摘要
鄂东南地区存在大量中酸性小岩体,部分小岩体与斑岩型铜钼金矿床关系密切。对位于鄂东南东区南部的何锡铺花岗闪长斑岩体进行了锆石U-Pb定年和Hf同位素组成测定。定年结果显示:花岗闪长斑岩样品的岩浆结晶年龄为(142±1)Ma,属早白垩世。这与鄂东南地区和九江-瑞昌地区含矿小岩体形成年代基本一致。何锡铺岩体锆石176 Hf/177 Hf比值为0.282 372~0.282 656,在t=142 Ma时,对应的εHf(t)值为-11.1^-1.1,平均值为-6.3。锆石εHf(t)值具不均一性,类似于阮宜湾岩体,而不同于铜山口岩体和龙角山岩体。岩体具高Sr/Y比值,无明显Eu负异常。全岩初始锶同位素比值(87Sr/86Sr)i为0.705 88,εNd(t)值为-4.9。全岩地球化学、Sr-Nd同位素和锆石Hf同位素特征一致表明富集地幔是何锡铺岩体的重要源区,原始幔源岩浆可能存在古老地壳物质的混染。何锡铺岩体不仅具有与铜山口岩体类似的岩石学特征,还具有与其类似的地球化学特征。幔源物质的参与指示该岩体具有形成斑岩型铜钼金矿床的潜力。
The Hexipu pluton is located in southern Hubei Province where the granodiorite porphyries and associated ore deposits are widely spread. This paper presents the integrated study of U-Pb age and Lu-Hf isotope composition in zircons from the Hexipu pluton. Zircon U-Pb age for Hexipu pluton is （142 ±1） Ma, which suggests an Early Cretaceous emplacement, which is consistent with other ore-bearing grano- diorite porphyries of southeast Hubei Province and Jiujiang-Ruichang area. The in situ Hf isotope analysis reveals 176Hf/177Hf ratios from 0. 282 372 to 0. 282 656,and εHf（t） value from -11.1 to -1.1 with the av- erage value of -6.3. The cHf（t） value of zircons from Hexipu pluton are inhomogenous, which is similar to that of the Ruanyiwan pluton and distinctive from that of the Tongshankou pluton and Longjiaoshan plu- ton. The Hexipu pluton has high Sr/Y value,with no obvious Eu negative anomaly. The whole rock initial Sr isotope ratios （87Sr/86Sr） is 0. 705 88,and εNd（t） vaule is -4. 9. The whole rock geochemistry,Sr-Nd i- sotope and zircon Hf isotopic characteristics indicate that the enriched mantle is an important magma source of the Hexipu pluton. The original mantle magma may be contaminated by the old crustal material. The Hexipu pluton and the Tongshankou pluton have similar petrography and geochemical characteristics. The addition of mantle derived materials indicates that there is a potential for the formation of porphyry Cu-Mo-Au deposit.
出处
《地质科技情报》
CSCD
北大核心
2017年第6期104-112,共9页
Geological Science and Technology Information
基金
中国地质调查局地质调查项目(1212011120863
12120114039401
121201009000150002)
