【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εHf(t)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。更多还原

【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 K2 O(K2 O/Na2 O>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 initial87 Sr/86 Sr 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 of176 Hf/177 Hf values(0.282317～0.282460) is small, with negative εHf(t) values(-12.39～-7.62) and relatively high δ18 O 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.更多还原