scholarly journals Supplemental Material: Subduction erosion and crustal material recycling indicated by adakites in central Tibet

2021 ◽  
Author(s):  
Zong-Yong Yang ◽  
QIANG WANG ◽  
et al.
Keyword(s):  
Analytical Methods ◽  
Crustal Material ◽  
Material Recycling ◽  
Subduction Erosion ◽  
Central Tibet

Supplemental figures, analytical methods and results, and data and results tables.<br>

scholarly journals Supplemental Material: Subduction erosion and crustal material recycling indicated by adakites in central Tibet

2021 ◽  
Author(s):  
Zong-Yong Yang ◽  
QIANG WANG ◽  
et al.
Keyword(s):  
Analytical Methods ◽  
Crustal Material ◽  
Material Recycling ◽  
Subduction Erosion ◽  
Central Tibet

Supplemental figures, analytical methods and results, and data and results tables.<br>

scholarly journals Supplemental Material: Crustal material recycling induced by subduction erosion and subduction-channel exhumation: A case study of central Tibet (western China) based on P-T-t paths of the eclogite-bearing Baqing metamorphic complex

2020 ◽  
Author(s):  
Xin Jin ◽  
Yu-Xiu Zhang ◽  
Kai-Jun Zhang ◽  
et al.
Keyword(s):  
Western China ◽  
Metamorphic Rocks ◽  
Crustal Material ◽  
Metamorphic Complex ◽  
Subduction Channel ◽  
Material Recycling ◽  
Subduction Erosion ◽  
Mineral Compositions ◽  
Central Tibet

Compositional mapping images of one garnet, Triassic paleo-geographic facies of Qiangtang, summarized published Paleozoic and Proterozoic ages in Tibetan Plateau and Himalaya, mineral compositions, and chronology data of the Baqing metamorphic rocks.

Subduction erosion and crustal material recycling indicated by adakites in central Tibet

Geology ◽  
2021 ◽  
Author(s):  
Zong-Yong Yang ◽  
Qiang Wang ◽  
Lu-Lu Hao ◽  
Derek A. Wyman ◽  
Lin Ma ◽  
...  
Keyword(s):  
Crustal Material ◽  
Convergent Margins ◽  
Nd Isotopes ◽  
Magmatic Arc ◽  
Material Recycling ◽  
Intrusive Rocks ◽  
Subducted Oceanic Crust ◽  
Subduction Erosion ◽  
Central Tibet ◽  
Qiangtang Terrane

Subduction erosion is important for crustal material recycling and is widespread in modern active convergent margins. However, such a process is rarely identified in fossil convergent systems, which casts doubt on the importance of subduction erosion through the geological record. We report on ca. 155 Ma Kangqiong (pluton) intrusive rocks of a Mesozoic magmatic arc in the southern Qiangtang terrane, central Tibet. These rocks mainly consist of trondhjemites and tonalites and are similar to slab-derived adakites with mantle-like zircon oxygen isotope compositions (δ18O = 5.2‰–5.6‰), they display more evolved Sr-Nd isotopes and higher Th/La relative to mid-oceanic ridge basalts from the Bangong-Nujiang suture, and they contain abundant amphibole and biotite. These characteristics indicate magma generation via H2O-fluxed melting of eroded forearc crust debris with subducted oceanic crust at 1.5–2.5 GPa and 700–800 °C. In addition, the intrusions are exposed &lt;20 km north of the Bangong-Nujiang suture. Given the formation of adakites, narrow arc-suture distance, migration of the Jurassic frontal arc toward the continent interior, and other independent geological archives, we suggest that the hydrated forearc crust materials were removed from the overlying plate and carried into the mantle by subduction erosion. Our study provides the first direct magmatic evidence for a subduction erosion process in pre-Cenozoic convergent systems, which confirms an important role for such processes in subduction-zone material recycling.

scholarly journals Supplemental Material: Crustal material recycling induced by subduction erosion and subduction-channel exhumation: A case study of central Tibet (western China) based on P-T-t paths of the eclogite-bearing Baqing metamorphic complex

2020 ◽  
Author(s):  
Xin Jin ◽  
Yu-Xiu Zhang ◽  
Kai-Jun Zhang ◽  
et al.
Keyword(s):  
Western China ◽  
Metamorphic Rocks ◽  
Crustal Material ◽  
Metamorphic Complex ◽  
Subduction Channel ◽  
Material Recycling ◽  
Subduction Erosion ◽  
Mineral Compositions ◽  
Central Tibet

Compositional mapping images of one garnet, Triassic paleo-geographic facies of Qiangtang, summarized published Paleozoic and Proterozoic ages in Tibetan Plateau and Himalaya, mineral compositions, and chronology data of the Baqing metamorphic rocks.

Crustal material recycling induced by subduction erosion and subduction-channel exhumation: A case study of central Tibet (western China) based on P-T-t paths of the eclogite-bearing Baqing metamorphic complex

2020 ◽  
Author(s):  
Xin Jin ◽  
Yu-Xiu Zhang ◽  
Donna L. Whitney ◽  
Kai-Jun Zhang ◽  
Natalie H. Raia ◽  
...  
Keyword(s):  
Mantle Wedge ◽  
Crustal Material ◽  
Metamorphic Complex ◽  
The South ◽  
Subduction Channel ◽  
Crustal Recycling ◽  
The North ◽  
Subduction Erosion ◽  
Proterozoic Basement ◽  
Central Tibet

Subduction and exhumation processes, interacting with each other, play a key role in crustal recycling. Downgoing oceanic lithosphere constitutes the dominant input at subduction margins, but subduction erosion, the removal of crustal material from the overriding plate, may add additional ingredients and complexity to the subduction factory. Different exhumation models have been proposed to explain how subducted materials are exhumed and therefore contribute to crustal recycling, e.g., exhumation up the subduction channel versus diapiric rise through the mantle wedge that overlies the subducted plate. The recently discovered Baqing eclogite-bearing high-pressure metamorphic complex, central Tibet, China, provides an excellent opportunity to decode the exhumation process, the origin of subduction-related magmatism, and the crustal structure of the North Qiangtang block, in addition to elucidating processes of crustal recycling. Pressure-temperature-time (P-T-t) paths and zircon U-Pb ages and trace-element compositions for Baqing high-pressure rocks were used to evaluate exhumation processes and to determine the geochemical and tectonic affinity of the Baqing metamorphic complex. The Baqing metamorphic complex is mainly composed of eclogite, gneiss, and schist. It is located between two geologically distinct terranes—the South Qiangtang block, which has early Paleozoic basement, and the North Qiangtang block, which has Proterozoic basement. In the schist, zircon cores with steep heavy rare earth element (HREE) slopes and oscillatory zoning yielded inherited ages that are similar to detrital zircon ages for the South Qiangtang block schist; in contrast, zircon rims with flat HREE slopes yielded metamorphic ages of 224 Ma that are similar to the metamorphic ages obtained for the Baqing eclogite. In contrast, zircons from the gneiss yielded an upper-intercept age of 1033 ± 32 Ma (interpreted as the crystallization age) and a lower-intercept metamorphic age of 198 ± 4 Ma. Field relations indicate that gneiss and eclogite/amphibolite were exhumed together, so the ∼20 m.y. gap between the gneiss and the metabasite metamorphism may indicate a long exhumation duration. In the region, Proterozoic ages of ca. 1000 Ma are known only from the North Qiangtang block; we thus propose that the Baqing gneiss originated from North Qiangtang block Proterozoic basement, which, along with North Qiangtang block Triassic arc magmatic rocks and the discrepancies between ancient and current arc-trench distances, results in estimates of ∼20−170 km of Triassic subduction erosion. Results of P-T analyses show that most eclogite, amphibolite, and schist shared a similar clockwise P-T path, different from that of the gneiss, which records a higher geothermal gradient. The clockwise P-T trajectory, long exhumation duration, lack of significant heating during exhumation, and the South Qiangtang block affinity of the schist (host rock of the Baqing eclogite) are consistent with subduction-channel exhumation rather than diapiric rise through the mantle wedge. Geochemical similarities between the North Qiangtang block Triassic subduction-related rocks and the Baqing gneiss may signal the involvement of unexhumed Baqing metamorphic complex in the recycling of the Qiangtang crust.

scholarly journals Supplemental Material: Cambrian magmatic flare-up, central Tibet: Magma mixing in proto-Tethyan arc along north Gondwanan margin

2021 ◽  
Author(s):  
Pei-yuan Hu ◽  
et al.
Keyword(s):  
Tibetan Plateau ◽  
Analytical Methods ◽  
Magma Mixing ◽  
Mixing Model ◽  
Lhasa Terrane ◽  
The North ◽  
Magmatic Rocks ◽  
Central Tibetan Plateau ◽  
Central Tibet

Data, magma mixing model, and analytical methods of the Cambrian magmatic rocks from the North Lhasa terrane, central Tibetan Plateau.

scholarly journals Supplemental Material: Passive-margin magmatism caused by enhanced slab-pull forces in central Tibet

2020 ◽  
Author(s):  
WEI DAN ◽  
et al.
Keyword(s):  
Analytical Methods ◽  
Passive Margin ◽  
Central Tibet

Analytical methods, Tables S1–S6 and Figures S1–S5.<br>

scholarly journals Supplemental Material: Passive-margin magmatism caused by enhanced slab-pull forces in central Tibet

2020 ◽  
Author(s):  
WEI DAN ◽  
et al.
Keyword(s):  
Analytical Methods ◽  
Passive Margin ◽  
Central Tibet

Analytical methods, Tables S1–S6 and Figures S1–S5.<br>

Subduction zone recycling processes and the rock record of crustal suture zonesThis article is one of a series of papers published in this Special Issue on the theme Lithoprobe — parameters, processes, and the evolution of a continent.

2010 ◽  
Vol 47 (5) ◽  
pp. 633-654 ◽  
Author(s):  
David W. Scholl ◽  
Roland von Huene
Keyword(s):  
Subduction Zones ◽  
Crustal Material ◽  
Basement Rock ◽  
Special Issue ◽  
Linear Rate ◽  
Tectonic Processes ◽  
Crustal Thinning ◽  
Rock Record ◽  
Seaward Edge ◽  
Subduction Erosion

Offshore observations at modern ocean-margin subduction zones (OMSZs) reveal that bodies of accreted material are commonly volumetrically small or missing, that crustal thinning and subsidence (3–5 km) has occurred, and that most trench axes lie close (5–30 km) to the seaward tapering edge of coastal basement rock. Onshore mapping commonly documents missing or only narrow terranes of former forearc rock and the inboard migration of the arc magmatic front. These observations are evidence that subduction is accompanied by the removal of sediment and crustal material from the submerged forearc by the kindred tectonic processes, respectively, of sediment subduction and subduction erosion. Subduction erosion truncates the margin (migrates the trench inboard) at ∼2.5 km/Ma. Onshore observations at ancient crust-suturing subduction zones (CSSZs) imply that collisional suturing is accompanied by sediment subduction and truncation of both upper and lower plates. During a protracted period of suturing (20–50 million years), a 100–200 km wide (or wider) band of the seaward edge of each plate can be removed subductively. Truncation of the upper plate is effected by subduction erosion, and that of the lower plate by the necking and break-off of its subducted edge. The average linear rate of crustal loss for each plate is estimated at ∼1.5 km/Ma, or ∼3 km/Ma combined. Because significant crustal loss occurs before and during tectonic fusing of colliding crustal blocks, structures and rock bodies that might be expected to record a former OMSZ and the formation of a CSSZ may be absent, unimpressively small, or preserved only as exhumed masses of once deeply subducted material.

Combining geophysical and petrological estimates of the thermal structure of southern Tibet

2020 ◽  
Author(s):  
Tim Craig ◽  
Peter Kelemen ◽  
Bradley Hacker ◽  
Alex Copley
Keyword(s):  
Middle Miocene ◽  
Thermal Structure ◽  
The Tibetan Plateau ◽  
Crustal Material ◽  
Recent Past ◽  
Southern Tibet ◽  
Indian Lithosphere ◽  
Earthquake Distribution ◽  
Central Tibet ◽  
Geochemical Constraints

&lt;p&gt;The thermal structure of the Tibetan plateau remains largely unknown. Numerous avenues, both geophysical and petrological, provide fragmentary pressure/temperature information, both at the present, and on the evolution of the thermal structure over the recent past. However, these individual constraints have proven hard to reconcile with each other. This study presents a series of models for the simple underthrusting of India beneath southern Tibet that are capable of matching all available constraints on its thermal structure, both at the present day and since the Miocene. Three consistent features to such models emerge: (i) present day geophysical observations require the presence of relatively cold underthrust Indian lithosphere beneath southern Tibet; (ii) geochemical constraints require the removal of Indian mantle from beneath southern Tibet at some point during the early Miocene, although the mechanism of this removal, and whether it includes the removal of any crustal material is not constrained by our models; and (iii) the combination of the southern extent of Miocene mantle-derived magmatism and the present-day geophysical structure and earthquake distribution of southern Tibet require that the time-averaged rate of underthrusting of India relative to central Tibet since the middle Miocene has been faster than it is at present.&lt;/p&gt;

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