Geochronologic-petrochemical studies of the Hongshishan mafic–ultramafic intrusion, Beishan area, Xinjiang (NW China): petrogenesis and tectonic implications
Geochronologic-petrochemical studies of the Hongshishan mafic–ultramafic intrusion, Beishan area, Xinjiang (NW China): petrogenesis and tectonic implications
复制标题
DOI：
10.1080/00206814.2010.543011
复制
发表时间：
2012-02
影响因子：
2.6
通讯作者：
B. Su;K. Qin;P. Sakyi;Dongmei Tang;Ping Liu;S. Malaviarachchi;Qing-Hua Xiao;He Sun
中科院分区：
文献类型：
--
作者：
B. Su;K. Qin;P. Sakyi;Dongmei Tang;Ping Liu;S. Malaviarachchi;Qing-Hua Xiao;He Sun
红石山镁铁质-超镁铁质岩体（西姆斯锆石U-Pb年龄286.4 ± 2.8Ma）由纯橄榄岩、单斜橄榄岩、橄榄岩和辉长岩组成。主要元素表现出系统相关性。微量元素分布模式一致，稀土元素（REE）模式平坦，Eu正异常，大离子亲石元素（LILE）富集，Nb、Ta亏损，表明分离结晶作用是岩浆演化的重要因素。岩石学和地球化学变化的钻孔岩心样品表明，轻微的同化和渐进的岩浆注入与镍，铜矿化密切相关。质量平衡估计和Sr-Nd同位素表明，红石山的母岩浆是高Mg和低Ti的拉斑玄武岩，并来自岩石圈地幔源已被俯冲板片交代部分熔融前修改。古天山-准噶尔洋向南俯冲的进一步制约是一个汇编的推断，俯冲引起的修改地幔源分布在东部天山-北山地区的镁铁质-超镁铁质侵入体。综合区域性正Nd（t）花岗岩、高Mg低Ti玄武岩浆（镁铁质-超镁铁质侵入体）和稍晚的高Ti玄武岩，认为它们的成因可能是二叠纪地幔柱活动的产物。
The Hongshishan mafic–ultramafic intrusion (SIMS zircon U–Pb age 286.4 ± 2.8 Ma) consists of dunite, clinopyroxene peridotite, troctolite, and gabbro. Major elements display systematic correlations. Trace elements have identical distribution patterns, including flat rare-earth element (REE) patterns with positive Eu anomalies and enrichments in large ion lithophile elements (LILE) but depletions in Nb and Ta, indicating fractional crystallization as a key factor in magmatic evolution. Petrologic and geochemical variations in drill core samples demonstrate that minor assimilation and progressive magma injections were closely associated with Ni–Cu mineralization. Mass balance estimates and Sr–Nd isotopes reveal that the Hongshishan parental magmas were high-Mg and low-Ti tholeiitic basalts and were derived from a lithospheric mantle source that had been modified by subducted slab metasomatism before partial melting. Southward subduction of the Palaeo-Tianshan–Junggar Ocean is further constrained by a compilation of inferred, subduction-induced modifications of mantle sources in mafic–ultramafic intrusions distributed in the eastern Tianshan–Beishan area. Integrating the regional positive ϵNd(t) granites, high-Mg and low-Ti basaltic magmas (mafic–ultramafic intrusions), and slightly later high-Ti basalts in NW China suggests that their petrogenesis could be attributed to Permian mantle plume activities.