摘要
我国的华南地区是一个钨、锡、钼、铋、铀、铌钽、铅锌、稀有、稀土多金属成矿区。近年来,高精度年代学数据表明上述矿产集中爆发形成于晚侏罗世的165~150Ma。野外和实验证据表明,花岗岩可以划分为高分异花岗岩、低分异花岗岩和未分异花岗岩。从目前的研究结果来看,钨、锡、铌钽、锂、铍等成矿作用都与高分异花岗岩密切相关。建立与这些矿产有关高分异花岗岩的普适性的矿物学、矿物地球化学和全岩地球化学的指标,有助于判断植被覆盖严重和风化严重地区、数据积累较少的岩体的成矿潜力。位于福建省长汀县境内的河田花岗岩体新鲜露头少,大部分岩体都掩盖在厚厚的风化层下,且植被覆盖严重,但是该岩体中已发现多处锡、钨、铅锌矿(化)点。本研究发现,该岩体的锆石U-Pb年龄、石榴子石和全岩地球化学特征与江西西华山第二期成矿花岗岩具有高度相似性,因此推断河田岩体可能具有成钨锡多金属(超)大型矿的成矿潜力。此外,当花岗岩向高分异阶段不断演化的过程中,某些元素比值(例如Rb/Sr、Zr/Hf和Nb/Ta)可以作为衡量岩浆的结晶分异程度的参数;西华山和河田花岗岩在达到熔体-流体相互作用阶段时,全岩Zr含量和Zr/Hf比值大概在Zr=50×10-6和Zr/Hf=15处发生转折。同时,与不成矿花岗岩中的石榴子石相比,成矿花岗岩中石榴子石的Sn、Y和Yb元素含量明显升高,可达2~10倍,因此,高分异花岗岩的石榴子石的微量元素特征可能是重要的找矿标志之一。
South China is an important polymetallic metallogenic region for tungsten, tin, molybdenum, bismuth, uranium, lead, zinc, and rare earth elements. Recently available chronological data demonstrate that the aforementioned mineral resources occurred intensively in the Late Jurassic （165~150 Ma）. Field and experimental observations indicate that these granites can be divided into three series based on degrees of differentiation and fractionation： low fractionated, highly fractionated, and cumulus crystal granites. Existing research results have shown that metallogenesis of W, Sn, Nb, Ta, Li and B, etc are closely related to highly fractionated granite. Therefore, marker establishment of mineral and whole rock geochemistry of these deposits related to highly fractionated granite will be conductive to understanding the mineralization potential in heavily vegetation covered and strongly weathered areas as well as poorly investigated rock masses. Hetain granitic pluton in Changting county of Fujian province is poorly exposed, with most under the thick weathered layer and covered by thick vegetation. But the several prospects of Sn, W, Pb and Zn have been discovered occurring in the rock masses. This study shows that the zircon U Pb age, garnet and whole rock geochemical features of the Hetian pluton are highly similar to those of the second stage granite in Xihuashan of Jiangxi province. It can be inferred that the Hetian rock mass is of metallogenetic potential for W and Sn super large ore deposits. In addition, during the continuous evolution process of granite into high fractionation stage, some elements ratios （such as Rb/Sr, Zr/Hf, and Nb） can be used as parameters to weight degree of crystallization fractionation. When melts reach to interaction stage of melt and fluid, the whole rock zircon content and Zr/Hf ratio of the Xihuashan and Hetian granitic masses will change at Zr=50×10-6and Zr/Hf=15. Meanwhile, compared with garnet in poorly metallgoenic granite, Sn, Y and Yb contents in metallogenic granite increase distinctly, likely two to ten times higher. Therefore, trace elements features of the garnet from the highly fractionated granite can likely serve as one of the key prospecting markers.
作者
郭春丽
曾令森
高利娥
苏红中
马星华
尹冰
GUO Chunli ZENG Lingsen GAO Li＇e SU Hongzhong MA Xinghua YIN Bing(MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing , 100037, China MLR Key Laboratory of Continental Tectonics and Dynamics, Institute of Geology, Chinese Academy of Geological Sciences, Beijing , 100037, China China University of Geosciences , Beijing , 100037, China Hunan Shizhuyuan Nonferrous Metals Liability Co. Ltd, Chenzhou, Hunan, 100037, China)
出处
《地质学报》
EI
CAS
CSCD
北大核心
2017年第8期1796-1817,共22页
Acta Geologica Sinica
基金
国家自然科学面上基金项目(编号:41273043
41425010)
地质调查项目(编号:DD20160056)
国家重点研发计划课题(编号:2016YFC06002008)资助的成果
关键词
高分异花岗岩
石榴子石
Zr/Hf比值
找矿标志
华南
福建河田花岗岩体
江西西华山花岗岩体
Highly fractionated granites
garnet
Zr/Hf ratio
prospecting markers
South China
Hetian granitic pluton in Fujian Province
Xihuashan granitic pluton in Jiangxi Province
