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The Neuquén Basin: an Overview

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The Neuquén Basin: an Overview 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, Argentina Abstract: The Neuqu6n Basin of Argentina and central Chile contains a near-continuous Late Triassic-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 Jurassic-Early Cretaceous marine fossil 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 Late Triassic- 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 Gondwana. 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-Early Jurassic: 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-Early Cretaceous: 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~ Barremian < LIJ Hauterivian Valanginian Berriasian 145 Ma. 8 Tithonian <, < Kimmendgian i o Tordi!lo Fm ~ Oxfordian LI. Callovian iii Bathonian 2~ (5 0 a Bajocian 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.
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