Citation: | LI Lijuan,ZHANG Tao,LI Qiang,et al. Petrogenesis and Tectonic Implications of Carboniferous Granites and Its Dark Enclaves in the Western Awulale Mountain, Western Tianshan[J]. Northwestern Geology,2024,57(3):73−90. doi: 10.12401/j.nwg.2024011 |
The petrogenesis and dynamic background of the magmatic rocks in the West Tianshan Mountains are of great significance to reveal the tectonic evolution history of the restoration area. In this paper, the granite and its dark enclaves in the northwestern area of Kunes Zhongyangchang in the western Awulale Mountain were selected for petrology and zircon U-Pb chronology and petrogeochemical analysis. The results show that the dark enclaves are fine-grained diorite, with K2O=0.93~2.50, K2O/Na2O=0.20~0.21, A/CNK=0.83~0.87 and σ=2.33~3.02, which are quasi-aluminous calc-alkaline rock series. Host granites belong to I type granites with K2O=2.92~3.48, K2O/Na2O=0.60~0.79, Ritman index σ=1.87~2.17, and A/CNK =1.01~1.04, which are weakly peraluminous calc-alkaline rock series. Both of them are enriched in large ion lithophile elements (LILE, e.g. Rb、Ba、Pb) and depleted in high field strength elements (HSFE, e.g. Nb, Ta, Ti), The total amount of rare earth elements is low, accompanied by the relative enrichment of light rare earth elements, and the relative loss of heavy rare earth element. The diorite enclaves have no significant Eu and Sr anomalies, while the granites have obvious negative Eu anomalies and strong loss of Sr, P and Ti elements. Zircon U-Pb dating shows that the formation age of granite is (320.0±2.7) Ma, belonging to the early Late Carboniferous. The diagenetic age of the diorite enclaves is (344.5±1.4) Ma, belonging to the Early Carboniferous. The type of diorite enclaves is xenolith, which were captured during the rising of the host granitic magma. The geochemical and chronological characteristics of the rocks reveal that they have different petrogenesis. The dioritic enclaves were formed during the northern Tianshan Ocean subduction southward, and the granite intrusion was located in the post-collision extension environment, which was formed due to the upwelling of the asthenosphere, leading to the partial melting of the lower crust. Based on regional geological data, it is likely that the early Carboniferous to late Carboniferous is an important stage of tectonic system transformation in the western Tianshan Mountain, that is, the tectonic environment transformed from compression to extension.
白建科, 李智佩, 徐学义, 等. 西天山阿吾拉勒地区下石炭统大哈拉军山组火山岩LA-ICPMS锆石U-Pb年龄及地质意义[A]. 中国矿物岩石地球化学学会. 中国矿物岩石地球化学学会第13届学术年会论文集[C].2011, 558.
|
|
|
|
|
江西省地质矿产勘探开发局. 新疆维吾尔自治区1∶5万区域地质矿产调查报告[R].江西省地质矿产勘探开发局, 2005.
|
|
|
|
|
|
|
|
李钊. 伊宁地块阿吾拉勒—巩乃斯地区大哈拉军山组与伊什基里克组火山岩对比研究[D]. 西安: 长安大学, 2016, 1−179.
LI Zhao. Comparative study on the volcanic rocks of Dahalajunshan Formation and Yishijilike Formation, Awulale-Gongnaisi area, Yining Block, Xinjiang[D]. Xi’an: Chang’an University, 2016, 1−179.
|
|
茹艳娇. 西天山大哈拉军山组火山岩地层序列、岩石成因与构造环境[D]. 西安: 长安大学, 2012, 1−123.
RU Yanjiao. The Stratigraphic Sequanence, Petrogenesis and Tectonic Setting of the Volcanic Rocks of the Dahalajunshan Formation, Western Tianshan Mountain, China[D]. Xi’an: Chang’an University, 2012, 1−123.
|
|
|
|
|
|
|
|
|
|
|
|
张永玲, 张治国, 刘希军, 等. 内蒙朝克山辉长岩中单斜辉石矿物化学特征及地质意义[J]. 西北地质, 2024, 57(1): 122−138.
ZHANG Yongling, ZHANG Zhiguo, LIU Xijun, et al. Mineralogical Chemistry Characteristics and Geological Significance of the Clinopyroxene from Chaokeshan Gabbro, Inner Mongolia[J]. Northwestern Geology, 2024, 57(1): 122−138.
|
赵军. 新疆阿吾拉勒成矿带西段铜矿成矿环境与成矿规律研究[D]. 西安: 长安大学, 2013, 1−161.
ZHAO Jun. Study on the Metallogenic Settings and Metallogenic Regularity Of copper Deposits in Western Awulale Mountain, Xinjiang[D]. Xi’an: Chang’an University, 2013, 1−161.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Eby G N, Krueger H W, Creasy J W. Geology, Geochronology and geochemistry of the White Moutain batholith, New Hampshire[A]. In Puffer J H and Ragland P C, eds, Eastern North American Mesozoic magmatism[C]. Geological Society of America Special Paper, 1992, 268: 379−398.
|
|
|
|
|
|
|
|
|
|
|
|
|
Middlemost E A K. Magmas and Magmatic Rocks[M]. London: Longman, 1985, 1−266.
|
|
|
Pearce J A. Trace Element Characteristics of Lavas from Destructive Plate Boundaries[A]. In: Thoepe R S, ed. Andesites[M]. John Willey and Suns, New York, 1982.
|
|
|
Picher W S. Granite type and tectonic environment. Mountain Building Processes[M]. London: Academic Press, 1983, 19−40.
|
|
|
|
|
Rudnick R L, Gao S. Composition of the Continental Crust[A]. In: Rudnick R, ed. The Crust, Treatise on Geochemistry[M]. Elsevier, Amsterdam, 2003, 3: 1−64.
|
|
|
|
|
|
|
|
|
|
|