bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Neuquén Basin: an overview
Authors: Howell John A. , Schwarz Ernesto , Spalletti Luis A. , Veiga Gonzalo D. 
Published: April 2008

Abstract

The Neuquén 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 evolution: 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 excellent 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 × 10
6
m
3
of oil produced and an estimated 161.9 × 10
6
m
3
remaining. The principal 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.
Tectonic evolution of the Andes of Neuquén: constraints derived from the magmatic arc and foreland deformation
Authors: Ramos Victor A. , Folguera Andrés 
Published: April 2008

Abstract
The Andes of the Neuquén region (36° − 38°S latitude) of the Central Andes have distinctive characteristics that result from the alternation of periods of generalized extension followed by periods of compression. As a result of these processes the Loncopué trough is a unique long depression at the foothills parallel to the Principal Cordillera that consists of a complex half-graben system produced during Oligocene times and extensionally reactivated in the Pliocene-Pleistocene. Its northern sector represents the present contractional orogenic front.
The nature and volume of arc-related igneous rocks, the location of the volcanic fronts, expansions and retreats of the magmatism, and the associated igneous activity in the foreland, together with the analyses of the superimposed structural styles, permit the constraint of the alternating tectonic regimes. On these bases, different stages from Jurassic to Present are correlated with changes in the geometry of the Benioff zone through time. Periods of subduction-zone steepening are associated with large volumes of poorly evolved magmas and generalized extension, while shallowing of the subduction zone is linked to foreland migration of more evolved magmas associated with contraction and uplift in the Principal Cordillera.
The injection of hot asthenospheric material from the subcontinental mantle into the asthenospheric wedge during steepening of the subduction zone produced melting and poorly evolved magmas in an extensional setting. These periods are linked to oceanic plate reorganizations in the late Oligocene and in the early Pliocene.
Tectonic evolution of the Andean Fold and Thrust Belt of the southern Neuquén Basin, Argentina
Authors: Zapata T. , Folguera A. 
Published: April 2008

Abstract
The Andean Fold and Thrust belt between 36° and 39°S can be divided in two sectors. The Eastern Sector corresponds to the Agrio Fold and Thrust Belt (FTB) characterized by a major exhumation during the Late Cretaceous, and minor deformation during the late Eocene and Late Miocene. The Western Sector corresponds to the main cordillera and is characterized by a complex evolution that involves periods of out-of-sequence thrusting with respect to the previously deformed outer sector, and pulses of relaxation of the compressive structure. Cretaceous uplift constituted an orogenic wedge that extended to the inner sectors of the Agrio FTB. Eocene compression was mainly concentrated within the Western Sector but may have reactivated the pre-existing structures of the Agrio FTB, such as the Cordillera del Viento. Late Miocene minor compressional deformation occurred in the retro-arc area and extended into the foreland area. This deformation event produced the closure of a short-lived intra-arc basin (Cura Mallín Basin, 25-15 Ma) at the innermost sector of the FTB. The Pliocene and Quaternary, between 37°30′ and 39°S, have been periods of relaxation of the inner part of the FTB and fossilization of the Agrio Fold and Thrust Belt.
Localization of episodic late Oligocene-Early Miocene and Pliocene to the present extensional structures in the intra- and inner retro-arc is controlled by pre-existing Jurassic half-grabens related to the formation of the Neuquén Basin. The Jurassic rift seems to be controlled by deep crustal-lithospheric discontinuities derived from a Proterozoic-Palaeozoic history of amalgamation in the area, now deeply buried under multiple episodes of Mesozoic-Tertiary synorogenic and synextensional sedimentation.
Sedimentary evolution and depositional architecture of a lowstand sequence set: the Lower Cretaceous Mulichinco Formation, Neuquén Basin, Argentina
Authors: Schwarz Ernesto , Howell John A. 
Published: April 2008

Abstract
The Valanginian-aged Mulichinco Formation was deposited in the Neuquén Basin (west-central Argentina) during and immediately after a major fall in sea level, partially triggered by a tectonic inversion pulse. The formation represents a lowstand wedge where excellent outcrops, together with refined biostratigraphic coverage, have permitted the detailed examination of contemporaneous non-marine and marine deposits. Fourteen facies associations were identified in the Mulichinco Formation. They represent accumulation in a variety of environments ranging from gravelly fluvial braidplains to outer-shelf marine settings. Distribution of depositional environments, together with the identification of key surfaces and stratal patterns, has resulted in the identification of early and late lowstand, transgressive and highstand systems tracts. Accordingly, the Mulichinco lowstand wedge comprises one third-order sequence that lasted about 2 Ma and represents a lowstand sequence set. The character of shoreline sedimentation was highly variable along strike within the Mulichinco depositional area and alluvial deposits were not developed within incised valleys. Tectonically derived topography, basin physiography and fault-controlled subsidence are interpreted to have been the main controls on the evolution of the Mulichinco lowstand wedge. The results of this study have important implications for understanding both the history of Neuquén Basin and illustrating the previously undocumented architectural complexity that may exist within lowstand wedges.
Anatomy of a mixed marine-non-marine lowstand wedge in a ramp setting. The Record of a Barremian-Aptian complex relative sea-level fall in the central Neuquén Basin, Argentina
Authors: Veiga Gonzalo D. , Howell John A. , Strömbäck Anna 
Published: April 2008

Abstract
During the Cretaceous, western Argentina was occupied by the Neuquén Basin, a back-arc-foreland basin that was open through the proto-Andes to the Pacific Ocean in the west. The Neuquén Basin contains a thick succession of sediments that include the offshore marine deposits of the Agrio Formation. These deposits represent a time when the arc was an island chain and the Neuquén Basin was freely connected to the Pacific. This offshore marine succession is punctuated by two intervals of arid continental deposits that represent major, second-order, relative falls in sea level. In both of these cases there is no evidence of tectonic uplift or angular truncation along a basal bounding unconformity. The upper of the two lowstand wedges is characterized by a complex arragement of shallow-marine and continental deposits. Shallow-marine deposits sharply overlying offshore shales and capped by a master sequence boundary are interpreted as falling-stage deposits recording a complex relative sea-level fall. On top of a regional erosion surface, a drying-upwards succession of fluvial-aeolian deposits is developed, recording a fully non-marine stage in the evolution of the basin. These deposits are overlain by a marginal marine evaporite succession. The absence of a return to fully open-marine conditions is attributed to uplift in the Andes and marks the transition of the Neuquén Basin from a back-arc to a foreland system. This succession has important implications for the basin’s evolution and in the timing of the uplift of the Andes, is a very spectacular example of a lowstand wedge and is also a major hydrocarbon reservoir.
Organic facies variations in the Valanginian-mid-Hauterivian interval of the Agrio Formation (Chos Malal Area, Neuquén, Argentina): local significance and global context
Authors: Tyson Richard V. , Esherwood Philip , Pattison Katherine A. 
Published: April 2008

Abstract
Marine shales and marls of the Valanginian-Hauterivian Agrio Formation have been studied at five localities in order to assess lateral variations over a 100 km S-N, shelf to basin transition. The two main organic-rich intervals at the base of the Pilmatue Member (Valanginian) and the base of Agua de la Mula Member (late early Hauterivian) have been characterized using a combination of bulk organic chemistry and palynofacies. Except for the former at the southern end of the transect, both intervals have mean total organic carbon (TOC) contents of 2–3% and are dominated by marine amorphous organic matter, suggesting a similar dysoxic genetic organic facies. The mean hydrogen indices determined from the slope of S2 v. TOC are 174 in the Pilmatue Member, but 387 in the basal part of the Agua de la Mula Member, a difference that mainly reflects the range in thermal maturity (late v. early oil window, respectively). Significant lateral variation occurs in the Pilmatue Member, with dark organic-rich intervals being rare in the south but dominant at the northern (distal) end of the transect; this trend is matched by a progressive increase in the peak or mean carbonate-free TOC and hydrogen indices, the latter reaching 6% and 297, respectively, near Estancia Pampa Tril. The bulk of the Agua de la Mula Member in the south is developed in organic-poor oxic facies, with a predominance of terrestrial phytoclasts and type IV kerogen, but dysoxic-anoxic conditions apparently predominate in the northern area. Valanginian-Hauterivian black shale facies appear generally rare on a global basis, but their occurrence can be related to the combination of the progressive rise in sea level during the Early Cretaceous and locally more restricted conditions.
Analogue benchmarks of shortening and extension experiments
Authors: Schreurs Guido , Buiter Susanne J. H. , Boutelier David , Corti Giacomo , Costa Elisabetta , Cruden Alexander R. , Daniel Jean-Marc , Hoth Silvan , Koyi Hemin A. , Kukowski Nina , Lohrmann Jo , Ravaglia Antonio , Schlische Roy W. , Withjack Martha Oliver , Yamada Yasuhiro , Cavozzi Cristian , Del Ventisette Chiara , Brady Jennifer A. Elder , Hoffmann-Rothe Arne , Mengus Jean-Marie , Montanari Domenico , Nilforoushan Faramarz 
Published: April 2008

Abstract
We report a direct comparison of scaled analogue experiments to test the reproducibility of model results among ten different experimental modelling laboratories. We present results for two experiments: a brittle thrust wedge experiment and a brittleviscous extension experiment. The experimental set-up, the model construction technique, the viscous material and the base and wall properties were prescribed. However, each laboratory used its own frictional analogue material and experimental apparatus. Comparison of results for the shortening experiment highlights large differences in model evolution that may have resulted from (1) differences in boundary conditions (indenter or basal-pull models), (2) differences in model widths, (3) location of observation (for example, sidewall versus centre of model), (4) material properties, (5) base and sidewall frictional properties, and (6) differences in set-up technique of individual experimenters. Six laboratories carried out the shortening experiment with a mobile wall. The overall evolution of their models is broadly similar, with the development of a thrust wedge characterized by forward thrust propagation and by back thrusting. However, significant variations are observed in spacing between thrusts, their dip angles, number of forward thrusts and back thrusts, and surface slopes. The structural evolution of the brittle-viscious extension experiments is similar to a high degree. Faulting initiates in the brittle layers above the viscous layer in close vicinity to the basal velocity discontinuity. Measurements of fault dip angles and fault spacing vary among laboratories. Comparison of experimental results indicates an encouraging overall agreement in model evolution, but also highlights important variations in the geometry and evolution of the resulting structures that may be induced by differences in modelling materials, model dimensions, experimental set-ups and observation location.
The numerical sandbox: comparison of model results for a shortening and an extension experiment
Authors: Buiter Susanne J. H. , Babeyko Andrey Yu. , Ellis Susan , Gerya Taras V. , Kaus Boris J. P. , Kellner Antje , Schreurs Guido , Yamada Yasuhiro 
Published: April 2008

Abstract
We report results of a study comparing numerical models of sandbox-type experiments. Two experimental designs were examined: (1) A brittle shortening experiment in which a thrust wedge is built in material of alternating frictional strength; and (2) an extension experiment in which a weak, basal viscous layer affects normal fault localization and propagation in overlying brittle materials. Eight different numerical codes, both commercial and academic, were tested against each other. Our results show that: (1) The overall evolution of all numerical codes is broadly similar. (2) Shortening is accommodated by in-sequence forward propagation of thrusts. The surface slope of the thrust wedge is within the stable field predicted by critical taper theory. (3) Details of thrust spacing, dip angle and number of thrusts vary between different codes for the shortening experiment. (4) Shear zones initiate at the velocity discontinuity in the extension experiment. The asymmetric evolution of the models is similar for all numerical codes. (5) Resolution affects strain localization and the number of shear zones that develop in strain-softening brittle material. (6) The variability between numerical codes is greater for the shortening than the extension experiment.
Comparison to equivalent analogue experiments shows that the overall dynamic evolution of the numerical and analogue models is similar, in spite of the difficulty of achieving an exact representation of the analogue conditions with a numerical model. We find that the degree of variability between individual numerical results is about the same as between individual analogue models. Differences among and between numerical and analogue results are found in predictions of location, spacing and dip angle of shear zones. Our results show that numerical models using different solution techniques can to first order successfully reproduce structures observed in analogue sandbox experiments. The comparisons serve to highlight robust features in tectonic modelling of thrust wedges and brittle-viscous extension.
Interaction between normal faults and pre-existing thrust systems in analogue models
Authors: Corti Giacomo , Lucia Serena , Bonini Marco , Sani Federico , Mazzarini Francesco 
Published: April 2008

Abstract

The influence of pre-existing thrusts on the development of later normal faults was investigated using scaled laboratory analogue models. Experiments consisted of a phase of shortening followed by extension at variable angles of obliquity (α) to the shortening direction. Results suggest that the angle α has a major influence on the surface fault pattern and on the interaction between shortening-related structures and later extensional structures. Three different modes of interactions were identified depending upon the extension kinematics. (1) For orthogonal extension (α = 0°), shortening-related fold and thrust structures strongly influence the development of normal faults: graben structures nucleate within anticlines and the normal faults reactivate thrusts at depth (
branching at depth mode of interaction
). (2) For highly oblique extension (α ≥ 45°), shortening-related structures exert no influence on normal faults as extension-related steeply-dipping faults (characterized by an oblique component of movement) displace early thrusts (
no interaction mode
). (3) For intermediate obliquity angles (α = 15°, 30°), an
intermediate mode of interaction
characterizes the experiments, where the
no interaction
and
branching at depth
modes coexist in different regions of models. Modelling results can be used to infer regional extension directions as is shown for the Northern Appenines (Italy).
Relative importance of trenchward upper plate motion and friction along the plate interface for the topographic evolution of subduction-related mountain belts
Authors: Hampel Andrea , Pfiffner Adrian 
Published: April 2008

Abstract
We present finite-element models that investigate the relative importance of both trenchward motion of the upper plate and interplate coupling for the development of topography at convergent margins. Commonly, the role of a trenchward moving continental plate for the growth of topography is neglected in both modelling and field studies. Instead, forces exerted by the downgoing plate on the continental plate as well as interplate coupling are thought to be responsible for the deformation of the upper plate. Our model set-up includes an oceanic plate, which is in contact with a continental plate along a frictional plate interface and driven by slab pull. Both lithospheres have an elasto-visco-plastic rheology. The models demonstrate that friction along the plate interface can only lead to a high topography if the upper plate is moving toward the trench. Without such a trenchward advance, no high topography is generated, as the upper plate subsides owing to the drag exerted by the subducting plate. Increasing the coefficient of friction only amplifies the drag and increases the amount of subsidence. Our findings imply that trenchward motion of the continental plate plays a key role for the development of mountain belts at convergent margins; subduction of an oceanic plate even with high interplate coupling cannot explain the formation of Andeantype orogens.
Analogue modelling of a reactivated, basement controlled strike-slip zone, Sierra de Albarracín, Spain: application of sandbox modelling to polyphase deformation
Authors: Merten S. , Smit W. G. , Nieuwland D. A. , Rondeel H. E. 
Published: April 2008

Abstract
This paper presents the results of an analogue modelling study on the reactivation of Riedel shears generated by basement-induced sinistral strike-slip faulting. It is based on a natural example in the Sierra de Albarracín, Iberian Range (Spain). The area has a polyphase deformation history, defined by the Variscan and Alpine orogenies. Late Variscan deformation was concentrated in a wide NW-SE shear zone with accompanying kilometre-scale E-W Riedel shears, which divided the Palaeozoic basement into large fault blocks. Alpine reactivation resulted in differential movements on the Riedel shears, as evidenced by a NW-SE chain of Palaeozoic inliers surrounded by a Mesozoic cover that generally shows minor deformations except near the E-W Riedel shears, where strata locally appear in near-vertical to overturned position.
Sandbox analogue modelling was applied to improve insight into the structural history. It focused on the kinematics of spontaneously developed en echelon Riedel shears, reactivated in a rotated stress field. Sand with a controlled added strength was used to form Riedel shears in a first deformation phase to act as weak zones for a second phase.
The modelling showed that in the first deformation phase large pop-up structures developed between the Riedel shears in a basement-induced sinistral strike-slip zone. Later reactivation in the N060°E and N135°E shortening directions was taken up respectively by sinistral-reverse and dextral-reverse shear along the pre-existing Riedel shears, but only if the sand on one side of the fault zone was allowed to move freely along the other. Scissor faulting along the Riedel shears with their complex 3D-geometry increased the height of the up-squeezed blocks. For experiments with fixed boundaries and no oil-water emulsion layer between the base plate and sand pack, thrusting at the backstop occurred rather than reactivation of the Riedel shears. This approach provided robust insights on the 4D development of the Sierra de Albarracín area.
Lithospheric scale gravitational flow: the impact of body forces on orogenic processes from Archaean to Phanerozoic
Authors: Rey Patrice F. , Houseman Gregory 
Published: April 2008

Abstract
In the Archaean, the combination of warmer continental geotherm with a lighter sub-continental lithospheric mantle suggests that gravitational forces played a more significant role in continental lithospheric deformation. To test this hypothesis, we compare the evolution of the deformation and the regional state of stress in ‘Archaean-like’ and ‘Phanerozoic-like’ lithospheres submitted to the same boundary conditions in a triaxial stress-field with imposed convergence in one direction. For plausible physical parameters, thickening of normal to cold Phanerozoic lithospheres produces relatively weak buoyancy forces, either extensional or compressional. In contrast, for Archaean continental lithospheres, or for anomalously warm Phanerozoic lithospheres, lateral gravitationally-driven flow prevents significant thickening. This conclusion is broadly consistent with: (1) the relative homogeneity of the erosional level now exposed at the surface of Archaean cratons, (2) the sub-aerial conditions that prevailed during the emplacement of up to 20 km of greenstone cover, (3) the relatively rare occurrence in the Archaean record of voluminous detrital sediments, (4) the near absence of significant tectonic, metamorphic and magmatic age gradients across Archaean cratons, (5) the relative homogeneity of strain across large areas, and (6) the ubiquitous presence of crustal-scale strike slip faults in many Late Archaean cratons.