Subduction of the Indian lower crust beneath southern Tibet revealed by the post-collisional potassic and ultrapotassic rocks in SW Tibet

Tian, Senlin; Yang, Zhen; Hou, Zhenshan; Mo, Xuanxue; Hu, Wenjie; Zhao, Yue; Zhao, Xi

doi:10.1016/j.gr.2015.09.005

Cited by 68 publications

(50 citation statements)

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“…This was also accompanied by a period of slightly accelerated Indian convergence (Figure ). Later slow to minimal early Miocene cooling was probably associated with the proposed decrease in subduction angle of the Indian slab following its breakoff as recorded by contemporary ultrapotassic magmatism in southern Lhasa [ Tian et al , ] (Figure ). This cooling pattern coincides with a slightly decrease in the India‐Asia convergence at that time (~25–15 Ma) [ van Hinsbergen et al , ].…”

Section: Discussionmentioning

confidence: 99%

“…The grey bars mark the timing of onset of cooling episodes. (b) Relative India‐Asia convergent velocities of Eastern/Western Himalayan Syntaxis (E/WHS) from ~120 Ma to present [ van Hinsbergen et al , ] showing timing of the Morondova and Deccan LIPs, Initial India‐Asia collision [ DeCelles et al , ; Hu et al , ], Neo‐Tethys slab breakoff [ Ji et al , ], Indian slab tearing [ Zhang et al , ], and Indian slab breakoff reflected by ultrapotassic magmatism of the southern Lhasa terrane [ Tian et al , ]; LIP = Large Igneous Province.…”

Section: Thermal History Modelingmentioning

confidence: 98%

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India‐Asia convergence: Insights from burial and exhumation of the Xigaze fore‐arc basin, south Tibet

Kohn

Sandiford

et al. 2017

JGR Solid Earth

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The composite fore‐arc/syncollisional Xigaze basin in south Tibet preserves a key record of India‐Asia collision. New apatite fission track and zircon (U‐Th)/He data from an N‐S transect across the preserved fore‐arc basin sequence near Xigaze show a consistent northward Late Cretaceous to middle Miocene younging trend, while coexisting apatite (U‐Th‐Sm)/He ages are all Miocene. Corresponding detrital zircon U‐Pb data are also reported for constraining the Cretaceous depositional ages of the Xigaze basin sequence in the region. Thermal history modeling indicates that the basin experienced northward propagating episodic exhumation, along with a northward migration of the depocenter and a pre‐existing Cenozoic syncollisional basin sequence which had been removed. In the southern part, fore‐arc exhumation commenced in the Late Cretaceous (~89 ± 2 Ma). Following transition to a syncollisional basin in the Paleocene, sedimentation in the central and northern Xigaze basin continued until the latest Eocene (~34 ± 4 Ma). Ongoing folding and thrusting (e.g., Great Counter Thrusts) caused by progressive plate convergence during late Oligocene‐early Miocene time resulted in regional uplift and considerable basin denudation, which fed two fluvial basins along its northern and southern flanks and exposed the basement ophiolite. Subsequent incision of the Yarlung River resulted in Miocene cooling in the region. Different episodes in the exhumation history of the Xigaze basin, caused by thrusting of an accretionary wedge and ophiolitic basement, can be linked to changes in India‐Asia convergence rates and the changing subduction pattern of the Indian and Neo‐Tethyan slabs.

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Section: Discussionmentioning

confidence: 99%

Section: Thermal History Modelingmentioning

confidence: 98%

India‐Asia convergence: Insights from burial and exhumation of the Xigaze fore‐arc basin, south Tibet

Kohn

Sandiford

et al. 2017

JGR Solid Earth

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“…The quartz monzonite porphyry samples are characterized by high SiO 2 (72.48–75.32 wt.%) and Al 2 O 3 (14.13–14.60 wt.%) contents and high K 2 O/Na 2 O (3.37–4.83) ratios, which are comparable with the postcollisional potassic rocks in South Tibet (Liu et al, , ; Zhang et al, ; Tian et al, ). In addition, they have different geochemical characteristics (e.g., low MgO [0.25–0.36 wt.%], Fe 2 O 3 [1.12–1.81 wt.%], Cr [1.55–4.75 ppm], and Ni [1.16–3 ppm]) from those of Miocene mantle‐derived ultrapotassic rocks in the Lhasa terrane (Miller et al, ; Ding et al, ; Zhao et al, ; Guo et al, ; Liu et al, ; Liu et al, ), and are also different from the Miocene adakitic rocks in South Tibet which show obvious geochemical characteristics of low Sr (32–98 ppm) and Sr/Y ratios (6–9) and relatively high Y (6.14–16.2 ppm) and Yb (0.7–1.33 ppm; Chen et al, ; Chung et al, ; Guo et al, ; Hou et al, ; Li et al, ; Li et al, ; Xu et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…So far, several models have been proposed to interpret the origin of Miocene postcollisional potassic rocks. These include (a) partial melting of the heterogeneous subcontinental lithospheric mantle (SCLM) metasomatized by fluids derived from dehydration of the subducted Indian lower crust (Ding et al, ; Miller et al, ; Tian et al, ), (b) partial melting of a mafic lower‐crustal source (Chen et al, ), (c) partial melting of the overthickened and isotopically heterogeneous Lhasa terrane crust (Liu et al, , ), and (d) partial melting of mélanges associated with the subducted Indian continent crust and mantle wedge materials in a continental subduction channel (Zhang, Guo, Zhang, Cheng, & Sun, ). Similarly, several models have been proposed for the formation mechanism of Miocene postcollisional adakitic rocks.…”

Section: Introductionmentioning

confidence: 99%

Miocene potassic and adakitic intrusions in eastern central Lhasa terrane, Tibet: Implications for origin and tectonic of postcollisional magmatism

Zhi

Cao

et al. 2019

Geological Journal

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Miocene postcollisional potassic and adakitic rocks are widely distributed in the southern Lhasa terrane and western central Lhasa terrane. However, coeval potassic and adakitic rocks in eastern central Lhasa terrane were rarely recognized, and their origins and formation mechanism remain controversial. In this paper, we provide new geochronological and geochemical data for the Miocene postcollisional potassic and adakitic intrusions exposed in the Qingdu area, eastern central Lhasa terrane, southern Tibet. The Qingdu Miocene intrusions consist of quartz monzonite porphyry and biotite granite with coeval zircon U–Pb ages of 14.1 Ma and 14.0 Ma, respectively. They have high SiO2 (67.98–75.32 wt.%), Al2O3 (14.13–14.78 wt.%), and K2O (4.06–6.18 wt.%) and low MgO (0.25–1.46 wt.%) contents. They are both enriched in light rare earth elements (LREEs) and depleted in heavy rare earth elements (HREEs), with high (La/Yb)N (25.37–42.32) ratios. The biotite granite samples have low Y (7.10–9.96 ppm) and Yb (0.61–0.85 ppm) contents, and high Sr (229–384 ppm) contents and high Sr/Y (30–41) ratios, which show adakitic geochemical characteristics, whereas the quartz monzonite porphyry samples show potassic geochemical characteristics. They display initial (87Sr/86Sr)i ratios of 0.7083–0.7103, εHf(t) values of −6.7 to −0.1, εNd(t) values of −8.96 to −7.44, (208Pb/204Pb)i ratios of 39.028–39.110, (207Pb/204Pb)i ratios of 15.662–15.684, and (206Pb/204Pb)i ratios of 18.541–18.577. These signatures indicate that both the potassic and adakitic intrusions are more likely to originate from partial melting of a thickened lower crust, which were mainly the products of the binary mixing between the juvenile and ancient crust components. Based on the spatial distributions and isotopic features of the postcollisional potassic and adakitic rocks in the Lhasa terrane, we suggest that the differences of the lower crustal composition played a crucial role in causing the geochemical variations of the Miocene postcollisional adakitic and potassic rocks in Lhasa terrane.

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“…The Alpine–Himalayan belt is one of the largest continuous orogenic belts in the world and represents a classic continental collision with suture zones and microcontinental blocks. It extends from the eastern Mediterranean to the Himalayas and formed as a consequence of closure of the Neo‐Tethyan Ocean (Ricou, ; Rolland, Billo, Corsini, Sosson, & Galoyan, ; Stampfli & Borel, ; Tian et al, ; Trifonov, Ivanova, & Bachmanov, ). The Zagros Orogen is in the central part of the Alpine–Himalayan orogenic belt and formed as a result of the collision between the African–Arabian continent and the Iranian microcontinent in Late Cretaceous to Cenozoic times (Agard, Omrani, Jolivet, & Mouthereau, ; Agard et al, ; Alavi, , ; Berberian & King, ; Hafkenscheid, Wortel, & Spakman, ).…”

Section: Introductionmentioning

confidence: 99%

Geochemistry and apatite U–Pb geochronology of alkaline gabbros from the Nodoushan plutonic complex, Sanandaj–Sirjan Zone, Central Iran: Evidence for Early Palaeozoic rifting of northern Gondwana

et al. 2018

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The Zagros Orogen formed during the Cenozoic collision of Arabia with Eurasia and resulted in the closure of the Neo‐Tethys Ocean. Collision was preceded by a complicated tectonic history involving Pan‐African orogenesis, Late Palaeozoic rifting and the formation of Neo‐Tethys, and subsequent Mesozoic convergence on the northern margin of the ocean contemporaneous with ophiolite obduction on its southern margin. The Sanandaj–Sirjan Zone (SaSZ) is a metamorphic belt within the Zagros Orogen of Gondwanan provenance. U–Pb zircon geochronology has revealed the presence of Pan‐African igneous and metamorphic basement complexes, in addition to minor late Palaeozoic plutons and abundant Jurassic plutonic rocks. This study presents a LA‐ICP‐MS U–Pb apatite age of 440.7 ± 3.7 Ma from a gabbroic body on the central north‐eastern margin of the SaSZ (Nodoushan region). Based on petrography and geochemistry, en route fractional crystallization of ascending magma was an important process in the evolution of the intrusive rocks. Geochemical characteristics imply that the south‐west Nodoushan alkaline gabbroic magma was originated from the asthenospheric mantle source, whereas the high ratios of (La/Yb)N and (Dy/Yb)N are related to the low degree of partial melting from the garnet‐bearing mantle source. Enrichment pattern of Nb, Ta, and Ti and depletion of Rb, Th, and Y are similar to the OIB pattern and intraplate alkaline magmatic rocks. High εNd(t) values (+1.29 to +1.50), low initial Sr isotopic ratios (0.703679–0.704098), and trace element ratios (e.g., Nb/La, Ce/Pb, Ba/Nb, and Th/Nb) indicate that crustal contamination was insignificant in its petrogenesis. The petrogenesis of the Nodoushan alkaline gabbroic rocks could be related to the presence of extensional phase, upwelling and decompressional melting of asthenospheric mantle in the rift basin which was associated with the opening of the Paleo‐Tethys Ocean in Late Ordovician to Silurian times.

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Subduction of the Indian lower crust beneath southern Tibet revealed by the post-collisional potassic and ultrapotassic rocks in SW Tibet

Cited by 68 publications

References 130 publications

India‐Asia convergence: Insights from burial and exhumation of the Xigaze fore‐arc basin, south Tibet

India‐Asia convergence: Insights from burial and exhumation of the Xigaze fore‐arc basin, south Tibet

Miocene potassic and adakitic intrusions in eastern central Lhasa terrane, Tibet: Implications for origin and tectonic of postcollisional magmatism

Geochemistry and apatite U–Pb geochronology of alkaline gabbros from the Nodoushan plutonic complex, Sanandaj–Sirjan Zone, Central Iran: Evidence for Early Palaeozoic rifting of northern Gondwana

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