摘要
藏北羌塘盆地中央隆起带果干加年山北坡首次发现了较丰富的珊瑚化石。珊瑚主要属种有8属10种及未定种:Distichophyllia norica(Frech),Gablonzeria irregularis Deng&Zhang,Margarophyllia stylophylloides(Vinassa deRegny),M.zogangensisDeng&Zhang,Margarophyllia? sp.,Montlivaltia tenuise Deng&Zhang,Pamiroserisrectilamellosa(Winkler),Paradistichophyllum verticalis Deng&Zhang,Paradistichophyllum?sp.,StylophyllopsismosjvariFrech等。产出这些珊瑚化石的灰岩地层原来被认为是混杂在晚三叠世望湖岭组碎屑岩中的古生代灰岩断块,而新发现的珊瑚指示地层时代并非是古生代,而是晚三叠世。这说明果干加年山地区不存在上三叠统碎屑岩和古生界灰岩混杂的现象。果干加年山地区的晚三叠世沉积不仅包含有望湖岭组的碎屑岩,还包含有夹在碎屑岩之间的浅海相灰岩。本次研究和前人的资料表明羌塘中央隆起带在晚三叠世并非是隆起剥蚀区,而是海洋沉积区。因而,以往建立在中央隆起带为隆起剥蚀区认识基础上的羌塘盆地晚三叠世沉积古地理环境和"一隆两坳"的大地构造格局认识需要重新考虑。
Coral fossils were first found at the north slope of the Guoganjianian Mountain in the Qiangtang Central Uplift in the north Tibet（Xizang）. The coral fossils were identified to be 8 genus and 10 species, including Distichophyllia norica （Frech）, Gablonzeria irregularis Deng Zhang, Margarophyllia stylophylloides （Vinassa de Regny ）, M. zogangensis Deng Zhang, Margarophyllia？ sp., Montlivaltia tenuise Deng Zhang, Pamiroseris rectilamellosa （Winkler）, Paradistichophyllum verticalis Deng Zhang, Paradistichophyllum？ sp., Stylophyllopsis mosjvari Frech. The limestone yielding the coral fossils was previously thought to be the Palaeozoic by the lithostratigraphic correlation , and was treated as exotic blocks jumbling in the Late Triassic Wanghuling Formation clasolite. However, the coral fossils indicated the limestone was rather the Late Triassic than the Palaeozoic in age, therefore, the late Triassic sediments in the Guoganjianian Mountain area comprised not only the Wanghuling Formation clasolite but also the interbedded limestone among the Wanghuling Formation clasolite. it doesn＇t exsit the tectonic phenomenon that the Palaeozoic limestone was jumbled in the Late Triassic clastic sediments. The Qiangtang Central Uplift was thought to have been uplifted and seperated the Qiangtang Basin into the North and the South Qiangtang Depressions during the Late Triassic before, however the newly discovered coral fossils, together with the radiolaria and coral biostratigraphic data in the Caima＇er Co area reported by others, displayed the existence of the Late Triassic marine depositions in the Qiangtang Central Uplift, and further indicated that the Qiangtang Central Uplift was rather marine sedimentary area rather than terrestrial erosion area during the Late Triassic. Thus it is necessary to reconsider the previously established ＂One Uplift and Two Depressions ＂tectonic understanding and the palaegraphic restorations of the Qiangtang Basin during the Late Triassic.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2010年第8期1095-1104,共10页
Acta Geologica Sinica
基金
中国地质科学院地质研究所基本科研业务费项目(编号J0719
J0807和J0902)
国土资源部百名优秀青年科技人才计划项目
国家自然科学基金项目(编号40772023
40502004和40572018)
中国地质调查局项目(编号1212010911030
1212010561605和1212010611702)
中石化项目"藏北戈木错盆地及其相关地区基本石油地质条件研究"联合资助成果
关键词
西藏
羌塘盆地
中央隆起带
望湖岭组
晚三叠世
珊瑚
Tibet
the Qiangtang Basin
the Qiangtang Central Uplift
the Wanghuling Formation
the Late Triassic
coral
