Late Messinian, Sorbas Basin, SE Spain)

Sedimentary GeoIogy ELSEVIER Sedimentary Geology 116 (1998) 27-56

Late highstand patterns of shifting and stepping coastal barriers and washover-fans (late Messinian, Sorbas Basin, SE Spain)

Th.B. Roep a,l, ej. Dabrio b,2, A.R. Fortuin a,*, M.O. Polo b

a Department o/ Sedimentar)' Geolog)'. Faculty of Earth Scíence.l. Vri¡e Unil'ersireit. De Bode/mm IOfi5. 1O!:!1 HV Amsterdam. The Ner/¡erlands h DplO. de Estratigrafía and IIlSlituto de Geología Económica-CS/e. Unirersidad Complutense. 28040-Madríd. Spaín

Received 23 Deccmr.er 1996: acceptcd 23 Septcmber 1997

Abstract

The late Messinian Sorbas Member, up to 75 m thick, consists in it;; lype area of a parasequence sel of three prograding coastal barriers (sequences I-III). associated with lagoon and washover sedimenlS. Around the town of Sorbas these strata can be studied exceptionally wel! due 10 absence of burrowing by raised Messinian salinities and exposure along a network of up to 30 m deep canyons. Fifteen vertical sections were logged and careí'ully correlated. This permits to reconstruct and discuss pattems of relative sea-Ievel movements between decímetres. up to 15 m within a parasequence. Excellent examples oí' non-tidal transgressive facies are characterized by lagoon and washover sedimenls instead oí' the usual combinatíon oí' wa,hover and tidal deposits (channel and ftood-tidal delta). Implications í'or the sandstone connectivity are given. The lower two sequences are deposited in ,J, relatively tectonically enhanced wedge-shaped accommodation space. They show both fining-up, deepening sequences, followed by prograding eoarsening-up shoaling sequences and can be compared lO the c1assical parasequences of lhe Westem Interior Basin (USA). Progradation of sequence II was intemlpted by a major slide event (most likely triggered by an earthquake), which caused more than 400 m seaward slumping of a stretch of 1 km of coasta! sands. The architecture of sequence lIT Is more complex due to limited accommodation spaee characterístic for the late híghstand, so tha! this sett'.ng was very sensitive to sea-Ievel tluctuations. This resulted in an intricate pattem of juxtaposed and superposed lagoonal muds, washover üms and swash zones. So-called 'stranded' coast;:J barriers occur, which were lef! behind after seaward Jump of the coastline over more than 1.5 km during forced regression. The pattem oí' reconstructed sea-Ievel positions is weIl comparable to the sequential partem shown by the correlated equivalent, along the northem basin margin, which belong to the so-called Terminal Carbonate Complex. The problem of ranking the complex sequence III as one or more parasequences and it, consequences for cyclostratigraphy are shortly discussed. Two models of washover formation are given, respectively during more rapid and more slow sea-Ievel rise. The intluence oí' synsedimentary folding on the location of barriers is discussed and also the source arca of extra- and intraclasts supplied to barriers and washovers. After deposition of ¡he Sorbas Member the sea withdrew from the Sorbas Basin, probably as a result of the majar downdrop in lhe Mediterranean at the maximum i,olation during the Salinity Crisis. It 15 suggested that the semi-enclosed selting of the basin resulted only in Iímited. localized eros ion, in contrast to the deeper adjacent Vera Basin, which was more open to the Mediterranean. © 1998 Elsevier Scíence B. V. AIl rights reserved.

Keywords: Messinian: sea-Ievel tluctuations; beach barrien.; washover fan: sequence stratigraphy

• Corresponding author. E-mail: [email protected] ¡ Th.B. Roep deceased 15 September 1997. :: E-mail: [email protected],

1. Introduction marls and gypsum (Krijgsman et al., 1995; Hilgen et aL 1995; Sierro et aL, 1996) and evidence pre Sedimentary bodies deposited in coastal settings sented for late Messinian precessiona1 parasequence reflect a highly variable architecture, which is mainly stacking in ltalian successíons (Lickorish and But governed by factors as sediment supply, wave- and ler, 1996). For the Sorbas sequences this aspect is tidal processes, coastal morphology and accommo presently under investigation. dation space. Seaward, these coastal sedimentary The anatomy and dynamics of lhe coastal barriers units interfinger with muddy shelf deposits, but land can be best studied around the town of Sorbas, thanks ward these either end abruptly, or show rapid facies to the uníque presence of up to 30 m deep river changes to tidal, lagoonal, washover-fan and ftuvi canyons which are oriented more or i¡ess perpendicu atile deposits. With time the pattern becomes more lar to each other. These coastal depm.its can be better complieated as the above-mentioned 1'aetors change, studied here than in many other basins because of the especially when landward erosional surfaces start to followíng factors: burrowing is almost absent due to playa prominent role as soon a'i a position aboye raised salinities (Roep et al., 1979): a three-dimen base-Ievel is reached. sional insight is possible due to good exposure along Apart from presently well known possibilities to variously oriented canyon walls; early diagenesis at discriminate the vertical upward and downward rel tops of sequences (beach-rock formatíon; stroma ative movements of sea-level within sequences of tolites) led to better preservation of the shallowest eoastal deposits, a more eomplieated effort is to deposited strata: deposition in a protected embay incorporate the three-dimensional evolution of the ment of the Messinian Mediterranean, practically shoreline. Another eomplexity is the determination without tides and under climate-controlled sea-Ievel of the timeframe in which the distinguished pattems fluctuations. Considering this excellent preservation, of eoastal sequences have been formed. Generally, the purpose of this paper is 10 describe and discuss coastal deposits do not easily lend themselves for the development of the Sorbas eoastal deposits as precise dating of successive depositional steps. Re a function of available accommodation space, slope cent and subrecent deposits form an exception, e.g. gradient and position 01' the basin margin under sea through C-14 dating possibilities. Although sequence level changes of diverse magnitudes. In addition. stratigraphy helps to distinguish related sediment the enigmatic aspect of where to look within the packets deposited under conditions of varying ac Messinian stratigraphic record 01' the Sorbas Basin commodation space, care1'ul sedimentological analy for the major sequence boundary 1'ormed when the sis should precede a sequence stratigraphic scheme sea-level of the Mediterranean dropped kilometres (Van Wagoner and Bertram. 1995). Even then it is down. will be discussed briefly. good to keep in mind that the number of variations on the general sequence stratigraphic model is Iim 2. Geological setting ited only by the imaginatíon (Posamentier and Allen, 1993). Late Cenozoic sedimentation in the eastem Betic The late Messinian Sorbas Member and its lateral Cordillera in SE Spain (Fig. 1) took place in equivalent at the basin margin (TCC) in southem partly interconnected intramontane pull-apart basins, Spain offers an excellent example of coastal de shaped by the ongoing approaeh oí' the A1'rican and posits laid down in a tectonically active basin margin European plates. 80th the substratum 01' the basins that was strongly affected by sea-level fluctuations and the adjacent mountain ranges ís made up 01' of various orders (Roep et al., 1979; Dabrio and metamorphic and metasedimentary rocks belonging Polo, 1995; Goldstein and Franseen, 1995; Martín 10 the Internal Zone of the Betic Cordillera (Fig. 1). and Braga, 1996). Dabrio and Polo (1995) connected The Sorbas Basin is delimited by the Sierra de los these with third-, fourth- and fifth-order cycles sensu Filabres to the north and the Sierra Alhamilla and Vail et al. (1977). AIso should be thought of cycIicity Sierra Cabrera to the south (Fig. 1). Many textural forced by precession (and/or obliquity), given the and compositional properties 01' the Late Miocene strong cyclicity 01' the underlying Messinian marine basin fill are inherited 1'rom these adjacent highs, 7:B. Roep et al. / Sedimenta')' Geology 116 ( 1998) 27-56 29

Neogene basins

Neogene volcanics

10 km Cabo de Gata ------_._--- Fig. 1. Tectonic sketch map ,)f fue Sorbas Basin and surrounding areas, indicaring localitie, cited in the tex!. especially from the Fílabres massif, which supplied tbree members: a basal onlapping shallow-marine most of the detritus. calcarenite unit (Azagador Member), overlain by In the Sorbas Basin strike-slip deforrnation was open marine marlstones (Abad Member) of early mainly active in late Tortonian time (Montenat et al., Messinian age (Ruegg, 1964; Dronkert and Pag 1987; Biermann, 1995; Stapel et al., 1996), causing nier, 1977; Troelstra et al., 1980; Weijermars et al., folding, uplift and a northward shift of the south 1985; Van de Poe!, 1994). At that time bioherrns and em basin margin (Ott d'Estevou, 1980; Montenat fringing reefs (Canteras Member) settled along the and Ott d'Estevou, 1996). During Messinian times basin margins. These deposits show complex mu the important N-S-trending sinistral Palomares fault tual relationships (Martín and Braga, 1994; Fig. 2) (Fig. 1) was active, which is located some 25 km east and intertinger with Abad marl s towards the centre of Sorbas, causing displacements in the order of 25 of the basin. The overlying Caños Formatíon rep km (V61k, 1967; Montenat el al.. 1987; Biermann, resents the deposits formed during the Messinian 1995). This fault system is intersected by the NE salinity crisis and is made up of three members, SW-oriented Serrata fault zone, which was active respectively called the Yesares, Sorbas, and Zor during various episodes from the Middle Miocene reras members (Fig. 2). The Yesares Member mainly onwards in the adjoining Nijar Basin (Montenat et consists of selenite gypsum which locally is over al., 1987; Boorsma, 1993; Bierrnann, 1995). 120 m thick (Dronkert, 1977; Ott d' Estevou, 1980, Sediments tilling the Sorbas Basin range in age Dronkert, 1985; Gautier et al., 1994). Following the from Middle Miocene to Quatemary (Fig. 2). Af fall of sea-Ievel that favoured the subaqueous deposi ter the late Tortonian phase of transpressional de lÍon of Yesares gypsum by evaporation, a less satine forrnation the Messínian Turre Forrnation (V61k and onlapping succession was deposited, the Sorbas and Rondee!, 1964) was deposited, which inc\udes Member. 30 T.B. Roep et al. / Sedimenta/}' Geology 116 (1991:1) 27-56

PLlOCENE --?- z ~ Z Cñ fJ) w ::::2:

150 m

~ stromatolife - discontinuity

Fig. 2. Messinian stratigraphic framework for [he Sorbas Basin (modified after Martín and Braga. 1994). using the lithostratigraphic units introduced by Ruegg (1964). VOlk and Rondecl (1964) and Dronkert and Pagnier (1977),

During deposition of the Sorbas Member the Sor be seen to onlap the topographical heights of the bas Basin was a narrow embayment open to the east older fringing reefs during a second time of normal (Fig. 3) and possibly also to the southeast because to slightly more saline sea water inftuxes after the de uplift of the Sierra Cabrera mainly occurred lateL position of the Yesares Member (Martín et al., 1993). The member is up to 70 m thick and consists of three The lateral relation between the Sorbas Member and superposed coastal sandstone bodies (sequences 1- the TCC was certified by Dabrio and Polo (1995), lII, Figs. 4-6), separated by shelf muds. Each de who correlated typical sections of both units, using positional sequence shows upward coarsening and lithology, sequential patterns and stromatolite layers. shallowing and eastward progradation. Finely lami The TCC has been widely studied in the Mediter nated e1ays and marls occur at the base representing ranean in relation with reef growth (Esteban, 1979; the offshore facies. Upward, micaceous sands, sandy Dabrio et al., 1981; Martín and Braga, 1994) and the calcarenites and conglomerates follow, indicative of Messinian salinity crisis (Martín et al., 1993; Van de an offtapping beach-barrier environment (Roep et al., Poel, 1994). 1979). Coastal sands and calcarenites with local algal After deposition of the Sorbas Member and its mats (stromatolites) dominate in the western, more lateral TCC equivalents, deposition of the terrestrial landward areas, whereas offshore muds predominate Zorreras Member followed. This unit of red mud towards the eastern parts of the basin. stones, sandstones and conglomerates is up to 60 The Sorbas Member overlies evaporites in the m thick and shows an upward- and westward-coars centre of the basin, or collapse breccias of di s ening trend. The member typically ineludes two sol ved marginal edges of the latter sediment. In interbeds of white lagoonal limestone containing a marginal areas it also may onlap the reef cores and so-called caspibrackish Lago Mare fauna (Hydro their e1inoforms. Then oolitic limestones (represent bia, ostracods and small shells) indicating a latest ing shallow-marine bars) and algal mats predom Messinian age (Roep and Beets, 1977; Roep and inate and this facies association is known as the Van Harten, 1979; Ott d' Estevou, 1980; Van de Poe\. Terminal Carbonate Complex (TCC, Esteban and 1994). This characteristic biofacies is widespread in Giner, 1977; Esteban, 1979). This TCC al so ineludes the entire Mediterranean province (Cita et al., 1990). Porites patch-reefs and thrombolites and in places The Zorreras Member ends with 2-3 m of yellow, like Góchar (Fig. 1), these add to conglomeratic fossiliferous Pliocene sands and conglomerates and and fine-grained siliciclastics (Dabrio et al., 1985b; is followed by reddish Plio-Pleistocene ftuviatile Martín et al., 1993; Dabrio and Polo, 1995) that can conglomerates (Góchar Formation). TB. Roep et al./Sedimentar)' Geologv 116 I 1998} 27-56 31

coarse siliciclastic input

Cerrón de Hueli (gypsum)

NNW - SSE Messínían Sorbas Cerrón topography 1 Gochar-Cariatiz Member de Hueli

Yesares northwards ...... c migration of Member depocentres W-E Sorbas 2 sea level

Fig. 3. Simplified palaeogeography and sehematÍe represemative cross-sectíons of the late Messinian Sorbas Basin, with the main stratigraphic uníts cíted in the tex!. (Modi'íed from Dabrio and Polo, 1995.) Note that post-depositional eompaction and ftexure of the basin accentuates the apparen! dip of units and shape of the basin. 32 T.8. Roep et (l/./Sedimentar:; Geo/U!(Y J /6 (1998) 27-56

Zorreras Member

Sorbas Member

[!.QJ sectlons \V beal:h faces

Zorreras Member D reddish clay and sandstone _ Whne lagoonallimestone Sorbas Member

coastal sequ~nce 111

o SOOm coastal sequence 11 slump (a) coastal sequence I sheH to basin sedímenls

Fig. 4, Maps of lhe Sorbas study area. (a) Geologícal map, showing the distribulÍon of the coastal sequences I-·III and the localities of ¡he sections discussed. (b) Panoramic view. looking towards lhe west (drawn after oblique air-photo), showing lhe particular canyon morphology and localion of sequen ces I-III. TB. Roep el al. / Sedimentar:.' Ge%gv 1/6 (1998) 27-56 33

w E

100m Top 01 Messinian gypsum vvvvv o 250 500 750 1000m

r- ~,- ~::;;r:~':reccia-- ~~=~ ~~:~sr~~~::O~ ----~- ~~Shover tan --~ v.v v;~f~:~:ne I L-.v- Beachrock layer _, __ ~urro:::__ __' ______C=:J~d~0.:E!.J Fig. 5. Generalised W-E facies diaf:ram of lhe Sorbas Member. indicating lhe posilion of the sections outlined in Fig. 4.

3. Methods of study and presentation of data 4. Introduction to the Sorbas coastal parasequences In order to obtain a maximum insight in the facies geometry, all exposures in the canyon walls around Essentially, the Sorbas Member constitutes a stack Sorbas and along the roads were first sketched, care of three parasequences (sensu Van Wagoner and fully measured and mapped (Fig. 4a). Altogether Bertram, 1995), arranged in an up-stepping and bas fifteen sections were logged (Fig. 4a). Lateral tracing inward-stepping pattern. Coastal progradation oc along the clitfs of individual units and projection of curred more gradually and regularly during the first sections along the depositional strike enabled us to two sequences. This resulted in classical coarsen prepare a schematic facies diagram (Fig. 5), which ing-up sequences with shelf mud at the bottom is based on the lithologically correlated numbered and calcarenites at the top, often showing gently sections (Fig. 6). seaward-inclined swash lamination. In contrast, the This paper is organised in such a way that first a third sequence displays a much more complex facies general outline and discussion of the logged sections partern, due to extensive presence of washover-fan are presented. Next follow paragraphs concentrat sands and lagoonal muds in back-balTier sertings. ing on the transgressive units of sequences Il and This is interpreted as the result of more abrupt shifts 111, which demonstrate best the nature of the trans of the coastline under conditions of a more restricted gressions and progradations and patterns related to accommodation space than the previolls sequences. smaller sea-Ievel ftuctuations. The paper then con The pattern of three stacked parasequences occurring tinues with a discussion concerning the location and just before the late Messinian downdrop event (dis development of barrier islands and lagoons in the cussed in Section 11) suggests that these can best basin, sequence stratigraphic aspec1:s and relations be attributed to a late highstand sequence set. For a with the Terminal Carbonate Complex. detailed account of the sedimentological aspects of the Sorbas Member the reader is refen'ed to papers by Roep and Beets (1977) and Roep et al. (1979), w +- 1 2 3 4 5 6B 7 15 first white ' limeslone layer j ZorrerasMb m stromatolite '- '- '- progr.

" " ...

:--l II ~ 8' ~ 9 10 ~ 6A 8 ¡:¡ ,-.. "- mslwhite limestone layer (7ÁJrteras Mb) / Om f;:, m stromatolite iS ,~

~ --- ~ progr. g

washover fan O; '- II progr. ~ ~ progr. N '¡l 'lD lJ, barrier + 2x upsrep 0\

"~~8l: (a) '---- fig. 6. Corrclated sedíment logs of [he sections aruumJ Sorbas. For locatiun. see Fig. 4. rB, Roep et al, /Sedimentary Geology 116 (1998) 27-56 35

16 U+lIB 13

oolite --t-~---m I progr. I transgr. / lagoon \ washover n

I earthquake legend disturbed ~ suomatolite laminite [ Om 00 oolites <'? lateral tlúnning =- limestone ~---" channels mud planebed (swash)

sandstone ~ convex bar (wave) Q,.,~<> conglomera te ~'-;C- low-angle bar 4'~". beachrock breccia ~~ mega-crossbedding (wave) 'Lr'o beachrock surface ===, low-angle lamination m bioturbation ~2, planebed (wave) t rootlets micro-troughs (wave) r ).~ )L ~:< I birdieet imprints ----- symmetric. rippk.>s (wave) L10 6' gastropods slump ~ shells disturbed bedding (earthquake)

Fig, 6 (continuedl.

The stratigraphic cross-section (Fig. 5) presents pink and brown coloured muds and sandstones of a schematic overview of the most important lateral the Zorreras Member appear below the first white changes within the parasequences. It is based on lagoonal limes tone layer separating it from the top the fifteen logged sections (Fig. 4a, Fig. 6), using of Sorbas Member. Relative to this reference line, the base of the first (lowermost) oí the two white the top of the prograding sandy calcarenite sequence lagoonal limestone beds of the Zorreras Member 1 differentialIy subsided 27 m over a distance of as horizontal reference lineo This 0.5 to 1 m thick, ~ 1 km, measured at right angles to the shoreline basin-wide occurring 'Lago Mare' bed is interpreted (towards the east) between sections 5 and 10. as an isochronous, almost horizontally deposited sur Most subsidence (and/or compaction) must have face. Around Sorbas it rests directly on top of the taken place before deposition of prograding coastal calcarenites and sandstones of the Sorbas Member, sequence n, because this unit only shows a differen but further east, in the basin centre, up to 15 m of tial subsidence of 8 m lO the east, between sections 36 TE. Roep el al. I Sedimenta,!' Geo!ogy 116 (/998) 27-56

8 and 10. The wedge-shaped accommodation space swash lamination and lateral increase in the amount was filled up by offshore to coastal sediments with of burrowing and draping by stromatolites. After this a symmetrical facies trend consisting of a lower fin sea-level fall, renewed transgressioll again moved a ing-upward part (deepening, transgressive sequence) girdle of washover fans landward, filling the avail and an upper coarsening-upward part (shallowing, able accommodation space, overstepping the pre prograding sequence). vious barrier. Finally, progradation oceurred in the Renewed sea-level rise after unit II produced a most seaward part of the complex unit IIJ, resulting more box-shaped accommodation space for deposi in a third coarsening-up unit in the east. tion of unit III. This means that the accommodation At certain moments stromatolites draped the bar space available for deposition of units II and III had rier island and ¡agoon, suggesting a lemporary cessa a different geometry, determining a different facies tion of the siliciclastic input to the former shore. This distribution. Unit III furthermore provides fine ex seems to be related to inactivity andlor abandon amples of seaward-stepping and landward-stepping ment(?) of the barrier, perhaps caused by jumping to coastlines as well as progradation in the deeper east a new location. Stromatolites also have been found em parL in an early transgressive setting overlying beach Parasequence J. During its deposition the coast rock surfaces and erosional channels at the base of Une prograded over at least 1 km, measured at right wave-rippled fining-up sequences. angles to the preserved swash zones depositing a Iithosome of coastal sandstone, informally referred 5. Sequence 11 10 as sandy calcarenite unir 1. Synsedimentary faults, liquefaction phenomena and meter-scale convolu 5.1. The transgressive parl lions indicate tectonic instability during deposition. This unit will not be discussed in more detail. The finest example of the transgressive phase Parasequence JI. Due to eastward tilting and prior shows (seetion 8, Figs. 6 and 7 bottom) that the lO renewed transgression a wedge-shaped accommo seaward dipping swash zone at the: top of unit 1 is dation space formed and the sequence starts with a followed by a thin layer of lagoonal clay. A high spectacularly well preserved ftooding surface. It is bar, up to 2.1 m , is overlying this lagoonal clay. followed by a wedge of offshore mudstone, coarsen but al so interfingering with ir. It inereases in height ing upward in prograding sandy calcarenites. Progra in the landward direction (to SW) and shows inter daríon of these geometricalIy complex calcarenites mittent growth. Each growth pulse :shows a landward took place over at least 1.5 km, Observed variations steepening of the foresets, sometimes with backftow in thickness of these strata, formed aboye normal ripples, developed in the wedge-shaped toesets ex wave base, allow to deduce vatiations of sea-leve) tending into the lagoon. The latter ripples suggest of a scale of decimetres to 15 m. A relative sea strong landward currents. The toesets also contain level rise can be deduced from the stacking of swash bird-foot imprints produced during periods of low zones and seaward stepping-up of the sandy cal water after ovenvash. The bar is ínterpreted as a ret carenÍle sequence over shelf muds. Liquefaction and rograding barrier under massive, but episodic over slumping moved sand from the coastal zone to the wash that stepped into a lagoon. shelf, probably as a result of earthquakes. When the bar was overstepped by the transgres Parasequence Jl!. During initial transgression sive sea, wave action in the foreshore locally eroded landward up-stepping washover fans were formed. the gravelly beach-rock surface ancl carved up to 0.5 which interfingered with lagoonal muds. With ongo m deep hollows in the top of the bar. A few blocks ing transgression, ravinement surfaces affected these of beach rock remained behind on this ravinement washover fans. This induced the formation of an ero surface, As transgression proceedi:d, the frequency sively overIying barrier with an active swash zone and magnitude of overwash increased and transport facíng the sea to the east. Subsequent sea-level drop of sedíment to the back-barrier became massive, as forced the coastline to jump seaward. This process the foreshore overstepped the barrier island. This is shown by steepening-up and lateral fining of the effect is demonstrated by the change from high- to rB" Roep et ar ¡Sedimentan" Geolofl,v 116 (1998) 27-56 37

sediment moving sigmoidal calcarenite unit landwards during transgressed storms and overwash barrier island overwash· ------______

loa",ening swash and thickaning • upwards sequance Vertical scsla axsggerated

fíne sand: shoreface . - ~ regresslon :;,' _ _ laminated mudstone (progradation) ü/ -_- and fine sandstone: shelf (offshore) fine sand: shoreface wave-rippled sandstone: reworking of submerged bar in shoreface erosion and gravel: retrograding foreshore sandstone and !}ravel: landward migration of bamer ¡sland (back-banier) _. J5I.9.0 subaerial erosion regression :; '-c-- (progradation) ~/ sandstone: prograding foreshore , (swash lamination) wave-ripple cross-Iamination wave-ripple cross-stratification 10m even lamination Fig. 7. Facies association (Iower figure) ami sedimemary interpretarion (upper lígure) of lhe coaslal deposi!s in the Rambla de Cinta Blanca, north of Sorbas. Seaward progradation 01' a coastal barrier (CU J) is followed by retrogradatíon towards the lagoon and drowning of the complex that was converted into a ,hoal on the shoreface. Note erosion of ¡he upper par! of the beach profile by the rctreating shoreface. The conceptual model (modified after Dabrio e! aL 1996) shows back-barrier and washover development during a fas! sea-Ievel rise. In such a case laterally mor~ continuous uníts of bcach-deríved sand with sigmoidal geornetry are generated, whích interfinger with lagoonal rnuds. Compare with Fig. 13. low-angle cross-bedding (Fig. 7). Subsequent rapid so towards the sea, forming storm beds. More land transgression is indicated by a well preserved fin ward the bar is lacking. This lateral difference and ing- and thinning-upward sequence ol' only a l'ew the good preservation of the thin fining-up sequence metres thick. This sequence shows ¡¡ transition l'rom is interpreted as evidence for rapid transgression small gravelly wave-fonned troughs to micaceous (Dabrio et al., 1985b). sandstone with micro-troughs to wave ripples in mud Other examples of similar fining- and thinning setting and finally distal storm layers. Presence of a upward transgressive sequences on top ol' unit 1, but few hummocky cross-stratified sandstone beds with deposited under less energetic conditions, together wave-rippled tops and thinning in seaward dírection, indicate that the thickness of the transgressive sand indicate minor transport of sand to the shelf during slightly increases in the direction of the land, which storms. This means that during transgression over 15 a further indication of the rapid backstepping of wash moved barrier sands landward and storms did the coastline. 38 TB. Roep el al. / Sedimentar}' Geology 116 (1998) 27-56

Concluding, the transgression after deposition of offshore muds and limestone intercalations upwards, parasequence 1 is interpreted to have been rapid the following is encountered within 10 to 15 m: considering the minor amount of erosion, the thin (1) Thin fine-grained, graded or very low-angle fining-upward transgressive sequence and the varied laminated storm beds altemating with mud (inferred lithological expression below the prograding part of original depth 15-40 m). In the higher parts they are unit Il. associated with thin swelling and thinning ripples with only low-angle laminations, formed by incip 5.2. The prograding part ient orbital motion at the sea bottom without flow separation over the ripple crests. The prograded part of sequence Il, already de (2) Syrnrnetrical (pointed) wave ripples formed scribed and interpreted by Roep et al. (1979) is in fine, micaceous sand altemating with mud at an only updated here. The muddy lower part is in inferred original depth of ~ 10-15 m. terpreted as offshore mud, deposited below normal (3) Small-scale trough-shaped cross-bedded sand wave base. The coarsening-up sandy and conglomer stone lacking a preferred orientatiort due to frequent atic upper part (Fig. 8, lower column, interpreted as a wave activity aboye normal wave base (inferred coastal sequence aboye wave base) can be well com depth less than 10 m). pared to present-day coastal subenvironments in the (4) Upwards. the wave-ripple cross-Iamination Mediterranean (Fig. 8, upper part). From the deepest shows wider troughs. associated with thickening-up

wind set up berm beach-rock surface sea level (stonn) 6 " .. /' mean sea level Om burrows 6m

foreshore backshore (swash zone) shoreface 2 , , - -- _ .. -. '. ideal sequence ------of progradation Jength: a few tens of metres

~~~~- parallel-Iaminated sandstone (backshore) 6 coarse sand-fine gravel beach-rock surface and clasts seaward-inciined, parallel-Iaminated sandstone (shoreface, swash zone) plunge step (some gravel) swash ridges pointing landward

5 wave-ripple (mega) cross stratified sandstone (pseudo herringbone)

4 3 wave-ripple cross laminated sandstone 2 wave-ripple cross laminated sandstone parallel-Iaminated sandstone (storm sand layers) mud

Fig. 8. Ideal facies succession in microtidal sandy beaches of Sorbas. compared 10 present-day coastal sub-environmenls in the westem Medilerranean. T.B. Roep el al. ISedimenlary Geology 116 (1998) 27-56 39 intercalations of parallel laminaled sand, due to (6) Beach-rock breccia and burrowing structures. episodic more intensive orbital motion which wiped The inferred depositional depth is from current sea out the wave ripples. The inferred depositional depth level to ~ 1-3 m aboye mean sea-Ievel. At the top of of the parallel-laminated sand ranged between 9 and the sequence intense burrowing occurs. This member 6 m. The eastward palaeocurrent trend of occasional represents foreshore and backshore sediments. Lo climbing ripples is normal, or slightly oblique to cally, ca\careous breccias occur overlying an irregu the shoreline, suggesting a seaward migration of the lar erosional surface. According to Roep et al. (1979) wave-generated ripples due to the retum orbital move these features are related to beach-rock erosiono Care ment of waves. Strong westerly winds, still common must be taken not to mistake a beach-rock breccia for in this area, may have enhanced this pattem. a beach-rock surface; the former may be washed into (5) Upward and landward, wave-generated deeper levels and does not necessarily indicate the trough-shaped mega-cross-bedding interfingers with upper foreshore to berm zone of the beach face. planar cross-bedding, indicating the seaward (to NE) Conc1uding, these features, such as good round growth of the pi unge step at the base of the fore ness and high sorting of the grains, their occur shore under the action of backswash. Coexistence rence in this particular vertical sequential pattem of these two types of cross-bedding renders out and overall geometry, are proper indicators of reftec crops the appearance of herringbone cross-bedding, tive coasts where the slope of the shelf is relatively but the wave-related genesis is c1ear by the associ steep and waves reach the coast almost undisturbed. ation with the swashzone. Furthermore wave ripples Reftective beaches require low waves (less than 1 are associated with these features and never small m high), and coarse sediment (>0.6 mm). Conse scale bidirectional current ripples (tidal linsen and quently they tend to occur in coasts sheltered or sub ftaser bedding). The deposits represent the lower part jected to moderate to high energy (Short and Wright, of the foreshore, where breaking waves accumulate 1983). Most of the sediment in reftective beaches the coarsest sediment available (Miller and Ziegler, accumulates in the upper foreshore generating high 1968; Dabrio et al., 1985a). In low-energy coasts the berms and beach cusps. The foreshore is rather steep breaker zone is characterised by a step at the base (on average 2-50 for beach units made up of coarse of the swash zone (Clifton et al., 1971; Davis et al., sand) with a plunge step in the lower part, where 1972) which probably marks the transition between the coarsest sediment concentrates. Towards the sea upper and lower ftow regimes (Tanner, 1968). the shoreface is les s inclined, but relatively deep, The seaward inc1ined parallel lamination curves without bar s or other morphological features. downward to lesser dips at the lower, distal parts of the shoreface facies, and changes into planar cross-bed 5.3. Estimates of sea-Ievel variations ding directed offshore (set thickness LO to 20 cm). In fossil examples of sandy beaches the step is pre Careful correlation and study of the sections pro served as a change from parallellamination (the com vides evidence for sea-Ievel changes at 15 m, metre mon deposits of the foreshore swash zone) to tabu and decimetre scales and examples will be discussed lar cross-bedding pointing to the open sea (Fig. 10; here. The mean thickness of the sandy and conglom Dabrio et al., 1985a; Somoza et al., 1986-87). eratic part (~ 10m; Fig. 6) is interpreted as the local Along tideless coasts, such as the present Mediter normal wave base. Thicker intervals are therefore ranean, the plunge step below the swashzone oc interpreted to be essentially the result of increased curs between O m and -1 m below mean sea-Ievel accommodation space related to a relative sea-level (Dabrio, 1982). Therefore, the interfingering zone of rise; similarly, thinner intervals reftect a sea-level low-angle seaward-dipping parallel lamination and drop. To facilitate description the successive sea seaward-oriented cross-bedding of the Sorbas Mem level positions have been numbered in Fig. 9 (1-5 ber is al so interpreted to indicate this palaeodepth for this sequence; 6-14 for sequence 111, discussed (Fig. 10). The maximum water depth of the wave in the next section). generated megatrough-cross-bedding of unit 5 is es After tilting of sequence 1 relative sea-level rose timated to have been 6 m at the mosto ~32 m from position 1 (Fig. 9) to position 2 at high- 40 T.B. Roep el al.! Sedimentarl' Geolog\' 116 (1998) 27-56

w E 12 10 13 11 14 O~~~~~~~~~~~==~~~~~~·

50 m

o 250 500 750 1000m

Sequence 11 Sequen ce III

Fig. 9. Estímates sea-level fluctuations ín sequences n and III through time relatívc to ¡he posítíon of ¡he Zorreras whíte limestone datum plane. Io facilitate description the sea-Ievel posítions 1-14 are indicated (l11 inset. Because of lhe unknown time constraints the díslances on [he time axis are arbítrary. stand. From position 2 to 3 a sea-level drop of at least correlatable Iimestone layer further east is Iying di 3 m can be reconstructed in the top of unit 11, be reclly on deep-water laminites, suggesting that the tween columns 1 and 2 (Fig. 6) using the overlying stromatolites of the ridge could have grown at ~ 10m horizontally deposited lagoonal and washover sedi waterdepth. On the other hand all other stromatolite ments as reference level to measure the amount of occurrences in the Sorbas Basin are inferred to have seaward lowering of the top of unit JI. In position grown in very shal1ow-marine and lagoonal settings. 3 the swash zone carne to rest clirectly on a deeper In case of a shallow origin it seems that during times part of the coastal sequence with small-scale wave of lowered sea-Ievel with abandonment of a specific ripples and troughs. Further lowering of relative sea beach or barrier island the ridges were colonized by level to 8 m i5 Iikely and even a lowering to "-' 13 algae and stromatolite sedimentation thrived. Later, m is possible given the locally exposed stromatolites with relum of the sea and renewed beach deposits, the (Fig. 6; columns 6A and 16). Together these stroma exuberant growth of the stromatol ¡tes carne to an end. toliles forrn a ~200 m w¡de and up lO 500 m long After the sea-Ievel drop of 8 or 13 m from po narrow ridge extending in a north-south direction. sition 3, it rose maximally ~ 11 m lo position 4. This indicates a time of non-deposition of siliciclas A rise of at least 8 m can be reconstructed in two tic sediments. The ridge has an irregular top and is ways. First, from the superposition of two beachrock overlain by sandy calcarenites of the upper shoreface levels occurring 8 m apart along the path down to and foreshore. The original water deplh at which the the Rambla de Cinta Blanca canyon (westem en stromatolites formed 1S uncertain. On one hand a thin trance of Sorbas, Roep et al., 1979, their fig. 4. log IB. Roep el al. /Sedimenta,,' Geology 116 (1998) 27-56 41

SEAWARD _

111 Edge of canyon

ruined house Trace 01 coastal 11. rulned house -+- "WindoW~-==:=~2====:::::::;:::¡;.::::::= __íS __ ~_~ ___ ._~;_-~_~;;:_~::~ -.. - _.

Shelfmud Stromatolite

Fíg. 10. Seaward (lo the right) upstepping .:oastal wedges (sequence II, near section 8) due to a sea-Ievel ríse of ca. 8 m, as exposed in the canyon wall of Rambla de Cinta Blanca, northwest of Sorbas (after photograph; height of canyon wall 'v 15 m).

A). A similar amount can also be deduced from the 2-4 m thick thinning- and thickening-up sequences seaward upstepping 01' the toes 01' the sandy coastal due to increasing and decreasing wave activity. Cor sequence, interfingeríng with more muddy deeper relation with the prograded parts 01' parasequences deposited parts (Fig. 10), in the canyon wall north I-IJI, however, is not always possible. In these se 01' the church 01' Sorbas (best secn from the Red quences increase 01' wave activity due to shoaling is Cross Station). Here, it is also possible to recon expressed as thickening-up sand layers with transi struct the coastal gradient, by carefully following tion from lazy wave ripples to pointecl wave ripples. erosional and depositional surfaces (Figs. 5 and 10). Usually the thinning-up part 01' the sequential pat It dips ~3°, crossing the sandy par: 01' the sequence. tem is thinner than the thickening-up parto This is Usually, such gradients can not be observed in a interpreted as a result 01' more slow, gradual progra prograding coastal sequence, due t::l irregular scours datíon 01' the toe 01' the coastal slope (thickening caused by fluctuating weather conditions and back upward) and a more rapíd back-stepping 01' it during and forward movement 01' the barrier. Roep et al. transgression (thinníng upward). (1979) reconstructed this gradíent using a heavily F1uctuations of sea-Ievel on a decimetre scale burrowed surface due to a temporary stillstand of (and obviously 01' shorter duratíon) can be concluded barríer movement, or temporaríly improved life con from detailed analysis 01' the boundaries between ditions (decreased salinity). the described facies 01' prograding beach barriers; in Afler a major slump event, discussed in the next particular, interbedding 01' the facies types 5 and 6 paragraph, sea-Ievel remained more or less stable in the idealized vertical sequence (Fig. 8) and the duríng progradatíon 01' sequence II (from position 4 fact that the step at the lower shoreface indicates to 5. Fig. 9). the sea-Ievel (datum) at the time of deposition with Further basinward than the cross-section 01' Fig. 9, a precision 01' centimetres (Somoza et al., 1986-87; in an offshore mud setting, also evidence for fluctuat Fig. 11). These oscillations are of comparable scale ing sea-Ievels can be found. Here. they are shown by and dimensions as those known from half-century 42 TE. Roep el al.! Sedimentan; Geologv ¡ 16 (1998127~56

retrogradatíon from epísode A to B -1 ---~---~ ~-+ B - RISE ~~~~~~""""'--- ~ ~; ~ ~ALL I ,,<:~~~~~.: -- ~ ~"' ~<:',:..... plunge-step 3 progradation during episode A I fig. 11. Use (Jf planar cross-beddíng genermed by seaward mígratíon of the pI unge step in the lower foreshore. 10 reconstruct beach progradation and relrogradalion. and lo deduce short-Ierm trends of sea-level oscíllatíons (modífied afler Bardají el aL 1990). minor ftuctuations ol' sea-leve!, cited 1'or southem slumped sandstone rnasses were used as foundation Spain (Somoza el aL 1986-87; Zazo et al., 1994). for the eeramic ovens and houses of the lower part of ExeelIent examples can be observed near km 495.2 the village. The distorted sediments can be followed at eN 340 and near the springs 01' Sorbas. in this in the Rio de Aguas over aboUl 1 km in a dírection case within sequence L parallel to the original coastline (i.c. N-S) and over more than 400 m at right to it. before younger 5.4. Slumping and sliding sediments cover the exposure (Fig. 4a). Most likely, the original slump scar was oriented N-S along the At several times during progradation the coastal present eastem edge of the mesa cm which the vil sediments were a1'1'ected by large-scale slumping and lage has been buile Part 01' this slump may also be liquefaction. As the Sorbas Basin is situated nearby the slump scar exposed 600 m northeast 01' the church major strike-slip 1'aults that were active 1'rom Tortonian 01' Sorbas in the Rio de Aguas, where ir is situated in to Recent times such chaotie intercalations were prob the wave-rippled original shoreface. that was subse ably triggered by earthquakes on a relatively steep quently healed by rippled sands. slope, rather than by overloading and outbuilding of After the slumping, progradation continued, but coastal sediments over shell' muds. Moreover. other obviously the barrier never recovered from these indications l'or tectonical1y induced synsedimentary changes: lhe sandy part 01' the prograding sequence movements abound in the area. Sorne examples are became thinner and finer grained; the muddy, wave given here. (1) Synsedimentary 1'aulting and relaled rippled part thickened and more contorted bedding deavage blurring lhe original struetures (sequence 1, occurred in younger parts further east. These side km 496.5. eN 340; column 16, Fig. 6). This zone e1'fects seem relatcd to such a degree of tectonically is sharply truncated by a swash zone in the top 01' induced change that either an oyerall decrease of sequence 1. (2) Large-scale convolutions on a me fetch occurred. or that sorne shielding from wave ac tre scale occur both in sequence 1 and II (sequence 1 tivity was provided. AIso increased subsidence and near the eastem bridge 01' Sorbas. cf. Roep and Beets. instabílity of the basin margin must be taken into 1977; sequence 11 near columns IlB and 14, Fig. 6). account. (3) Large-scale ftuidization struclures on a scale of 2-3 m (road eN 340 at km 497.3. close to the road to 6. Sequence IU Lubrín). In the latter locality water escape took place along a line oriented N 10oE. A few metres to the east, 6.1. General rotated blocks, associated with ¡istric N-S-directed fault scars. indicate mass movement to the east. The total thickness of this sequence 01' ~20 m The largest slump occurs in sequence n, at the east implies that during its deposition water depth cannot cm side of the village of Sorbas. where the seaward- have exceeded 20 m and generally was less (~1O T.B. Roep et al. ¡Sedimenta/}' Geology 116 (1998) 27-56 43

m), regarding the height and position within it of (birds: crane, rale, plover and of a wolf or líon) have bird-foot tracks, swash zones, beach-rock levels and been observed (Roep and Beets, 1977; Roep et al., thickness of prograding units (Fig. 6). Sequence III 1979; J. Kenter, pers. commun., 1984). exhibits the most complex architecture due to inter rupted progradation, which resulted in an intricate 6.2. Estimates o/sea-level changes pattero of juxtaposed and superposed lagoonal muds. washover fans and swash zones. The swash zones be After deposition of sequence n. sea-Ievel rise ini long either to 'stranded' coastal barriers, left behind tially must have been in the order of 16 m (shifting after seaward jump of the coastline during regres from position 5 to 6 in Fig. 9). This rise is indi sion, or are connected with erosional parts of the cated by the thickness of washover fans in the west coastline at the cost of landward-lying washover sed and position of beach-rock breccia in sections 2 and iments, or belong to a prograding c03stal sequence. 3 (Fig. 6), Because the latter overlie the washover This more complex geometry is evidently related to fans erosively, a landward shift at lhe cost of the a more limited accommodation space, when minor washovers is indicated, Associated with the thick relative sea-Ievel ftuctuations have great influence. layers of beach-rock breccia is a wel! developed Slight regressions, for example, may cause an off swash zone (exposed along N 340 at km 495.4, sorne shore bar to build up quickly near or aboye sea-leve\, 300 m west of Sorbas; Fig. 5, section 3). This swash after which the coastline jumps seaward. zone is part of a small elevated ridge, which can be The westero part of the facies diagram (Fíg. 5) followed to the south over more than 1 km (Fig. 4) shows that large parts of the original space was and ínterpreted as a 'stranded barrier'. This barrier filled up by lagoonal sediments alld washover fans, (Fig. 12) implies a relatively deep sea in front of it which show thinning and up-stepping in a landward to the east (a space now occupied by the washover direction. In the parallel laminated lagoonal muds fans west of km 596.1, Hostal Sorbas; Fig. 13). Af mud cracks, raindrop imprints. salt pseudomorphs, ter its formation an imponant seaward (regressive) insects, rootlets and plant remains and animal tracks jump must have occurred. related to an estimated

w E

Fíg, 12. Sketch 01' the swash zone of a 'stranded barrier'. as exposed along the TOad at km 495.4. west of Sorbas. Seaward is to the righ!. Due to seaward jumpíng of a new barrier progressive shielding to wave activíty in this bar is inferred from steepening-up 01' tbe Jow-angle swash laminarion tpointed at by rhe geologist) and íncrease of burrowing. causing bluning 01' the stratification (10 ¡he righ!), 44 lB. Roep el al. I Sedímentarv Geology 116 (1998) 27-56

coarsening , and thickeníng upwalds Irend

Fig. ]3. Location detaíls of washover fan deposits (upper figure), showing landward thinning (lo the lefr). The proximal part (ro the right) shows stacked channels and coarse íntraclasl lag deposit. At the distal part the washover bar shows episodic shift (R reactivation surface). Occasionally former bar fronts show wave ripples (oriented N3000 E) indícating a shallow lagoonal setting after a storm event causing landward shift of the bar fronl. Low-angle. high-angle and sigmoid cross-beds in ¡he bar índicate westward sand transport. The bottom figure shows a conceptual model of washover development during relatively slow sea-level ríse (modífied after Dabrío et aL. 1996). A series of ¡aterally and vcrtically stacked washover-fans ís formed due to repeated overwash al lalerally disconnected SpOIS of lhe barrier. Compare Wilh Fig. 7.

sea-level faIl of altogether ~14 m. The swash zone rowing, in part within the swash larnination itself. clearIy shows its deterioratíon (Fig. 12) by a basin The forced regression was accomplished in several ward-increasing steepness of the swash larnination steps with temporary stillstands, smaIl rises and ero associated with finer grain size and increasing bur- sion events. Slight erosion may have taken place 7:B. Roep el al.! Sedimentary Ge%g)" //6 (/998) 27-56 45

(for exampJe indicated by the sharp contact between at least 15 m is inferred from the most basinward a coarse-grained congJomeratíc swash zone and the deposíted sequence. Offshore muds with only the top of an intensely burrowed uppcr part of a sandy slightest traces of wave activity are directly overlain coastal sequence in the riverbed 01' Rambla de Cinta by a slump of 1 m thickness, followed by a 3 m Blanca (Fig. 6, columns 4 and 5; Fig. 9, position 7). thick gravelly beach- or washover-sequence, which The stranded barrier and regressive seaward part in tum is overlain by continental strata of the Zor is onJapped by an up to 20 m thick piJe of washover reras Member. In the top of the Sorbas sequence a fans, indicating renewed transgression (Fig. 5). 'pisolitic layer' occurs (see al so Section 11), which These deposits seem to be the result of two trans can be correlated over 3 km with the stromatolites gressions interrupted by a forced regression, leaving at the top of unit I1I, column 14 (Fig. 6). Thís cor behind a second stranded barrier (marked '?' in be relation indicates that most of the time this basinal tween sea-leve] positíons 8 and 9, Fig. 9, because section was welI below wave base. not all sedimentological details could be clarified). This second stranded barrier can be followed in N 7. Sequences in washover fans S direction along two paths descending along the cliffs from both the NW and SW comer of the Many good examples of landward-thinning and town. From position 9 (Fig. 9) a torced regres upstepping washovers can be found in the Sorbas sion caused an eastward shift to 10, after which area, such as near columns 1-2, 6B-·7 (Fig. 6) and renewed transgression proceeded from 11 to posi at the northwest comer of the town, as can be seen lion 12. The transgressive surfacf: is well exposed from the Red Cross Station (Roep and Beets, 1977). in the flrst curves a]ong the road to Lubrin (~100 Sedimentary details are shown in Fig. 13. In a verti m west of section 14, Fig. 6) and is marked by a cal sense, such successions may be thought to show beach-rock breccia and a thinning:-up wave-rippled mainly a thickening upward, because of the transgres sequence. This ravinement surface: can be followed sively advancing coastline. However, such a simple further westward in sections 13, 12 and 11B (Fig. 6), sequential order is not maintained. We observed both in which direction the transgressive sequence thick thickening-up, thinning-up and irregular sequences. ens into a wedge-shaped sandbody characterized by Rather the picture emerges of compensatíon cycles, wave-formed megatroughs. This unit is interpreted as described by Mutti and Sonnino (1981) for sub as the toe of a transgressed barrier. Further west marine fan lobes. The following scenario is inferred: the transgressive surface is lost in the canyon of the al place s where a barrier is píerced during storm, rel recent Rio de Aguas, but can be picked up again in atively thick stacks of washover fans accumulate at sectÍons 10, 15 and 7 (Fig. 6). the proximal side (Fíg. 13). Owing to their fan shape After this transgressive episode progradation was they thin away from the breach, distally towards land resumed and the sea-leve1 shifted from position 12 and proximally lowards the parts of the barrier where to 13, marking a small lowering (of ~8 m) and the barrier was not broken. Later other bed thickness then shifted to 14 (marking a flnal small transgres trends may develop in case the barrier ísland is broken sion, with deposition of lagoonal mud, washover or surpassed in different places. This, coupled wíth sandstone, beach-rock breccia, ooEtic limestone and variable rates of sea-Ievel rise, will produce diverse stromatolites). It is clear to us that the mean sea types of large-scale cross-bedding in the landward level rose hardly enough to cover a coastal zone migrating back-barrier (Figs. 7 and 13). with topographical irregularities, thus providing little With regard to hydrocarbon exploration it is in accommodatíon space. Even small fluctuatíons were teresting to note that the sandstone connectivity in a able to produce a variety of deposítional pattems. transgressive setting with lagoon and washover sed Hereafter, the Messínian sea definitively withdrew iments is quite different from one with a tidal ínlet from the area around Sorbas. Its latest ínfluence can and inner delta. In the latter case the barrier sands be studied 4 km to the east of Sorbas (south of are deeply eroded by the ínlet channel, whereas in km 501.6 at CN 340, Roep and Beets, 1977; Roep the case of washover channels erosion is very mod and Van Harten, 1979). Here a sea-Ievel drop of est (Fig. 13). In the case of the Sorbas examples 46 lB. Roep el al. / Sedimenton' Geolog)' l16 (1998) 27-56 both marine mud tongues and lagoonal mud tongues, cross-bedding-like layers of lamÍnated sandstone and whích respectívely pínch out landward and seaward, calcarenite represent storm layers, Imervals of wave would act as a permeability fence (Fig, 5). Due to the ripple cross-Iamínation or parallel-lamination occur reduced accommodation space in sequence II1 trans depending on water depth. Lack of burrowing in gressíve washover girdles occur in juxtaposítion with many le veis suggests oxygen depletion anclJor ab regressive, erosive 'stranded bamers'. This setting normal salinities and especially characterizes the therefore may both reduce and enhance lateral fluid deeper offshore muds. Marine fossils are either ab migration. Stromatolitic íntercalations further reduce sent in these deposits, or few specimt!ns are found of the permeability. which the autochthonous nature is questionable (Ott d'Estevou, 1980). 8. Source area of extra- and intra-clasts The lagoonal deposits consist of yellow and white parallellaminated silt and clay with i.nterbedded thin Because of prominent lithological differences be (1-3 cm) layers of fining-upward ;¡andstone. Sed tween the various deposits in the beach zone, sorne iments of the wedge-shaped calcarenite layers of attention should be gíven to the source areas of sedi washover-fan facies are derived from the barrier. ments in the coastal barriers, lagoon, and washovers This implies multiple sediment sources and there as compared to the offshore facies. fore requires coastal processes (Fig, 14) such as: The beach deposits comprise both calcareniles (1) streams supplying siliciclastícs of variable grain with coated graíns and oolites mixed with coarser size; (2) in-situ precipitatíon of carbonate as oolites, grains (gravels), in part of terrigenous origin, Many coated grains, stromatolítes and thrombolites (this coarser fragments are flat-rounded calcarenites. one probably under a warm climate, as s,uggested by oc to several centimetres in diameter. and were derived currences of halite pseudomorphs in lagoonal muds); from within the barrier during beach retreat. Usu (3) linoral drift (along-shore currents) transporting ally they are associated with erosional surfaces and sediment into the bamer from sources that. accord washover channels. Particularly the larger pebbles ing to their lithology, were located to the nonh. may derive from eroded beach rocks. The offshore sediments are mostly silíciclastic, 9. Tectonic factors controlling the location and fine mÍcaceous sandstones, silts and clays, Sorne development of barrier islands and lagoons layers are dark grey due to abundant organic mat ter. lnterbedded wave-rippled, undulating laminated, Next to relative sea-Ievel changes and differential parallel-laminated, and sorne small-scale hummocky uplift, al so related geometrical factors such as gentle

calcarenite river drainage S-N •••••• , eroded from (siliciclastic) barrier island

calcarenite generated on barrier island

barrier ¡stand (mixed silicíclastíc/carbonate)

drift siliciclastic shelf sediment overwash Fig. 14, Sketch of inferred sediment circulation in the barricr island and lagoon systems of Sorbas. T.B. Roep el al. I Sedimentan' Geulogy 116 ( 1998) 27-56 47

W-E SORBAS Stalue Hotel School Peones Río de Aguas Chacho Hill Camineros (bridge) & La Viuda

ca, 100m

Fig, 15. Schematic W-E cross-~eclion of tle coaslal units of Ihe Sorbas Member in the eliffs 01' Sorbas, The section is roughly normal to Ihe palaeocoastlíne and shows the intluenee of mínor, approximately N-S-oriented syndepositional folds. Compare with panorama in Fig.4b. and locally occurring synsedimentary folding appear road CN 340. Mather and Westhead ( 1993) observed to have influenced the stratigraphic architecture al' also in Plio-Pleistocene Sorbas locations minar N-S the Sorbas Member, notably the prominent N-S ori trendíng, but variably oriented folds and noted that entation 01' the beach ridges and lagoons. Initially, their genesis could have been stímulated by the un it was assumed that this direction was related to the derlying evaporites. lt i5 interesting to note that the angle 01' incidence 01' waves under prevailing winds. fluidization structures and slumps cíted in unit II also Although this is probably a large part al' the ex are bound to N-S-oriented faults and slide scars. planation, increasing knowledge 01' the geometrical The creation of a roughly N-S-trending ridge and relations made ít clear to us that at least part 01' the swell morphology around Sorbas had palaeogeo palaeogeographical trends must have been induced graphic implications: the rising areas ranticlines') by subtle tectonic deformation. Most 01' this type 01' acted as nudeation areas for barrier islands, whereas deformation occurred during and after the deposition the intervcning gentle depressions favoured the de 01' sequence II. A view on such a structure can be ob velopment of lagoons. Qne of the main effects was tained along the provincial road (CN 340, km 496.3- the generation al' a slightly subsiding zone just be 496.8, Fig. 15). Here (from km 496.4 visible below low Sorbas town where lagoon and washover fans the school), the existence of such slightly depressed, are best developed. or elevated narrow zones is further suggested by the A crucial point is that the (present) difference in pinching out of lagoonal deposits against the gentle elevations between these areas is usually 3 or 4 m. palaeoslope, both to the east and southwest in unit and most 01' the irregularity was compensated after IlI. The very gentle folding with a roughly N-S deposítíon of unit 1Il. Thus, the lowermost lagoonal axial direction visible here, seems to be associated caIcareous layer of the Lago Mare facies, used as with a conjugate set of secondary antithetic NW -SE reference line in Fig. 5, is a horizontal surface. and synthetic NNE-SSW shears, reported by Mather The moderate accommodation space added to the and Westhead (1993) and Stapel et aL (1996). Re topographically slightly irregular floor of the basin gional palaeostress analysis (Biermann, 1995; Stapel promoted the jumpíng character of the barrier islands et aL. 1996) indicates a maximurn principal stress during deposition of unit m. axis orientation of N350"E for the late Messinian to Late Pliocene sediments of the Sorbas Basin, 10. Relations with the terminal carbonate which was synchronous with sinistral motíon along complex the Palomares fault zone (Fig. 1). Recent NW-SE faults crossing Sorbas are visible and measurable in The TCC of the northern margin of the Sor the walls 01' the houses and the church, and also in bas Basin consists mainly 01' silicidastic fluvially +

Terminal Carbonate Complex Zorreras Member (ZM) N-S horizontally-deposited lagoon carbonates 01 Lago Mare (L) facies present sea level :--l rellef !'= tall ::o ~ ~ :-'" _3.33 ~" ~ ;:¡ .4 :tst-¡'~ 2.3 ,2 te; 1 =>- 2.2 .;:¡ < 21'" I CJ s 1 ".:, spring .. house ~ o: ORIGINAL OIP PRESERVEO ORIGINAL OIP EXAGGERATEO -\C ~ SCALE '"jl ~. u, SSSBioturbation M Thrombolites Oolites J Conglomerate vertical: ca. 50 m '" horizontal: ca. 350 m A Wave ripples ~...Porites m Sandstone R:AAAAStromatolites (S)

Fig. 16. Reconslruction 01' Ihe shelf lo slopc syslern as occurring al the easlern rnargin 01' Ihe river gorge oI' the Rambla de Gnchar. wilh indication of deduced custatic oscillation (EI-3), Nole Ihat sorne post-dcpositional compaclion look place. callsing downbending of Ihe layers 01' Ihe TCe and the Zorreras Mcrnber I'mm Ihe walcrhollse to the SOlltn (modified aner Dabrio and Polo, 1995), T.B. Roep el ai.! Sedimentan' Geology 116 (1998) 27~56 49 derived coastal conglomerates that ehange Iate rally cally, Ophiomorpha burrows and water-escape struc into sands. Both the conglomerates and the sands tures occur. Dabrio and Polo (1995) interpret these are intercalated with oolitic Iimestone, small Porires sequences as a result of upward aggradation and patch reefs, and microbial carbonates (stromatolites progradation of fan-shaped units, sorne of lhem con and thrombolites). These coastal 10 slope units are nected to topographically more elevaled patch reefs, arranged in a complex omap pattern (Dabrio and during minor fiuctuations of sea-Ievel (Fig. 16, right Polo, 1995; Fig. 16). hand column). Martín et al. (1993) descri bed t he features of the Unit 3 mainly consists of layers of conglomer Messinian silicielastic microbial carbonates in de ate, sand and stromatolite/thrombolite. Large-scale tail and interpreted them as a normal-marine facies, wave-ripple cross-stratification occurs in the lower shown by Porites within the domes (sorne bored by most part (supposedly 'deeper' part of the talus slope Lithophaga), algae, ineluding coraJline algae, ver in the opinion of Martín et al., 1993). The metre-size metids and encrusting forams. A s.ignificant part of sequences essentíally show a basal erosional surface, the present stratal dip, however, is a post-deposi followed by conglomerates, wave-ripple cross-strat tional feature (Fig. 16), and not an original one, as ified and cross-laminated sandstones, overlain by argued by the latter authors to justify the role played thin-bedded, paraIJel-laminated sandstones passing by the original slope in controlling the morphology upward into stromatolites (three levels found, indi and distriburion of stromatolites. Post-depositional cated SI-3 in Fig. 16, right hand column). Accord compaction and tectonics account for the exagger ing to Dabrio and Polo (1995) these sequences are ated dip of the younger beds of [he TCC and the related to high-frequency eustatic cycJes, in which Zorreras Member (including the originally horizon the stromatolites indicate the end 01' a highstand. The tally deposited white 'Lago Mare limestones) in authors suggested that the thinner sequences might the southem part of the outcrop. Differential com be related to oscillations of sea-Ievel 01' higher fre paction, due to the limited extension toward the quency than in unit 2, and acting on a surface much basin of the underlying cemented reel'al limestone less inclined than in unit 2 (in fact it would be almost may have played a major role. horizontal). An important aspeet of the TCC is the obvious Most importantly, Dabrio and Polo (1995) corre sequentiality. In the outcrop of Gochar it comprises lated the Gochar sequences from the northem basin three major units of decametre scale, which consist margin with those from Sorbas (Fig. 17). With regard ol' thinner metre to decametre scaled coarsening- or 10 the relative sea-Ievel reconstructions presented in thinning-upward sequences (for details, see Dabrio Fig. 9, we now consider ir likely that the major sea and Polo, 1995). level excursions for parasequence II (points 2 and Unit 1 of the latter authors (Fig. 16; or parase 4) correlate with the highest, stromatolite-capped se quence 1 according to the present terminology) con quences (2.1 and 2.3, Fig. 16) of Gochar. Similarly, sists of a variety of facies: coastal conglomerates the four fluctuations coneluded for Gochar in unit 3 and wave-rippled oolitic Iimestone, poorIy preserved (Fig. 16) might welI be the equivalents of points 6, stromatolites and conglomerates that change basin 9,12 and 14 ofsequence III. Fig. 9. ward into sands. Unit 2 ineludes at least five prograding units, 11. Late Messinian retreat of the Sorbas sea two of which (2.1 and 2.3) are related to Porites patch reefs. Stromatolites draped a part of the patch As one 01' the Mediterranean marginal basins, also reefs, in particular the talus facies consisting of the Sorbas Basin underwent the complex series of calcarenites and calcisiltites. These form metre- to depositional events related to the rnuch discussed decametre-size coarsening-upward sequences: larn Mediterranean Messinian salinity crisis (Hsü et aL, inated mudstones at the base pass upwards into 1973, 1977). Very briefiy summarized this crisis wave-Iaminated medium to fine sands (storm sand comprises the folIowing major steps. (1) Restricted layers), and burrowed wave-ripple cross-Iaminated watermass exchange with the Atlantic ultimately re and cross-bedded calcarenites and sandstones. Lo- sulting in evaporite deposition in the marginal basins. 50 T.B. Roep et al. /Sedimentar)' Geology J 16 (1998) 27-56 GOCHAR SORBAS

el) ca:: a::W wm a:wa:~ O~ N 3 S2 3.1 3.2 3.3 -2:5- a:: w 2.3 2.4 m ~ w 2.2 ~ S el) m 2.1 ""a:: O el)

® Bivalves SI) Burrowing 4> Gastropods el\, Ophiomorpha burrows ~ Stromatolites Wave·ripple cross lamination Fíg. 17. Synthetíc successíon of the Sorbas strata and suggested correlatíon of th.: three sequences with ¡he synthetíc seclÍon of Rambla de Góchar at the northern basin margin (S = stromatolite layer). Note lhat wedge-shaped units make vertical scales in Góchar inaccurale. (Moditied after Dabrio and Polo, 1995,)

(2) With complete closure from the Atlantic a major Sorbas sea so far have mainly been a matter of spec desiccation phase occurred wÍth a proven sea-level ulation (surnmarized in Van de Poe], 1994). Where drop exceeding 2000 m (Stampfii and Hocker, 1989), then to find the intra-Messinian downdrop traces in (3) The salinity crisis ends with deposition of a trans the sediments of the Sorbas Basin: below or aboye gressive brackish, so-called Lago Mare facies which the Sorbas Member? Traces of this widely reported may have involved supply of Paratethyan waters, (4) sea-level drop (see recent discussion by Clauzon et The return to normal marine waters was reestab aL, 1996) are hard lO find. In case the sea forming lished by opening of the Gibraltar passage at the the Sorbas Member already belonged to the terminal onset of the Pliocene, Messinian Lago Mare event, as suggested by Van The Sorbas Basin, with its well known gypsifer de Poel (1994), it would postdate 'the down drop ous sediments underlying the Sorbas Member, how event', At least the Zorreras Member, which includes ever, does not clearly ex pose traces of a major intra the white lagoonal beds with Mare' fauna, is a Messinian sea-level drop that can be related to the post-downdrop unít. late Messinian desiccation event. In fact, the fac After the major downdrop of the Mediterranean, tors governing the final retreat of the late Messinian Porites and other reef-building corals never returned T.B Roep el al, / Sedimenta!)' Ce%g." 116 (1998) 27-56 51

NW / First white layer (lagoon) SE :::i:~:: ::0~:::::;: ¡:¡:;:;:::;: :::'.;: :'.;:;: ;:;:;: ;:::;:::;:;: ¡:::;::::::: ;f::: :;:;: :',;:;: ::;::: :'. :',::::::;:;:::;: ;:;:; Zorreras Member i \ • .~: :/.~::::::::::::: 1:::: :S::: :S::::S::: S::: :S:: ::~:: :5::::S:::: S:': ¿~:.:";-: 'Pi~olite la er :A~':':':':':;'-~~:':':':':':':':':':'(:·:'¿':':r:·:··s:':': >:'S:-.-:·:':~·~ J • ~ y ~ ~. ':-> •••• S··,·~·~~o I (i~.J. Whlte. "14 u.·.·.'.·.·.·A?;~.'.·,·"' .... "''-'' ...." j .. 5'...... S·· ',' S·...... ) .., .. ) .., ... ~.. ' .... , ... ~,. _! sandstone .~. :~:.:.' ..:- '_ _ ~ _ ~ ,,' 'c ",,"" .c::::::. <=> <:::::> .. ,...... --s~ S~___ ",,;;"" ======---= Red clay O- ___ -;t!''' ~-~ ..... _------",,"" ... "" Wave rípples White sandstone :.',:.:. : : : : : : : : . : ...... , ...... ------.... _~ Conglomerate 09-:-°:-'. ~.Q.:...... - Pisolite block Laminites Sorbas Member

Fig, 18. Reconstructed channel incísion (~6 m deep) occurring at the top of the Sorbas Member near km 499.5 and possibly the local expression of the 10\\lstand due to the late .\vlessinian Mediterranean desiccmion event. The channel is overlaín by pink c1ay and sands. plus the tirst white 'Lago !vlare' bed of the Zorreras Member, The chunnel has a complex intill consisting of pebble conglomerate with a block reworked from ¡he eroded pisolític layer and whíte sandstone ar the base, The upper pan includes mottled red clays and silts. biorurbated white sandstones and a smaller channel-fill (wíth Hydmbia and small shells of 'Lago Mare' affínily), to it (Esteban, 1979). The finding of stunted Porites therefore the most Iíkely candidate representing this aboye a layer of selenite gypsum west of the road event. will therefore be discussed (Fig. 18). to Lucainena (Fíg. 1), in association with oolitic Large amounts of thin shells and Hydmbia of limestone in a marginal Sorbas Mt:mber setting not Lago Mare origin can both be found in the top only confirms a TCC connection, but also indicates most layers of whíte Sorbas sandy calcarenites along deposition before the downdrop event. This implies, the road to Lucainena and in a small gully (east at variance with Rouchy and Saint Martín (1992) of the ruins of the Venta de la Lencia) near km and Martín and Braga (1994, 1996), that lhe ma 499.5. In this lalter locality the shells occur in a jor intra-Messinian unconformity o::curring between channel cutting into the "pisolite layer' (Roep et al., the fringing reefs and the TCC at the basin mar 1979), a bed consisting of smalI irregular algal balls, gins, more likely reflects the result of regressions probably green algae. The channel is ~6 m deep. coupled with deposition of the t:vaporites in the The pisolite bed could be traced from the centre of marginal basins, than the majar desiccation evento the Sorbas Basin (near km 501) to the Lubrín road Presence of conformable contacts lJetween both the (at km 497.3), where it merges into the uppennost Yesares evaporitic strata and the underlying open stromatolítes of section 14. marine Abad sediments and the gradual Yesares Such minor evidence for local erosioI1 during a Sorbas Member contacls, are interpreted as indica sea-level fal! in the Sorbas Basin centre suggests that tions that the Sorbas Member is a pre-downdrop in fact the basin centre never was deeply eroded. Per unit than can be correlated with the TCC (Fig. 17). haps a palaeogeographic barrier betwcen the Sorbas Thus, in our vision traces of an important downdrop Basín and the Mediterranean protected it from deep event first of all should be sought within or at the erosiono Increasíng Late Miocene shielding of the top of the Sorbas Member. A locality in the basin Sorbas BasiI1 ís suggested by strong field evidence centre showing an erosion event al this stratigraphic for late Messinian uplift of the Sierra Cabrera (study level, underlying the Zorreras Lago Mare bed, and in progress). Another argument for an existing bar- 52 T.8. Roep el al./Sedimentary Geology 116 (1998) 27-56 rier is the strontíum isotope ratios of ostracod shells atively large accommodation space created by differ from the overlying white Lago Mare deposits in the enlial tectonic movements, are simple shallowing-up Sorbas Basin. Beets (1992) found that these devi sequences due to barrier progradation. These can be ale from those from Lago Mare deposils in central well eompared with classical prograding examples Mediterranean basins. According lO the latter author such as from the Cretaeeous Western Interior basins the differences indicate different water masses with of the USA (Van Wagoner and Bertram, 1995). increased Sr supply from the Sierra de los Filabres. In the field sequenee III also is readily reeognized In the adjoining Vera Basin, in c:ontrast where ev as a parasequence. Upon closer inspection, however, idence for strong local terminal Messinian erosion it appears to consist of juxtaposed transgressive and has been found (Fortuin el al., 1995), the latter au prograding parts, separated by erosional surfaces and thors measured Sr-isotope ralios of ostracod shells flooding surfaces due to sea-level fluctuations within similar to those of adjoining Medíterranean basins. a limited accommodation space. These sea-level fluc Soon after retum of the normal-marine Pliocene tuations were in the order 01' 10, and even up to 15 sea, the area emerged definitively as a result of m (Fig. 9). Minor transgressions induced formatíon overall uplift. of landward-moving washover-fan systems interea lated in lagoonal muds, whieh finally were eroded by 12. Conclusions the barrier. Periods of foreed regression caused the seaward stepping of temporary barriers. During this The special value of the Sorbas sequences lies process these may show landward eros ion, or sea in the three-dimensionally exposed shoreline archi ward progradation dependent of the smaller sea-level tecture. Both extremely well exposed transgressive fluctuations. surfaces and rarely reported, equally well preserved, Due to its more compIex facies architecture, se wave-dominated deepening-up sequences are shown quence III might form a nomenclatural problem: due to lack 01' burrowing. Toge':her, the sequences is it one parasequence or in faet a composite of perrnit to estímate amounts of rising and falling sea four stacked parasequences, i.e. of similar ranking level (Fig. 9), although clear time constraints are still as sequences 1 and 11, given the largest sea-level lacking. fluctuations dedueed? The internal erosion surfaees In sequence-stratigraphic terrninology (Van Wag may be labelled 'minor sequence boundaries', a1' oner and Bertram, 1995) the units can best be clas ter usage by Van Wagoner and Bertram (1995), but sified as parasequences with an upstepping and bas such a term mainly serves to indicate sequence inward upstepping pattern 01' the late highstand. The stratigraphic eomplexities. In 1'aet, ranking of such lower two sequences, which were deposited in a rel- composite sequences will remain problematie, un-

Fig. 19. Conceptual models of variaticn in stratigraphic architecture in response to various types of relative sea-level changes and associated lateral shift of the shoreline ,'modihed after Dabrio and Polo. 1996). IlIustrated are six U-V[) hypothetical eustatic sea-Ievel curves (Ihe sínuous línes in the middle) deduced from these deposits and associated shiflS 01' Ihe coast line Ihal can be reconslructed from Ihe lateral and vertical stacking of the ('oastal sediments (left). (l) Coaslal onlap record, a steady rise 01' sea-level (which. in princíple. í3 consídered 10 be continuous; sce thick heavy líne) during a single eustatic oscillalÍon (sil. 512, etc. indicate successive positíons 01' sea-Ievel). However. a disconlÍnuous rhe may produce the same effect. particularly if scrutiny of sections i5 not c10se enough. During this process the shoreline moves landwlfds and upwards. (IIl Discontinuous coastal onlap may reftect a continuous sea-Ievel rise wilh variable sediment input (thick line at tle left), a two-step rise wilh an intervening interruption, or sudden jump upwards Oine in ¡he centre). or (even) an interveníng mino!' fal! (Iine at the right). In the meanlÍme. the shorelíne progresses as in the former case. (IlIl Coastal offlap record, (quasí) steady sea-leve!. Seaward ,hift of shoreline may (or may not) be preceded by other shifts (dotted line with question mark). (IV) A complex coastal offlap with ¡hree progrJ.ding beach units (B-1. B-2. B-3) al dífferent topographic elevations, each composed of minor prograding units (a, b. e). record, al least a firsl sea-Ievel TÍse followed by eustatic oscillations reaching progressívely lower elevations. The ,horeline follows a zigzagging pattern. (V) Two beach uníts (B·1 older than B-2). each Wilh minor offlapping unir, la. b. e) record al least two ;;ea-level rr,axíma reaching progressively higher elevations. with an interveníng stillstand, or minor fall thal complete ¡hese oscillations. The shorelme follows a zigzagging pattern. (VI) A combínation of former cases may produce much more complex stratigraphical architectures. stlch as in the discontínuous coaslal onlap plus simple offlap. T.B. Roep el al. / Sedimentary Geology 116 (1998) 27-56 53

GEOMETRY EUSTATIC SHIFTOF (ARCHITECTURE) OSClllATION COASTlINE

relativa sea level time space rise j/

11 DISCONTINUOUS COASTAL ONLAP

...... ~..

111 SIMPLE Of'FLAP

8[3~.t_ .. _ .. _ .. _...... ~ ...... abe .. 8[4 .~_ •• _ •• _ •• ~.' .B-2a ...... zt-.,illll""'" " B-2b 8-2 _ - - :~1:: ...... :':::.. -2e .... :::.. : . :::.: .. a.~c ~ - V 2 ¡ B-la 8-1 __ _ . B-le - DISCONTINUOUS COASTAL ONLAP + OFFLAP --.... ---....-_..... ~~-- VI ~~if#~~''''~ ... "...... ".... _.~ ... - -::; ...... ··· .. ··B-1 ---..-."...::" :. - DISCONTINUOUS COtíSTAL ONLAP + SIMPLE OFFLAP 54 TE. Roep er al./ Sedinu'ntary Geologv 116 (1998j 27-56 til the approximate duratíon of the various orders in response to various types of relative sea-Ievel of sea-Ievel excursions is knowr. and similar order change and associated lateral shift of the shoreline. patterns can be compared. This aspect may hamper SÍtuations 1, II and III and theÍr combination in cyclostratigraphic studies involvillg the distinction of example VI al! can be found in sequence II, whereas orbitally forced (Milankovitch) cycles in this type of examples IV and V can be found in sequence 1Il. environment. but in the case of the Sorbas sequences Differentiation in the field between situatíons IV (of which their relation with precession cyclicity is and V may be difficult when the boundaries are under study) rhe lalter problem could be solved. incompletely exposed. Furthermore, the lateral and As pointed out in Section 10, parasequence 1II of vertical relationships are much more complicated the basin centre can be well correlated with unit due to the interplay of various orders of magnitude 3 of Dabrio and Polo (1995) of the northern basin of sea-Ievel changes. margino There the subcycles clearly reflect a lower The largest downdrop ol' Mediterranean sea-Ievel order of magnitude while unit 3 is of similar size occurred after the deposition of the three Sorbas se as the two underlying ones. Thlls parasequence III quences. An overalllack of intensive erosion, except indeed may be assumed to have the same ranking for local channels scoured in the topmost sequence. as parasequences I and n. Given the clear evidence is seen as an indication thar the area then was pro that the three Sorbas sequences \vere deposited under tected from major channel entrenchment, such as various orders of relative sea-Ievel fluctuations it is reported from nearby offshore areas and from many concluded that the factor accomrnodation space is of other Mediterranean basins. crucial importance to be able te readily distinguish between the effects of larger and smaller sea-level Acknowledgements fluctuatíons. In other words, with limíted accom modation space erroneous sequential (stratígraphic) Various topics were discussed with quite sorne interpretatíons are easily made. colleagues, of whom we mention Dirk Beets, Wolf The lateral jumping and erosional surfaces in gang Schlager, Tiny Geel, Henk van de Poel, Jeroen parasequence III seem to be good indicators for a Kenter, Francisco Sierro, Cees Biermann, Gerco much more reduced accommodHion space, as is the StapeL Wout Krijgsman and J.L. Hemandez En exaggerated influence of waves in the foreshore as rile. We acknowledge the constructive criticism of destructive agents. Minor transgressions lead to for the reviewers Franco Ricci-Lucchi and Tom Aigner. mation of a landward-moving washover-fan system The Dutch authors wish to thank the former stu intercalated in lagoonal muds and finally become dents Johan ten Veen, Jelger Kooistra and Natasja eroded by the barrier. Periods of forced regression Vugts for their unflagging enthusiasm during their lead to seaward-stepping tempürary barriers, which fieldwork periods in various parts of the Sorbas may move landward in the way just described or Basin. CJD and MDP received financial support prograde seawards dependent Jf smal!er sea-Ievel from Project EU EV5V-CT94-0445. TBR acknowl fluctuations. Two models are given ol' washover for edges sponsoring by the Industrial Associates Fund mation, respectively during mxe rapid and more (Prof. W. Schlager). This is contribution Nr. 970140 slow sea-Ievel rise (Figs. 7 and 13). Transgressíons of the Netherlands Research School of Sedimentary in the non-tidal Sorbas setting lead to depositíon Geology (NSG). of washover fans in lagoonal mud with only minor piercing of the barrier, instead of other more com References mon systems with large lidal channels, This aspect restricts sandstone connectivity, so important in hy Baniaji. T., Dabrio. CL Goy. J,L,. SomOZa. L.. Zazo. C .. 1990. drocarbon exploration. On the other hand, forced Pleistocene fan deltas in southeastem Iherian Península: sedi regression wíth 'stranded' erosive barriers will en mentary control s and sea-Ievel changes. In: ColleIla. A .. Prior. D,S. (Eds.). Coarse Graincd Deltas. Int. Assoc. Sedimento!. hance the sand connectivity. Spec. Puhl. 10. 129-151. Six conceptual models have been added (Fig. 19) Beets. CJ .. 1992. Ca1ibration of Late Cenozoic Marine Stron to illustrate variations in stratigraphic architecture tium ¡sotope Variations and its Chronostratigraphic and Geo- TE. Roep et al. / Sedimentar; Geology 116 (1998) 27-56 55

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