南岭西段姑婆山–花山花岗岩基差异剥蚀机理与风化矿床分布特征  

Differential Erosion of the Guposhan-Huashan Batholith in Western Nanling Mountains and Distribution of Weathered Ore Deposits

作　　者：冯梦[1] 许成[1] 王睿[2] 康志强[3] 

机构地区：[1]北京大学地球与空间科学学院,北京100871 [2]许昌职业技术学院,河南许昌461000 [3]桂林理工大学广西隐伏金属矿产勘查重点实验室,广西桂林541004

出　　处：《大地构造与成矿学》2015年第4期670-679,共10页Geotectonica et Metallogenia

基　　金：国家自然科学基金项目(40772126;41162005);广西自然科学基金重点项目(2010GXNSFD013001)联合资助

摘　　要：姑婆山–花山花岗岩基位于南岭花岗岩带的西段,为燕山早期多次岩浆侵位的产物。姑婆山–花山花岗岩基由东西向展布的姑婆山花岗岩体和花山花岗岩体组成,两岩体规模、形态及主体组成单元基本相同,且主体单元均为成矿岩体,但两岩体构造型式迥异。姑婆山花岗岩体具有外侵式、反环带构造型式,岩石能量较小、抗风化剥蚀能力较弱、形成较早的里松单元出露于岩体的中部,四周被岩石能量较大、抗风化剥蚀能力较强、形成较晚的望高和新路单元所环绕,地貌上对应的表现为岩体中央成凹陷盆地,四周为中山陡坡地形,由此导致岩体内水系向岩体中央盆地汇聚,并在岩体中央盆地及集中外泄的里松河河谷阶地内富集形成风化矿床;与此相反,花山花岗岩体具有内侵式、正环带构造型式,岩石能量较大、抗风化剥蚀能力较强、形成较晚的华美和望高单元位于岩体的中部,四周被岩石能量较小、抗风化剥蚀能力较弱、形成较早的里松等单元所环绕,地貌上对应的表现为岩体中央呈中山地形,四周多为低山丘陵,水系从岩体向外呈放射状分布,这种放射型水系不易于在岩体内部形成较大规模的风化矿床,砂锡及风化型稀土矿随河水搬运距离较远,最终在岩体外环(或边缘)地势较低的思勤江汇水盆地及河谷阶地内沉积富集形成大型砂锡及风化型稀土矿。姑婆山和花山两姐妹花岗岩体不同的构造型式是形成两岩体地貌景观差异的内在因素,同时也是导致两岩体风化矿床空间分布差异的根本原因。The Guposhan-Huashan batholith is located in the western segment of the Nanling Range Granitic Belt. The batholith is made of multiple intrusive units emplaced in the Early Yanshanian of Mesozoic Era. The batholith includes the Guposhan pluton in the east and the Huashan pluton in the west. Both plutons are similar in size and shape and composed of similar ore–forming granites. The plutons show concentric zonation with contrasting emplacement mode. The Guposhan pluton was built in an outward incremental growth mode. Its earliest intrusive unit, the more mafic and less resistant （to weathering and erosion） Lisong intrusive unit with lower chemical energy, is located in the central part and surrounded by the younger, more felsic and resistant Wanggao and Xinlu intrusive units with higher chemical energy. Accordingly, the differential weathering and erosion resulted in a depression or a basin in the center which is surrounded by high, steep-sloped mountains. As such, the inward radial drainage pattern led to the formation of placer and residual ore deposits in the basin and in the Lisong River valley. In contrast, the Huashan pluton was built in an inward incremental growth mode with the younger Wanggao and Xinlu units in the central area. Therefore, the more felsic and resistant Wanggao and Xinlu granites form high mountains surrounded by low hills of the Lisong unit. The resulting drainage pattern is an outward radial pattern. Exploration in the past years has led to the discoveries of a number of large- and small- scale tin placer and weathering-type rare earth ore deposits in basins and river valleys around the periphery of the pluton.

关 键 词：花岗岩 构造型式 岩石能量 差异剥蚀 风化矿床 南岭西段 

分 类 号：P611.2[天文地球—矿床学]