南雄盆地晚白垩世-古新世陆源沉积组份变化的古气候指示

利用陆源沉积中的碎屑组份(泥岩中的碎屑黏土矿物种类和砂岩中砂、粉砂碎屑类型)相对含量变化,对广东北部和江西南部的南雄盆地晚白垩世-古新世古气候进行了分析.结果显示,砂岩碎屑组份含量气候指数(长石/石英比,F/Q)介于0.02~0.14之间;(碎屑)黏土矿物组合主要以伊利石为主,平均79%;伊利石结晶度指数与化学指数分别为0.25~0.39、0.31~0.7.进一步分析表明,研究区这一时期以干旱气候为主,存在暖湿气候间断,古气候演化可分为三个阶段:晚白垩世马斯特里赫特期以干旱-半干旱性气候为主,古新世丹尼期早期转变为相对湿热或与干旱-半干旱气候交替,古新世丹尼期晚期恢复到半干旱性气候,但比第一阶段湿度可能稍有增加.这一总体干旱-半干旱气候格局及其变化总体与同期全球气候变化一致.

Paleoclimate Indication of Terrigenous Clastic Rock's Component during the Late Cretaceous-Early Paleocene in the Nanxiong Basin

According to relative content of terrigenous clastic rock's components (clay minerals of claystone and clastic composition of sandstone), analyzing paleoclimate of Late Cretaceous - Paleocene Nanxiong Basin in northern Guangdong and southern Jiangxi. The climate index of sandstone clastic components (feldspar/quartz, F/Q) is between 0.02 to 0.14; Clay mineral assemblage is mainly illite, with an average of 79%; Illite crystallinity index and chemical index is 0.25~0.39 and 0.31~0.7. During this period, the climate of the study area is mainly arid climate, with some warm and humid climate intermittent, paleoclimate can be divided into three stages: arid-semiarid Maastrichtian, warm and moist semiarid early Danian, and the semiarid late Danian. Climate evolution is consistent with the same period of global climate change.