Premium
Subduction and Collision of the Jinsha River Paleo‐Tethys: Constraints from Zircon U‐Pb Dating and Geochemistry of the Ludian Batholith in the Jiangda–Deqen–Weixi Continental Margin Arc
Author(s) -
HE Juan,
WANG Baodi,
WANG Qiyu
Publication year - 2020
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/1755-6724.14554
Subject(s) - batholith , geology , subduction , permian , geochemistry , continental arc , zircon , continental margin , quartz monzonite , early triassic , island arc , continental crust , mantle (geology) , paleontology , pluton , tectonics , structural basin
The Jiangda–Deqen–Weixi continental margin arc (DWCA) developed along the base of the Changdu–Simao Block and was formed as a result of the subduction of the Jinsha River Ocean Slab and the subsequent collision. The Ludian batholith is located in the southern part of the DWCA and is the largest batholith in northwest Yunnan. Granite samples from the Ludian batholith yield an early Middle Permian age of 271.0 ± 2.8 Ma. The geochemical data of the early Middle Permian granitoids show high Si 2 O, low P 2 O 5 and MgO contents that belong to calc‐alkaline series and peraluminous I‐type rocks. Their ∊ Hf( t ) values range from –5.01 to +0.58, indicating that they were formed by hybrid magmas related to the subduction of the Jinsha River Tethys Ocean. The monzonite and monzogranite samples yield Late Permian ages of 250.6 ± 1.8 Ma and 252.1 ± 1.3 Ma, respectively. The Late Permian granitoids are high‐K calc alkaline and shoshonite series metaluminous I‐type rocks. Their ∊ Hf( t ) values range from –4.12 to –1.68 and from –7.88 to –6.64, respectively. The mixing of crustal and mantle melts formed the parental magma of the Late Permian granitoids. This study, combined with previous work, demonstrates the process from subduction to collision of the Jinsha River Paleo‐Tethys Ocean.