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The India-Asia collision zone is the archetype to calibrate geological responses to continent-continent collision, but hosts a paradox: There is no orogen-wide geological record of oceanic subduction after initial collision around 60-55 Ma, yet thousands of kilometers of post-collisional subduction occurred before the arrival of unsubductable continental lithosphere that currently horizontally underlies Tibet. Kinematically restoring incipient horizontal underthrusting accurately predicts geologically estimated diachronous slab break-off, unlocking the Miocene of Himalaya-Tibet as a natural laboratory for unsubductable lithosphere convergence. Additionally, three endmember paleogeographic scenarios exist with different predictions for the nature of post-collisional subducted lithosphere but each is defended and challenged based on similar data types. This paper attempts at breaking through this impasse by identifying how the three paleogeographic scenarios each challenge paradigms in geodynamics, orogenesis, magmatism or paleogeographic reconstruction and identify opportunities for methodological advances in paleomagnetism, sediment provenance analysis, and seismology to conclusively constrain Greater Indian paleogeography.

Central Anatolia (Turkey) is a small and nascent example of a high orogenic plateau, providing a natural laboratory to study processes driving plateau rise. The 1-km-high plateau interior uplifted since c. 8–5 Ma, with a further phase of kilometre-scale uplift affecting the southern plateau margin since 0.45 Ma. Several causes of plateau rise have been proposed: peeling or dripping delamination of the lithospheric mantle; asthenospheric upwelling through slab gaps created by slab fragmentation or break-off, and; continental underthrusting and crustal shortening below the southern plateau margin. The Neogene history of the plateau has not been diagnostic of the causes of plateau rise. We thus evaluate proposed uplift causes in the context of the Anatolian orogenesis, which formed the plateau lithosphere during subduction since the Cretaceous. We combine this analysis with available constraints on uplift, and geophysical data that illuminate the modern mantle (and crustal) structure. Our analysis suggests that lithospheric dripping, which followed arc magmatism and shortening in the Kirsehir Block (eastern Central Anatolia), is the most likely cause of plateau interior uplift. Lithospheric dripping is, however, an unlikely sole driver of multi-phase uplift along the southern plateau margin. There, underthrusting of the African continental margin, recorded by c. 11–7 Ma thrusting on Cyprus, is a viable cause of uplift since 0.45 Ma, but cannot account for earlier uplift since c. 8–5 Ma. Instead, slab break-off below the southern plateau margin is likely in light of geophysical data. On the SW plateau margin, small-scale peeling delamination of the Central Taurides by the Antalya slab since early Miocene times accounts for >150 km slab retreat with no corresponding upper-plate deformation. A southwest-travelling wave of subsidence and uplift signalled this retreat and may have contributed to coeval oroclinal bending of the western Central Taurides and southeastwar

Mountain height at convergent plate margins is limited by the megathrust shear force, but it remains unclear how this constraint affects the topographic evolution and mountain building at the transition from subduction to collision. Generally, mountain height increases during the subduction-collision transition in response to crustal thickening or processes like mantle delamination and slab breakoff, but the main parameters controlling how much mountain height increases remain poorly understood. Here we show, based on analytical and finite-element force-balance models, that the increase in mountain height depends on the magnitude of the megathrust shear force and the reduction of submarine margin relief. During the subduction stage, the shear force is balanced by the gravitational effect of the margin relief and the deviatoric stresses in the upper plate are low. When the submarine margin relief is reduced during the closure of the ocean basin, the effect of the gravitational force decreases and the upper plate experiences enhanced deviatoric compression, which allows the mountain height to increase until a near-neutral stress state beneath the high mountains is restored. If the increase in mountain height cannot keep pace with the submarine relief reduction, the compression of the upper plate increases by a few tens of MPa, which promotes tectonic shortening and mountain building. Our analysis implies that mountain height can increase by hundreds of meters to a few kilometers during collision, depending primarily on the trench depth during the subduction stage and possible syncollisional changes of the megathrust shear force.

The South China Block (SCB) has been regarded by many as an integral part of Gondwana, but proposed timing and processes for its accretion to Gondwana vary and remain contentious, largely owing to the lack of reliable Pan-African age paleomagnetic data and tectono-magmatic records from the SCB. Integrated in situ U-Pb ages and Hf-O isotope analyses of detrital zircons from geochronologically well-calibrated Ediacaran-Cambrian sedimentary rocks of western SCB reveal age populations of 2.51, 1.85, 1.20, 0.80, and 0.52 Ga. Detrital zircon age spectra indicate a major tectonic transition for the SCB during 0.56–0.54 Ga, interpreted to reflect the beginning of the collision between SCB-Indochina and NW India blocks. The collisional event lasted until early Ordovician, leading to the suturing of the SCB-Indochina to the northern margin of East Gondwana.

Key in understanding the geodynamics governing subduction and orogeny is reconstructing the paleogeography of ‘Greater India’ the Indian plate lithosphere that subducted since Tethyan Himalayan continental collision with Asia. Here, we discuss this reconstruction from paleogeographic, kinematic, and geodynamic perspectives and isolate the evolution scenario that is consistent with all three. We follow recent constraints advocating a ~58 Ma initial collision and update a previous kinematic restoration of intra-Asian shortening with a recently proposed model that reconciles long-debated large and small estimates of Indochina extrusion. Our new reconstruction is tested against paleomagnetic data, and against seismic tomographic constraints on paleo-subduction zone locations. The resulting restoration shows ~1000–1200 km of post-collisional intra-Asian shortening, leaving a 2600–3400 km wide Greater India. From a paleogeographic, sediment provenance perspective, Eocene sediments in the Lesser Himalaya and on undeformed India may be derived from Tibet, suggesting that all Greater Indian lithosphere was continental, but may alternatively be sourced from the contemporaneous western Indian orogen unrelated to India-Asia collision. A quantitative kinematic, paleomagnetic perspective prefers major Cretaceous extension and a ‘Greater India Basin’ opening within Greater India, but data uncertainty may speculatively allow for minimal extension. Finally, from a geodynamic perspective, assuming a fully continental Greater India would require that subduction rates close to 20 cm/yr was driven by a down-going lithosphere-crust assemblage more buoyant than the mantle, which seems physically improbable. We conclude that the Greater India Basin scenario is the only sustainable one from all three perspectives. We infer that old pre-collisional lithosphere rapidly entered the lower mantle sustaining high subduction rates, whilst post-collisional continental and young Greater India bas

The Permian Cape Fold Belt extends 1300 km along the western and southern coastal margins of South Africa. It comprises complexly deformed rocks of the lower-Palaeozoic Cape Supergroup, and Mesozoic parts of the Karoo Supergroup. Large-scale thrusts expose portions of the underlying Saldania Belt; a low-grade metamorphic belt intruded by granites of the ca. 550-500 Ma Cape Granite Suite. Both the Cape Fold Belt and Saldania Belt are segments of ancient continent-scale orogenic systems. The former is thought to be a portion of the Permian Gondwanides Orogen that extended from the Sierra de la Ventana Fold Belt of Argentina, across southern Africa, and into the Falkland (Malvinas) Islands, and Ellsworth-Whitmore Mountains of Antarctica, whereas the latter is considered one of the many Neoproterozoic-Cambrian Pan-African/Brasilliano terranes developed during the amalgamation of west Gondwana. However, fragmentation of Gondwana and separation of the Cape Fold Belt from its neighbouring terranes during the Cretaceous has provided major challenges in understanding both the geodynamic evolution of the poorly exposed Saldania Belt and the mechanics by which the Cape Orogen formed within the Gondwana interior. Gondwanan tectonic models often rely on geochronological provenance studies to not only link sedimentary sources and sinks, but to also correlate sedimentary successions in separated terranes. Previous geochronological provenance studies on the Cape Fold Belt have utilised U-Pb dating of detrital zircons to suggest that sediments of the Saldania Belt and Cape Supergroup were largely sourced from Mesoproterozoic rocks of the Namaqua-Natal Metamorphic Belt to the immediate north and underlying the Cape Fold Belt, as well as undifferentiated Pan-African and/or Brasilliano terranes. However, as zircon is able to survive orogenic recycling and long-distance transport, U-Pb detrital zircon studies have been unable to identify the most recent and proximal sources of sediments

In many mountain belts, deformation concentrates along mechanically weak fault zones inherited from earlier tectonic events. This work investigates the effects of two modes of structural weakening on the orientation of rifting and later tectonic inversion with respect to the imposed divergence/convergence direction in a high-resolution 3D finite difference model with a viscous-frictional rheology. In the first set of experiments, weakening consists in a decrease in frictional strength with increasing shear strain. The generated normal faults strike orthogonal to the imposed divergence direction. These faults are reactivated during tectonic inversion and absorb 50 to 70 percent of accumulated strain. In the second set of experiments, frictional strength is a decreasing function of shear strain rate. The generated faults are oblique to the divergence direction, implying oblique fault slip. Fault reactivation depends on the obliquity of the inverted rift to convergence direction, where larger obliquity leads to more intense fault reactivation. These new numerical results are compared to previous analogue and numerical models on the one hand, and natural examples of intracontinental mountain ranges due to tectonic inversion on the other hand. These comparisons demonstrate that both modes of frictional weakening should be taken into account when seeking to understand large-scale rifting and inversion tectonics.

In this paper we present a series of thermo-mechanical experiments on continent-continent collision zones to investigate the role of lateral strength contrasts in terms of collision dynamics and orogen geometries. Our results show that differences in crustal rheology, may lead to a variety of different patterns of deformation and crustal geometries. Upper plate indentation forms a sequence of foreland propagating thrust units made of brittle upper crust on the lower plate. The strong deformation of the lower plate stands in stark contrast to the undeformed upper plate. In contrast, subduction of strong lithosphere beneath a weak upper plate forms a complex pattern of deformation. Deformation initiates on the lower plate and forms an antiformal stack made of brittle upper crust, before it indents the upper plate. Hence, deformation is present on both, the lower and upper plate, despite differences in initial strength. The outcome of this study has direct implications to natural collision zones, where differences in strength between the upper and lower plate exist. For example, along strike variability of upper vs. lower plate shortening in the Alps are likely to be controlled by contrasts in crustal strength. Furthermore, we suggest that the antiformal stack in the axial zone of the Pyrenees might indicate a strong lower plate at the onset of collision. Our results may therefore provide important constraints for the rheological state of continents during collision.

La vida esta conformada por una serie de hechos y fenómenos que narran historias 1 de acontecimientos ocurridos en tiempos y espacios específicos; conformando realidades en común, a través de la relación con la naturaleza y los vínculos que se establecen ya sea con un cuerpo, una casa, un territorio, un pueblo, una nación, entre otros. Dichos espacios son contenedores de un fragmento de la existencia desde lo individual a lo colectivo en una organicidad simbiótica. Hacia la Orogénesis2 parte de una pregunta por el ser que se cuestiona sobre si mismo y sus orígenes, desde el habitar consiente y reciproco en empatía con el Territorio. En este caso me situó como individuo dentro del territorio de la vereda EL Pato del corregimiento de Pance, en la ciudad de Cali donde pretendo construir una relación sensible con la montaña y el nacimiento del agua, nuestro recurso vital, territorio común, orgánico3 y sus afectaciones causadas por las relaciones utilitarias que los seres humanos establecen con el Rio Pance respondiendo a una problemática habitacional.

La vida esta conformada por una serie de hechos y fenómenos que narran historias 1 de acontecimientos ocurridos en tiempos y espacios específicos; conformando realidades en común, a través de la relación con la naturaleza y los vínculos que se establecen ya sea con un cuerpo, una casa, un territorio, un pueblo, una nación, entre otros. Dichos espacios son contenedores de un fragmento de la existencia desde lo individual a lo colectivo en una organicidad simbiótica. Hacia la Orogénesis2 parte de una pregunta por el ser que se cuestiona sobre si mismo y sus orígenes, desde el habitar consiente y reciproco en empatía con el Territorio. En este caso me situó como individuo dentro del territorio de la vereda EL Pato del corregimiento de Pance, en la ciudad de Cali donde pretendo construir una relación sensible con la montaña y el nacimiento del agua, nuestro recurso vital, territorio común, orgánico3 y sus afectaciones causadas por las relaciones utilitarias que los seres humanos establecen con el Rio Pance respondiendo a una problemática habitacional.

Across the world we observe spectacular mountain belts that formed as a result of two colliding plates. Frequently this process is disturbed by the influence of neighbouring geological processes, such as the formation of adjacent mountain belts, adding significant kinematic and geometric complexities to the collisional systems. To understand the relative contributions of the processes involved it is essential to identify the individual interfering processes and to quantify their influence on the evolution of the mountain system. The Eastern Alps (Europe) is such a complex mountain belt and is the prime target of this research with particular interest in the transitions to the neighbouring Dinaric mountain belt and the Pannonian Basin. These transitions provide a unique opportunity to unravel the effects of interfering tectonic processes based on field studies, low temperature geochronology and physical analogue modelling. The geological evolution of the Eastern Alps and Dinarides is largely related to the motion of the African continental plate towards the European plate, with the microcontinent Adria located in between the two. The plate motion of the latter plays a key role in driving the deformation of the Eastern Alps as well as the Dinaric mountain chain. With respect to the Eastern Alps the Adriatic plate is traditionally viewed as a bulldozer that deforms, uplifts and laterally displaces the Eastern Alps. However, we show that these geological processes are also compatible with a tectonic scenario in which the Adriatic plate subducts below the Alps. The subduction also provides a crucial mechanism to create the formation of the Southern Alps, which affects at the same time the geological evolution of the northern Dinarides. The experimental results also strongly suggest that the geological evolution of the Eastern Alps during the last 30 Ma is best explained by phases of oblique and subsequent orthogonal Alps-Adria convergence. This has led to the cha

A lingering question in Cordilleran tectonics is how high plateaus form in the absence of continental collision. The type example of an active Cordilleran high plateau is found in the Central Andes of Peru, Bolivia, Argentina, and Chile. Along this section of the South American Cordillera, tectonics are primarily driven by subduction of the oceanic Nazca Plate beneath the continental South American Plate. Extending over 1,800 km along the active continental margin, the Central Andean Plateau (CAP) reaches a maximum width of around 400 km with several peaks in excess of 6 km. Numerous morphotectonic subdivisions of the CAP highlight the complex along-strike variability of the Plateau providing a natural laboratory for investigating the relative contribution of tectonic processes involved in building and maintaining Cordilleran high plateaus. The scale of this problem extends far beyond the scope of any one geoscientific discipline requiring a multidisciplinary approach. Our contribution to this scientific problem and the focus of the work presented in this dissertation is to better understand the current lithospheric and uppermost mantle structure along the CAP. This is achieved by integrating recent advances in seismic imaging techniques with a growing availability of high-quality seismic data into three distinct studies across the South American continent. In the first study, we present a shear-wave velocity model for the crust below the Altiplano-Puna Volcanic Complex (APVC). The target of this study is to constrain the crustal volume of a large magma reservoir inferred to exist below the APVC. When combined with geological and petrological constraints, the large-volume magma reservoir imaged in this study suggests a significant magmatic contribution to the growth of the Plateau in excess of one kilometer over the last ten million years. In addition to the tectonic contributions of this work, we introduce a new method of jointly inverting surface-wave dispersion d

[EN]This paper discusses the issue of the origin and maintenance of biodiversity on tropical mountains, with emphasis on the Neotropics, and concludes that present-day biodiversity patterns of highland biotas cannot be understood without the combined action of Neogene tectonics and Pleistocene climatic changes., [ES]En este artículo se discute el origen y mantenimiento de la biodiversidad en las montañas tropicales, con énfasis en el Neotrópico, y se concluye que los patrones de biodiversidad de las biotas de gran altura no pueden ser explicados sin la acción combinada de la tectónica neógena y los cambios climáticos del Pleistoceno.

This study utilizes new geochemical analyses of fluids (formation water and gas) collected predominately from Devonian organic-rich shales and reservoir sandstones from the northern Appalachian Basin margin to investigate basin scale hydrologic processes, water-rock reactions, microbial activity, and natural gas generation. Elemental and isotopic composition of co-produced formation waters and natural gas show that the majority of methane in Devonian organic-rich shales and reservoir sandstones is thermogenic in origin with localized accumulations of microbial gas. Microbial methanogenesis appears to be primarily limited by redox buffered conditions favoring microbial sulfate reduction. Thermal maturity (bioavailability) of shale organic matter and the paucity of formation waters may also explain the lack of extensive microbial methane accumulations. Iodine and strontium isotopes, coupled to elemental chemistry demonstrate basin scale fluid flow and clay mineral diagenesis. Evidence for this is based on anomalously high ¹²⁹I/I values sourced from uranium deposits (fissiogenic production of ¹²⁹I) at the structural front of the Appalachian Basin. Radiogenic ⁸⁷Sr/⁸⁶Sr (up to 0.7220), and depleted boron and potassium concentrations support smectite clay diagenesis at temperatures greater than 120 °C. The development of fissiogenic ¹²⁹I as a tracer of basin scale fluid flow is a novel application of iodine isotopes provided that the sources of cosmogenic and anthropogenic ¹²⁹I are reasonably well constrained. The anomalously high ¹²⁹I/I in Appalachian Basin brines may be alternatively explained by microbial fractionation based on a correlation with decreasing δ¹³C-DIC values and decreasing sulfate concentrations in the range of sulfate reduction. These results demonstrate that the microbial fractionation of iodine isotopes may be possible and an important consideration when interpreting ¹²⁹I/I, regardless of the source of ¹²⁹I. Results from this study have important impl

The kinematics and architecture of orogenic systems may be heavily influenced by climate, but little research has focused on the long-term effects of glacial erosion on orogenesis. Low-temperature thermochronometry and subsidiary structural, earthquake relocation, and offshore seismic reflection data from the St. Elias orogen are the basis for a new architectural model and demonstrate an association between glacial denudation and orogenic evolution. These data show that exhumation and deformation within the St. Elias orogen are focused across a thin-skinned fold and thrust belt on the windward flank, whereas the leeward flank functions as a deformational backstop. A previously unrecognized structure beneath the Bagley ice field separates these domains with south-side-up motion. This structure is interpreted to be a backthrust, making the orogen doubly-vergent. Suggestive of accelerated fault motion in response to climate change, bedrock cooling rates within the hanging wall of the backthrust and across the entire subaerial wedge accelerated ~ten-fold coeval with the onset of intense glacial conditions. Within the orogenic wedge, the zone of highest Quaternary exhumation (5 km/myr (±25%)) is focused around a narrow zone where the glacial equilibrium line altitude (ELA) intersects mean topography. This zone of rapid exhumation, not present prior to the onset of intense glacial conditions, cuts across the structural trend of the orogen and is more narrowly focused than the zone of orographic precipitation. Augmented glacial erosion around glacial ELA also coincided with a regional shift in deformation away from prominent forethrusts including the North American-Yakutat terrane suture (Chugach St. Elias fault) and the seaward deformation front (Pamplona zone). Accelerated denudation across the subaerial wedge thus appears to have forced the redistribution of strain along the backthrust and a series of forethrusts that lie beneath the zone of highest glacial flux, which

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