Evolution of Devonian depositional environment in northern Longmenshan tectonic belt
Evolution of Devonian depositional environment in northern Longmenshan tectonic belt
复制标题
DOI：
--
复制
发表时间：
2010
期刊：
影响因子：
--
通讯作者：
Wang Ying-rong
中科院分区：
文献类型：
--
作者：
Wang Ying-rong
北龙门山构造带位于泥盆纪上扬子古陆边缘，继承了陆架斜坡断裂，沉积环境受斜坡区北川、南坝断裂控制，平面上自西向东分为海槽、台缘浅滩、开放台地和限制台地区。志留纪末期，加里东运动将整个扬子地台抬升为古陆，为长江流域提供了大量陆源物质。泥盆纪沉积。早泥盆世，地壳衰退，开始海侵。青川—南坝断裂与马角坝—雁门坝断裂之间的甘西、平邑铺、六河沉积环境为浅海碳酸盐岩和滨陆碎屑岩。中泥盆世，海侵更加强烈，空间更加广泛。天景山古隆起完全被海水覆盖，到达汉南朝天一龙东北。晚泥盆世，海侵范围进一步扩大，海域终止于天井山古隆起边缘，区内仅有碳酸盐岩沉积，无物源供给。泥盆纪龙门山沉积环境演化主要经历了平邑堡、甘西—观雾山和沙窝子—毛坝沉积旋回。总体规律是长时间、慢速海侵和短时、高速、大范围海退。
The northern Longmenshan tectonic belt located at the egde of Upper Yangtze ancient land in Devonian,inherited the continental shelf slope fault.The depositional environment is controlled by Beichuan and Nanba faults in slope area,and divided into ocean trough,platform edge shoal,open platform and restricted platform areas from west to east at plane.At the end of Silurian,Caledonian movement uplifted the whole Yangtze platform to be ancient land,which supplied massive terrestrial materials to Devonian deposition.In Early Devonian,the crust declined and transgression started.The depositional environment in Ganxi,Pingyipu and Liuhe between the Qingchuan—Nanba fault and Majiaoba—Yanmenba fault is of neritic carbonate rocks and shoreland clastic rocks.In Middle Devonian,the transgression is more intensive with space of more extensive.Tianjingshan ancient uplift is completely covered by sea water and reached to Chaotianyilongdongbei in the Hannan ancient land,while the geomorphic difference between Sichuan and Guizhou ancient lands became smaller with reduced provenance supply,the sediments are mixed mainly by clastic and carbonate rocks.In Late Devonian,the maritime space terminated in the margin of Tianjingshan ancient uplift with the further expansion of transgression.There was only carbonate deposition with no source supply in this area.The evolution of depositional environment of Longmenshan in Devonian mainly experienced the Pingyipu,Ganxi—Guanwushan and Shawozi-Maoba sedimentary cycles.The general pattern is long-time and slow-velocity transgression,and short-time,high-velocity and large-range regression.