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引用本文:张德贤1 束正祥1 曹 汇2 鲁安怀1. 西秦岭造山带夏河—合作地区印支期岩浆活动及成矿作用——以德乌鲁石英闪长岩和老豆石英闪长斑岩为例[J]. 中国地质, 2015, (5): 1257-1273.
ZHANG De-xian1, SHU Zheng-xiang 1, CAO Hui2, LU An-huai1. Indosinian magmatism and tectonic setting of Xiahe-Hezuo area, western Qinling Mountains——implications from the Dewulu quartz diorite and Laodou quartz dioritic porphyry[J]. Geology in China, 2015, (5): 1257-1273(in Chinese with English abstract).
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西秦岭造山带夏河—合作地区印支期岩浆活动及成矿作用——以德乌鲁石英闪长岩和老豆石英闪长斑岩为例
张德贤1 束正祥1 曹 汇2 鲁安怀1
1. 中南大学有色金属成矿预测与地质环境监测教育部重点实验室, 地球科学与信息物理学院,湖南 长沙 410083;2. 大陆构造与动力学国家重点实验室,中国地质科学院地质研究所,北京 100037
摘要:
提要:西秦岭造山带印支期岩浆活动十分频繁,发育在夏河—合作地区的德乌鲁石英闪长岩和老豆花岗闪长岩与区域上金矿床的形成密切相关。岩石地球化学特征表明,这两类岩石地球化学性质相似,均为过铝质钙碱性中性岩。微量元素具有富集大离子亲石元素LILE,如Rb、Th、U等和轻稀土元素,亏损Ba、K、Nb、Sr、Ti和低Sr和Y的特点。稀土元素组成表现为轻稀土富集而重稀土亏损,轻重稀土分馏强烈,且具有弱的负铕异常。LA-ICP-MS锆石U-Pb同位素测年获得2个德乌鲁石英闪长岩样品(LD103和LD107)的加权平均年龄分别为(245.8±1.7) Ma和(243.4±1.9) Ma(图10-a),而3个老豆花岗闪长岩样品(LD102、LD106和LD113-2)的加权平均年龄分别为(241.4±2.1) Ma、(238.2±1.7)Ma和(241.4±1.6) Ma。德乌鲁石英闪长岩和老豆花岗闪长岩具有低Sr的特点,属于喜马拉雅型花岗岩,是由来自不同深源部分熔融形成的不同批次岩浆多次侵位聚集而成的,有利于与喜马拉雅型花岗岩有关的斑岩型Cu-Au、矽卡岩型Cu-Au和浅成低温Cu-Au-Sb矿床的形成。
关键词:  西秦岭造山带  岩浆作用  大地构造背景  印支期
DOI:
分类号:
基金项目:大陆构造与动力学国家重点实验室开放基金(K201405) 资助。
Indosinian magmatism and tectonic setting of Xiahe-Hezuo area, western Qinling Mountains——implications from the Dewulu quartz diorite and Laodou quartz dioritic porphyry
ZHANG De-xian1, SHU Zheng-xiang 1, CAO Hui2, LU An-huai11,2,3
1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitor of Ministry of Education;2.School of Geosciences and Info-physics, Central South University, Changsha 410083, Hunan, China;3.2. State Key Laboratory of Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China
Abstract:
Abstract: The tectonic setting of western Qinling orogenic belt was studied through the research on the petrogeochemical characteristics and U-Pb age of zircon from Dawulu quartz-diorite and Laodou granitic-diorite using LA ICP-MS. These two kinds of rocks belong to peraluminous calc-alkaline middle rocks. Trace element studies suggest that the rocks are predominately characterized by enrichment of LILE elements such as Rb, Th and U and other light rare-earth elements, depletion of Ba ,K, Nb, Sr, P, and low Sr and Y, suggesting typical characteristics of Himalaya-type granite. REE data indicate that the light rare earth elements were abundant, and heavy rare-earth elements are poor in these rocks. The light and heavy rare -earth fractionation is obvious. δEu has a weak negative anomaly. U-Pb age of zircon indicates that the weighted average ages of both Dewulu quartz-diorite and Laodou granitic diorite are (245.8±1.7) Ma and (243.4±1.9) Ma, (241.4±2.1) Ma, (38.2±1.7)Ma and (241.4±1.6) Ma respectively, which suggests that these two intrusions formed at the earlier stage of Indosinian. It is pointed out that Laodou granitic diorite and Dewulu quartz diorite were derived from the different sources which came from the different depths, and the emplacement and accumulation were from multiple origins. The Laodou granitic diorite and Dewulu quartz diorite are projected into the range of arc magma. The tectonic setting research suggests that the western Qinling lies in the continental-to-continental collision in the earlier Indosinian period, and hence this region is favorable in search for porphyry Cu-Au deposits, skarn Cu-Au deposits and epithermal Cu-Au-Sb deposits.
Key words:  western Qingling orogenic belt  magmatism  tectonic setting  Indosinian