高校地质学报2016，Vol.22Issue(1)：12-29,18.DOI:10.16108/j.issn1006-7493.2015114
诸广山南体桃金洞花岗岩成因和铀成矿潜力探讨
Study on Petrogenesis and Uranium Mineralization Potential of Taojindong Granite in Southern Zhuguangshan Composite Pluton
摘要
Abstract
In this paper, geochronology and petrogeochemistry and Sr-Nd isotopic geochemistry of Taojindong granite are studied and compared with those of other Indosinian granites in the eastern part of the southern Zhuguangshan composite pluton. LA-ICP-MS zircon U-Pb dating for Taojindong granite yields an age of 204 ± 2.1 Ma, suggesting its intrusion in the late Indosinian period. Chemically, this granite is peraluminou, and shows relatively high contents of silica(SiO2=69.7%~75.0%), alkali(K2O+Na2O=7.74%~9.08%)and FeOT, and low abundance of magnesium. Thus, the Taojindong granite is characterized as calc-alkalic- to alkali-calcic, peraluminous, and ferroan. The rock samples display high total REE contents(∑REE=226~272 × 10-6), with LREE/HREE ratios of 6.27~11.4 and(La/Yb)N ratios of 4.01~15.0, and a negative Eu anomaly(δEu=0.15~0.42). This granite is enriched in Rb, Th and U,and depleted in Ba, Sr, Ti and Eu, showing characteristics of a typical low Ba and Sr granite. Isotope geochemical analysis reveals high and variable initial 87Sr/86Sr ratios(0.71922~0.72040), yet low and constantεNd(t)values(-10.0~-10.2)with two stage model age of 1.80~1.82 Ga. All these features suggest that the Taojindong granite is a typical crust-derived granite. The granitic magma may have been derived from low-intermediate degree partial melting in a crustal extension-thinning tectonic environment in the late Indosinian period, of metagreywackes rocks whose origin was crust rocks separated from the mantle in the Paleoproterozoic. In the southern Zhuguangshan composite pluton, compared with non-uranium-mineralization-bearing granites, the uranium-mineralization- bearing granites experienced stronger hydrothermal alterations, and show wider variations in FeOT/(FeOT+MgO) ratios, higher uranium concentration, more depletion in CaO, Ba, Sr, Ti and Eu, lower εNd(t) values and more ancient two stage model ages. The non-uranium-mineralization-bearing granites were derived from metagreywackes and relatively depleted in U. Taojindong granites have not experienced significant hydrothermal alteration and have no characteristics of intense alteration like uranium-mineralization-bearing granites. The geochemical features of the Taojindong granites are similar to those of the Indosinian non-uranium-mineralization-bearing granites in the southern part of the Zhuguangshan composite pluton, and its uranium potential is slight.关键词
铁质花岗岩/花岗岩产铀潜力/印支晚期桃金洞花岗岩/诸广山南体Key words
ferroan granite/uranium mineralization potential of granite/late Indosinian Taojindong granites/Zhuguangshan composite pluton分类
天文与地球科学引用本文复制引用
兰鸿锋,凌洪飞,孙立强,王凯兴,欧阳平宁,刘建伟,王洪作..诸广山南体桃金洞花岗岩成因和铀成矿潜力探讨[J].高校地质学报,2016,22(1):12-29,18.基金项目
973课题(2012CB416703) （2012CB416703）
中国核工业地质局十二五高校铀矿地质科研项目 （）
