Paleomagnetic result of the Cenozoic volcanic rocks from the Tuoyun Basin, southwest Tien Shan of China and its tectonic implications

2004 ◽  
Vol 49 (12) ◽  
pp. 1288 ◽  
Author(s):  
Yongcheng WANG
Keyword(s):  
Volcanic Rocks ◽  
Tien Shan ◽  
Tectonic Implications ◽  
Paleomagnetic Result ◽  
Tuoyun Basin

U-depleted versus U-enriched signatures in complementary crust-mantle sources of volcanic rocks from Asia

2021 ◽  
Author(s):  
Sergei Rasskazov ◽  
Irina Chuvashova ◽  
Tatiana Yasnygina ◽  
Elena Saranina
Keyword(s):  
Lower Mantle ◽  
Partition Coefficients ◽  
Volcanic Rocks ◽  
Anomalous Behavior ◽  
Water Soluble ◽  
Tien Shan ◽  
Mantle Sources ◽  
Continental Lower Crust ◽  
Morb Source ◽  
Transitional Processes

<p>The Nb/U~47 and Th/U~4 ratios are considered as indicative for the OIB source referred by some authors to lower mantle plumes that in fact have no specific geochemical signatures but HIMU component. The Th/U ratio may vary because of the different garnet–melt and/or clinopyroxene–melt partition coefficients of U and Th. Anomalously high or low Th/U values in rocks can also be related to the input or removal of U, the migration of which is controlled by its mobility under oxidizing conditions owing to the formation of water-soluble uranyl  compounds with hexavalent U. These variations definitely distinguish non-plume magmatic sources. The Th/U ratio decreases to 2.5 in the MORB source and increases to 6 in the continental lower crust one. We describe anomalous behavior of uranium in sources of Cenozoic basalts and basaltic andesites from Primorye, Lesser Khingan, Tunka Valley, as well as similar Cretaceous-Paleogene rocks from Tien Shan. Significant deviations of the Th/U and Nb/U ratios from the OIB values are characteristics mostly of garnet-free sources. The U-depleted and U-enriched signatures are used as sensitive indicators for deciphering crust–mantle transitional processes.</p><p>This work is supported by the RSF grant 18-77-10027.</p>

scholarly journals Lower Moscovian limestones of the Bogdashan Range (NW China) as an indicator of cessation of arc magmatism in the Junggar region

2019 ◽  
Vol 27 (1) ◽  
pp. 57-78
Author(s):  
D. V. Alexeiev ◽  
Yu. S. Biske ◽  
A. V. Djenchuraeva ◽  
B. Wang ◽  
O. L. Kossovaya ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Foreland Basin ◽  
Northwest China ◽  
Island Arc ◽  
Tien Shan ◽  
Lower Permian ◽  
Carbonate Sediments ◽  
Tropical Zone ◽  
Middle Carboniferous ◽  
Marine Facies

The field revision of the Carboniferous and Lower Permian stratigraphy of the northern Bogdashan (South Junggar, Northwest China) shows that the Lower to Middle Carboniferous island arc volcanic rocks, widely developed in this region, are overlapped everywhere by carbonate and terrigenous-carbonate sediments, containing occasional lava flows and overlain up the section by thick terrigenous series practically devoid of volcanic rocks. The deposition of limestone occurred at the stage of dying off of a volcanic arc, and the question of their age is of fundamental importance for dating this event. Carbonates are represented by facies of lagoons, shoals, and bioherms that formed on the leveled surface of the arc and on the slopes of the last active volcanoes. Bioherms are Waulsortian mounds and are mainly composed of algal limestones and carbonate mud. There are no framestones composed of corals and sponges (chaetetids) typical of the tropical zone. The facies of shallow crinoid-fusulinid limestones typical of the adjacent territories of the Southern Tien Shan and Tarim are poorly represented. Paleogeographically, the position of bioherms corresponds to the northern boundary of the realm of Pennsylvanian reefs. On the basis of foraminifers, brachiopods, and corals, the age of carbonates is early Moscovian (ca. 315–310 Ma). Cessation of island-arc volcanism, followed by the accumulation of limestone in Bogdashan, occurred sub-synchronously with formation of the West Junggar (Bayingou) suture and may reflect docking of the Bogdashan arc to the Yili active margin of the Kazakhstan continent. Further subsidence of Bogdashan and adjacent regions of the Junggar and Turfan basins, which was somewhat slower at the end of the Carboniferous and more intense in the Early and Middle Permian, may reflect the development of the foreland basin that formed along the northern flank of the Tien Shan orogen. Marine facies were locally preserved in this basin until the Artinskian (ca. 285 Ma), and later the Junggar and Turfan basins lost connection to the ocean and developed in continental environments.

scholarly journals Rate of Slip From Multiple Quaternary Dating Methods and Paleoseismic Investigations Along the Talas‐Fergana Fault: Tectonic Implications for the Tien Shan Range

Tectonics ◽  
2019 ◽  
Vol 38 (7) ◽  
pp. 2477-2505 ◽  
Author(s):  
M. Rizza ◽  
K. Abdrakhmatov ◽  
R. Walker ◽  
R. Braucher ◽  
V. Guillou ◽  
...  
Keyword(s):  
Tien Shan ◽  
Tectonic Implications ◽  
Dating Methods
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