现代地质2025，Vol.39Issue(3)：588-597,10.DOI:10.19657/j.geoscience.1000-8527.2025.039
准噶尔盆地西北缘石炭系火山岩地球化学特征及其成因机制
Geochemical Characteristics and Petrogenesis of Carboniferous Volcanic Rocks in the Northwestern Margin of the Junggar Basin
摘要
Abstract
This study investigates Carboniferous volcanic rocks(basalt,basaltic andesite,and andesite)from the Hara Arat Mountain(Hashan)area on the northwestern margin of the Junggar Basin to elucidate their petro-genesis and tectonic setting.Results indicate that these three rock types exhibit moderate MgO content(3.21％-6.82％),moderate to high Al2O3 content(11.30％-17.78％),and elevated total alkali content(K2O+Na2O=4.24％-7.24％).Basalt samples show relatively low K2O content,reflecting Na-enrichment relative to K,and are classified as low-K tholeiitic basalts.In contrast,basaltic andesites and andesites display high calc-alkaline element contents,consistent with island arc volcanic rock characteristics.Isotopic analyses reveal medium-low 87Sr/86Sr ratios(0.702877-0.706620)and high εNd(t)values(+4.59 to+9.85),indicating magma interaction between crustal and mantle components in a deep magma chamber.Compared to basalts,ba-saltic andesites and andesites show enrichment in large ion lithophile elements(e.g.,Ba),relative enrichment in high field strength elements(e.g.,U,Pb),and depletion in Nb,typical of subduction-related island arc magmatism.Trace element and rare earth element patterns suggest that basalts originated from depleted mantle melts under a convergent tectonic regime,while intermediate volcanic rocks record the subduction of oceanic plates beneath continental plates.This process involved the replacement of the depleted mantle wedge by sedi-ments or melts derived from the dehydrating subducting slab,followed by partial melting to form basaltic andes-ites and andesites.Combined with regional geological data,the subduction of the oceanic plate persisted until the late Carboniferous.关键词
准噶尔盆地/哈山/石炭系/火山岩/岩石成因Key words
Junggar Basin/Hashan/Carboniferous/volcanic rock/petrogenesis分类
天文与地球科学引用本文复制引用
牛花朋,何晓,刘姗,焦小芹,张关龙,王千军,周健,赵贤,于洪洲,熊峥嵘..准噶尔盆地西北缘石炭系火山岩地球化学特征及其成因机制[J].现代地质,2025,39(3):588-597,10.基金项目
中国石油大学(北京)2024年度"学科前沿交叉探索专项"(2462024XKQY004) （北京）
国家科技重大专项(2024ZD14049-004) （2024ZD14049-004）
中国石油化工股份公司项目(P22067). （P22067）
