Lower Triassic Sequence Stratigraphy of the Western Part of the Germanic Basin (West of Black Forest): Fluvial System Evolution Through Time and Space

Sedimentary Geology 186 (2006) 187–211 www.elsevier.com/locate/sedgeo

Lower Triassic sequence stratigraphy of the western part of the Germanic Basin (west of Black Forest): Fluvial system evolution through time and space

Sylvie Bourquin a,*, Samuel Peron a, Marc Durand b

a Ge´osciences Rennes, UMR 6118, Univ. Rennes 1, 35042 Rennes cedex, France b 47 rue de Lavaux, 54520 Laxou, France Received 30 September 2004; received in revised form 21 October 2005; accepted 10 November 2005

Abstract

The aim of this paper is to analyse the fluvial evolution of the Lower Triassic in the western part of the Germanic Basin through time and space, as well as the impact of the geodynamic and climatic setting on the preservation of fluvial deposits. The Lower Triassic crops out only in the Vosges Massif and the Black Forest, so well-log studies are required to realise sequence stratigraphy correlations and establish comparisons with others parts of the Germanic Basin. In a first step, we use well-log data analyses to characterise the electrofacies associations in the Triassic and then define the well-log signatures of each formation. In a second step, the characterisation and recognition of genetic sequences and their stacking pattern allow us to define seven minor cycles integrated into two major cycles. Finally, the quantification of the lithologies at different stages of basin evolution leads to the reconstruction of paleoenvironmental maps to illustrate facies evolution through space and time. A comparison with cycles defined in the Germanic Basin allows us to propose correlations of the Lower Triassic on either side of the Rhine Graben and leads to a discussion of the evolution of fluvial systems through time and space. During the Scythian, the fluvial style is characterised by braided fluvial systems evolving laterally into lake deposits towards the central part of the Germanic Basin. During this stage, the basin was a huge depression with very few marine connections in its extreme eastern part. The stratigraphic cycles represent rhythmic fluctuations in relative lake level that could be attributed to sediment supply and/or lake level variations in an arid setting. Four minor stratigraphic cycles are observed that are integrated within a single major stratigraphic cycle. During the period of the stratigraphic base-level rise of the major cycle, a maximum of 233 m of sediment would represent a duration of sedimentation in the Paris Basin of at least 1.8 m.y. During the period of the stratigraphic base-level fall of the major cycle, a maximum of 65 m of sediment would have accumulated over 2.5 m.y. On the western edge of the Germanic Basin, the top of the Scythian is marked by a major sedimentary break characterised by a planation surface, with preservation of the first paleosols, followed by the Hardegsen unconformity. This unconformity is tectonically deformed, leading to the development of a new sedimentation area in the west of the basin. The fluvial sedimentation above this discontinuity shows a trend towards enhanced development of floodplain or lacustrine-type environments at its western margin, with the formation of paleosols. The fluvial systems are linked with sabkhas, and then with a shallow sea connected to the Tethys Ocean. In this context, the

* Corresponding author. Fax: +33 2 23 23 61 06. E-mail address: [email protected] (S. Bourquin).

0037-0738/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.sedgeo.2005.11.018 188 S. Bourquin et al. / Sedimentary Geology 186 (2006) 187–211 stratigraphic cycles are caused by variations in relative sea level and/or sediment supply. The fluvial deposits are preserved in an exoreic basin. D 2005 Elsevier B.V. All rights reserved.

Keywords: Lower Triassic; Fluvial sedimentation; Sequence stratigraphy; Well-log analysis; Paris and Germanic basins; Paleoenvironmental maps

1. Introduction 2. Geological setting

The Triassic is a period of transition associated with During the Early Triassic, the Paris and Bresse-Jura the beginning of the break-up of the Pangean supercon- basins formed the western end of the Germanic Basin. tinent and the development of the Mesozoic basins, in a The Paris Basin only existed as an independent basin globally warm and dry climate (Ziegler, 1990; Frakes et from the Middle Carnian onwards (Bourquin and Guil- al., 1992; Dercourt et al., 1993; Lucas, 1998; Golonka locheau, 1993, 1996). In the Vosges (Fig. 1B), the and Ford, 2000; Reinhardt and Ricken, 2000; Boucot Lower Buntsandstein units (Senones Sandstones or and Gray, 2001). Anweiller Sandstones) can be attributed to the Upper- Within the basins around the western part of Tethys, most Permian, i.e. Zechstein equivalents (Durand et al., the Triassic succession is characterised by (Dubois and 1994). Whereas in the major part of the Germanic basin, Umbach, 1974; Courel et al., 1980): (i) fluvial and the bBuntsandstein GroupQ is separated from the Rotlie- playa deposits during the Early Triassic, i.e. Buntsand- gends by the typical-Zechstein carbonate-evaporite fa- stein facies, (ii) evaporite and marine deposits during cies (Uppermost Permian), in France the latter are the Middle Triassic, i.e. Muschelkalk facies and (iii) completely lacking. This is why the French geologists mainly evaporite and fluvial deposits during the Late place the base of their bBuntsandsteinQ at the level of a Triassic, i.e. Keuper facies. In western Europe, the major unconformity between fanglomerate prone depos- Buntsandstein is mainly represented by two fluvial its, localised in relatively restricted basins, and wide- styles: (i) large bed-load sand sheets associated with spread fluvial deposits (Courel et al., 1980). Such a lake deposits characterising the Lower and Middle concept of bBuntsandsteinQ prevailed in South Germany Buntsandstein (i.e. Scythian, Ro¨hling, 1991; Aigner until the adoption of a unified lithostratigraphic scale and Bachmann, 1992), which pass vertically up into (Richter-Bernburg, 1974). Thus, in the French sedimen- (ii) fluvial systems bordering an evaporite sabkha or a tary basins, deposits referred to as bBuntsandsteinQ can shallow sea, typical of the Upper Buntsandstein (i.e. be attributed either to Permian or to Triassic (Durand, in Upper Scythian to Middle Anisian, Durand, 1978; press). Actually, the bLower BuntsandsteinQ of the Courel et al., 1980; Durand et al., 1994). Vosges (Senones Sandstone and Anweiller Sandstone) At the scale of the western part of the Germanic can be attributed to the Upper Permian, i.e. Zechstein Basin, this study aims to analyse (i) the evolution of equivalents (Durand et al., 1994). the fluvial systems through time and space and (ii) Therefore, the Middle and Upper Buntsandstein units the mechanism of preservation of fluvial deposits in are attributed mainly to the Lower Triassic. These facies the geodynamic and climatic context of the Early are characterised by fluvial deposits that make up the Triassic. following formations (Fig. 1C), from base to top (Courel To investigate the relationship between the fluvial et al., 1980): bConglome´rat basalQ, bGre`s vosgiensQ, environments and the stratigraphic context, we pro- bConglome´rat principalQ, bCouches interme´diairesQ, pose (1) sequence stratigraphy correlations based on and bGre`s a` VoltziaQ. The bCouches intermediaiesQ For- well-logs (Fig. 1) located in the western part of the mation is commonly separated from the bConglome´rat Germanic Basin (Paris Basin, including Rhine Gra- principalQ by the bZone limite violetteQ Formation that ben, and Bresse-Jura Basin), (2) to reconstruct characterises by the first occurrence of Triassic soils in paleoenvironmental maps from a quantification of this area. The bed-load fluvial systems of bConglome´rat the lithologies based on well-log and outcrops data, basalQ, bGre`s vosgiensQ and bConglome´rat principalQ are and (3) to compare and correlate our results with data attributed to braided type networks developed in an arid from other parts of the Germanic Basin (Richter-Bern- climatic environment, as indicated by the occurrence of burg, 1974; Ro¨hling, 1991; Aigner and Bachmann, reworked and in situ aeolian sand dunes and wind worn 1992; Van der Zwan and Spaak, 1992; Bachmann and pebbles (Durand, 1972, 1978; Durand et al., 1994). The Lerche, 1998). bed-load fluvial deposits of the bCouches inter- S. Bourquin et al. / Sedimentary Geology 186 (2006) 187–211 189

Fig. 1. (A) Location of the studied area and the Bockenem well (Bo). (B) Location of studied wells and transect. B: Bertray1; G: Granville 109; M: Montplone1; F: Francheville1; L: Lorettes1, S: Saulcy; J: Johansweiller; SSF: Soultz-sous-Foreˆts, K: Kraichgau; E: Emberme´nil. (C) Lithostrati- graphic column, sedimentary environment variations and biostratigraphic data for the Lower Triassic succession in the eastern part of the Paris Basin based on Francheville well (after Bourquin et al., 1995). (a): Durand and Jurain (1969), Gall (1971), (b): Kozur (1972), Adloff et al. (1982), Khatib-Nguyen and Thi (1977), (c): Kozur (1972), Khatib-Nguyen and Thi (1977). me´diairesQ correspond to low sinuosity rivers with trans- al., 1994). The only biostratigraphic evidence in this verse bars (Durand, 1978), and are associated with Buntsandstein series concerns the bGre`s a` VoltziaQ, hydromorphic paleosols (Durand, 1978; Durand and where macrofauna and palynoflora allow the attribution Meyer, 1982). The bGre`s a` VoltziaQ shows an evolution of a Lower to Middle Anisian age according to location from low sinuosity fluvial systems in the bGre`s a` (Durand and Jurain, 1969; Gall, 1971). The bGre`s a` meulesQ, with weak marine influence, to the fluvio- VoltziaQ evolves upwards to deposits with increasingly marine environment of the bGre`s argileuxQ (Gall, marine influence (bGre`s coquillierQ, bComplexe de 1971; Durand, 1978; Courel et al., 1980; Durand et VolmunsterQ, bDolomie a` Myophora orbicularisQ), then 190 S. Bourquin et al. / Sedimentary Geology 186 (2006) 187–211 into the evaporitic facies (bCouches rougesQ...) of the Graben (Soultz-sous-Foreˆts well, Fig. 1B), is entirely Upper Anisian and, finally, the marine deposits of the cored in the Lower Triassic succession. Ladinian. The vertical evolution from bCouches inter- The 2D and 3D geometries established in this study me´diairesQ to the marine deposits of the Ladinian char- are based on well-log correlations. Around 580 wells are acterises a general backstepping trend, in which the correlated using the principles of high-resolution se- maximum flooding surface (mfs) is located at the top quence stratigraphy, i.e. the stacking pattern of the smal- of the bCalcaires a`Ce´ratitesQ Formation dated as Ladi- lest stratigraphic units (Van Wagoner et al., 1988; nian (Duringer and Hagdorn, 1987). Paleocurrent direc- Homewood et al., 1992) within a sedimentary succession tions obtained from fluvial facies indicate a mainly (parasequence, Van Wagoner et al., 1990; Mitchum and eastward flow (Durand, 1978). Van Wagoner, 1991, or genetic unit, Cross, 1988; Guil- The terminology used for the Buntsandstein forma- locheau, 1991; Cross et al., 1993). Sequence stratigraphy tions in the Palatinate is not the same as that applied in in continental deposits is based on the analysis of fluctua- the Paris Basin. The equivalent of the bGre`s vosgiensQ tions in stratigraphic base-level (Wheeler, 1964a,b; Cross Formation is divided into three units, which are, from et al., 1993; Gardner and Cross, 1994; Shanley and base to top: the Trifels, Rehberg, and Karlstal forma- McCabe, 1994; Cross and Lessenger, 1998; Mutto and tions. These three units are characterised by increasing Steel, 2000), i.e. the accommodation space combined clay content. with sediment supply. The stratigraphic units reflect the Recent studies of the Middle Buntsandstein fluvial brealised accommodationQ, i.e. volume of sediment actu- deposits, based on outcrops and some well-log data, ally accumulated (Cross, 1988; Mutto and Steel, 2000). from the eastern part of the Paris Basin, have proposed In fluvial or fluviolacustrine deposits (Legarreta et al., that the lower Triassic includes two stratigraphic cycles 1993; Olsen, 1995; Currie, 1997; Leeder and Stewart, (Guillocheau, 1991; Friedenberg, 1994; Bourquin et al., 1997; Legarreta and Uliana, 1998; Eschard et al., 1998; 1995). The first one would correspond to the evolution Bourquin et al., 1998), each of the smallest stratigraphic from the bConglome´rat basalQ to the top of bGre`s units corresponds to a period of low preservation or vosgiensQ, while the second would extend from the erosion (paleosol and/or lag deposits) followed by a base of the bConglome´rat principalQ, considered as a period of high preservation (well developed fluvial se- major unconformity, to the Ladinian mfs (Fig. 1C). quence up until a maximum flooding episode represented However, no correlation has been carried out (1) within by floodplain or lacustrine sedimentation). Therefore, the bConglome´rat basalQ and the bGre`s vosgiensQ in the such cycles are bounded by two maximum flooding Paris Basin, and (2) between the Triassic of the Paris intervals. By observing the stacking arrangement of ge- Basin (western part of the Vosges Massif), the Rhine netic sequences, different scales of stratigraphic cycle Graben and the Black Forest. can be identified. With increasing scale and duration, The present study of well-log data for the Triassic these stratigraphic cycles are termed genetic sequence west of the Black Forest (Paris Basin, Rhine Graben sets, minor stratigraphic cycles and major stratigraphic and Bresse-Jura Basin) allows us to propose correla- cycles (Bourquin and Guillocheau, 1996; Bourquin et al., tions and define the stratigraphic context of the Lower 1998). The maximum flooding episodes can be readily Triassic units. picked out on well-logs. However, the use of gamma-ray and sonic logs alone may give rise to misinterpretation. 3. Procedure Indeed, sandstones containing large amounts of radioactive minerals (potash feldspar, heavy minerals, etc.) may The Lower Triassic crops out only in the western part produce high gamma-ray values similar to those ob- of the Paris Basin, in the Vosges Massif and in the Black served in clays (Bourquin et al., 1998). Forest. The outcrops are discontinuous and if the basal unit (with Permian–Triassic boundary) or uppermost unit 4. Well-log facies and stratigraphic units (bConglome´rat principalQ) are not present, it is almost characterisation impossible to determine the stratigraphic position. Only well-log data can provide a continuous record. By study- 4.1. Triassic electrofacies ing the complete set of wells in the Paris Basin, Rhine Graben and Bresse-Jura Basin, we can carry out correla- By comparing well-log data with outcrops located in tions and propose paleogeographic maps for the Early the eastern part of the Paris basin (Fig. 1B), we can Triassic. The available well-logs are gamma-ray, resis- characterise the well-log signature of the Triassic for- tivity and sonic logs. Only one well, located in the Rhine mations (Fig. 2). The Permian–Triassic boundary is .Buqi ta./SdmnayGooy16(06 187–211 (2006) 186 Geology Sedimentary / al. et Bourquin S.

Fig. 2. Well-log signature of Triassic formations, and correlations between three successive wells based on the genetic sequence stacking pattern and ordering of stratigraphic cycles. See Fig. 1B for location. 191 192 S. Bourquin et al. / Sedimentary Geology 186 (2006) 187–211 marked by a sharp transition between the Lower Bunt- owing to the upward increase in abundance of silty- sandstein fluvio-lacustrine environments, i.e. Permian, clayey electrofacies (Fig. 2), while the top of the with high gamma-ray and sonic log values, and elec- Karlstal Formation shows a greater development of trofacies with low gamma-ray values of the Middle sandstone electrofacies. Therefore, for the Middle Buntsandstein, i.e. Triassic. The Middle Buntsandstein Buntsandstein, we can define three cut-off values is characterised by low to medium gamma-ray values from well-log data (Fig. 2): (between 20 and 75 API), and the Upper Buntsandstein by medium to high gamma-ray values (between 50 and –ifGRN45 API and Dt N90 As/f=silty-clay and clay 170 API). Using combined well-logs and cuttings data, electrofacies, we can distinguish the conglomerate formations of the –ifGRb40 and 80bDt b90 As/f=sandstone electro- Middle Buntsandstein (i.e. bConglome´rat basalQ and facies bConglome´rat principalQ) from the bGre`s vosgiensQ –if20bGRb80 and Dt b80 As/f=conglomeratic elec- sandstone Formation. At outcrop, these conglomerate trofacies formations are made up of well-cemented coarse sandstones, pebbles and cobbles. The bConglome´rat basalQ In the field, the transition between Middle and is polygenetic (mainly containing clasts of siliceous Upper Buntsandstein is marked by the bZone limite material, quartz, quartzite and lydite, but also rhyolite violetteQ, which is characterised by red-violet clays and granite), while the bConglome´rat principalQ con- with the development of hydromorphic paleosols. The tains only siliceous clasts. Consequently, the well-log Upper Buntsandstein is characterised by two forma- signature of the conglomerate facies is characterised by tions, namely, the bCouches interme´diairesQ and the low sonic values (between 55 and 80 As/f) and low to bGre`s a` VoltziaQ (see Section 2). The former corre- medium gamma-ray values if radioactive minerals are sponds to low-sinuosity rivers associated with flood- present (20 to 40 API for the bConglome´rat principalQ plain and lacustrine environments. The latter formation and up to 70 API for the bConglome´rat basalQ). At corresponds to fluvial environments with increasingly outcrop, the bGre`s vosgiensQ Formation is composed of marine influence upwards into the Lower Muschelkalk, sandstone, and rare conglomeratic facies, containing 80 which displays marine facies (see Section 2). The Mid- to 95% quartz and feldspar. As a result, the sandstone dle Muschelkalk shows the earliest evaporitic beds in electrofacies yield gamma-ray values comprised be- the Paris basin. On well-log data, the Upper Buntsand- tween 20 and 40 API, with sonic values between 80 stein is well marked by higher gamma-ray values than and 90 As/ft (Fig. 2). At outcrop, some silty-clay or those observed in the Middle Buntsandstein. Moreover, clay interbeds can be observed within the formations the boundary between the Middle and Upper Buntsand- of the Middle Buntsandstein. Within the Lower bGre`s stein is marked by one or two electrofacies with high vosgiensQ, these interbeds are thin (less than 40 cm), gamma-ray values that characterise the clay facies of characterising either floodplain deposits associated the bZone limite violetteQ (Fig. 2). In some cases, with bed-load rivers in arid climatic environments or conglomeratic facies can be detected in the basal part settling deposits produced by cessation of the migra- of the bCouches interme´diairesQ, which could corre- tion of fluvial barforms (Durand, 1972, 1978; in press; spond to the bConglome´rat de BitcheQ defined in north- Durand et al., 1994). Within the Palatinate area (Fig. ern Lorraine (Me´nillet et al., 1989). Within the Upper 2B), the bGre`s vosgiensQ become richer in silty-clay Buntsandstein, it is easy to distinguish the sandstone material upward, thus defining three formations, from facies from the silty-clay or clay facies (GRN45 API base to top: the Trifels, Rehberg and Karlstal forma- and DtN90 As/f). Within the Muschelkalk, the evaporite tions (Dachroth, 1985). This succession reflects a and dolomite facies can be distinguished by low vertical evolution from fluvial bed-load rivers to the gamma-ray and sonic values as well as high resistivity. playa environments of the Karlstal Formation. At However, the distinction between dolomite and anhy- outcrop, the upper part of the Karlstal Formation drite is difficult without density and porosity logs becomes more fluvial (bed-load rivers with few thin (Bourquin and Guillocheau, 1996). floodplain deposits). The well-log data allow us to distinguish the silty-clay from the sandstone electro- 4.2. Triassic genetic sequence definition and vertical facies (Fig. 2): gamma-ray (GR) values higher than 45 stacking pattern API and sonic (Dt) values higher than 90 As/ft for silty-clay electrofacies. The Trifels, Rehberg and Karl- As discussed by various authors (Legarreta et al., stal formations are well recognized from well-log data 1993; Olsen, 1995; Currie, 1997; Leeder and Stewart, S. Bourquin et al. / Sedimentary Geology 186 (2006) 187–211 193

1997; Legarreta and Uliana, 1998; Eschard et al., 1998; 40 m) than those observed within the lacustrine or Bourquin et al., 1998), genetic units in fluvial environ- marine facies of the Upper Buntsandstein (7–15 m, ments are usually composed of: and even 4 m within lacustrine electrofacies). This difference is due to the lower abundance of floodplain – a condensed lower part: transit or erosion surface, deposits in the Early Triassic succession (Fig. 2). Each well-developed paleosols, amalgamated channels genetic unit can be correlated at the scale of the representing periods of stratigraphic base-level fall, eastern part of the Paris Basin; they are recognized i.e. decreasing accommodation space and/or increas- in all the wells log within the Triassic series. The ing sediment supply; stacking pattern of genetic units allows us to define – an aggrading upper part, with well developed fluvial genetic unit sets, minor cycles and major cycles. For preservation representing periods of stratigraphic some cycles, the location of the maximum flooding base-level rise, i.e. increasing accommodation surface is uncertain. In such cases, we cannot attribute space and/or decreasing sediment supply. a stratigraphic base-level fall to the upper part of the cycle. The turnaround surface between rise and fall of Each genetic unit is bounded by two maximum stratigraphic base-level, characterised in fluvial envir- flooding surfaces characterised by regionally correlat- onments by by-pass or erosion (amalgamated chan- ed floodplain or lacustrine sedimentation. In continen- nels, erosion or paleosol), is sometimes impossible to tal environments, it is difficult to distinguish recognize from well-log data alone (Bourquin and autocyclic events (resulting from local processes Guillocheau, 1996; Bourquin et al., 1998). Moreover, such as avulsion) from allocyclic factors (climate, in the arid context of the Early Triassic, no paleosols eustatic effects, deformation and sediment supply) were formed. Complementary facies analyses, based that can be regionally observed and lead to strati- on cores and outcrop data, are in progress to resolve graphic base-level variations (Olsen and Larsen, this question. 1993; Postma et al., 1993; Schumm, 1993; Shanley While it is difficult to quantify the duration of and McCabe, 1994; Dalrymple et al., 1998; Bourquin cycles, a comparison with stratigraphic studies in et al., 2002). the Germanic basin nevertheless allows us to esti- From well-log data, it is possible to distinguish clay mate the duration of major cycles (see discussion in facies attributed to floodplain or lacustrine environ- Section 7). ments (Bourquin et al., 1998). The smallest unit, bounded by two clay electrofacies and correlated at 4.3. Construction of Triassic paleoenvironmental maps the scale of the formation, is considered as a genetic unit. The vertical stacking patterns of genetic units The paleoenvironmental maps are drawn up be- allow us to distinguish different scales of stratigraphic tween two stratigraphic lines to show the fluvial sys- cycle. In continental environments, the genetic tem evolution in time and space. The isopach and sequences and genetic sequence sets can be correlated lithological data come from well-logs and outcrops only at the scale of a formation (Bourquin et al., 1998; data. All the maps are bounded in the eastern part Brault et al., 2003). The minor cycles are correlated at by the Rhine Graben data. For the Vosges Massif, the the basin scale. maps integrate the outcrop data (Durand, 1978 and The correlations here are carried out between the Geological maps of the eastern Paris Basin, scale Variscan basement or pre-Triassic deposits and the 1/50,000). Since the Middle Buntsandstein consists anhydrite bed characterising the basal part of the of sandstones with very few clay layers, only con- bCouches GrisesQ Formation defined in the eastern glomerate percentages and isopachs are indicated on part of the basin (middle part of the Middle Muschelk- the maps. The Upper Buntsandstein paleoenvironment alk, Fig. 1B). The Middle and Upper Buntsandstein maps show the dominant environments over the con- exhibits four orders of stratigraphic cycles (Fig. 2): sidered time span. (1) genetic sequence, (2) genetic sequence sets, (3) minor stratigraphic cycles (denoted B1 to B7, Fig. 2) 5. High-resolution sequence stratigraphy and (4) major stratigraphic cycles (Sythian and Ani- correlations of the Lower Triassic sian–Carnian cycles). For the Middle Buntsandstein, characterised by The results of the correlations the 580 wells studied fluvial bed-load rivers in an arid context, the genetic in the Paris basin and Rhine Grabben are summarized units inferred from well-log data are thicker (15 to on a NE–SW section between the Rhine Graben 194 S. Bourquin et al. / Sedimentary Geology 186 (2006) 187–211

(Soultz-sous-Foreˆts well) and the area south of Orleáns then prograding conglomerates (Figs. 4 and 5). These (Figs. 1B, 4, and 5). conglomerates migrate basinwards and grade laterally into sandstones. In the Vosges Massif outcrops and 5.1. Middle Buntsandstein cycles Embermeńil well, these conglomerates correspond to the bConglome´rat principalQ Formation (Fig. 3). The Middle Buntsandstein formations (‘‘Conglom- The lithogical map of this cycle (Fig. 7B) shows that e´rat basal’’, ‘‘Gre`s vosgiens’’ and ‘‘Conglome´rat prin- the conglomerates spread across the basin. The cipal’’) exhibit one major cycle divided into four minor bConglome´rat principalQ Formation rarely occurs at cycles (noted B1 to B4, Figs. 2 and 3). outcrop north of the Vosges Massif, near the German The data available (gamma-ray and sonic logs com- Frontier, where it is eroded. In outcrop, the bined with cutting data) allow us to quantify the occur- bConglome´rat basalQ and of the bConglome´rat princi- rence of sandstones, conglomerates and clays (see pal’’ display the same petrographic materials, notably Section 4.1). Within the Middle Buntsandstein, the Silurian and Proterozoic graphitic cherts that are de- series consists essentially of sandstones with very few rived from the Armorican Massif (Durand et al., 1994; floodplain deposits that, however, allow the recognition Dabard, 2000), implying same provenance. The transi- of genetic sequence (see Section 4.2). tion between the bGre`s vosgiensQ and the bConglome´rat The correlations reveal the onlap of the Triassic principalQ only reflects a progressive increasing in grav- sedimentation onto the basement (Figs. 4 and 5). The el content and then an acceleration of the prograding bed-load fluvial sediments, attributed to braided rivers, phase. The base of the bConglome´rat principalQ is came from the west (present-day Armorican Massif, diachronous: conglomeratic facies are younger in the Durand, 1978; Durand et al., 1994) and progressively western part of the basin (Cycle B4, Fig. 5). fill in the topographic depression. Floodplain deposits Geometrically, the correlations (Figs. 2 and 5) reveal are rare and characterised by clay layers a few centi- the landward migration of the silty clay facies (attrib- metres thick. The conglomerate deposits are mainly uted to playa deposits of the Karlstal Formation) into a located in the western part of the sedimentation area. retrogradation trend, until the maximum flooding sur- The four minor stratigraphic cycles (B1 to B4) can be face of the cycle B3, and then a progradational tend of correlated across the Paris Basin up to the Rhine Gra- sandstone and conglomerate deposits of the ben in the east, showing that the bConglome´rat basalQ bConglome´rat principalQ Formation. This evolution Formation is diachronous. characterised a major cycle, where the period of the The B1 cycle corresponds, in the Vosges Massif stratigraphic base-level rise is represented by the cycle outcrops and Embermeńil well, to the deposits of the B1 to B3 and the period of the stratigraphic base-level bConglome´rat basalQ Formation (Figs. 3 and 4). This fall by the cycle B4 (Figs. 2 and 3). This cycle is cycle is characterised by the vertical passage of well- located above the Permian and below the Anisian, preserved fluvial conglomerates into floodplain depos- thus it is called the Scythian cycle. its (Fig. 4). In more distal parts of the basin, the con- The top of cycle B4 is marked by a major discon- glomerates grade eastwards into sandstones. tinuity, which is characterised a sedimentary break. The B2 and B3 cycles (Figs. 3 and 4) are intra-bGre`s This episode can be correlated with the forming of vosgiensQ Formation, and record well-preserved fluvial the bZone Limite VioletteQ that crops out in many sandstones to floodplain deposits, the basal conglomer- parts of Lorraine (Fig. 2). The bZone Limite VioletteQ ate facies being located in the westernmost area (Fig. overlies the bConglome´rat principalQ Formation and 4). From cycles B1 to B3, we observe a general back- contains paleosols (dolocrete and silcrete), providing stepping of conglomerate facies. evidence for very low sedimentation rates (Durand and The isopach maps drawn up for each cycle (Figs. 6 Meyer, 1982). In north Lorraine, the bZone Limite and 7A) indicate the basement–sedimentation area VioletteQ and even the bConglome´rat principalQ are boundary, as well as the location of conglomerate facies locally eroded. This is indicated locally by the occur- through time and space. The more proximal facies are rence of a conglomerate containing bConglome´rat located to the west. These maps show the general back- principalQ pebbles mixed with pedogenic carbonate stepping of conglomerate facies and their lateral east- and cornelian pebbles reworked from the bZone Limite ward evolution to sandstone deposits (Figs 6A, B VioletteQ. This unit, known as bKarneolkonglomeratQ in and 7A). the Palatinate (Reis and von Ammon, 1903), corre- The B4 cycle shows well-preserved fluvial sand- sponds to the bConglome´rat de BitcheQ defined in stones overlain by a maximum flooding episode and northern Lorraine (Meńillet et al., 1989). In addition, S. Bourquin et al. / Sedimentary Geology 186 (2006) 187–211 195

Fig. 3. Lithostratigraphic column, sedimentary environment variations, major and minor stratigraphic cycles for the Lower Triassic succession in the eastern part of the Paris Basin based on Emberme´nil well. well-log data allow to recognize locally conglomerate surface corresponds to the bHardegsen unconformityQ facies (see Section 4.1) above the discontinuity (e.g. expressed in many parts of the Germanic basin (Dur- Saulcy and Johansweiller, Figs. 2 and 5). The erosional and et al., 1994). 196 S. Bourquin et al. / Sedimentary Geology 186 (2006) 187–211

The transect (Figs. 4 and 5) and the four maps (Figs. shows a different expression in the eastern and western 6 and 7) allow us to quantify the 3D evolution of the parts of the basin. Indeed, the correlations demonstrate Triassic series and to characterise (1) the geometries of that the Upper Buntsandstein formations are diachro- sedimentation units infilling the basement topography, nous (Figs. 2 and 9), as previously established by bio- (2) the general onlapping of these series, (3) the retro- stratigraphic data across the outcrop area (Durand and gradational pattern of the playa deposits, (4) the pro- Jurain, 1969; Gall, 1971). For example, the bGre`s a` gradation of the bConglome´rat principalQ Formation, VoltziaQ is located in the lower part of cycle B7 in the and (5) the diachronism of the Middle Buntsandstein Johansweiller well, but in the upper part of this cycle formations (Trifels, Rehberg, Karlstal, bConglomerat farther eastwards (Fig. 9). Moreover, these correlations basalQ, and bConglome´rat principalQ formations, Figs. point out the lateral evolution from dolomitic and anhy- 2and5). dritic clays, attributed to shallow marine and sabkha facies, in the eastern edge of the studied area (Gall, 5.2. Upper Buntsandstein cycles 1971; Durand, 1978; Courel et al., 1980; Durand et al., 1994), to sandstones in the west. Geometrically, The lithostratigraphic succession comprising the the transect reveals the landward migration – i.e. to Upper Buntsandstein formations (bCouches inter- the west – of dolomitic clay facies (marine deposits) me´diairesQ and bGre`s a` VoltziaQ), the Lower Muschelk- in a major retrogradational trend (Fig. 5). The upper part alk (bGre`s coquillierQ, bComplexe de VolmunsterQ, and of the cycle B7 is characterised by the first occurrence of bDolomie a` Myophoria orbicularisQ), and the lower part anhydritic deposits (landward equivalent of dolomitic of the Middle Muschelkalk (bCouches rougesQ Forma- facies observed in the Soultz-sous-Foreˆts well) overly- tion) corresponds to three minor cycles (noted B5 to ing previous marine facies in a retrogradation trend B7, Fig. 2). They belong to the lower part of the major (Fig. 5). Two detailed facies maps are drawn up for Anisian–Carnian cycle. this cycle, one in its lower part, which correspond to The sandstones facies of the Upper Buntsandstein the bGre`s a` VoltziaQ Formation of Lorraine outcrops correspond to low sinuosity fluvial channels (Durand, and Embermeńil well (Figs. 3 and 8B), and the other 1978; Durand et al., 1994). The well-log data allow a in its upper part which corresponds to the Lower quantification of sandstones, floodplain and/or lake Muschelkalk formations and bCouches rougesQ Forma- deposits and sabkha lithofacies and the expression of tion of Lorraine outcrops and Embermeńil well (Figs. the genetic units in these depositional environments 3 and 8C). These two maps show the westward mi- (see Sections 4.1 and 4.2). gration of the paleoenvironments and the geographic The well-log analyses allow to characterise the oc- distribution of the two facies of the bGre`s a` VoltziaQ currence of a new depositional area in the western part (Gre`s a` MeulesQ: sandstone facies, Fig. 8B, and bGre`s of the Paris Basin (Figs. 4 and 5). Its sediments seem to argileuxQ: silty clay facies, Fig. 8B). The fluvial sys- be contemporaneous with those located above the dis- tems are localised mainly along the basin border continuity in the eastern part of the basin, where the (previous basement area) and evolved basinwards three cycles can be correlated. into shallow marine deposits (Fig. 8B, C). In the Lorraine outcrop area and in the Embermeńil borehole, the two first cycles above the discontinuity 6. Comparison with other parts of the Germanic (B5, B6) correspond to the bCouches interme´diairesQ Basin Formation (Fig. 3). They show an evolution from sandstone to clay facies (Figs. 4 and 5) attributed, by In the Soultz-sous-Foreˆts well, located in the Rhine comparison with outcrops data, to low sinuosity fluvial Graben, Vernoux et al. (1995) proposed use of the channel sandstones to well-developed lake or flood- Palatine terminology (Fig. 10). Therefore, in this part plain fine deposits (Durand, 1978; Durand and Meyer, of the basin, the Trifels and Rehberg formations 1982). The facies map of these cycles (Fig. 8A) shows would be equivalent to the cycles B1, B2 and the the distribution of the sandstone and clay deposits. This lower part of the B3 cycle (Lower bGre`s vosgiensQ, distribution could express the location and orientation Figs. 2 and 10). The Karlstal Formation would corre- of the low sinuosity river and floodplain environments spond to the upper part of the B3 cycle and the lower during the considered period. part of the B4 cycle (Upper bGre`s vosgiensQ, Figs. 2 Cycle B7 corresponds to the bGre`s a` VoltziaQ Forma- and 10). tion up to bCouches rougesQ Formation of Lorraine The comparison with the Germanic Basin cycles outcrops and Embermeńil well (Fig. 3). This cycle (Fig. 10) is carried out by correlating the Soultz-sous- S. Bourquin et al. / Sedimentary Geology 186 (2006) 187–211 pp. 197–200

Fig. 4. (A) WSW–ENE correlations of Lower Triassic stratigraphic cycles, between the south of Orle´ans (Bertray well), and the Rhine Basin (Soultz-sous-Foreˆts well) in the western part of the Germanic Basin. (B) Transect location. See Fig. 1B for more details. S. Bourquin et al. / Sedimentary Geology 186 (2006) 187–211 201 ˆts well) B for more details. Fig. 1 ). (B) Transect location. See Fig. 3 ), (2) geometries from the Hardegsen unconformity to the basal ´ans (Bertray well) and the Rhine Basin (Soultzsous-Fore Fig. 3 Formation defined in the eastern part of the Paris Basin (middle part of the Middle Muschelkalk, Q Couches grises b Fig. 5. (A) Geometries and lithology of the Lower Triassic stratigraphic cycles, along the transect between the area south of Orle deduced from well-log analysis: (1) geometries from Variscan basement or pre-Triassic deposits to the Hardegsen unconformity ( anhydrite bed of the 25 202 S. Bourquin et al. / Sedimentary Geology 186 (2006) 187–211

Fig. 6. Isopach maps with superimposed lithology (% of conglomerate) for stratigraphic cycles B1 and B2 (see Figs. 3–5), constructed from well-log data and outcrops information (geological maps, scale 1/50,000, and Durand, 1978).

Foreˆts and Kraichgau 1002 wells and then the com- The correlations with the Kraichgau well, located bined well-logs for Bockenem 1 and Bockenem A100 between the Black Forest and the Odenwald, allow us (Fig. 3 of Aigner and Bachmann, 1992). to identify the Middle Buntsandstein cycles defined in S. Bourquin et al. / Sedimentary Geology 186 (2006) 187–211 203

Fig. 7. Isopach maps with superimposed lithology (% of conglomerate) for the B3 (A) and B4 (B) stratigraphic cycles (see Figs. 3–5), constructed from well-log data and outcrops information (geological maps, scale 1/50,000, and Durand, 1978). the Paris Basin. However, an additional stratigraphic (Junghans et al., 2002). A comparison with the com- cycle is present at the base of the Lower Triassic bined Bockenem wells (Aigner and Bachmann, 1992) successions in this part of the Germanic Basin. This demonstrates that sequence 1, as defined in the Ger- cycle is attributed to the Induan by magnetostratigraphy manic basin (Calvo¨rde and Bernburg formations), 204 S. Bourquin et al. / Sedimentary Geology 186 (2006) 187–211

would appear to have no equivalent in the Paris Basin where only erosion and/or sediment transport occur at that time. The cycles B1, B2 and B3, corresponding to the lower part of the major cycle defined in the Paris Basin, could be equivalent to sequence 2 (Volpriehau- sen Formation), and cycle B4 to sequence 3 (Detfurth and Hardegsen formations). The individual sequences observed in the Germanic Basin are characterised by an evolution from fluvial sandstones to playa lake deposits. The maximum flooding episode of the major stratigraphic cycle defined in the Paris Basin appears equivalent to the mfs of sequence 2 (i.e. Volpriehau- sen), where more or less marine fauna is present in the central part of the Germanic Basin (Richter-Bernburg, 1974; Roman, 2004). The cycle B4, i.e. upper part of the Karlstal formation in Palatinate, would be equivalent to the Detfurth Formation. However, in this western end of the Germanic Basin, the sandstones equivalent to the Detfuth Formation do not display a basal low-relief angular unconformity as seen in the central Germanic Basin (Wolburg, 1968, 1969; Ro¨hling, 1991). In Lorraine, the top of the cycle B4 is marked by a major sedimentary break period of by- pass with first development of paleosols (i.e. bZone limite violetteQ, Mu¨ller, 1954; Ortlam, 1967; Gall et al., 1977). This episode could be equivalent of Hard- egsen Formation, where the evidence of biological activity (ichnites, rhizolites, palynomorphs) does not allow a correlation with the arid condition of the bConglome´rat principalQ Formation. Similarly, the discontinuity observed in the Paris Basin corresponds to the Hardegsen unconformity, representing one of the most pronounced extensional tectonic event observed in the Germanic Triassic (Trusheim, 1961, 1963; Wol- burg, 1968; Ro¨hling, 1991). In the Germanic Basin, the base of the Solling For- mation corresponds to the erosional episode of the Hard- egsen unconformity, during which 100 m of Middle Buntsandstein deposits could be locally eroded (Aigner and Bachmann, 1992). Moreover Geluk (1998) shows that the base of the Solling Formation becomes progressively younger to the west, accompanied by a decrease in thickness. In this study, this formation appears to be missing due to non-deposition or erosion. The Solling Fig. 8. Paleoenvironmental maps of the Upper Buntsandstein stratigraphic cycles, drawn up from well-log data and outcrop informa- sandstones preserved in the basin could be equivalent to tion (geological maps, scale 1/50,000, and Durand, 1978): (A) an episode of sediment by-pass at the basin margin. paleoenvironmental map of the B5 and B6 minor stratigraphic The Ro¨t Formation, corresponding to evaporitic ma- cycles (bCouches interme´diairesQ Formation at Embermeńil well rine and sabkha deposits, represents the first occurrence see Figs. 3–5), (B) paleoenvionmental map of the lower part of the of halite deposition in the Germanic Basin. It could be B7 minor stratigraphic cycle (bGre`s a` VoltziaQ Formation at Ember- meńil well, see Figs. 3–5), and (C) paleoenvionmental map of the equivalent to the B5 cycle. The cycles B6 and B7 could upper part of the B7 minor stratigraphic cycle (bGre`s coquille´sQ to be equivalent to the first cycle of the Muschelkalk in bCouches rougesQ formations at Embermeńil well, Figs. 3–5). the central Germanic Basin. The second sequence of the S. Bourquin et al. / Sedimentary Geology 186 (2006) 187–211 205

Fig. 9. E–W correlations of the Upper Buntsandstein stratigraphic cycles showing the diachronous nature of the formations. See location Fig. 1B.

Muschelkalk in that area is equivalent to the bCouches non-deposition or erosion of the uppermost Zechstein grises–LettenkohleQ cycle in Lorraine. cycles at the basin margin (Ro¨hling, 1991; Szurlies et al., 2003). The Scythian major cycle observed in the Paris 7. Discussion Basin corresponds to a stratigraphic base-level rise con- tinuing up to a maximum flooding episode, which could The correlations on the western margin of the Ger- correspond to the deposition of the lacustrine facies of manic Basin and a comparison with other parts of this the Volpriehausen Formation in the central Germanic basin allow us to propose correlations of the Buntsand- Basin (Fig. 10). The basal part of the Karlstal Formation stein on either side of the Rhine Graben, and lead to a would be the landward lateral equivalent of these lake discussion of the evolution of fluvial systems through deposits. Within this retrogradational pattern, three time and space. cycles (B1 to B3) can be observed on the western margin The Lower Triassic displays a succession with two (Figs. 2, 5–7). The stratigraphic base-level fall of this general fluvial systems. The earlier system, located be- major cycle corresponds to the cycle B4 and shows a tween the supra-Permian discontinuity and the Hardeg- progradational trend of sandstone and conglomerate sen unconformity, is made up of braided fluvial deposits deposits of the bConglome´rat principalQ Formation evolving laterally into ephemeral playa lacustrine facies (Figs. 2, 5, and 7B). in the central part of the Germanic Basin. The general Geluk and Ro¨hling (1997) have made high-resolu- onlapping of the Triassic is well characterised by corre- tion correlations of the Lower Triassic series in the lations on its western margin (Figs. 2, 5, and 6). There- Netherlands and north-western Germany. In common fore, the Lower Triassic of the central part of the with Szurlies et al. (2003), Geluk and Ro¨hling (1997) Germanic Basin would began significantly earlier than based their well-log correlations on genetic units, that of on the western margin. The bBro¨ckelschieferQ and which are considered to represent 100 ka Milanko- the Lower Buntsandstein formations, which were depos- vitch eccentricity cycles. These cycles are observed ited in sebkha or playa systems, respectively, are only in the central part of the Germanic Basin because of found in the central basin and do not have equivalents on the deposition of fluviolacustrine facies. On the west- the western margin. These deposits characterise the re- ern margin, i.e. in the Paris Basin, only fluvial gressive tendency of the uppermost Zechstein, which deposits are present and so only the major floodings continues into the lower Buntsandstein (Aigner and of lakes are recorded in the floodplain deposits. Bachmann, 1992; Aigner et al., 1998). The angular Consequently, these authors (op. cit.) estimate that unconformity at the base of the Triassic was caused by the duration of deposition of the Lower Buntsand- 206 S. Bourquin et al. / Sedimentary Geology 186 (2006) 187–211

Fig. 10. Correlation between the Rhine Graben (Soultz-sous-Foreˆts well) and the Palatinate (Kraichgau 1002 well), and comparison with stratigraphic cycles defined in the central Germanic Basin (Bockenem, 50 km SE of Hannover, from Aigner and Bachmann, 1992). See Fig. 1A and B for location. stein (Calvo¨rde and Bernburg formations) is at least m of preserved sediment, taking place during the 2 m.y. (Szurlies et al., 2003), and assign it to the stratigraphic base-level rise, and 2.5 m.y. for a max- Induan. Geluk and Ro¨hling (1997) estimate the de- imum of 65 m of preserved sediment during the positional duration of the Volpriehausen Formation at period of the stratigraphic base-level fall. On this about 1.8 m.y, and the Detfurth plus Hardegsen western margin, the Hardegsen unconformity overlain formations at about 2.5 m.y. These three formations a major sedimentary break characterised by a plana- are attributed to the Olenekian. In the Netherlands, tion surface and first development of paleosols that the sedimentary hiatus between the Volpriehausen overlies the bConglome´rat principalQ Formation. No and Detfurth formations is estimated at about 0.5 major erosion or angular unconformity is observed m.y. In the same area, the hiatus equivalent to the near the basal part of the bConglome´rat principalQ Hardegsen unconformity would have a duration of Formation, which is characterised only by an accel- 1.5 m.y., situated within the Olenekian. Consequent- eration of the prograding phase. ly, the duration of the Paris Basin sedimentation In the dry climatic regime of the Lower Triassic (Van would be at least 1.8 m.y. for a maximum of 233 der Zwan and Spaak, 1992), the first cycles could be S. Bourquin et al. / Sedimentary Geology 186 (2006) 187–211 207

Fig. 11. (A) Scythian (Olenekian) paleogeographic map of the southern part of the Germanic Basin with superimposed paleoenvironments and fluvial systems: (i) Kinematic reconstruction (Van der Voo, 1993; Besse et al., 1998; Besse, personal communication), (ii) fluvial systems: in Germany (Richter-Bernburg, 1974; Ro¨hling, 1991; Aigner and Bachmann, 1992; Wachutka and Aigner, 2001), in England and Wales (Audley- Charles, 1992), in Bulgaria (Belivanova, 1998), in Netherlands (Clemmensen, 1979; Geluk and Ro¨hling, 1997; Geluk, 1998), in the North Sea (Goldsmith et al., 2003), in Eifel basin (Mader, 1983; Mader and Teyssen, 1985), in southern Scandinavia (Olaussen et al., 1994), in France (Durand, 1978 and this study). AM: Armorican Massif, BM: Bohemian Massif, RM: Rhenish Masssf; LBM: London Braban Massif. (B) Scythian (Olenekian) paleoenvironmental reconstruction of the western part of the Germanic Basin. 208 S. Bourquin et al. / Sedimentary Geology 186 (2006) 187–211 attributed to lake and sediment supply variations in an bConglome´rat principalQ are locally eroded. During arid environment. During the Scythian, the river catch- the Hardegsen phase, an important structural reorgani- ment areas are mainly located in the present-day Ar- sation occurred in the NW Europe (Geluk and Ro¨hling, morican Massif, and the paleocurrents are generally 1998), leading to the formation of the main rift in NW oriented towards the NNE (Fig. 11). The facies associ- Germany (Best et al., 1983; Ro¨hling, 1991). This tec- ation is essentially composed of stacked channel fill tonic event gave rise to a new sedimentation area, in the facies with very few flood plain deposits (b3%) and south part of the Paris Basin (south of Paris, Fig. 8), without paleosols. Channel fills are sometimes associ- where fluvial sediments could be preserved. ated with aeolian deposits. In more distal areas of the On the western margin of the Germanic Basin (Fig. Germanic Basin, the sedimentation corresponds to 9), sedimentation above the Hardegsen Unconformity is ephemeral playa lakes or aeolian deposits (Clemmen- characterised by a major retrograding trend (Aigner and sen, 1979; Clemmensen and Tirsgaard, 1990; Aigner Bachmann, 1992; Aigner et al., 1998). The fluvial and Bachmann, 1992; Ulicny, 2004). In this context, systems are the lateral equivalents of marine deposits. two hypotheses could explain the preservation of fluvial Finally, the Germanic Basin is connected with the systems. According to one hypothesis, the siliciclastic Tethys Ocean (Dercourt et al., 1993), and the fluvial sediment supply from the Hercynian- (Variscan) moun- systems are developed in an exoreic basin setting. The tain was constant, and thus the cycles result solely from correlations reveal the existence of maximum flooding lake level fluctuations. The lake levels could be con- episodes recorded in lake and/or floodplain deposits. In trolled by monsoonal activity, under the influence of such fluvio-coastal depositional environments, the lake- sea-level fluctuations (Van der Zwan and Spaak, 1992). level fluctuations may be attributed to relative sea-level Alternatively, the basin was situated in an arid environ- variations. In the area located south of Paris, the fluvial ment and the variation of the sediment supply was system appears not to be connected with the eastern controlled by precipitation in the mountain ranges. To part of the basin. This connection only becomes estab- investigate the relationships between sedimentation and lished during accumulation of the bCouches grisesQ. climate, studies are in progress to simulate Early Trias- sic climates. Moreover, sedimentological studies on 8. Conclusions cores and outcrops are being carried out to quantify the ephemeral character of the fluvial system and quan- The correlation of the Lower Triassic succession tify the occurrence of aeolian deposits. located on the western margin of the Germanic Basin The bConglome´rat principalQ Formation is charac- allows us to characterise the stratigraphic evolution of terised by a progradation of coarse-grained sediment. the fluvial sedimentation. The comparison of the strati- The origin of the sediment is the same as for the graphic cycles observed there with those described in Vosgian sandstones. This progradation could be in- other parts of the basin makes it possible to assess the duced by a slowing down of subsidence or by sediment duration of cycles and reconstruct the basin evolution. supply variations such as described by numerical mod- The early Triassic can be separated into two phases. elling for short time scales (Heller and Paola, 1992; The first phase, during the Scythian, is characterised by Paola et al., 1992; Paola, 2000; Marr et al., 2000). braided fluvial systems evolving laterally into lake In this part of the basin, the top of Scythian major deposits toward the central part of the Germanic Basin. cycle is marked by a major break of sedimentation, At this time, the basin is a huge basin depression with characterising a period of very low sedimentation only few marine connections in the eastern part. The rate, with planation surface and the first development stratigraphic cycles reflect relative lake-level fluctuation of paleosols (bZone limite violetteQ). Above it, the that could be attributed to sediment supply and/or lake major Hardegsen unconformity is observed for the level variation in an arid context. The second phase first time in the subsurface of this part of the basin occurs after a major sedimentary break (planation sur- (Figs. 2, 4, and 5). Above this unconformity, the Tri- face and pedogenesis) followed by the formation of the assic series, that exhibit a major change in fluvial Hardegsen unconformity. This surface is tectonically system style, show onlap, which implies some tectonic deformed, leading to the creation of a new sedimentation activity just before the renewal of sedimentation area to the west of the basin. Above this unconformity, marked by the bCouches interme´diairesQ, rich in angular the fluvial sedimentation, attributed to the Anisian, quartz and fresh feldspars. Some local incisions are shows an enhanced development of floodplains (with observed in outcrops located in the north of Lorraine preservation of paleosol) associated with lacustrine. The where the bZone limite violetteQ and the top of the fluvial systems are connected with a shallow sea facies in S. Bourquin et al. / Sedimentary Geology 186 (2006) 187–211 209 communication with the Tethys Ocean. In this context, and geodynamic implications—an example of the Keuper Chaunoy the stratigraphic cycles are induced by variations in Sandstones, Paris Basin. Sediment. Geol. 121, 207–237. Bourquin, S., Robin, C., Guillocheau, F., Gaulier, J.-M., 2002. Three- relative sea level and/or sediment supply. The fluvial dimensional accommodation analysis of the Keuper of the Paris deposits are preserved in an exoreic basin. Basin: discrimination between tectonics, eustasy, and sediment supply in the stratigraphic record. Mar. Pet. Geol. 19, 469–498. Acknowledgments Brault, N., Bourquin, S., Dabard, M.-P., Bonnet, S., Guillocheau, F., Courville, P., Esteóule Choux, J., Stepanoff, F., 2003. Mio-Plio- We are grateful for the financial support of INSU/ cene to Pleistocene paleotopographic evolution from a sequence b Q b stratigraphy analysis: relative influence of tectonics and climate. CNRS programme ECLIPSE entitled Quantification Sediment. Geol. 163, 175–210. des flux se´dimentaires au Trias: re´ponse des syste`mes Clemmensen, L.B., 1979. Triassic lacustrine red-beds and palaeocli- se´dimentaires continentaux aux sollicitations clima- mate: the bBuntsandsteinQ of Helgoland and the Malmros Klint tiques et tectoniquesQ. We gratefully acknowledge Pr. Member of East Greenland. Geol. Rundsch. 6, 748–774. Dr. G. Bachmann, Pr. Dr. B. W. Sellwood and an Clemmensen, L.B., Tirsgaard, H., 1990. Sand-drift surfaces: a neglected type of bounding surface. Geology 18, 1142–1145. anonymous referee for their critical and constructive Courel, L., Durand, M., Maget, P., Maiaux, C., Menillet, F., Pareyn, reviews of the paper. Dr M.S.N. Carpenter post-edited C., et al., 1980. Trias. In: Me´gnien, C. (Eds.), Synthe`se geólogi- the English style. que du Bassin de Paris, Me´m., vol. 101. BRGM, pp. 37–74. Cross, T.A., 1988. Controls on coal distribution in transgressive– regressive cycles. In: Wilgus, C.K., Hastings, B.S., Kendall, References C.G.st.C., Posamentier, H.W., Ross, C.A., Van Wagoner, J.C. (Eds.), Sea-level Change: An Integrated Approach, Soc. Econ. Adloff, M.C., Doubinger, J., Geisler, D., 1982. E´ tude palynologique Paleontol. and Mineral, Spec. Publ, vol. 42. pp. 371–380. et se´diomentologique dans le Muschelkalk moyen de Lorraine. Cross, T.A., Lessenger, M.A., 1998. Sediment volume partitioning: Me´m. Sci. Terre (Nancy) 25, 91–104. rationale, stratigraphic model evaluation and high-resolution Aigner, T., Bachmann, G.H., 1992. Sequence-stratigraphic framework stratigraphic correlation. Spec. Publ. - Nor. Pet. Soc. 8, 171–195. of the German Triassic. Sediment. Geol. 80, 115–135. Cross, T.A., Baker, M.R., Chapin, M.A., Clark, M.S., Gardner, M.H., Aigner, T., Hornung, J., Junghans, W.-D., Po¨ppelreiter, M., 1998. Base- Hanson, M.S., Lessenger, M.A., Little, L.D., McDonough, K.-J., level cycles in the Triassic of the South-German Basin: a short Sonnenfeld, M.D., Valazek, D.W., Williams, M.R., Witter, D.N., progress report. In: Bachmann, G.H., Lerche, I. (Eds.), Epiconti- 1993. Applications of high-resolution sequence stratigraphy to nental Triassic, Zbl. Geol. Palaönt. Teil 1, vol. 7–8. , pp. 537–544. reservoir analysis. In: Eschard, R., Doligez, B. (Eds.), Subsurface Audley-Charles, M.G., 1992. Triassic. In: Duff, P.M.D., Smith, A.J. Reservoir Characterization from Outcrop Observations. Editions (Eds.), Geology of England and Wales. Geological Society, Lon- Technip, Paris, pp. 11–33. don, pp. 307–324. Currie, B.S., 1997. Sequence stratigraphy of nonmarine Jurassic– Bachmann, G.H., Lerche, I., 1998. Epicontinental Triassic. Zentralbl. Cretaceous rocks, central Cordilleran foreland-basin system. Geol. Palaöntol., Teil 1 7–12, 1609. Geol. Soc. Amer. Bull. 109, 1206–1222. Belivanova, V., 1998. Triassic in the Golo Bardo Mountain—one Dabard, M.-P., 2000. Petrogenesis of graphitic cherts in the Armor- example for the Balkanide facial type of Triassic in Bulgaria. ican segment of the Cadomian orogenic belt (NW France). Sed- Zentralbl. Geol. Palaöntol., Teil I 2, 1105–1121. imentology 47, 787–800. Besse, J., Torcq, F., Gallet, Y., Ricou, L.E., Krystyn, L., Saidi, A., Dachroth, W., 1985. Fluvial sedimentary styles and associated depo- 1998. Late Permian to Late Triassic palaeomagnetic data from sitional environments in the Buntsandstein west of River Rhine, in Iran: constraints on the migration of the Iranian block through the Saar area and Pfalz (F.R. Germany) and Vosges (France). In: Tethyan ocean and initial destruction of Pangaea. Geophys. J. Int. Mader, D. (Ed.), Aspects of fluvial sedimentation in the Lower 135, 77–92. Triassic Buntsandstein of Europe, Lecture Notes in Earth Best, G., Kockel, F., Scho¨neich, H., 1983. Geological history of the Sciences, vol. 4. Springer, pp. 197–248. southern Horn Graben. Geol. Mijnb. 62, 25–34. Dalrymple, M., Prosser, J., Williams, B.A., 1998. Dynamic system Boucot, A.J., Gray, J., 2001. A critic of Phanerozoic climatic models approach to the regional controls on deposition and architecture of involving changes in the CO2 content of the atmosphere. Earth- alluvial sequences, illustrated in the Statfjord formation (United Sci. Rev. 56, 1–159. Kingdom, northern North sea). In: Shanley, K.W., McCabe, P.J. Bourquin, S., Guillocheau, F., 1993. Geóme´trie des se´quences de (Eds.), Relative Role of Eustasy, Climate and Tectonism in Con- de´poˆt du Keuper (Ladinien a` Rhe´tien) du Bassin de Paris: impli- tinental Rocks, Soc. Ec. Paleontol. Mineral Spec. Publ. vol. 59, cations geódynamiques. C. R. Acad. Sci. Paris 317, 1341–1348. pp. 65–81. Bourquin, S., Guillocheau, F., 1996. Keuper stratigraphic cycles in the Dercourt, J., Ricou, L.E., Vrielynck, B., 1993. Atlas Tethys palaeoen- Paris Basin and comparison with cycles in other Peritethyan vironmental maps. Beicip- Fronlab, Rueil Malnaison. basins (German Basin and Bresse-Jura Basin). Sediment. Geol. Dubois, P., Umbach, P., 1974. A` propos du Trias de deux bassins 105, 159–182. se´dimentaires français: le Bassin de Paris et le Bassin du Sud-Est. Bourquin, S., Friedenberg, R., Guillocheau, F., 1995. High-resolution Bull. Soc. Geól. Fr. 7, 698–707. sequence stratigraphy in the Triassic series of the Paris Basin: Durand, M., 1972. Re´partition des galets eólise´s dans le Buntsandstein geodynamic implications. Cuad. Geol. Iber. 19, 337–362. moyen lorrain. C. R. Somm. Seánces Soc. Geól. Fr. 5, 214–215. Bourquin, S., Rigollet, C., Bourges, P., 1998. High-resolution sequence Durand, M., 1978. Paleócourants et reconstitution paleógeógraphi- stratigraphy of an alluvial fan–fan delta environment: stratigraphic que: L’exemple du Buntsandstein des Vosges me´ridionales 210 S. Bourquin et al. / Sedimentary Geology 186 (2006) 187–211

(Trias infe´rieur et moyen continental). Sci. Terre (Nancy) 4 Guillocheau, F., 1991. Mise en e´vidence de grands cycles transgres- (22), 301–390. sion–re´gression d’origine tectonique dans les se´diments me´sozoı¨- Durand, M. in press. The problem of transition from Permian to ques du Bassin de Paris. C. R. Acad. Sci. Paris 312, 1587–1593. Triassic series in Southeast France. Comparison with other Peri- Heller, P.L., Paola, C., 1992. The large scale dynamics of grain-size tethyan regions. In: Lucas, S. (ed), Non-marine Permian Biostra- variation in alluvial basins: 2. Application to syntectonic con- tigraphy and Biochronology. Geol. Soc. Spec Publ., London. glomerate. Basin Res. 4, 91–102. Durand, M., Jurain, G., 1969. Ele´ments paleóntologiques nouveaux Homewood, P., Guillocheau, F., Eschard, R., Cross, T.A., 1992. du Trias des Vosges me´ridionales. C. R. Acad. Sci. Paris 269, Corre´lations haute re´solution et stratigraphie geńe´tique: une de´- 1047–1049. marche inte´greé. Bull. Centres Rech. Explor.-Prod. Elf-Aquitaine Durand, M., Meyer, R., 1982. Silicifications (silcre`tes) et e´vaporites 16, 357–381. dans la Zone-limite violette du Trias infe´rieur lorrain. Comparai- Junghans, W.-D., Ro¨sler, W., Aigner, T., Appel, E., 2002. Magnetos- son avec le Buntsandstein de Provence et le Permien des Vosges. tratigraphie an der Perm/Trias-Grenze der Bohrung Kraichgau Sci. Geól. Bull., Strasbourg 35, 17–39. 1002 (SW-Deutschland). Neues Jahrb. Geol. Palaöntol. Mh. 2, Durand, M., Chre´tien, J.C., Poinsignon, J.M., 1994. Des coˆnes de 92–106. de´jection permiens au grand fleuve triasique: evolution de la Khatib-Nguyen, Thi N.T., 1977. Contribution a` l’e´tude des Cono- se´dimentation continentale dans les Vosges du Nord autour de- dontes du Muschelkalk supe´rieur lorrain. The`se de 3e`me cycle, 250 Ma. Livret-guide d’excursion du Congre`s national de Univ. Nancy I. 81 pp. l’APBG. Editions Pierron, Sarreguemines. 32 pp. Kozur, H., 1972. Vorlaüfige Mitteilung zur Parallelisierung der ger- Duringer, P., Hagdorn, H., 1987. La zonation par ce´ratites du manischen und tethyalen Trias sowie einige Bemerkungen zur Muschelkalk supe´rieur lorrain (Trias, Est de la France). Diachro- Stufen- und Unterstufengliederung der Trias. Mitt. Ges. Geol. nisme des facie`s et migration vers l’Ouest du dispositif se´dimen- Bergbaustud., Innsbruck 21, 361–412. taire. Bull. Soc. Geól. Fr. 3,3 (8), 601–609. Leeder, M.R., Stewart, M.D., 1997. Fluvial incision and sequence Eschard, R., Lemouzy, P., Bacchiana, C., De´saubliaux, G., Parpant, J., stratigraphy: alluvial responses to relative sea-level fall and their Smart, B., 1998. Combining sequence stratigraphy, geostatistical detection in the geological record. In: Hesselbo, S.P., Parkinson, simulations, and production data for modeling a fluvial reservoir D.N. (Eds.), Sequence Stratigraphy in British Geology, Geol. Soc. in the Chaunoy Field (Triassic, France). Am. Assoc. Pet. Geol. Spec. Publ., vol. 103. pp. 25–39. Bull. 82, 545–568. Legarreta, L., Uliana, M.A., 1998. Anatomy of hinterland deposition- Frakes, L.A., Francis, J.E., Syktus, J.I., 1992. Climates Modes of the al sequences: Upper Cretaceous fluvial strata. In: Shanley, K.W. Phanerozoic: The History of the Earth’s Climate Over the Past 600 (Ed.), Neuquen basin, west-central Argentina. Million Years. Cambridge University Press, Cambridge. 310 pp. Legarreta, L., Uliana, M.A., Larotonda, C.A., Meconi, G., Friedenberg, R., 1994. Stratigraphie geńe´tique des de´poˆts continen- 1993. Approaches to non marine sequence stratigraphy— taux du Buntsandstein de l’Est du Bassin de Paris. Application theoretical models and examples from Argentine basins. In: aux stockages de gaz naturel en nappe aquife`re. Extension au Eschard, R., Doligez, B. (Eds.), Subsurface Reservoir Character- Bassin de Paris. The`se, Univ. de Strasbourg. 182 pp. ization from Outcrop Observations. Editions Technip, Paris, pp. Gall, J.C., 1971. Faunes et paysages du Gre`s a` Voltzia du Nord des 125–143. Vosges. Essai paleóećologique sur le Buntsandstein supe´rieur. Lucas, S.G., 1998. The epicontinental Triassic, an overview. In: Me´m. Serv. Carte Geól. Alsace Lorraine 34, 318. Bachmann, G.H., Lerche, I. Epicontinental Triassic. Zbl. Geol. Gall, J.C., Durand, M., Mu¨ller, E., 1977. Le Trias de part et d’autre du Palaönt. Teil 1, vol. 7–8. pp. 475–496. Rhin: corre´lations entre les marges et le centre du Bassin germa- Mader, D., 1983. Evolution of fluvial sedimentation in the Buntsand- nique. Bull. BRGM, se´r. 2, sect. IV 3, 193–204. stein (Lower Triassic) of the Eifel (Germany). Sediment. Geol. 37, Gardner, M.H., Cross, T.A., 1994. Middle Cretaceous paleogeog- 1–84. raphy of Utah. In: Caputo, M.V., Peterson, J.A., Franczyk, K.J. Mader, D., Teyssen, T., 1985. Palaeoenvironmental interpretation of (Eds.), Mesozoic Systems of the Rocky Mountain Region, USA. fluvial red beds by statistical analysis of palaeocurrent data: pp. 471–502. examples from the Buntsandstein (Lower Triassic) of the Eifel Geluk, M.C., 1998. Palaeogeographic and structural development of and Bavaria in the German Basain (Middle Europe). Sediment. the Triassic in the Netherlands—new insights. Zentralbl. Geol. Geol. 41, 1–74. Palaöntol., Teil I 1, 545–570. Marr, J.G., Swenson, J.B., Paola, C., Voller, V.R., 2000. A two- Geluk, M.C., Ro¨hling, H.-G., 1997. High-resolution sequence stratig- diffusion model of fluvial stratigraphy in closed depositional raphy of the Lower Triassic bBuntsandsteinQ in the Netherlands basins. Basin Res. 12, 381–398. and Northwestern Germany. Geol. Mijnb. 76, 227–246. Meńillet, F., Coulombeau, C., Geissert, F., Konrad, H.J., Schwoerer, Geluk, M.C., Ro¨hling, H.-G., 1998. High-resolution sequence P., 1989. Notice explicative de la feuille Lembach. 1:50,000 stratigraphy of the Lower Triassic Buntsandstein: a new tool Geological map of France, BRGM, Orleáns. 91 pp. for basin analysis. In: Bachmann, G.H., Lerche, I. (Eds.), Mitchum Jr., R.M., Van Wagoner, J.C., 1991. High-frequency Epicontinental Triassic, Zbl. Geol. Palaönt. Teil 1, vol. 7–8. sequences and their stacking patterns: sequence-stratigraphic ev- pp. 727–745. idence of high-frequency eustatic cycles. Sediment. Geol. 70, Goldsmith, P.J., Hudson, G., Van Veen, P., 2003. Chapter 9—Triassic. 131–160. In: Evans, D., Graham, C., Armour, A., Bathurst, P. (Eds.), The Mu¨ller, E.M., 1954. Beitra¨ge zur Kentniss der Stratigraphie und Millennium Atlas: Petroleum Geology of the Central and North- Palaögeographie des Oberen Buntsandsteins im Saar-Lothrin- ern North Sea. Geological Society of London, pp. 105–127. gischen Raum. Ann. Univ. Sarav. Sci., III 3, 176–201. Golonka, J., Ford, D., 2000. Pangean (Late Carboniferous–Middle Mutto, T., Steel, R.J., 2000. The accommodation concept in sequence Jurassic) paleoenvironment and lithofacies. Palaeogeogr. Palaeo- stratigraphy: some dimensional problems and possible redefini- climatol. Palaeocol. 161, 1–34. tion. Sediment. Geol. 130, 1–10. S. Bourquin et al. / Sedimentary Geology 186 (2006) 187–211 211

Olaussen, S., Larsen, B.T., Steel, R., 1994. The Upper Carboniferous- tratigraphy of the Permian–Triassic boundary interval in Central Permian Oslo Rift: basin fill in relation to tectonic development. Germany. Earth Planet. Sci. Lett. 212, 263–278. Pangea: Global Environments and Resources, Mem., vol. 17. Trusheim, F., 1961. U¨ ber Diskordanzen im mitlleren Buntsandstein Canadian Society of Petroleum Geologists, pp. 175–197. Norddeutschlands zwischen Weser und Ems. Erdo¨l-Zeitschrift 77, Olsen, T., 1995. Sequence stratigraphy, alluvial architecture and 361–367. potential reservoir heterogeneities of the fluvial deposits: evidence Trusheim, F., 1963. Zur Gliederung des Buntsandsteins. Erdo¨l-Zeits- from outcrop studies in Price Canyon, Utah (Upper Cretaceous chrift 79, 277–292. and Lower Tertiary). In: Steel, R.J., Felt, V.L., Johannessen, E.P., Ulicny, D., 2004. A drying-upward aeolian system of the Bohdasin Mathieu, C. (Eds.), Sequence Stratigraphy of the Northwestern Formation (Early Triassic), Sudetes of NE Czech Republic: record European Margin, NPF Spec. Publ., vol. 5, pp. 75–96. of seasonality and long-term palaeoclimate change. Sediment. Olsen, H., Larsen, P.-H., 1993. Structural and climatic controls on Geol. 167, 17–39. fluvial depositional systems: Devonian, North-East Greenland. Van der Voo, R., 1993. Palaeomagnetism of the Atlantic, Tethys and Int. Assoc. Sediment. Spec. Publ. 17, 401–423. Iapetus Oceans. Cambridge University Press. 411 pp. Ortlam, D., 1967. Fossile Bo¨den als Leithorizonte fu¨r Gliederung des vanderZwan, C.J., Spaak, P., 1992. Lower and Middle Triassic se- Ho¨heren Buntsandsteins im no¨rdlichen Schwarzwald und su¨dli- quence stratigraphy and climatology of the Netherlands, a model. chen Odenwald. Geol. Jahrb. 84, 485–590. Paleogeogr. Palaeoclimatol. Palaeoecol. 91, 277–290. Paola, C., 2000. Quantitative models for sedimentary basin filling. Van Wagoner, J.C., Posamentier, H.W., Mitchum Jr., R.M., Vail, P.R., Sedimentology 47 (suppl.1), 121–178. Sarg, J.F., Loutit, T.S., Hardenbol, J., 1988. An overview of the Paola, C., Heller, P.L., Angevine, C.L., 1992. The large scale dynam- fundamentals of sequence stratigraphy and key definitions. In: ics of grain-size variation in alluvial basins: 1. Theory. Basin Res. Wilgus, C.K., Hastings, B.S., Kendall, C.G.St.C., Posamentier, 4, 73–90. H.W., Ross, C.A, Van Wagoner, J.C. (Eds.), Sea-level Change: Postma, G., Fortuin, A.R., Van Wamel, W.A., 1993. Basin-fill patterns An Integrated Approach, Soc. Econ. Paleontol. Mineral. Spec. controlled by tectonics and climate: the Neogene bfore-arcQ basins Publ., vol. 42. pp. 39–46. of eastern Crete as a case history. Int. Assoc. Sediment. Spec. Van Wagoner, J.C., Mitchum Jr., R.M., Campion, K.M., Rahma- Publ. 20, 335–362. nian, V.D., 1990. Siliciclastic sequence stratigraphy in well Reinhardt, L., Ricken, W., 2000. The stratigraphic and geochemical logs, core and outcrops: concepts for high-resolution correlation record of playa cycle: monitoring a Pangean monsoon-like system of time and facies. Am. Assoc. Pet. Geol., Methods Explor. Ser. (Triassic, Middle Keuper, S. Germany). Paleogeogr. Paleogeocli- 7, 55. matol. Paleoecol. 161, 205–227. Vernoux, J.F., Genter, A., Razin, P., Vinchon, C., 1995. Geological Reis, O.M., vonAmmon, L., 1903. Erlau¨terungen zu Blatt Zwei- and petrophysical parameters of a deep fractured sandstone for- bru¨cken der geognostischen Karte 1/100000 des Ko¨nigreiches mation as applied to geothermal exploitation. BRGM Report Bayern. R38622. 70 pp. Richter-Bernburg, G., 1974. Stratigraphische Synopsis des deutschen Wachutka, M., Aigner, T., 2001. Reservoirgeologie und Petrophysik: Buntsandsteins. Geol. Jahrb. 25, 127–132. eine Aufschluss-Analogstudie im Buntsandstein (Trias, Schwarz- Ro¨hling, H.-G., 1991. A lithostratigraphic subdivision of the Lower wald, SW-Deutschland). Z. Angew. Geol. 47, 191–198. Triassic in the Northwest German Lowlands and the German Wheeler, H.E., 1964. Base-level, lithosphere surface and time-stratig- sector of the North Sea, based on gamma-ray and sonic logs. raphy. Geol. Soc. Amer. Bull. 75, 599–610. Geol. Jahrb., Reihe A Allg. Reg. Geol. BR Dtschl. Nachbargeb. Wheeler, H.E., 1964. Baselevel, fstransit cycle. In: Merriam, D.F. Tekton. Stratigr. Pala¨ontol. 119, 3–24. (Ed.), Symposium on Cyclic Sedimentation, Bull. Kansas Geol. Roman, A., 2004, Sequenzstratigraphie und Fazies des Unteren und Surv, vol. 169, pp. 623–630. v. 1. Mittleren Buntsandsteins im o¨stlichen Teil des Germanischen Wolburg, J., 1968. Vom zyklischen Aufbau des Buntsandsteins. Beckens (Deutschland, Polen), Dissertation University of Witten- Neues Jahrb. Geol. Pala¨ontol. Mh. 9, 535–559. berg Halle (2004). 140 pp. Wolburg, J., 1969. Die epirogenetischen Phasen der Muschelk- Schumm, S.A., 1993. River response to base-level change: implica- alk- und Keuper-Entwicklung Nordwest-Deutschlands, mit tions for sequence stratigraphy. J. Geol. 101, 279–294. einem Ru¨ckblick auf den Buntsandstein. Geotekton. Forsch. Shanley, K.W., McCabe, P.J., 1994. Perspectives on the sequence 32, 1–65. stratigraphy of continental strata. Am. Assoc. Pet. Geol 78, Ziegler, P.A., 1990. Permo-Triassic development of Pangea. In: 544–568. Ziegler, P.A. (Ed.), Geological Atlas of Western and Central Eur- Szurlies, M., Bachmann, G.H., Menning, M., Nowaczyk, N.R., Ka¨d- ope, Shell International Petroleum Maatschappij B.V., The Hague, ing, K.-C., 2003. Magnetostratigraphy and high-resolution lithos- pp. 68–90.