Geochemical analysis of magmatic rocks from Shyok Suture Zone (SSZ) Trans-Himalaya, NW India: Insights for geodynamic evolution of the terrane

Lithos ◽  
2022 ◽  
pp. 106594
Author(s):  
S. Sivaprabha ◽  
Irfan M. Bhat ◽  
T. Ahmad ◽  
T. Tanaka ◽  
S. Balakrishnan ◽  
...  
Keyword(s):  
Suture Zone ◽  
Geochemical Analysis ◽  
Geodynamic Evolution ◽  
Magmatic Rocks

Slab break-off origin of 105 Ma A-type porphyritic granites in the Asa area of Tibet

2020 ◽  
Vol 157 (8) ◽  
pp. 1281-1298
Author(s):  
Hang Li ◽  
Ming Wang ◽  
Xiao-Wen Zeng ◽  
An-Bo Luo ◽  
Yun-Peng Yu ◽  
...  
Keyword(s):  
Oceanic Crust ◽  
Early Cretaceous ◽  
Lower Crust ◽  
Isotopic Analysis ◽  
Geochemical Analysis ◽  
Geodynamic Evolution ◽  
Southern Tibet ◽  
Magmatic Rocks ◽  
Oceanic Sediment ◽  
Slab Window

AbstractThe study of the petrogenesis of some magmatic rocks with special geochemical attributes provides effective information for us to explore the deep geodynamic background of their formation. A series of granitic porphyry dykes have been found in the mélange zone of the Asa region in southern Tibet, whose genesis may be closely related to the evolution of the Meso-Tethyan Ocean. Regional geodynamic evolution is investigated by whole-rock geochemical analysis, zircon U–Pb dating and Lu–Hf isotopic analysis of two porphyritic granites. The Asa porphyritic granites have high SiO2 (74.29–78.65 wt %) and alkalis (Na2O + K2O = 6.51–9.35 wt %) contents, and low Al2O3 (11.60–14.51 wt %), CaO (0.04–0.19 wt MgO (0.01–0.10 wt %) contents. They are enriched in Zr, Nb, Ce, Y and Hf and depleted in Ti, Ba, Sr and P, consistent with A-type granites. The samples are relatively rich in LREEs, with LREE/HREE ratios of 1.73–3.04. They display negative Eu anomalies (Eu/Eu* = 0.24–0.28) and obvious Ce anomalies in some samples. Zircon U–Pb analyses show that the porphyritic granites formed in late Early Cretaceous time, 107.4 to 105.5 Ma. Zircon εHf(t) values are in the range of 6.9 to 12.0. These data indicate that the porphyritic granites were sourced from interaction between mantle-derived and juvenile lower crust-derived melts, with the addition of oceanic sediment-derived melts. This occurred when the subducting Bangong–Nujiang oceanic crust split to create a slab window. Rising asthenosphere triggered re-melting of lower crust basalts, resulting in the formation of the late Early Cretaceous A-type granites around Asa.

scholarly journals Geochemical-isotopic characteristics and K-Ar ages of magmatic rocks from Hundar valley, Shyok Suture Zone, Ladakh

1970 ◽  
Vol 5 (7) ◽  
pp. 18
Author(s):  
T Ahmad ◽  
S Sivaprabha ◽  
S Balakrishnan ◽  
NX Thanh ◽  
T Itaya ◽  
...  
Keyword(s):  
Suture Zone ◽  
Special Issue ◽  
Magmatic Rocks

DOI = 10.3126/hjs.v5i7.1229 Himalayan Journal of Sciences Vol.5(7) (Special Issue) 2008 p.18

scholarly journals Geochronology and Geochemistry of the Magmatic Rocks from Zedong Ophiolite, Eastern Yarlung-Zangbo Suture Zone, Tibet

2017 ◽  
Vol 91 (s1) ◽  
pp. 45-45
Author(s):  
Fahui XIONG ◽  
Jingsui YANG ◽  
Paul T. ROBINSON ◽  
Jian GAO ◽  
Lan ZHANG ◽  
...  
Keyword(s):  
Suture Zone ◽  
Magmatic Rocks ◽  
Yarlung Zangbo Suture Zone

Closure of the Bangong–Nujiang Tethyan Ocean in the central Tibet: Results from the provenance of the Duoni Formation

2019 ◽  
Vol 89 (10) ◽  
pp. 1039-1054 ◽  
Author(s):  
Zhicai Zhu ◽  
Qingguo Zhai ◽  
Peiyuan Hu ◽  
Sunlin Chung ◽  
Yue Tang ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Late Cretaceous ◽  
Suture Zone ◽  
The Tibetan Plateau ◽  
Tectonic History ◽  
Magmatic Rocks ◽  
Two Samples ◽  
Delta Sequence ◽  
History Of ◽  
Central Tibet

ABSTRACT The closure of the Bangong–Nujiang Tethyan Ocean (BNTO) and consequent Lhasa–Qiangtang collision is vital to reasonably understanding the early tectonic history of the Tibetan Plateau before the India-Eurasia collision. The timing of the Lhasa–Qiangtang collision was mainly constrained by the ophiolite and magmatic rocks in previous studies, with only limited constraints from the sedimentary rocks within and adjacent to the Bangong–Nujiang suture zone. In the middle segment of the Bangong–Nujiang suture zone, the Duoni Formation, consisting of a fluvial delta sequence with minor andesite interlayers, was originally defined as the Late Cretaceous Jingzhushan Formation and interpreted as the products of the Lhasa–Qiangtang collision during the Late Cretaceous. Our new zircon U-Pb data from two samples of andesite interlayers demonstrate that it was deposited during the latest Early Cretaceous (ca. 113 Ma) rather than Late Cretaceous. Systemic studies on the sandstone detrital model, heavy-mineral assemblage, and clasts of conglomerate demonstrate a mixed source of both Lhasa and Qiangtang terranes and ophiolite complex. Clasts of conglomerate contain abundant angular peridotite, gabbro, basalt, chert, andesite, and granite, and minor quartzite and gneiss clasts also exist. Sandstones of the Duoni Formation are dominated by feldspathic–lithic graywacke (Qt25F14L61 and Qm13F14L73), indicative of a mixture of continental-arc and recycled-orogen source origin. Detrital minerals of chromite, clinopyroxene, epidote, and hornblende in sandstone also indicate an origin of ultramafic and mafic rocks, while garnets indicate a metamorphosed source. Paleocurrent data demonstrate bidirectional (southward and northward) source origins. Thus, we suggest that the deposition of the Duoni Formation took place in the processes of the Lhasa–Qiangtang collision during the latest Early Cretaceous (∼ 113 Ma), and the BNTO had been closed by this time.

scholarly journals Eclogites and other high-pressure rocks in the Himalaya: a review

2018 ◽  
Vol 483 (1) ◽  
pp. 183-213 ◽  
Author(s):  
Patrick J. O'Brien
Keyword(s):  
High Pressure ◽  
Granulite Facies ◽  
Suture Zone ◽  
Indian Plate ◽  
Accretionary Wedge ◽  
Nw Himalaya ◽  
Magmatic Rocks ◽  
Namche Barwa ◽  
Tso Morari ◽  
South Tibet

AbstractHimalayan high-pressure metamorphic rocks are restricted to three environments: the suture zone; close to the suture zone; and (mostly) far (>100 km) from the suture zone. In the NW Himalaya and South Tibet, Cretaceous-age blueschists (glaucophane-, lawsonite- or carpholite-bearing schists) formed in the accretionary wedge of the subducting Neo-Tethys. Microdiamond and associated phases from suture-zone ophiolites (Luobusa and Nidar) are, however, unrelated to Himalayan subduction–collision processes. Deeply subducted and rapidly exhumed Indian Plate basement and cover rocks directly adjacent to the suture zone enclose eclogites of Eocene age, some coesite-bearing (Kaghan/Neelum and Tso Morari), formed from Permian Panjal Trap, continental-type, basaltic magmatic rocks. Eclogites with a granulite-facies overprint, yielding Oligocene–Miocene ages, occur in the anatectic cordierite ± sillimanite-grade Indian Plate mostly significantly south of the suture zone (Kharta/Ama Drime/Arun, north Sikkim and NW Bhutan) but also directly at the suture zone at Namche Barwa. The sequence carpholite-, coesite-, kyanite- and cordierite-bearing rocks of these different units demonstrates the transition from oceanic subduction to continental collision via continental subduction. The granulitized eclogites in anatectic gneisses preserve evidence of former thick crust as in other wide hot orogens, such as the European Variscides.

scholarly journals PALAEONTOLOGICAL (RADIOLARIAN) LATE JURASSIC AGE CONSTRAINT FOR THE STEPANAVAN OPHIOLITE (LESSER CAUCASUS, ARMENIA)

2018 ◽  
Vol 40 (1) ◽  
pp. 31 ◽  
Author(s):  
T. Danelian ◽  
G. Galoyan ◽  
Y. Rolland ◽  
M. Sosson
Keyword(s):  
Oceanic Crust ◽  
Late Jurassic ◽  
Sedimentary Cover ◽  
Suture Zone ◽  
The South ◽  
Geodynamic Evolution ◽  
Oceanic Ridge ◽  
Slow Spreading ◽  
Lesser Caucasus ◽  
First Time

Micropalaeontological age evidence for the sedimentary cover of ophiolites is important to understand the palaeogeographic and geodynamic evolution of Tethyan realms. The Stepanavan ophiolitic suite of Northern Armenia consists of peridotites, gabbros, plagiogranite and lavas with a radiolarite sedimentary cover. It is regarded as the northern extension of the Sevan Akera ophiolitic zone and may be considered as the eastern extension of the Izmir-Ankara suture zone. It represents the relics of a slow-spreading mid oceanic ridge that was active between Eurasia and the South-Armenian Block of Gondwanian origin. Radiolaria extracted from radiolarites of the Stepanavan ophiolite provide for the first time a Late Jurassic (late Kimmeridgian to early Tithonian) age constraint for this part of Tethyan oceanic crust preserved in Lesser Caucasus.

High-temperature acid magmatic rocks from the Late Cretaceous suture zone between European plate and Adria microplate (Croatia)

2020 ◽  
Author(s):  
Petra Schneider ◽  
Dražen Balen
Keyword(s):  
High Temperature ◽  
Late Cretaceous ◽  
Suture Zone ◽  
Age Dating ◽  
Magma Source ◽  
Northwestern Part ◽  
Magmatic Complex ◽  
Magmatic Rocks ◽  
The Village ◽  
European Plate

<p>The Late Cretaceous magmatic rocks within the southwestern part of the Pannonian Basin basement (Croatia) occur in two areas: Voćin volcanic mass (VVM) at the northwestern part of Mt. Papuk (near town of Voćin, covering the area of ~10km<sup>2</sup>) and volcanic mass of Mt. Požeška Gora (PVM, area of ~30 km<sup>2</sup>). Both volcanic masses consist of basalts and rhyolites, and in lesser extent of pyroclastic material. Granite can be found it the PVM. Interconnection of this two masses and Late Cretaceous ages have been proposed based on the petrography and mineralogical features of previously studied samples and rather arguable data: K-Ar dating on basalts from VVM (~73−52 Ma) and Rb-Sr isochron age on granite and rhyolite from PVM (~72 Ma). The age has been recently refined with the zircon LA-ICP-MS age dating (~82 Ma), but the magma source of this bimodal formation, geotectonic position, setting and its regional importance still have not been explained in detail.</p><p>In order to conduct preliminary research, two localities with acid effusive rocks were sampled from the VVM (Rupnica geosite and Trešnjevica quarry), and three more from PVM (near the village of Vesela, Pakao Creek and the granite from quarry near the village of Gradski Vrhovci).</p><p>Acid rocks are characterized by a highly siliceous composition (up to 75 wt.% SiO<sub>2</sub>), enrichment in alkalies (high-K calc-alkaline towards to shoshonite series) and aluminium (peraluminous affinity), followed by high FeO<sub>T</sub>/(FeO<sub>T</sub>+MgO) ratios matching ferroan magmas. They classify as rhyolites or alkali-rhyolites/granite. Microelements including REE show that studied rocks have characteristics of A<sub>2</sub>-type of post-collisional/post-orogenic acid rocks, most common A-type of rocks formed during rifting caused by extension and thinning of continental crust. According to geotectonic classification diagrams, rocks from PVM show geochemical signature of volcanic arc, while VVM shows signature of within plate environment.</p><p>External zircon morphology seems to be uniform with prevailing J3−J5-type for rhyolites and D-type for granite and with average ratio of 2.2:1. Those types are characteristic for the high-temperature magmas (confirmed with the calculated Zr-saturation temperature of 850−930°C) originating from the lower crust or even upper mantle. Inclusions of hematite, F-apatite and anatase have been detected with Raman spectrometry in zircon from all samples, with the most significant findings of kumdykolite and kokchetavite inclusions detected in samples from Vesela and Gradski Vrhovci. Latter inclusions are metastable phases crystallized from enclosed melt and are indicators of a rapid cooling of the host magma.</p><p>According to the results presented here, acid rocks show rather uniform geochemistry, which speaks in favor of the early ideas of the unique magmatic complex, although today at the surface they are separated by ~35 km in distance. Those rocks show potential to be of great regional importance bearing new information about the evolution in the Late Cretaceous in the area of Sava Zone, a suture zone between Tisia Mega-Unit (European plate) and Adria microplate, which spatially and temporally marks the closure of the Neotethys Ocean.</p><p>Support by the Croatian Science Foundation (IP-2014-09-9541) is acknowledged.</p>

Sign in / Sign up

Export Citation Format

Share Document