大别山东南麓中新生代碎屑岩地球化学特征及其对物源的制约

位于大别山东南麓的安庆-潜山地区中新生代碎屑岩比较发育,主元素分析表明,砂岩主要为杂砂岩,其次是岩屑砂岩和长石砂岩。根据主元素、微量元素和稀土元素特征值分析结果,中、上三叠统和下、中侏罗统的源岩来源广泛,属于大陆岛弧、活动大陆边缘和被动大陆边缘构造背景,可能反映了前陆盆地物源的二元特征。古近系源岩主要为活动大陆边缘和大陆岛弧构造环境,说明物源仅来自大别山造山带。稀土元素比值及相关系数分析揭示,中晚三叠世黄马青群的源岩主要为宿松群的长英质片岩、浅粒岩以及大别杂岩,侏罗纪磨山组大致类似于大别群的花岗片麻岩,罗岭组与大别群比较类似。显示大别山造山带在中晚三叠世已经隆升并遭受剥露。

Geochemistry of the Mesozoic and Cenozoic detrital rocks and its constraints on provenance in the southeast foot of Dabie Mountains

The Mesozoic and Cenozoic detrital rocks developing in Anqing-Qianshan areas located on the southeast foot of Dabie Mountains,comprise of mainly greywacke,secondly lithic arenite and arkose on the base of their major elements.According to the analysis of major,trace and rare earth elements of the sandstones,the source rocks of Middle and Upper Triassic and Lower and Middle Jurassic have extensive provenance,which belongs to the tectonic setting of continental island arc,active continental margin and passive continental margin,and reflects the texture of double units of foreland basin provenance.The source rocks of Paleogene formed in the tectonic setting of active continental margin and continental island arc,which suggests that the provenance belonged to Dabie Orogenic Belt.According to the analysis of the ratios of rare earth elements and correlation analysis,the source rocks of Middle Triassic Huangmaqing Group comprises chiefly of felsic schist and Dabie complex,the source rocks of Jurassic Moshan Formation are similar to granite gneiss of Dabie Group,and Luoling Formation is similar to Dabie Group.So,these suggest that it is in Middle-Late Triassic that Dabie Orogen Belt had uplifted and suffered to exhumation.