Microcontinent subduction and S-type volcanism prior to India-Asia collision.
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ABSTRACT:
SUBMITTER: Yang Z
PROVIDER: S-EPMC8295362 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:New geochronological and geochemical data on magmatic activity from the India-Asia collision zone enables recognition of a distinct magmatic flare-up event that we ascribe to slab breakoff. This tie-point in the collisional record can be used to back-date to the time of initial impingement of the Indian continent with the Asian margin. Continental arc magmatism in southern Tibet during 80-40?Ma migrated from south to north and then back to south with significant mantle input at 70-43?Ma. A pronounced flare up in magmatic intensity (including ignimbrite and mafic rock) at ca. 52-51?Ma corresponds to a sudden decrease in the India-Asia convergence rate. Geological and geochemical data are consistent with mantle input controlled by slab rollback from ca. 70?Ma and slab breakoff at ca. 53?Ma. We propose that the slowdown of the Indian plate at ca. 51?Ma is largely the consequence of slab breakoff of the subducting Neo-Tethyan oceanic lithosphere, rather than the onset of the India-Asia collision as traditionally interpreted, implying that the initial India-Asia collision commenced earlier, likely at ca. 55?Ma.
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Project description:The formation of mountain belts or rift zones is commonly attributed to interactions between plates along their boundaries, but the widely distributed deformation of Asia from Himalaya to the Japan Sea and other back-arc basins is difficult to reconcile with this notion. Through comparison of the tectonic and kinematic records of the last 50 Ma with seismic tomography and anisotropy models, we show that the closure of the former Tethys Ocean and the extensional deformation of East Asia can be best explained if the asthenospheric mantle transporting India northward, forming the Himalaya and the Tibetan Plateau, reaches East Asia where it overrides the westward flowing Pacific mantle and contributes to subduction dynamics, distributing extensional deformation over a 3,000-km wide region. This deep asthenospheric flow partly controls the compressional stresses transmitted through the continent-continent collision, driving crustal thickening below the Himalayas and Tibet and the propagation of strike-slip faults across Asian lithosphere further north and east, as well as with the lithospheric and crustal flow powered by slab retreat east of the collision zone below East and SE Asia. The main shortening direction in the deforming continent between the collision zone and the Pacific subduction zones may in this case be a proxy for the direction of flow in the asthenosphere underneath, which may become a useful tool for studying mantle flow in the distant past. Our model of the India-Asia collision emphasizes the role of asthenospheric flow underneath continents and may offer alternative ways of understanding tectonic processes.
| S-EPMC6472563 | biostudies-literature
Project description:Cenozoic convergence between the Indian and Asian plates produced the archetypical continental collision zone comprising the Himalaya mountain belt and the Tibetan Plateau. How and where India-Asia convergence was accommodated after collision at or before 52 Ma remains a long-standing controversy. Since 52 Ma, the two plates have converged up to 3,600 ± 35 km, yet the upper crustal shortening documented from the geological record of Asia and the Himalaya is up to approximately 2,350-km less. Here we show that the discrepancy between the convergence and the shortening can be explained by subduction of highly extended continental and oceanic Indian lithosphere within the Himalaya between approximately 50 and 25 Ma. Paleomagnetic data show that this extended continental and oceanic "Greater India" promontory resulted from 2,675 ± 700 km of North-South extension between 120 and 70 Ma, accommodated between the Tibetan Himalaya and cratonic India. We suggest that the approximately 50 Ma "India"-Asia collision was a collision of a Tibetan-Himalayan microcontinent with Asia, followed by subduction of the largely oceanic Greater India Basin along a subduction zone at the location of the Greater Himalaya. The "hard" India-Asia collision with thicker and contiguous Indian continental lithosphere occurred around 25-20 Ma. This hard collision is coincident with far-field deformation in central Asia and rapid exhumation of Greater Himalaya crystalline rocks, and may be linked to intensification of the Asian monsoon system. This two-stage collision between India and Asia is also reflected in the deep mantle remnants of subduction imaged with seismic tomography.
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Project description:The origin of Samoan volcanism in the southwest Pacific remains enigmatic. Whether mantle melting is solely caused by a mantle plume is questionable because some volcanism, here referred to as non-hotspot volcanism, defies the plume model and its linear age-progression trend. Indeed, non-hotspot volcanism occurred as far as 740?km west of the predicted Samoan hotspot after 5?Ma. Here we use fully-dynamic laboratory subduction models and a tectonic reconstruction to show that the nearby Tonga-Kermadec-Hikurangi (TKH) subduction zone induces a broad mantle upwelling around the northern slab edge that coincides with the non-hotspot volcanic activity after 5?Ma. Using published potential mantle temperatures for the ambient mantle and Samoan mantle plume, we find that two geodynamic processes can explain mantle melting responsible for intraplate volcanism in the Samoan region. We propose that before 5?Ma, the volcanism is consistent with the plume model, whereas afterwards non-hotspot volcanism resulted from interaction between the Subduction-Induced Mantle Upwelling (SIMU) and Samoan mantle plume material that propagated west from the hotspot due to the toroidal component of slab rollback-induced mantle flow. In this geodynamic scenario, the SIMU drives decompression melting in the westward-swept plume material, thus producing the non-hotpot volcanism.
| S-EPMC6041271 | biostudies-literature
Project description:How and when India collided with Asia is crucial for global climate and continental dynamics. We present new palaeomagnetic data showing that the Xigaze forearc basin of southern Tibet was located at 24.2 ± 5.9°N during 54-57 Ma, providing a direct constraint on the position of the southernmost margin of Asia at this crucial stage. Our study suggests 1) the age and locus of the initial India-Asia collision are at ~50 Ma and ~24°N, respectively; 2) Tibet resisted India's northward push during the first ~16 Ma of initial impact from the collision and experienced little latitudinal displacement; and 3) Sometime a little after 34 Ma, Greater India was consumed and thicker Indian Craton subsequently made contact with Asia, resulting in ~6° northward drift of Asia. Our model has implications for the process by which the high proto-Tibetan plateau formed and for the two slowdowns of India's convergence rate with Asia.
| S-EPMC3514643 | biostudies-literature
Project description:How the continental lithosphere deforms far away from plate boundaries has been long debated. The Tianshan is a type-example of ongoing lithospheric deformation in an intracontinental setting. It formed during the Paleozoic accretion of the Altaids and was rejuvenated in the Cenozoic, which might be a far-field response to the India-Asia collision. Here we present seismic images of the lithosphere across the central Tianshan, which were constructed from receiver functions and Rayleigh wave dispersions along a N-S-trending linear seismic array. We observe an extensively deformed lithosphere in the Tianshan with inherited, structurally controlled brittle deformation in the shallow crust and plastic deformation near the Moho. We find that earlier multiple accretionary structures were preserved in the crust, which was deformed by pure-shear shortening in the south and thick-skinned tectonics in the north but was limitedly underthrusted by surrounding blocks. A balanced cross-section of Moho discontinuities supports the concept that intracontinental deformation in the Tianshan intensified synchronously with the direct contact between the underthrusting Indian slab and the Tarim Craton in the Late Miocene (~10 Ma). These findings provide a robust and unified seismic model for the Tianshan Orogen, and confirm that effective delivery of the India-Asia collision stress induced the rejuvenation of this intracontinental orogen.
| S-EPMC9243081 | biostudies-literature
Project description:Several unusual strong earthquakes occurred in central India along the Narmada-Son Lineament (NSL) zone, far from active plate boundaries. To understand the role of collisional processes in the origin of this seismicity, we develop a numerical thermomechanical model of shortening between the Indian Plate and Asia. We show that at the final stage of collision, the shortening rate of the high mountain areas slows. The continuing convergence of India and Asia triggers the initiation of a new collision zone in continental part of India. Various geological and geophysical observations indicate that the NSL is a weakest zone with northward thrusting of the thinner central Indian lithosphere underneath the thicker northern part of the Indian Plate. We hypothesize that the NSL was reactivated during the final stage of the India Asia convergence and it will possibly form a new mountain belt within the Indian continent.
| S-EPMC6048038 | biostudies-literature
Project description:Deep Earth degassing is a critical forcing factor for atmospheric CO2 variations and palaeoclimate changes in Earth's history. For the Cenozoic, the key driving mechanism of atmospheric CO2 variations remains controversial. Here we analyse three stages of collision-related magmatism in Tibet, which correspond temporally with the three major stages of atmospheric CO2 variations in the Cenozoic and explore the possibility of a causal link between these phenomena. To this end we present geochemical data for the three stages of magmatic rocks in Tibet, which we use to inform a model calculating the continental collision-induced CO2 emission flux associated with the evolving Neo-Tethyan to continental subduction over the Cenozoic. The correlation between our modelled CO2 emission rates and the global atmospheric CO2 curve is consistent with the hypothesis that the India-Asia collision was the primary driver of changes in atmospheric CO2 over the Cenozoic.
| S-EPMC8222363 | biostudies-literature
Project description:To better understand the Neotethyan paleogeography, a paleomagnetic and geochronological study has been performed on the Early Cretaceous Sangxiu Formation lava flows, which were dated from ~135.1 Ma to ~124.4 Ma, in the Tethyan Himalaya. The tilt-corrected site-mean characteristic remanent magnetization (ChRM) direction for 26 sites is Ds = 296.1°, Is = -65.7°, ks = 51.7, α95 = 4.0°, corresponding to a paleopole at 5.9°S, 308.0°E with A95 = 6.1°. Positive fold and reversal tests prove that the ChRM directions are prefolding primary magnetizations. These results, together with reliable Cretaceous-Paleocene paleomagnetic data observed from the Tethyan Himalaya and the Lhasa terrane, as well as the paleolatitude evolution indicated by the apparent polar wander paths (APWPs) of India, reveal that the Tethyan Himalaya was a part of Greater India during the Early Cretaceous (135.1-124.4 Ma) when the Neotethyan Ocean was up to ~6900 km, it rifted from India sometime after ~130 Ma, and that the India-Asia collision should be a dual-collision process including the first Tethyan Himalaya-Lhasa terrane collision at ~54.9 Ma and the final India-Tethyan Himalaya collision at ~36.7 Ma.
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Project description:During the Cretaceous, the Indian plate moved towards Eurasia at the fastest rates ever recorded. The details of this journey are preserved in the Indian Ocean seafloor, which document two distinct pulses of fast motion, separated by a noticeable slowdown. The nature of this rapid acceleration, followed by a rapid slowdown and then succeeded by a second speedup, is puzzling to explain. Using an extensive observation dataset and numerical models of subduction, we show that the arrival of the Reunion mantle plume started a sequence of events that can explain this history of plate motion. The forces applied by the plume initiate an intra-oceanic subduction zone, which eventually adds enough additional force to drive the plates at the anomalously fast speeds. The two-stage closure of a double subduction system, including accretion of an island arc at 50 million years ago, may help reconcile geological evidence for a protracted India-Eurasia collision.
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