 pp. pyrénéen. 1/1, pp. Martini, E., 1970. Standard Paleogene calcareous Kapellos. Ch. & Schaub, H., 1973. Zur Korrelation von nannoplancton zonation. Nature, 226/5245. pp. 560-561. Biozonierungen mil Grossforaminiferen und Nannoplankton Massieux, M., 1965. Presence d'iOvulites dans le 'calcaire 213 des Corbières et discussion la J. 1959. yprésien' septentrionalcs sur Pérès, M.. Contribution a la connaissance des nature de l'algue Griphoporella arabica Pfender. Revue Polychètes benthiques des profondeurs moyennes de la 8/4, 240-248. Mediterranée. Stat. Micropal.. pp. Ree. Trav. Mar. Endoume, 26 (bull. 16), 1966. -. Les algues du Nummulitique égyptien et des terrains pp. 103-135. crétacés-éocènes de quelques regions mésogéennes. - & Picard, J., 1958. Recherches sur les peuplements Deuxième Partie. Rev. Micropal., 9/3, pp. 135-146. benthiques de la Mediterranée nord-orientale. In: Result, sci. Maxwell. W. G. H., 1968. Atlas of the Great Barrier Reef. campagnes Calypso. Campagne 1955 en Mediterranée Amsterdam, London, New 258 nord-orientale. Ann. Inst. Ocean., 34, 213-291. Elsevier, York, pp. n. sei., pp. R. W. & P. J. G., 1961. Carbonate Petersen, C. G. Valuation of the sea -, Day, Fleming, J., 1913. II. The animal the sedimentation on Heron Island reef. Great Barrier Reef. communities of the sea bottom and their importance for Jour. Sed. Petr., 31/2, pp. 215-230. marine zoogeography. Rept. Danish Biol. Stat., 21, pp. 1 —42. Great Barrier Reef: 1915. -, & Swinchatt. J. P., 1970. regional —. On the animal communities of the sea-bottom in the variation in a terrigenous carbonate province. Geol. Soc. Skagerrak, the Christiania Fjord and the Danish waters. America 691-724. Bull., 81, pp. Rept. Danish Biol. Stat., 23, pp. 3-28. McRae, S. G., 1972. Glauconile. Earth Sci. Rev.. 8. pp Peterson. M. N. A. & Borch. C. C. von der, 1965. Chert: 397-^40. modern inorganic deposition in a carbonate-precipitating Mey. P. H. W.. Nagtegaal, P. J. C. Roberti, K. J. & locality. Science, 149, pp. 1501-1503. Hartevelt, J. J. A., 1968. Lithostratigraphic subdivision of Pfender, J. & Massieux, M., 1966. Les algues du Nummulitique post-Hercynian deposits in the south-central Pyrenees. Spain. égyptien et des terrains Crétacés-Eocènes de quelques Leidse Geol. Meded., 41. pp. 221-228. regions mésogéennes. Première Partie. Rev. Micropaléontol.. 1934. Der Bau mittleren Misch, P., der Südpyrenaen. Abh 9/2, pp. 111-132. Ges. Wiss. Göttingen, Math. Phys. KI. Ill, 12, pp. 1-168. Picard, J., 1965. Recherches qualitatives sur les biocoenoses Möbius. K., 1877. Die Auster und die Austernwirtschaft marines des substrats meubles gragables de la region Hempel & Parry, Berlin, 126 pp. marseillaise. Ree. Trav. Stat. Mar. Endoume, 52 (bull. 36), 1880. Foraminifera von zur -, Mauritius: Beitràge Meeresfauna pp. 1-160. der Insel Mauritius und der Seychellen, pp. 63-110. Plaziat, J.-C, 1972. Les transgressions éocènes sur la bordure Moore. R. C Treatise invertebrate 1969. on paleontology, part meridionale de la Montagne Noire à l'ouest de Minerve. N. volume I, Mollusca 6, Bivalvia. Geol. Soc. America & Stratigraphie, paléoécologie et paléogéographie (Feuilles de Univ. Kansas, 489 pp. Carcassonne et Lézignan à 1/50 000). Bull. B. R. G. M.. (2) 1973. Moorkcns. Th. L., Foraminiferen uit het stratotype van section 1. no. 3, pp. 21 —44. het Montiaan en de uit onderliggende lagen van de boring te -, 1975. L'Ilerdien à l'intérieur du Paleogene languedocien; ses übourg (Met een overzicht van de stratigrafie van het relations avec le Sparnacien, l'Ilerdien sud-pyrénéen, Paleoceen in Bull. België). Natuurwetensch. Tijdschr., 54/4-5, pp. l'Yprésien et le Paleocène. Soc. Géol. France, (7) 17/2, 117-127. pp. 168-182. A. e Mutli. E., Obrador, & Roseli. J., 1973. Sedimenti deltizii - & Renzi, M. de. 1968. Correlation à laide des macrofaunes di piana di marea nel Paleogene della Valle di Ager marines, entre l'Ilerdien du bassin de Tremp (Lérida. (provincia di Lérida, Spagna). Boll. Soc. Geol. Ital., 92, pp. Espagne) et la série Cuiso-Lutétienne des Corbières (Aude, 517-528. France). Mém. B. R. G. M., 58, pp. 575-581. Mutli. F... J. Obrador, A., Roseli, & Ghibaudo. G., 1974. Los Pomerol, Ch., 1975. La signification de l'Ilerdien et l'intérét de sedimentos litorales y deltaicos del Paleógeno del Valle de eet étage dans la stratigraphie du Paleogene mésogéen. Bull. Guia de las VII Ager. excursiones. Congr. Grupo Esp. Soc. Géol. France, (7) 17/2, pp. 213-217. Sediment., Bellaterra-Tremp, pp. 11-22. Premoli Silva, I. & Bolli, H. M., 1973. Late Cretaceous to Mutti, Roseli, E., J.. Ghibaudo, G. & Obrador, A.. 1975. The Eocene planktonic foraminifera and stratigraphy of Leg 15 Cretaceous Arén Sandstone in its Upper type-area. In: The sites in the Caribbean Sea. In: Initial reports ofthe Deep Sea evolution sedimentary of the Paleogene south Pyrenean Drilling Project. U. S. Government Printing Office, Basin. I.A.S. 9th Intern. Congr.. Nice, 1975, Part A, pp. Washington, 15, pp. 499-547. 7-15. Puigdefàbregas, C, Rupke, N. A. & Sole Sedo, J., 1975. The Myers, E. H., 1943. Life activities of foraminifera in relation to sedimentary evolution of the Jaca Basin. In: the sedimentary marine Proc. American Philos. ecology. Soc, 86/3, pp. evolution of the Paleogene South Pyrenean Basin. I.A.S. 9th 439-459. Intern. Congr., Nice, 1975, Part C, pp. 1-33. Nagtegaal, P. J. C, 1969. Sedimentology, paleoclimatology, Reguant, S., 1967. Lunulites bugei (Bryozoa Cheilostomata) and diagenesis of post-Hercynian continental deposits in the nueva especie del numulftico inferior de Tremp (Lérida). south-central Pyrenees, Spain. Leidse Geol. 42, Acta Geol. 70-74. Meded., pp. Hispànica, 2/3, pp. 143-238. Reichel, M., 1936-1937. Etude sur les Alvéolines. Schweiz. 11 Newell, N. D., 1956. Geological reconnaissance of Raroia (Kon Palàontol. Abh., 57 & 59, 147 pp., pis. Tiki) Atoll, Tuamotu Archipelago. Bull. Am. Nat. Hist., 109, Reineck, H.-E. & Singh, I. B., 1973. Depositional sedimentary pp. 317-372. environments. With reference to terrigenous elastics. Nio, S. D.. 1976. Marine factor in the transgressions as a Springer Verlag, Berlin. Heidelberg, New York, 439 pp. formation of sandwave complexes. Geol. Mijnbouw, 55/1-2, Renzi, M. de, 1965. Un corte detallado de la serie del 18-40. Paleoceno marino la pp. por carretera de Tremp a Nijman, W. & Nio. S. D., 1975. The Eocene Montanana delta Pont-de-Montanana, desde Claret hasta Figols de Tremp. of Lérida and Pubi. (Tremp-Graus Basin, provinces Huesca, Catedra Paleontol., 11, pp. 8-19. Southern N. In: The evolution 1967. El del limite entre Secundario Terciario en Pyrenees, Spain). sedimentary -, problema y of the Paleogene South Pyrenean Basin. I.A.S. 9th Intern. las proximidades de Serraduy, en el valle del Isàbena Nice, 1975, + Congr., Part B, 20 XXXVI pp. (Huesca). Acta Geol. Hisp., 2/1, pp. 19-24. 214 1968. Trois nouvelles de l'Ilerdien marin de Oberaragonien. Neues Jb. Min. Abh.. Beil. Bel. 71, Abt. B. -, coupes l'Aragon la 370-406. el leurs rapports avec le stratotype de l'Ilerdien, à Conca pp. A. G., Briden. J. C. & G. de Tremp (Espagne). Mém. B. R. G. M., 58, pp. 597-606. Smith, Drewry, E.. 1973. 1975. Sur la des Mollusques dans Ie stratotype de Phanerozoic world In: Organisms and continents -, repartition maps. time (ed. N. F. Paleontol.. 12, l'Ilerdien en rapport avec les faunes de Mollusques de through Hughes). Spec. Pap. Géol. I^»2. l'Eocène europeen. Buil. Soc. France, (7) 17/2, pp. pp. 199-200. Smout, A. H., 1963. The genus Pseudedomia and its phyletic Estudio de los de la with remarks and other Rioja y Lo Bianco, E., 1931. poliquetos relationships, on Orbitolites complex Mem. foraminifera. In: in A Peninsula iberica. Acad. Ciencias exactas. fisicas y Evolutionary trends foraminifera. natur.. Madrid, Ser. Cienc. Nat.. 2, pp. 1-471. collection of papers dedicated to I. M. van der Vlerk on the occasion of his 70th H. R. Roseli, J., 1973. Geologia de la Vali d'Ager. Ilerda. 34, pp. birthday (eds. G. von 179-185. Koenigswald et al.), pp. 224-281. 1975. Le & - & Robles, S., Paleogene marin de la Catalogne Soler, M. Puigdefàbregas, C., 1970. Lineas generales de la del Alto Occidental. Pirineos, Bull. Soc. Géol. France, (7) 17/2, pp. 195-198. geologia Aragón 96, pp. 5-20. - & 1972. Roux, M., 1976. Découverte dans Ie Golfe de Gascogne de -, Esquema litològico del Alto Aragón occidental. actuelles du Conocrinus 106, 3-15. deux espèces genre cénozoique Pirineos, pp. (échinodermes, crinoïdes pédonculés). C. R. Acad. Sci. Stach, L. W., 1936. Correlation of zoarial form with habitat Jour. 60-65. Paris, (D) 283; pp. 757-760. Geol., 44/1, pp. 1978a. Ontogenèse, variabilité et evolution morpho- Stanley, S. M., 1970. Shell form and life habits in the Bivalvia fonctionnelle du pédoncle et du calice chez les Millericrinida (Mollusca). Mem. Geol. Soc. Amer., 125, 296 pp. (échinodermes, crinoïdes). Géobios, 11/2, pp. 213-241. Stenzel, H. B., 1971. Oysters. Treatise on invertebrate variabilité la forme du calice Part N, 3 (of 3), Mollusca Bivalvia -, 1978b. Importance de la de paleontology. 6, (ed. R. chez les Bathycrinidae (échinodermes. crinoïdes): l'exemple C. Moore). Geol. Soc. Amer., Inc. & University Kansas, 272 de l'espèce eocène Conocrinus doncieuxi nov. sp. C. R. pp. B. Acad Sci. Paris, (D) 285 (in print). Stevens. A., 1973. Het Paleoceen in de vallei van Ager - & Montenat, C., 1977. Sites à crinoïdes pédonculés et (Zuid-Pyreneeën). Een sedimentologische studie. Unpub- des bassins messiniens dans les Cordillières lished master's 25 35 bathymétrie thesis, Leiden, pp., photos, I map, bétiques orientai (Espagne meridionale). Bull. Soc. géol. Fr., sections. (7) 19/2, pp. 405^416. Stoll, N. R. et al. (ed), 1961. International Code of Zoologie L. W. le. 1938. A of the microfaunal Nomenclature the XV international of Roy, preliminary study adopted by congress facies along a traverse across Peper Bay, West Coast of zoology. Internat. Trust for Zool. Nomencl., London, 176 Java. De in Ned. Afd. Ingenieur Indie, 5, 4, no. 8, pp. pp. M. 130-133. Straaten, L. J. U. van, I960. Marine mollusc shell Rupke, N. A., 1972. Geologie studies of an Early and Middle assemblages of the Rhone delta. Geol. Mijnbouw. 39/4, pp. Eocene Flysch Formation, Southwestern Pyrenees, Spain. 105-129. PhD thesis. Princeton University, 372 pp. -, 1970. Holocene and late-Pleistocene sedimentation in the Adriatic Sea. Geol. Rundschau. 60/1. pp. 106-131. 1964. Saavedra Garcia, J. L., Microfacies del Secundario y Terciario de la zona pirenaica espanola. Mem. Inst. Geol. Tambareau, Y.. 1975. Les ostracodes de l'llerdien pyrénéen Bull. Minerò Espaha, 65, pp. 1-217. Soc. Géol. France, (7) 17/2. pp. 187-190. Saenz de Santa Maria, F., 1976. Generalized Tertiary tectonics - & Toumarkine, M., 1975. Position de l'llerdien des Petites du Plantaurel of the Iberian Peninsula. Bol. Geol. Minerò, 87/5, pp. Pyrenees et dans la zonation des foraminifères 456-461. planctoniques. Signification de sa limite inférieure. Bull. Soc. Géol. Sars, M., 1868. Mémoires pour servir à la connaissance des France, (7) 17/2, pp. 183-186. crinoides vivants. & 65 & 1974. Le Thanétien-llerdien dans la Brogger Christie, Christiania, pp. -, Villatte, J., passage Sartenaer, en P., 1959. Premières recherches taphonomiques, region de Campo: comparaison avec les Petites Pyrenees. le facies à Turritella hist, scaphandre autonome, sur tricarinata Bull. Soc. nat., Toulouse, 110/3-4, pp. 340-361. forme communis de la vase molle terrigene du Golfe de Fos. Thorson, G., 1957. Bottom communities. In: Treatise on Ree. Trav. Stat. Mar. Endoume, 26 (bull. 16), pp. 15-38. marine ecology and palaeoecology. Vol. I, Ecology. Mem. Schaub, 1968. A de du Paleocène Geol. Soc. Amer., 67, 461-534. H., propos quelques étages et pp. de l'Eocène Bassin Paris leur correlation avec les du de et -, 1958. Parallel level-bottom communities, their temperature étages de la Tethys. Mém. B. R. G. M., 58, pp. 643-653. adaptation and their 'balance' between predators and food 1969. L'Ilerdien - état actuel du Mém. B. R. G animals. in Marine California, -, problème. Perspectives Biology, pp. 259-266. 67-86. M., 69, pp. Schlanger, S. O. & Konishi, K., 1975. The geographic Toulemont. A.. 1972. Influence de la nature granulométrique boundary between the coral-algal and the bryozoan-algal des sediments sur les structures benthiques. Baies de d'Audieme Cahiers Biol. limestone facies: a paleolatitude indicator. 9th Congr. Intern. Douamenez et (Ouest-Finistère). Sedimentol., theme 3 91-136. Nice, 1975, I, pp. 187-190, figs. Mar., 13/1, pp. Schopf, T. J. M., 1969. Paleoecology of ectoprocts (Bryozoans). Jour. Paleontol., 43/2, pp. 234-244. Vidal, M., 1875. Geologia de la provincia de Lérida. Boi. Com. 1970. Etude des séries Geol. 273-349. Seguret, M., tectonique nappes et Mapa Esp., 2, pp. décollées de la panie centrale du versant sud des Pyrenees. Villalta, J. F. & Roseli, J., 1963. Nota sobre la estratigrafia del W Caractère synsédimentaire, róle de la compression et de la Eoceno en el extremo del Valle de Ager (prov. de Lérida). PhD 229 gravite. thesis, Montpellier, pp. EstudiosGeol., 19. pp. 137-142. Selzer, G., 1934. Geologie der südpyrenaischen Sierren in Villane, J., 1965. Recherches sur quelques Conoclypus de 215 l'Eocène d'Kspagne. Bull. Soc. Géol. France, (7) 7. pp Wells. J. W.. 1957. Coral reefs. In: Treatise on Marine Ecology 866-870. and Palaeoecology, Vol. I, Ecology. Mem. Geol. Soc. Moeckel. F. & E.. 1969. Voigt, K.. Sturm. M., Bengelsdoif. Amer.. 67. pp. 609-631. Salinity-temperature-velocity profiles in the equatorial Wilcoxon, J. A.. 1973. Paleogene calcareous nannoplanclon Gulf of Guinea Proc. the in waters of the areas. symposium on from the Campo and Tremp sections of the llerdian stage oceanography and fisheries resources of the tropical Atlantic. NE-Spain. Rev. Esp. Micropaleont., 5/1. pp. 107-112. Abidjan. Ivory Coast. 20-28 October 1966. Unesco, FAO & 179-184. OAU. pp. Yonge. C. M., 1928. Structure and function of the organs of feeding and digestion in the septibranchs Cuspidaria and F. M. Weaver, & Wise. S. W.. Jr.. 1974. Opaline sediments of Poromya. Phil. Trans. Roy. Soc. London. (B) 216. pp. the southeastern coastal plain and Horizon A: biogenic 221-262. 899-901. origin. Science, 184, pp.