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引用本文:龚雪婧,曾建辉,曹殿华. 江西冷水坑矿床含矿花岗斑岩的Sr-Nd及锆石Hf-O同位素研究[J]. 中国地质, 2019, 46(4): 818-831.
GONG Xuejing,ZENG Jianhui,CAO Dianhua. Sr-Nd and zircon Hf-O isotopic constraints on the petrogenesis of the orebearing granitic porphyry at Lengshuikeng, Jiangxi Province[J]. Geology in China, 2019, 46(4): 818-831(in Chinese with English abstract).
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江西冷水坑矿床含矿花岗斑岩的Sr-Nd及锆石Hf-O同位素研究
龚雪婧1,2, 曾建辉3, 曹殿华1,2
1.中国地质科学院, 北京 100037;2.中国地质调查局-中国地质科学院地球深部探测中心, 北京 100037;3.江西省地质矿产勘查开发局九一二大队, 江西 鹰潭 335000
摘要:
江西冷水坑铅锌矿床是武夷成矿带北段的典型矿床,矿区内含矿花岗斑岩锆石U-Pb年龄为(162.0±2.0)Ma,岩浆分异程度较高,具有高SiO2(69.46%~75.52%)、高K2O(K2O/Na2O>3.22)、强过铝质(ASI=1.20~1.96)的特征。岩体发育较明显的Eu负异常,富集强不相容元素Rb、Th、U,而亏损高场强元素Ba、Sr、Nb、Ta、P、Ti。全岩同位素测试结果显示,冷水坑含矿花岗斑岩具有极高的87Sr/86Sr初始比值(0.74005~0.76518)与低的εNd值(-11.48~-10.78),锆石Hf-O同位素测定值变化范围较小,176Hf/177Hf介于0.282317~0.282460,具有负的εHft)值(-12.39~-7.62)和相对较高的δ18O值(7.23‰~8.81‰),指示岩浆主要来自于成熟地壳,可能起源于北武夷地区变质基底,源岩为基底变质岩,这可能与古太平洋板块俯冲形成的挤压背景下的地壳熔融有关。
关键词:  Sr-Nd-Hf-O同位素  花岗斑岩  冷水坑  武夷成矿带  华南
DOI:10.12029/gc20190412
分类号:P588.13;P597
基金项目:中国地质调查局项目(DD20160082,DD20190012)、国家自然科学基金(41802097)及国家重点研发计划“深地资源勘查开采”重点专项(2016YFC0600201)联合资助。
Sr-Nd and zircon Hf-O isotopic constraints on the petrogenesis of the orebearing granitic porphyry at Lengshuikeng, Jiangxi Province
GONG Xuejing1,2, ZENG Jianhui3, CAO Dianhua1,2
1.Chinese Academy of Geological Sciences, Beijing 100037, China;2.SinoProbe Center, Chinese Academy of Geological Sciences and China Geological Survey, Beijing 100037, China;3.No. 912 Geological Party of Jiangxi Bureau of Geology and Mineral Exploration and Development, Yingtan 335001, Jiangxi, China
Abstract:
The Lengshuikeng lead-zinc deposit in Jiangxi Province is a typical deposit in the northern section of the Wuyi metallogenic belt. The zircon SHRIMP U-Pb age of the ore-bearing granite porphyry in the mining area is (162.0±2.0) Ma. The granite porphyries are highly evolved, with high SiO2 (69.46%~75.52%), high K2O (K2O/Na2O>3.22) and strong peraluminous (ASI=1.20~1.96). The negative Eu anomalies of the rock mass are relatively strong, and enriched in LILE such as Rb, Th, and U, while the HFSE such as Ba, Sr, Nb, Ta, P, and Ti are depleted. In this study, the authors also report Sr-Nd and zircon Hf-O isotopic compositions of the granitic porphyries at Lengshuikeng. The results show that the granitic porphyries have relatively high initial 87Sr/86Sr ratios (0.74005~0.76518) and negative εNd values (-11.48~-10.78) as well as the zircon Hf-O isotope measurement value. The variation range of 176Hf/177Hf values (0.282317~0.282460) is small, with negative εHf(t) values (-12.39~-7.62) and relatively high δ18O values (7.23‰~8.81‰), indicating that the magma mainly came from the mature crust, which may have originated from metamorphic basement of North Wuyi area, and the source rocks were probably the metamorphic basement. The magmatic activity was probably related to the crust melting under the compressive background formed by northwestward subduction of the Paleo-Pacific Plate.
Key words:  Sr-Nd-Hf-O isotopes  granitic porphyry  Lengshuikeng  Wuyi metallogenic belt  Southeast China