ZHENG Sheng-jian, MA Jin-qing, HUANG Quan-zhen and
YAN Bing-quan
(Regional Geological Survey Party, Fujian Bureau of Geology and Mineral Exploration
and Development, Sanming, Fujian 365001,China)
Abstract:By using the new theory
and method of hierarchical division and clustering, the intrusive rocks in Fujian province
are divided into 110 units and incorporated into 27 super-units (sequences) and 21
independent rock units and a hierarchy system of rock units of the whole province is
preliminarily established. In the province, M-, I-, S- and A-type granites are all well
developed; large-scale volcanic eruption is generally lacking in S-type granites; whereas
I- andA-types and transitional type of I- and S-types have the features of originating
after or simultaneously with volcanic activity and from the same source as volcanic rocks
and being equivalent in size and areal extent to volcanic rocks. Different hierarchical
units of the intrusive rocks formed in different periods have different mineralization
types and scales.
Key words:Fujian province; intrusive rocks; hierarchical units
福建省地质构造发展自新太古代以来,经历了五台—吕梁、四堡—晋宁、加里东、华力西—印支、燕山、喜马拉雅各构造发展阶段,各构造期均有规模不等的岩浆侵入,尤以晚三叠世开始进入濒太平洋构造域[1]后,岩浆活动甚为频繁、强烈。侵入岩出露总面积逾42
300 km2,占全省陆地面积的34.87%,规模属华南诸省前列。各种岩石类型齐全,包括超基性、基性、中性、中酸性、酸性、碱性等岩类,按岩石谱系单位划分、归并方法[2],根据岩性、接触关系、同位素年龄及同源岩浆演化等规律,共划分为110个岩石单元,归并为18个超单元、9个序列和21个独立单元,分属于早元古代、晚元古代、志留纪、二叠纪、中三叠世、早侏罗世、晚侏罗世、早白垩世、晚白垩世和第三纪10个不同时期(表1)。主要岩石类型为钾长花岗岩及二长花岗岩,花岗岩类以结构演化为主,闪长岩类则以成分演化占主导地位。
无论是印支运动以来濒(环)太平洋断裂体系[3]的活动,或是印支运动以前时期陆间裂陷槽的发生与闭合,各期岩浆侵入活动规模与同期构造运动强度往往相若,均属活动大陆边缘的一套钙碱性岩浆组合,早白垩世晚期尚有大规模的碱性岩浆侵入,形成十分独特的晶洞碱长—碱性花岗岩带。各时期侵入岩的带状分布特征显示岩浆侵入受构造带控制的因素较突出,由于构造带的形成往往经历长期多次的复杂过程,受其控制的复式岩体是多期多阶段活动历史不同的岩浆活动组合体。吕梁—晋宁和加里东期侵入体沿韧性剪切带呈底辟或一定构造部位呈热轻汽球膨胀侵位机制较突出;华力西—印支期侵入体热轻汽球膨胀、底辟和岩墙扩张复合侵位机制较明显;燕山期侵入体火山口塌陷、顶蚀、岩墙扩张等被动侵位机制较醒目,伴有底辟、
热轻汽球膨胀等复合侵位机制。
表1 福建省侵入岩岩石谱系单位划分简表
Table 1 Summary of the hierarchical units of intrusive rocks in Fujian
province