Downloaded from http://sp.lyellcollection.org/ by guest on September 30, 2021

The Neuqu6n Basin: an overview

JOHN A. HOWELL l, ERNESTO SCHWARZ 2, LUIS A. SPALLETTI 3 & GONZALO D. VEIGA 3 1Centre for Integrated Petroleum Research, University of Bergen, Allegt. 41, N-5007 Bergen, Norway (e-mail: [email protected]) 2Department of Earth Sciences, University of Ottawa, 140 Louis Pasteur Pvt, Ottawa, Canada KIN 6N5 3Centro de Investigaciones Geoldgicas, Universidad Nacionald de La PIata-CONICET, Calle 1 No. 644, Bll9OOTAC, La Plata,

Abstract: The Neuqu6n Basin of Argentina and central Chile contains a near-continuous Late -Early Cenozoic succession deposited on the eastern side of the evolving Andean mountain chain. It is a polyphase basin characterized by three main stages of evol- ution: initial rift stage; subduction-related thermal sag; and foreland stage. The fill of the basin records the tectonic evolution of the central Andes with dramatic evidence for base- level changes that occurred both within the basin and along its margins. The record of these changes within the mixed siliclastic-carbonate succession makes the basin an excel- lent field laboratory for sequence stratigraphy and basin evolution. The 4000 m-thick fill of the basin also contains one of the most complete -Early marine records, with spectacular finds of both marine and continental vertebrates. The basin is also the most important hydrocarbon-producing province in southern South America, with 280.4 x 10 6 m 3 ofoil produced and an estimated 161.9 x 10 6 m 3 remaining. The prin- cipal components of the hydrocarbon system (source and reservoir) crop out at the surface close to the fields. The deposits of the basin also serve as excellent analogues to reservoir intervals worldwide.

This paper aims to provide a brief introduction to To present specific studies from the basin that the Neuqu~n Basin. It should provide a stepping highlights concepts and models in sequence stone for further reading and also for further stratigraphy that are exportable to other studies. This paper also serves as an introduction systems. to this Special Publication, which details the most recent work within the basin. The proposed goals of the Special Publication are as follows. Introduction to the Neuqu~n Basin • To present the Neuqu6n Basin as an inte- The Neuqu~n Basin is located on the eastern side grated case study in sequence stratigraphy of the Andes in Argentina and central Chile, and basin analysis. between 32 ° and 40°S latitude (Figs 1 & 2). It • To document the latest developments in covers an area of over 120 000 km 2 (Yrigoyen vertebrate and invertebrate palaeontology. 1991) and comprises a continuous record of up • To consider the basin in the context of the to 4000 m of stratigraphy. This - structural evolution of the central Andes. Early Cenozoic succession includes continental • To document the latest studies on specific and marine siliciclastics, carbonates and evapor- stratigraphic intervals in a way that allows ites that accumulated under a variety of basin the reader to build up a complete picture of styles (Fig. 3). the basin fill and the way in which the The basin has a broadly triangular shape various depositional systems have evolved (Fig. 1) and two main regions are commonly through time. recognized: the Neuqu6n Andes to the west,

From: VEIGA, G. D., SPALLETTI, L. A., HOWELL,J. A. & SCHWARZ,E. (eds) 2005. The NeuqudnBasin, Argentina:A Case Study in Sequence Stratigraphy and Basin Dynamics. Geological Society, London, Special Publications, 252, 1-14. 0305-8719/05/$15.00 (~) The Geological Society of London 2005. Downloaded from http://sp.lyellcollection.org/ by guest on September 30, 2021

J. A. HOWELL ETAL.

3NCEPC

~.

~EMUCO ...... ~ i!, S i...... w , J

ft~ ~lP

o 5

• BAPJLOCHE

Fig. 1. Sketch map of the Neuqu6n Basin showing the approximate location (boxes and stars) of the contributions included in this publication. 1, Ramos & Folguera; 2, Zapata & Folguera; 3, Aguirre-Urreta et al.; 4, McIlroy et al.; 5, Schwarz & Howell; 6, Veiga et al.; 7, Str6mNick et al.; 8, Doyle et al.; 9, Scasso et al.; 10, Sagasti; 1 l, Tyson et al.; 12, Morgans-Bells & McIlroy; 13, Gasparini & Femfindez; 14, Lazo et al.; 15, Coria & Salgado.

and the Neuqu~n Embayment to the east and SE. wide cratonic areas of the Sierra Pintada Massif The majority of the Basin's hydrocarbon fields and the North Patagonian Massif, respectively are located in the Neuqu~n Embayment where (Fig. 1). The western margin of the basin is the most of the Mesozoic sedimentary record is in Andean magmatic arc on the active western the subsurface and the strata are relatively uncle- margin of the Gondwanan-South American formed. This is in contrast to the Andean region Plate. where Late Cretaceous-Cenozoic deformation This geotectonic framework and the highly has resulted in the development of a series of complex history of the basin are largely con- N-S-oriented fold and thrust belts (Aconcagua, trolled by changes in the tectonics on the Marlargtie and Agrio fold and thrust belts, western margin of . The evolution Fig. 2) that provide excellent outcrops of the and development of the basin can be considered Mesozoic successions. in three stages (Fig. 3). During present times and throughout much of its history the triangular Neuqu6n Basin has 1. Late Triassic-: prior to the been limited on its NE and southern margins by onset of subduction on its western margin, Downloaded from http://sp.lyellcollection.org/ by guest on September 30, 2021

THE NEUQUI~N BASIN: AN OVERVIEW 3

Fig. 2. Major morphotectonic features of the Neuqu~n Basin and Andean Cordillera (Landsat image courtesy of Dr A. Folguera). Selected Cenozoic volcanoes are indicated by dotted lines. Inset shows image location in the Neuqu6n Basin.

this part of Gondwana was characterized by Late Cretaceous-Cenozoic: transition to a large transcurrent fault systems. This led to shallowly dipping subduction zone resulting extensional tectonics within the Neuqu6n in compression and flexural subsidence, Basin and the evolution of a series of associated with 45-57 km of crustal short- narrow, isolated depocentres (Manceda & ening (Introcaso et al. 1992; Ramos 1999b) Figueroa 1995; Vergani et al. 1995; and uplift of the foreland thrust belt. Franzese & Spalletti 2001). Early Jurassic-: develop- The final phase of Andean tectonism produced ment of a steeply dipping, active subduction the uplift of the tightly folded outcrops in the zone and the associated evolution of a western part of the area (Fig. 2). These outcrops magmatic arc along the western margin of expose a complete Mesozoic succession that Gondwana led to back-arc subsidence includes a very wide variety of depositional set- within the Neuqu~n Basin. This post-rift tings. The lateral extent and spatial distribution stage of basin development locally accounts of the deposits facilitates stratigraphic corre- for more than 4000 m of the basin fill lation and the tracing of regional unconformities. (Vergani et al. 1995). These outcrops have been used to understand Downloaded from http://sp.lyellcollection.org/ by guest on September 30, 2021

J. A. HOWELL ETAL.

Period Epoch Age Litostratig raphy Tectonic Biostratigraphic Pale oce ne...999 history resolution 65 Ma. f Maastrichtian !

~o:. ~ o t~,~o :t,,~Loncoche" Fm~ ~ , ~,.~~ :%° ~:~ ~:~O U.I Campanian

.J Rio'CoIoi'ad6 Fm :i, :. ~?:?i: :o° °:" LU Santonian (.9 coniacian # Turonian O9 2 Cenomanian <, ,,o, O Albian ,o i I O Aptian Huitrin I h r~ < LIJ Hauterivian

Valanginian

Berriasian 145 Ma. 8 Tithonian <, < Kimmendgian i o Tordi!lo Fm ~

Oxfordian LI.

iii Bathonian 2~ (5 0 a

Aalenian

Toarcian

Pliensbachian I _J Sinemudan SYNRIFT~ °e STA E Hettangian 220 Ma. TRIASSIC

PALAEOZOIC Huechulafquen Fm'/P]edra Santa Complex~ × × x :;< ,~ × " x ,~, ~< /, x ",

-,,t-- inversionperiods O Marine reptiles • Terrestrialreptiles

~ Continentaland/or votcaniclasticrocks [--1 Evaporiterocks i Poor/verypoor resolution

~ Volcanicrocks m Offshoreclastic/carbonate rocks Moderate resolution

~---~ Plutonicand metamorphicrocks ~ Shallow-marineclastic/ Good/excellent resolution carbonate rocks

Fig. 3. Chronostratigraphy, tectonic history and biostratigraphy of the Neuqu6n Basin. Lithostratigraphy is mostly after Legarreta & Gulisano (1989) and Legarreta & Uliana (1991). Only nomenclature of the Neuqu6n sector of the basin is depicted. Tectonic history after Vergani et al. (1995) and Franzese et al. (2003). Biostratigraphic resolution after Riccardi et aL (1999) (Jurassic), Aguirre-Urreta & Rawson (1997), Aguirre-Urreta et aL (1999) (Early Cretaceous) and Casadfo et al. (2004) (Late Cretaceous). Downloaded from http://sp.lyellcollection.org/ by guest on September 30, 2021

THE NEUQUI~N BASIN: AN OVERVIEW 5 hydrocarbon reservoir systems both in the Geodynamic evolution adjacent subsurface systems (Valente 1999; The Neuqu6n Basin originated in the Late Vergani et al. 2002) and also worldwide Triassic as a result of continental intraplate (Brands~eter et al. 2005). extension. During this period a series of exten- The palaeontology of the Neuqurn Basin is sional troughs were filled with volcaniclastic central to its global significance. The basin and continental deposits. During the subsequent contains one of the most complete records of growth of the Andean magmatic arc the basin Jurassic and Cretaceous marine invertebrates. became a back-arc system with widespread The completeness of this record has allowed marine sedimentation. Acceleration of plate con- the construction of accurate biostratigraphic vergence during the Late Cretaceous produced charts for western Gondwana (Aguirre-Urreta partial inversion and the development of a et al. 1999; Riccardi et al. 1999). These charts retro-arc flexural system. This was associated allow excellent correlation and dating within with a progressive change from marine to conti- the basin, and comparative correlation to faunas nental sedimentation. The evolution of the and successions from other parts of the world, Neuqurn Basin is intimately linked to the devel- for example North America and Thethys. The opment of the Neuqurn Andes and the geometry Mesozoic continental and marine reptile record of the subducting slab (Ramos & Folguera this of the Neuqurn Basin is one of the most volume). complete, varied and well preserved in the entire world. New theories with global impli- cations on taxonomy, palaeobiogeography, Late Triassic-Early Jurassic synrift phase palaeoecology and taphonomy merged from the The Late Triassic-Early Jurassic margin of study of these herpetofaunas (Gasparini 1996; Gondwana in the vicinity of the Neuqurn Basin Gasparini & Fermindez 1997; Gasparini et al. lacks evidence for slab subduction. The tectonic 1997, 1999; Wilson & Sereno 1998; Sereno system was dominated by a strike-slip regime 1999). subparallel to the western continental margin The Neuqurn Basin has been the subject (Franzese & Spalletti 2001). In the area of the of numerous studies since the beginning of the Neuqurn Basin extension related to the collapse 20th century. Prior to the 1960s early work of the Gondwana Orogen produced a series of included regional studies on the stratigraphy, long, narrow half-grabens (Fig. 4A) that were palaeontology, biostratigraphy and structural filled by a complex array of clastic and volcani- geology (e.g. Weaver 1931; Groeber 1946; elastic deposits associated with extensive lava Herrero Ducloux 1946; De Ferrariis 1947; flows (Franzese et al. 2006) (Lapa Formation, Groeber et al. 1953). From the 1960s to the Fig. 3, and equivalent units). Clastic deposits 1990s a concerted hydrocarbon exploration include alluvial, fluvial, shallow-marine, deltaic effort by YPF (the Argentinian National Oil and lacustrine deposits (Franzese & Spalletti Company), coupled with numerous academic 2001). Fault growth, interaction and a transition studies, led to significant advances in the under- to more regional subsidence during Early Jurassic standing of the basin. During this period the times resulted in a more widespread lacustrine different structural styles were defined (Ramos and shallow-marine facies distribution. 1978; Feehan 1984; Ploszkiewicz et al. 1984), the biostratigraphic charts for the Jurassic and the Cretaceous were refined and updated Early Jurassic-Early Cretaceous (Riccardi et al. 1971; Leanza 1973, 1981; Leanza et al. 1977; Riccardi 1983), and the post- rift phase early schemes for the regional sequence and During the Early- the subduc- seismic stratigraphy were developed (Gulisano tion regime along the western Gondwana et al. 1984; Mitchum & Uliana 1985; Legarreta margin was initiated (Franzese et al. 2003) and & Gulisano 1989; Legarreta & Uliana 1991, by the Late Jurassic the Andean magmatic arc 1999; Legarreta et al. 1993). Since the early was almost fully developed. Back-arc subsidence 1990s studies within the basin (including those led to an expansion of the marine realm and presented in this Special Publication) have flooding of the basin (Fig. 4B), which was con- utilized the regional frameworks to address nected to the proto-Pacific through gaps in the specific issues such as high-resolution sequence arc (Spalletti et al. 2000; Macdonald et al. stratigraphic problems, detailed palaeogeo- 2003). Initially sedimentation was strongly influ- graphic and sedimentological studies of specific enced by the topography inherited from the intervals, improved biostratigraphic charts and underlying synrift systems (Burgess et al. 2000; geochemical studies. Mcllroy et al. this volume). After this initial Downloaded from http://sp.lyellcollection.org/ by guest on September 30, 2021

6 J.A. HOWELL ET AL.

(A) Synrift Phase Mecha-nical su-b-s(dence - " Fault-bounded troughs and half-grabens = Volcanic, continental (+- ! marine) sedimentation in i depocentres

L 'I (B) Postrift Phase

~, Very low or arrested subduction ...... I

Marianas-type 7 subduction J

i = Regional thermal I subsidence != Mostly marine and ~+;~I ~ A ....I; ~ ~ ~.1-~ .I.; ~ ,..I

Fig. 4. Schematic evolution of the Neuqu~n Basin from the Late Triassic to the Cenozoic. (A) Late Triassic-Early Jurassic, characterized by pre-subduction rifting in a series of narrow grabens. (B) Jurassic-Early Cretaceous, onset of subduction on the western margin of Gondwana and the early development of the Andean chain. The basin is a large triangular embayment periodically separated from the proto-Pacific by uplift and relative sea-level fall. (C) Late Cretaceous Andean uplift, development of a foreland thrust belt and basin. Much of the basin fill is non-marine, although periodic transgression from the Atlantic results in some marine intervals. Based on Vergani et al. (1995), Ramos (1999b), Franzese & Spalletti (2001), Folguera & Ramos (2002) and Franzese et al. (2003). Original drafts courtesy of Dr J. Franzese. Downloaded from http://sp.lyellcollection.org/ by guest on September 30, 2021

THE NEUQUI~N BASIN: AN OVERVIEW 7 period the most important evolutionary phase of tectonic compression was occasionally coeval the Neuqu6n Basin started. Thick and wide- with the generation of small depocentres associ- spread successions were deposited during this ated with intense (arc and retro-arc) volcanic long period of protracted thermal subsidence activity (Fig. 2). Ramos & Folguera (this and regional back-arc extension. They include volume) provide a detailed analysis of the a complex series of transgressive-regressive main characteristics and evolution of these cycles of different magnitude, controlled by the magmatic-related depocentres. combined effects of changes in subsidence rates, localized uplift and eustatic sea-level oscillations (Cuyo, Lotena and Mendoza groups, Fig. 3). Chrono- and biostratigraphic framework The development of thick and virtually continuous Late Cretaceous- Cenozoic compression Jurassic-Early Cretaceous marine successions, together with a complete and varied record of and foreland basin phase ammonoid, brachiopod, bivalve and Towards the end of the Early Cretaceous changes faunas, has contributed to a highly refined bio- in the rates of South Atlantic spreading and a stratigraphy for the basin during this interval. reorganization of the Pacific plates, including a The Jurassic ammonite faunas are one of the decrease in the angle of slab subduction, resulted most continuous and complete records anywhere in the development of a compressional tectonic in the world. More than 30 ammonite biozones regime that caused inversion of previous exten- are defined for the Jurassic stages (Leanza sional structures (Vergani et al. 1995). At this 1973, 1981; Riccardi 1983; Riccardi et al. stage the NeuquEn region became a retro-arc 1990a-c, 1999). The only exception to this foreland basin (Fig. 4C), and significant almost complete record occurs in the Kimmerid- variations in the size and shape of the basin gian, where a major tectonic inversion phase (Legarreta & Uliana 1991) together with an east- caused a protracted fall in relative sea level and wards migration of the depocentres occurred a 7 Ma biostratigraphic gap (Fig. 3) (Riccardi (Franzese et al. 2003). et al. 1999). The active depositional systems within the A similar level of biostratigraphic refinement Neuqu6n Basin were strongly controlled by the has been attained for the Early Cretaceous compressive regime. Uplift and tectonic inver- strata (Leanza 1973, 1981; Leanza & Hugo sion in the mountain chain to the west led to 1977; Aguirre-Urreta & Rawson 1997; Aguirre- the deposition of more than 2000 m of continen- Urreta et al. 1999). The chronostratigraphy of tal deposits in the main depocentres (Rayoso and the Berriasian-Barremian interval is further Neuqu~n groups, Fig. 3) (Legarreta & Uliana refined using a combination of ammonites, 1991, 1999; Vergani et al. 1995). Towards the calcareous nannofossils and palynomorphs by end of the Cretaceous continental sedimentation Aguirre-Urreta et al. (this volume). The high was widespread and the Neuqu6n Basin merged resolution of the ammonite zones within the with other basins to the south (e.g. the San basin give a precision of 500 ka for some of Jorge Basin) to produce a unique giant depo- the biozones, making the area ideal for basin centre (Franzese et al. 2003). In the latest Cretac- analysis studies in which time-constrained strati- eous very high global sea levels resulted in the graphy is essential (e.g. Sagasti this volume; first marine transgression from the Atlantic, Sehwarz & Howell this volume). As the Creta- with shallow-marine deposits occurring over ceous-Tertiary (K/T) boundary can be ident- wide areas of the basin (Barrio 1990). ified within a marine succession on the basis Several thin- and thick-skinned fold and thrust of microfossil faunas (Casadfo et al. 2004), the belts developed as a result of the foreland basin basin is an ideal site for further research on the phase (Ramos 1999b) and their position constitu- causes and effects of K/T global extinctions. tes a major control on the present-day physi- In contrast, Mesozoic intervals that are charac- ography of the Neuqu~n region (Fig. 2). terized by continental-dominated deposition However, the compressional regime was not a in the basin (e.g. the Late Triassic and Late continuous, simple process through time. Cretaceous) lack a well-defined stratigraphic Zapata & Folguera (this volume) have ident- framework (Fig. 3). With the exception of a ified several different stages of tectonic com- marine Triassic-Early Jurassic succession in pression and relaxation in the evolution of the Atuel rift (Riccardi & Iglesia Llanos 1999), the Andean Fold and Thrust Belt between the the chrono- and biostratigraphic record for the Late Cretaceous and Cenozoic. Moreover, these Late Triassic is generally poor. In the case authors propose that flexural subsidence during of the Late Cretaceous, much of the record is Downloaded from http://sp.lyellcollection.org/ by guest on September 30, 2021

8 J.A. HOWELL ETAL. comprised of continental and arid-marginal (1995), Tankard et al. (1995), Pfingaro et al. marine deposits that include a rich fauna of (2002) and Veiga et al. (2002b), the sag phase terrestrial reptiles (Fig. 3), but lack that of subsidence was frequently disturbed by provide biostratigraphic constrains. The Palaeo- tectonic reactivations associated with changes gene biostratigraphic record is equally poor, in the subduction regime and intraplate although the presence of volcanic horizons reorganization. related to the arc magmatism provides an import- There are a number of aspects of the basin that ant geochronological database (Llambias & make it an excellent case study in sequence stra- Rapela 1989; Ramos 1999a; Jordan et al. 2001; tigraphy. The high-resolution biostratigraphic Folguera et al. 2004, and references therein). record provides a framework for study; the high-quality outcrops and the proximity to an abundance of subsurface information provide Jurassic-Cretaceous sequence good data to develop and constrain models, and the geodynamic setting outlined above produced stratigraphy well-developed cycles of relative sea level The majority of the succession that crops out change. In the early Jurassic the basin had a topo- in the Neuqu~n region was deposited in the graphy that was inherited from the late Triassic Jurassic-Cretaceous post-rift basin. During this rift phase (Burgess et al. 2000). During the period steep subduction of the Pacific plates remainder of the Jurassic and Early Cretaceous resulted in negative roll-back and a broad, gener- history the basin had a ramp-style geometry, ally extensional regime in both the arc and back- similar to other retro-arc basins (e.g. the arc settings (Ramos 1999b). Within the Neuqudn Western Interior Basin of the USA; Edwards Basin this extension was gentle and was exp- et al. 2005). ressed as broad-scale, regional subsidence The Early Jurassic of the Neuqurn Basin pro- rather than rifting with active extensional faults vides an excellent study in the significance of at the surface. The depositional systems were basin geometry on sequence and facies archi- marine-dominated and show well-defined tecture. The deep-water turbidite systems of the records of cyclic sea-level change at different (Burgess et al. 2000) scales. These cycles were a product of the and the shallow-marine tidal deposits of the complex interaction of eustatic oscillations, Lajas Formation (MelIroy et al. this volume) minor extension and thermal subsidence with were strongly influenced by the relict topography localized uplift and inversion, and form the inherited from the early rift phase. This topogra- focus of sequence stratigraphic studies of the phy controlled the distribution of depositional sedimentary record in the basin. lows, and in the Lajas Formation resulted in the In his pioneering study of the stratigraphy in localized amplification of the tidal wave and a the basin, Groeber (1946) identified two major thick, highly aggradational succession of tidal cycles (Jurfisico and Andico), each composed deposits. of several transgressive-regressive subcycles. Deposition in the late post-rift ramp setting Building on this work, several authors (Gulisano was characterized by well-developed cycles et al. 1984; Mitchum & Uliana 1985; Legarreta showing a complete record of lowstand, trans- & Gulisano 1989; Legarreta & Uliana 1991, gressive and highstand systems tracts. Surfaces 1996, 1999; Legarreta et al. 1993) produced a that bound these sequences are marked by a more detailed breakdown of these cycles and sharp basinward shifting of continental-domi- attributed them primarily to eustatic sea-level nated facies. Falling-stage deposits are present changes under a regime of thermal subsidence. in some cases (Veiga et al. this volume), but The dramatic sea-level falls that occurred are typically poorly developed. The transgressive during the Cretaceous (>100 m), such as the systems tracts are mainly composed of thick sequence boundaries at the base of the Avil6 offshore deposits (Doyle et al. this volume; and Troncoso members (Fig. 3) in which Sagasti this volume), even near the basin aeolian deposits overlie offshore marine margins. These deposits commonly show fea- (Veiga et al. 2002a; Veiga et al. this volume) tures of restricted marine circulation. The high- were attributed to sea level in the Pacific falling stand systems tracts are mainly composed of below a sill in the Andean arc that separated mixed offshore siliciclastics and carbonates that the Neuqurn Basin from the open ocean. pass upwards into progradational shoreface, Whilst appealing and an excellent starting deltaic and fluvial deposits (Fig. 3). The Lower point, this interpretation appears to have under- Cretaceous succession of the Neuqurn Basin rated the importance of intrabasinal and intra- includes a number of such examples of ramp- arc tectonics. According to Vergani et al. margin sequences. Downloaded from http://sp.lyellcollection.org/ by guest on September 30, 2021

THE NEUQUI~N BASIN: AN OVERVIEW 9

The extreme facies shifts that are associated Within low-frequency transgressive cycles, with the sequence boundaries are attributed to high-frequency subdivisions may be recognized the effects of relative sea-level fall, enhan- in the Neuqu6n Basin record. Seasso et al. (this ced and locally overprinted by phases of loca- volume) analysed the rhythmic succession of lized tectonic inversions. Although the and marls that characterize one of basinward shift in facies is commonly major, the high-frequency Tithonian highstands, con- the sequence boundaries are typically planar cluding that these offshore cycles are the result and incised valleys are rare (Schwarz et al. of systematic changes in productivity on the 2005; Sehwarz & Howell this volume). The sea surface, and supply of terrigenous and non- nature of the facies that overlie the sequence terrigenous material in suspended plumes. boundaries is partially controlled by the degree Sagasti (this volume) analysed high-frequency of connection that was maintained to the proto- cycles developed during two low-order Pacific Ocean. In some cases a complete desicca- -Barremian transgressive succes- tion of the basin occurred as the connection was sions. These outer ramp rhythms are interpreted severed (e.g. the aeolian deposits of the Troncoso as dilution cycles triggered by orbital climatic Member: Veiga et al. this volume), in others a changes within the Milankovitch range. limited connection was maintained and the low- Towards the end of the Early Cretaceous the stand deposits show evidence of open or Neuqu6n Basin started to experience one of its restricted marine circulation. Sehwarz & major tectonic changes, passing from the back- Howell examined one of these long-term arc sag phase to the early part of the foreland lowstand wedges, and highlight how tectonic phase. Veiga et al. (this volume) analysed the activity and basin physiography conditioned sequence stratigraphic architecture and the evol- the internal sequence architecture and the ution of the depositional systems through this relationship between contemporary marine and transition. Some striking differences are depic- non-marine depositional systems. ted from the previous sequence stratigraphic The low angle of the ramp margin also framework, with a well-developed falling-stage favoured rapid landwards migration of shorelines systems tract followed by a lowstand episode during the transgressions that followed the low- characterized by complete disconnection from stands. In many cases shallow-marine and off- the ocean and without re-establishment of shore deposits directly overlie fluvial and 'normal' marine conditions during the sub- aeolian facies. Str6mb~iek et al. (this volume) sequent transgression. analysed one of these transgressive events that occurred across the top of a lowstand aeolian sand sea. In this case the transgression was fast Palaeobiology enough to preserve at least some of the dune The biological record of the Neuqu~n Basin is topography with soft-sediment deformation and diverse and continuous, and, in addition to its slumping into the interdune lows, and only biostratigraphic significance, it also allows trans- localized reworking of the dune tops. cendent palaeoecological, taphonomical and Transgressive systems tracts within the post- palaeobiogeographical studies. As with other rift fill of the basin are characterized by thick studies in the basin, this work exceeds its local successions of offshore marine deposits that significance and contributes to interpretations commonly show evidence for restricted water that are applicable worldwide. circulation. Within these cyclically stacked The most famous palaeobiological record is black and marl successions Doyle et al. that of the Mesozoic reptiles of the Neuqu6n (this volume) examined how systematic variation Basin. So far the most important fossil reptiles in the Jurassic-Lower Cretaceous ichnological of southernmost South America (including and faunal record may be employed to interpret ) all come from the Neuqu6n Basin. the firmness of the marine substrate and different The rich dinosaur fauna has resulted in the defi- levels of oxygenation at the water-sediment nition of many new taxa (Coria & Salgado interface. Besides, a detailed study of organic 1995, 1996; Bonaparte 1996, 1998; Coria 2001; facies within transgressive intervals by Tyson Coria & Calvo 2002, among others), the develop- et al. (this volume) reveal that Cretaceous ment of evolutionary models (Wilson & Sereno anoxic events do not exactly correlate with 1998; Sereno 1999), and the study of faunal previously documented global anoxic events. assemblages and reptile palaeocommunities They are interpreted as the result of the (Novas 1997; Leanza et al. 2004). Coria & combination of a long-term rise in sea level Salgado (this volume) analysed the saurischian and the development of locally restricted dinosaur evolutionary trends and discussed the conditions. main causes of intra-Cretaceous extinctions. Downloaded from http://sp.lyellcollection.org/ by guest on September 30, 2021

10 J.A. HOWELL ET AL.

It is not just the dinosaurs of the Neuqu6n Despite a number of palynological contri- Basin that are outstanding. Marine reptiles are butions (cf. Quattrocchio & Sarjeant 1992; also very well preserved in the Jurassic and Quattrocchio et al. 1996, 2002; Martinez et al. Lower Cretaceous successions of the basin, as 2005) the mega-palaeofloristic record of the shown by Gasparini & Fernfindez (this Neuqu~n Basin is not as well documented. The volume). In particular, the wonderful record of contribution by Morgans-Bell & McIlroy (this Late Jurassic marine reptiles has allowed the volume) shows how morphological studies of studies on taphonomy and palaeobiological inter- Jurassic conifers can contribute to palaeoenvir- actions within an almost isolated marine embay- onmental and palaeoclimatic interpretations. ment (Fig. 5). These palaeontological studies have strongly contributed to new palaeobiogeo- graphic panoramas and to the definition of bio- Perspectives and future work logical connections between different oceanic Despite the significant volumes of previous realms (Gasparini 1996; Gasparini & Fernfindez work, including that detailed in this volume, 1997). studies of the Neuqu6n Basin are still in their While the reptile fauna of the basin is dra- infancy. Both the outcrops and the subsurface matic, the Mesozoic invertebrates are equally portions of the basin offer significant potential well preserved and represented. Besides the for further work that has global implications. biostratiographic significance of macro- and Detailed understanding of the subsurface microinvertebrate faunas, they have allowed the reservoirs that exist in the Neuqu6n Embayment development of detailed biofacial and tapho- is still not in the public domain (if it exists). nomic studies. Lazo et al. (this volume) show There are considerable opportunities for further the great variability of invertebrate palaeocom- comparison of the producing reservoirs with the munities developed in different subenvironments outcrops. Outcrop characterization and model- of the Neuqu6n marine ramp during the Early ling, compared and contrasted to oil-field pro- Cretaceous. duction data from the same intervals less than

......

Fig. 5. Reconstruction of the Tithonian marine herpetofauna of the Neuqu6n Basin (original drawing by J. Gonzfilez, courtesy of Dr Z.B. de Gasparini). Downloaded from http://sp.lyellcollection.org/ by guest on September 30, 2021

THE NEUQUI~N BASIN: AN OVERVIEW 11

50 km apart, provides potential for numerous highlights the enormous potential for future studies. As does linking the well log and study. seismic expression of the intervals to their outcrop expression. The subsurface data also References hold the key to many of the unsolved palaeo- geographic problems, and the potential for AGUIRRE-URRETA, M.B. & RAWSON, P.F. 1997. The high-quality, unweathered biostratigraphic data ammonite sequence in the from cores is far reaching. (Lower Cretaceous), Neuqu6n Basin, Argentina. Geological Magazine, 134, 449-458. When compared with other parts of the world AGUIRRE-URRETA, M.B., CONCHEYRO, A., with comparable outcrop quality, the outcrops of LORENZO, M., OTTONE, E.G. & RAWSON, P.F. the Neuqu6n Basin have received little attention. 1999. Advances in biostratigraphy of the Agrio In the future, further studies will be undertaken to Formation (Lower Cretaceous) of the Neuqudn improve our understanding of facies and Basin, Argentina: ammonites, palynomorphs, and sequence stratigraphy. There is considerable calcareous nannofossils. Palaeogeography, scope for inversion and forward modelling of Palaeoclimatology, Palaeoecology, 150, 33-47. the observed stratigraphic architectm'e, and BARRIO, C.A. 1990. Late Cretaceous-Early Tertiary such work will be central to understanding the sedimentation in a semi-arid foreland basin (Neuqudn Basin, western Argentina). Sedimentary details of the driving mechanisms behind the dra- Geology, 66, 255-275. matic sea-level falls and rapid flooding surfaces BRANDSiETER, I., MCLLROY, D., LIA, O., RINGROSE, that have been documented, and the timing and P. & N/Ess, A. 2005. Reservoir modelling duration of the lowstands. There is also consider- and simulation of Lajas Formation outcrops able scope for the development of depositional (Argentina) to constrain tidal reservoirs of the models and high-resolution sequence strati- Halten Terrace (Norway). Petroleum Geoscience, graphic schemes for the synrift and foreland 11, 37-46. stages of the basin history. Such studies will be BURGESS, P., FLINT, S. • JOHNSON, S. 2000. Sequence highly dependent on the construction of more stratigraphic interpretation of turbiditic strata: an example from Jurassic strata of the Neuqudn complete chronostratigraphic and biostrati- basin, Argentina. Geological Society of America graphic framework for these stages. Bulletin, 112, 1650-1666. Whilst the stratigraphic scheme for much of BONAPARTE, J.F. 1996. Cretaceous tetrapods of the basin history is very good, further attention Argentina. In: PFEIL, F. & ARRATIA, G. (eds) must be paid to more absolute dating of the vol- Contributions of Southern South America to canic and volcaniclastic rocks. This will result in Vertebrate Paleontology. Miinchner Geowis- a refinement of the current biostratigraphic senschaflliche Abhandlungen, Reihe A, Geologie schemes for the Jurassic and Cretaceous, and und Palai~ntolie, 30, 73-130. an improved understanding of the Triassic and BONAPARTE, J.F. 1998. Los dinosaurios de la Patago- nia Argentina. Publicacidn Museo Argentino de Cenozoic histories. Further improvements of Ciencias Naturales B. Rivadavia, 1-46. the stratigraphy of the basin will also arise CASADIO, S., GRIFFIN, M., PARRAS, A., from much greater integration of the existing CONCHEYRO, A., FELDMANN, R., GASPARINI, Z. and future subsurface data. & PARMA, S.G. 2004. Biotic and environmental Much of our existing knowledge of the basin changes across the Cretaceous/Paleocene bound- fill is taken from the outcrops towards the SE ary in Patagonia. In: 10 ° Reuni6n Argentina de and NE (passive, cratonic) margins of the Sedimentolog[a, Actas de Res~menes, Universidad basin. The geometry and physiography of the Nacional de San Luis, Argentina, 187-188. western (active) margin of the basin are far less CORIA, R.A. 2001. New theropod from the Late Cretaceous of Patagonia. ln: TANKE, D.H. & well understood. In the near future, studies on CARPENTER, K. (eds) Mesozoic Vertebrate Life. the Jurassic and Cretaceous sedimentary record Indiana University Press, Bloomington, 3-9. close to the magmatic arc will be required to COma, R.A. & CALVO, J.O. 2002. A new iguanodon- define the main sedimentary processes, to vali- tian ornithopod from Neuqudn Basin, Patagonia, date sequence stratigraphic schemes and to Argentina. Journal of Vertebrate Paleontology, locate the pathways across the magmatic arc 22, 503-509. that allowed connection of the Neuqudn Basin CORIA, R.A. & SALGAOO, L. 1995. A new giant carni- with the proto-Pacific Ocean. vorous dinosaur from the Cretaceous of Patagonia. Excellent outcrops, copious subsurface data, a Nature, 377, 224-226. CORIA, R.A. & SALGADO,L. 1996. A basal iguanodon- world class palaeontological record and a unique tian (-Ornithopoda) from the Late structural setting combine to make the Neuqu6n Cretaceous of South America. Journal of Basin a unique case study in basin evolution Vertebrate Paleontology, 16, 445-457. and fill. This Special Publication represents the DEFERRARIIS, C. 1947. Edad del arco o dorsal state of current understanding and hopefully antigua del Neuqudn oriental, de acuerdo con la Downloaded from http://sp.lyellcollection.org/ by guest on September 30, 2021

12 J.A. HOWELL ET AL.

estratigraffa de la zona inmediata. Revista de la GROEBER, P., STIPANICIC, P.N. & MINGRAMM, A. Asociacitn Geoldgica Argentina, 2, 256-283. 1953. Jur~isico. Geograffa de la RepFtblica EDWARDS, C., HOWELL, J. & FLINT, S. 2005. Argentina, 2, 143-347. Depositional and stratigraphic architecture of the GULISANO, C.A., GUTIf~RREZ PLEIMLING, A.R. & Santonian Emery of the Mancos Shale: DIGREGORIO, R.E. 1984. Anfilisis estratigr~ifico implications for Late Cretaceous evolution of the del intervalo Tithoniano-Valanginiano (Forma- Western Interior foreland basin of central Utah, ciones , Quintuco y Mulichinco) en U.S.A. Journal of Sedimentary Research, 75, el suroeste de la provincia de Neuqutn. IX Con- 280-299. greso Geoltgico Argentino, S. C. de Bariloche, 1, FEEHAN, J.G. 1984. Structural style of the central 221-235. Neuqudn basin, Argentina. MSc Thesis, University HERRERO-DUCLOUX, A. 1946. Contribuci6n al conoci- of South Carolina, Department of Geological rniento del Neuqutn extrandino. Bolet{n de Sciences. lnformaciones Petroleras, 22, 245-261. FOLGUERA, A. & RAMOS, V.A. 2002. Los efectos pro- INTROCASO, A., PACINO, M.C. & FRAGA, H: 1992. ducidos por la aproximaci6n, colisi6n y subducci6n Gravity, isostasy and Andean crustal shortening de dorsales pacfficas en los Andes Patag6nicos. between latitudes 30 ° and 35°S. Tectonophysics, Acta Geoltgica Hispana, 37, 329-353. 205, 31-48. FOLGUERA, A., RAMOS, V.A., HERMANNS, R. & JORDAN, T., BURNS, W., VEIGA, R., PANGARO, F., NARANJO, J. 2004. Neotectonics in the foothills COPELAND, P., KELLEY, S. & MPODOZIS, C. of the southernmost central Andes (37-38°S): 2001. Extension and basin formation in the Evidence of strike-slip displacement along the Southern Andes caused by increased convergence Antifiir-Copahue fault zone. Tectonics, 23 (5), rate: A Mid-Cenozoic trigger for the Andes. TC5008. Tectonics, 20, 308-324. FRANZESE, J.R. & SPALLETTI, L.A. 2001. Late LLAMBSAS, E.J. & RAPELA, C.W. 1989. Las volcanitas Triassic-early Jurassic continental extension in de Collipilli, Neuqudn (37°S) y su relaci6n con southwestern Gondwana: tectonic segmentation otras unidades pale6genas de la cordillera. Asocia- and pre-break-up rifting. Journal of South ci6n Geoltgica Argentina Revista, 44, 224-236. American Earth Sciences, 14, 257-270. LEANZA, H.A. 1973. Estudio sobre los cambios FRANZESE, J., SPALLETTI, L., GOMEZ PI~REZ, I. & faciales de los estratos lim/trofes jurfisico-cret~ici- cos entre Loncopu4 y Picfin Leuffi, Provincia del MACDONALD, D. 2003. Tectonic and paleoenviron- Neuqu4n, Repfiblica Argentina. Revista de la mental evolution of Mesozoic sedimentary basins Sociedad Geoldgica Argentina, 28, 97-132. along the Andes foothills of Argentina (3U- LEANZA, H.A. 1981. Faunas de ammonites del Jurfisico 54°S). Journal of South American Earth Sciences, superior y del Cretficico inferior de Amdrica del 16, 81-90. Sur, con especial consideraci6n de la Argentina. FRANZESE, J., VEIGA, G.D., SCHWARZ, E. & GOMEZ- In: VOLKHEIMER, W. & MUSSACHIO, E. (eds) P~REZ, I. 2006. Tectono-stratigraphic evolution Cuencas Sedimentarias del Jurdsico y Cretdcico of a Mesozoic rift border system: the Chachil de Amdrica del Sur. Museo Argentino de Ciencias depocentre, southern Neuqu4n Basin, Argentina. Naturales, Buenos Aires, Argentina, 2, 559-597. Journal of the Geological Society, London, in LEANZA, H.A. & HUGO, C.A. 1977. Sucesi6n de amo- press. nites y edad de la Formaci6n Vaca Muerta y sincr6- GASPARINI, Z. 1996. Biogeographic evolution of the nicas entre los paralelos 35 ° y 40 ° L.S. Cuenca Southamerican crocodiles. In: ARRATIA, G. (ed.) Neuquina-Mendocina. Revista de la Asociacitn Contributions of Southern South America to Geoldgica Argentina, 32, 248-264. Vertebrate Paleontology. Munchen Geowis- LEANZA, H.A., MARCHESE, H. & RIGGI, J. 1977. Estra- senschaftliche Abhandlungen A, 30, 159-184. tigraffa del Grupo Mendoza con especial referencia GASPARINI, Z. & FERNANDEZ, M. 1997. Tithonian a la Formaci6n Vaca Muerta entre los paralelos 35 ° marine reptiles of the Oriental Pacific. In: y 40 ° L.S., Cuenca Neuquina-Mendocina. Revista CALLAWAY, J. • NICHOLLS, E. (eds) Ancient de la Asociacidn Geoldgica Argentina, 32, Marine Reptiles, Volume 15. Academic Press, 190-208. New York, 435-450. LEANZA, H.A., APESTEGU[A, S., NOVAS, F. & DE LA GASPAR|NI, Z., SPALLETTI, L. & DE LA FUENTE, M. FUENTE, M. 2004. Cretaceous terrestrial beds 1997. Marine reptiles of a tithonian transgression, from the Neuqudn Basin (Argentina) and their western Neuqutn Basin, Argentina. Facies and tetrapod assemblages. Cretaceous Research, 25, Paleoenvironments. Geobios, 30, 701-712. 61-87. GASPARINI, Z., SPALLETTI, L., FERNANDEZ, M. & LEGARRETA, L. & GULISANO, C.A. 1989. Anfilisis DE LA FUENTE, M. 1999. Tithonian marine reptiles estratigr~ifico secuencial de la Cuenca Neuquina from the Neuqudn Basin: diversity and paleo- (Trifisico superior-Terciario inferior, Argentina). environments. Revue de Paldobiologie, 18, In: CHEBLI, G. & SPALLETTJ, L. (eds) Cuencas 335 -345. Sedimentarias . Serie Correlaci6n GROEBER, P. 1946. Observaciones geoldgicas a lo Geol6gica, Universidad Nacional de Tucumfin, 6, largo del meridiano 70 °. 1. Hoja Chos Malal. 221 - 243. Revista de la Sociedad Geoltgica Argentina, 1, LEGARRETA, L. 8,: ULIANA, M.A. 1991. Jurassic- 177-208. Cretaceous marine oscillations and geometry of Downloaded from http://sp.lyellcollection.org/ by guest on September 30, 2021

THE NEUQUI~N BASIN: AN OVERVIEW 13

back arc basin fill, Central Argentine Andes. QUATTROCCHIO, M.E., MARTINEZ, M.A., GARC[A, In: MACDONALD, D.I.M. (ed.) Sedimentation, V.M. & ZAVALA, C.A. 2002. Palinoestratigraffa Tectonics and Eustasy - Sea-level Changes at del Tithoniano-Hauteriviano del centro-oeste de Active Margins. International Association of Sedi- la Cuenca Neuquina, Argentina. In: 8th Congreso mentologists, Special Publications, 12, 429-450. Argentino de Paleontologfa y Bioestratigrafi'a, LEGARRETA, L. & ULIANA, M. 1996. The Jurassic Res{tmenes. Corrientes, Argentina, 75-76. succession in west-central Argentina: stratal pat- QUATTROCCHIO, M.E., SARJEANT, W.A.S. & terns, sequences and paleogeographic evolution. VOLKHE~MER, W. 1996. Marine and terrestrial Palaeogeography, Palaeoclimatology, Palaeoeco- Jurassic microfloras of the Neuqu4n Basin logy, 120, 303-330. (Argentina): palynological zonation. GeoResearch LEGARRETA, L. & ULIANA, M. 1999. E1 Jurfisico y Forum, 1-2, 167-178. Cretficico de la Cordillera Principal y la RAMOS, V.A. 1978. Estructura. In: Relatorio Geologfa Cuenca Neuquina. 1. Facies Sedimentarias. In: y Recursos Naturales del Neuqudn. VII Congreso CAMINOS, R. (ed.) Geologfa Argentina. Instituto Geol6gico Argentino, Neuqu4n, 99-125. de Geologfa y Recursos Minerales, Anales, 29, RAMOS, V.A. 1999a. Los depdsitos sinorog4nicos 399-416. terciarios de la regidn andina. In: CAMINOS, R. LEGARRETA, L., GULISANO, C.A. & ULIANA, M.A. (ed.) Geologfa Argentina. Instituto de Geologfa y 1993. Las secuencias sedimentarias jurfisico-cret~i- Recursos Minerales, Anales, 29, 651-682. cicas. In: Relatorio Geologfa y Recursos Minerales RAMOS, V.A. 1999b. Evolucidn Tectdnica de la de Mendoza. XII Congreso Geoldgico Argentino y Argentina. In: CAMINOS, R. (ed.) Geologfa II Congreso de Exploracitn de Hidrocarburos, Argentina. Instituto de Geologfa y Recursos Miner- Mendoza, 1(9), 87-114. ales, Anales, 29, 715-759. MACDONALD, D., GOMEZ-PI~REZ, I. ET AL. 2003. RICCARDI, A.C. 1983. The Jurassic of Argentina and Mesozoic break-up of SW Gondwana: Implications Chile. In: MOULLADE, M. & NAIRN, A.E. (eds) for South Atlantic regional hydrocarbon potential. The Phanerozoic Geology of the World, II. The Marine and Petroleum Geology, 20, 287-308. Mesozoic. Elsevier, Amsterdam, 201-263. MANCEDA, R. & FIGUEROA, D. 1995. Inversion of the RICCARDI, A.C. & IGLESIA LLANOS, M.P. 1999. Mesozoic Neuqutn rift in the Malargtie fold and Primer hallazgo de amonites en el Trifisico de la thrust belt, Mendoza, Argentina. In: TANKARD, Argentina. Revista de la Asociacidn Geoldgica A.J., SUAREZ SORUCO, R. & WELSINK, H.J. (eds) Argentina, 54, 298-300. Petroleum Basins of South America. AAPG R1CCARDI, A.C., WESTERMANN, G.E.G. & LEVY, R. Memoirs, 62, 369-382. 1971. The Lower Cretaceous Ammonitina Olcoste- MARTINEZ, M.A., QUATTROCCHIO, M.E. & phanus, Leopoldia and Favrella from west-central PRAMPARO, M.B. 2005. Anfilisis palinol6gico de la Formaci6n Los Molles, Grupo Cuyo, Jurfisico Argentina. Palaeontographica, 136, 83-121. medio de la cuenca Neuquina, Argentina. RICCARDI, A.C., DAMBORENEA, S.E. & MANCEIqIDO, Ameghiniana, 42, 67-92. M.O. 1990a. Lower Jurassic of South America MITCHUM, R.M. & ULIANA, M.A. 1985. Seismic stra- and Antarctic Peninsula. In: WESTERMANN, tigraphy of carbonate depositional sequences, G.E.G. & RICCARDI, A.C. (eds) Jurassic Taxa Upper Jurassic-Lower Cretaceous, Neuqutn Ranges and Correlation Charts for the Circum- Basin, Argentina. In: BERO, B.R. & WOOLVERTON, Pacific. Newsletters on Stratigraphy', 21(2), D.G. (eds) Seismic Stratigraphy: An Integrated 75-103. Approach to Hydrocarbon Exploration. AAPG RICCARDI, A.C., DAMBORENEA, S.E. & Memoirs, 39, 255-274. WESTERMANN, G.E.G. 1990b. Middle Jurassic of NOVAS, F.E. 1997. South American dinosaurs. In: South America and Antarctic Peninsula. In: CURRIE, P. & PAD1AN, K. (eds) Encyclopedia WESTERMANN, G.E.G. & PdCCARDh A.C. (eds) of Dinosaurs. Academic Press, San Diego, CA, Jurassic Taxa Ranges and Correlation Charts" for 678-689. the Circum-Pacific. Newsletters on Stratigraphy, PANGARO, F., VEIGA, R. & VERGANI, G. 2002. Evolu- 21(2), 105-128. ci6n tecto-sedimentaria del firea de Cerro Bandera, RICCARDI, A.C., LEANZA, H.A. & VOLKHEIMER, W. Cuenca Neuquina, Argentina. V Congreso Argen- 1990c. Upper Jurassic of South America and tino de Hidrocarburos, Mar del Plata (electronic Antarctic Peninsula. In: WESTERMANN, G.E.G. & format), IAPG, Buenos Aires, Argentina. RICCARDI, A.C. (eds) Jurassic Taxa Ranges and PLOSZKIEW1CZ, J.V., ORCHUELA,I.A., VAILLARD,J.C. Correlation Charts for the Circum-Pacific. & VIIqES, R.F. 1984. Compresi6n y desplazamiento Newsletters on Stratigraphy, 21 (2), 129-147. lateral en la zona de falla de Huincul, estructuras RICCARDI, A.C., DAMBORENEA, S.E. & MANCEIqIDO, asociadas, provincia del Neuqutn. IX Congreso M.O. 1999. E1 Jurfisico y Cret~icico de la Cordillera Geoltgico Argentino, San Carlos de Bariloche, 2, Principal y la Cuenca Neuquina. 3. Bioestratigraffa. 163-169. In: CAMINOS, R. (ed.) Geologfa Argentina. Instituto QUATTROCCHIO, M.E. & SARJEANT, W.A.S. 1992. de Geolog/a y Recursos Minerales, Anales, 29, Dinoflagellate cysts and acritarchs from the 419-432. Middle and Upper Jurassic of the Neuqutn Basin, SCHWARZ, E., SPALLETTI, L.A. & HOWELL, J.A. 2005. Argentina. Revista Espatiola de Micropaleontolo- Sedimentary response to a tectonically-induced gfa, 24, 67-118. sea-level fall in a shallow back-arc basin: the Downloaded from http://sp.lyellcollection.org/ by guest on September 30, 2021

14 J.A. HOWELL ET AL.

Mulicbinco Formation (Lower Cretaceous), Huincul, Cuenca Neuquina-Argentina. V Con- Neuqu~n Basin, Argentina. Sedimentology, in press. greso Argentino de Hidrocarburos, Mar del Plata SERENO, P.C. 1999. The evolution of dinosaurs. (electronic format), IAPG, Buenos Aires, Science, 284, 2137-2147. Argentina. SPALLETTI, L., FRANZESE, J., MATHEOS, S., & VEROArq, G.D., TANKARD, A.J., BELOTTI, H.J. & SCHWARZ, E. 2000. Sequence stratigraphy of a WELSINK, H.J. 1995. Tectonic evolution and tidally-dominated carbonate- siliciclastic ramp; paleogeography of the Neuqu6n Basin, Argentina. the Tithonian of the southern Neuqu6n Basin, In: TANKARD, A.J., SUAREZ SORUCO, R. & Argentina. Journal of the Geological Society, WELSINK, H.J. (eds) Petroleum Basins of South London, 157, 433-446. America. AAPG Memoirs, 62, 383-402. TANKARD, A.J., ULIANA, M.A. ErAL 1995. Structural VERGANI, G.D., SELVA, G. & BOGaETTI, D.A. 2002. and tectonic controls of basin evolution in Estratigraffa y modelo de facies del Miembro southwestern Gondwana during the Phanerozoic. Troncoso Inferior, Formaci6n Huitr/n (Aptiano), In: TANKARD, A.J., SUAREZ SORUCO, R. & en el noroeste de la Cuenca Neuquina, WELSINK, H.J. (eds) Petroleum Basins of South Argentina. In: C~N6OLAN~, C.A., CA~ALER~, N., America. AAPG Memoirs, 62, 5-52. LINARES, E., LtSPEZ DE LUCHI, M.G., VALENTE, S. 1999. Modelo deposicional para las are- OSTERA, H.A. & PANARELLO, H.O. (eds) XV niscas inferiores de la Formacidn Mulichinco, Congreso Geol6gico Argentino, E1 Calafate, 1, Dorso de los Chihuidos, Neuqu6n. 1V Congreso 613-618. de Exploraci6n y Desarrollo de Hidrocarburos, WEAVER, C.E. 1931. Paleontology of the Jurassic and Mar del Plata, 2, 749-771. Cretaceous of West Central Argentina. Memoir of VE1GA, G.D., SPALLETT1, L.A. & FLINT, S. 2002a. the University of Washington, 1, 1-469. Aeolian/fluvial interactions and high resolution WmSON, J.A. & SERENO, P.C. 1998. Early Evolution sequence stratigraphy of a non-marine lowstand and Higher-Level Phylogeny of Sauropod wedge: The Avil6 Member of the Argio Formation Dinosaurs. Society of Vertebrate Paleontology, (Lower Cretaceous) in central Neuqu6n Basin, Memoirs, 5, 1-68. Argentina. Sedimentology, 49, 1001-1019. YRIGOYEN, M.R. 1991. Hydrocarbon resources from VEIGA, R., PANGARO, F. • FERNANDEZ, M. 2002b. Argentina. In: World Petroleum Congress, Modelado bidimensional y migraci6n de hidro- Buenos Aires. Petrotecnia, 13, Special Issue, 38- carburos en el ~mbito occidental de la Dorsal de 54.