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庐枞中生代火山盆地位于长江中下游断陷带,地处扬子板块的北缘。庐枞盆地内火山岩和侵入岩分布广泛,包括龙门院、砖桥、双庙和浮山4组火山岩以及34个出露地表的侵入、岩体。庐枞盆地内与成矿关系密切的侵入岩体的时空格架和岩浆演化等相关研究工作已经广泛开展,但对于盆地南部的花岗岩类侵入岩研究工作则相对薄弱,制约了对庐枞盆地岩浆作用及深部成矿预测的深入研究。本次工作在详细野外地质工作的基础上,系统对盆地南部的沙墩岩体、船艄石岩体、青山岩体、何家凹岩体、梅林岩体、古塘冲岩体和周家山岩体开展了岩石学、地球化学和年代学研究,确定其主要岩性为石英正长岩和钾长花岗岩,岩石全碱含量均较高,准铝质或过铝质;稀土含量中等,较强Eu亏损,呈略右倾的海鸥型稀土配分模式,成岩时代分别为:126.5±1.1 Ma、126.2±1.2 Ma、126.7±1.3 Ma、126.9±1.4 Ma、125.9±1.3 Ma、126.7±1.4 Ma和124.9±1.3 Ma,均形成于早白垩世。通过与庐枞盆地不同侵入岩的系统对比,提出这些岩体与庐枞盆地晚期侵入岩时代接近,岩石学特征类似,应为同一岩浆作用的产物,形成于区域岩石圈伸展的构造环境。
Luzong Mesozoic volcanic basin is located in the middle and lower reaches of the Yangtze River fault zone, located in the northern margin of the Yangtze plate. Volcanic rocks and intrusive rocks are widely distributed in the Luzong Basin, including 4 volcanic rocks of Longmenyuan, Brickbridge, Shuangmiao and Fushan, and 34 intrusion of surface ground and rock mass. The related research work on the space-time framework and magmatic evolution of intruded rock mass closely related to metallogenesis has been carried out extensively in Luzong Basin. However, the study on granitic intrusive rocks in the southern basin is relatively weak, which has restricted the development of magma in Luzong Basin Function and deep mineralization prediction. Based on detailed geologic work in the field, this work systematically analyzes the sand-pier rock mass, schist rock mass, Qingshan rock mass, Hejia rock mass, Meilin rock mass, Gu-Tong-Chong rock mass and Zhou Jiashan Petrological, geochemical and geochronological studies have been carried out on rock mass. The main lithologies of the rock mass are quartz syenite and potash-bearing granite. The total alkali content of the rock is high, quasi-aluminum or perlite, and the content of rare-earth is medium Strong Eu depletion, and a slightly rightward seagull-type REE pattern with diagenetic ages of 126.5 ± 1.1 Ma, 126.2 ± 1.2 Ma, 126.7 ± 1.3 Ma, 126.9 ± 1.4 Ma, 125.9 ± 1.3 Ma, 126.7 ± 1.4 Ma and 124.9 ± 1.3 Ma, both formed in the Early Cretaceous. Based on the systematic comparison with different intrusive rocks in Luzong Basin, it is suggested that these intrusive rocks are close to the Late Paleocene intrusive rocks in the Luzong Basin, with similar petrological characteristics and should be the product of the same magma formed in the tectonic environment in which the lithosphere extends.