摘要
青海省同仁地区处于祁连和西秦岭造山带的接合部,构造演化历史悠久。对该地区隆务峡一带的三叠系剖面进行了详细测制。根据在该剖面上所获得的化石资料,初步厘定了该套地层的地质时代。在该剖面早三叠世晚期的江里沟组上段发现一套风暴岩沉积,丘状层理非常发育。剖面下部以Sc、Sd组合和Sc、Sd、Se组合为主,并伴随着风暴浊流沉积,属于一套较深水的沉积;上部以Sa1、Sc、Sd、Se组合和Sa2、Sc组合为主,是一套属于风暴浪基面附近的沉积产物。根据这些沉积构造特点和基本层序,判断其为远源风暴岩至B型近源风暴岩,下部为一套较深水型的远源风暴岩沉积,向上过渡为一套B型近源风暴岩沉积。风暴岩的发现表明,该区早三叠世晚期的沉积环境为风暴浪基面附近,早期海水逐渐变浅,晚期又出现了一个小的海侵。
Tongren area of Qinghai Province is located on the copulae of Qilian and West Qinling orogene, which has undergone a long enduring tectonic evolution process. A well disclosed Triassic section in the Longwuhe area was surveyed in detailed during this work. According to the fossils collected from this section, this paper has ascertained the chronology of this stratum roughly. A tempestite set was discovered in the upper member of the Jiangligou formation, which belongs to late Early Triassic by geologic timing, the hummocky bedding structure is well developed here. Major sedimentary combination of the lower part of the tempestite set belongs to relative deep water sediments, namely Sc, Sd and Sc, Sd, Se combination, accompanied by the stormy turbid deposition, while the upper part is Sa1, Sc, Sd, Se and Sa2, Sc combination, which belongs to sediments formed closed to the base level of storm wave. It＇s indicated by these features reflected from the sedimentary structure and basic sedimentary sequence that it belongs to distal type or proximal type B tempestite. The lower part of the section is a set of distal tempestite from relative deeper water environment which gradually transit into a near source type B tempestite upwards. Occurrence of these tempestite indicates that the sedimentary environ- ment of late Early Triassic in this area was somehow closed to the base level of storm wave. The sea level went down at the beginning, and then there was a small-scale transgression.
出处
《地质通报》
CAS
CSCD
北大核心
2009年第1期63-71,共9页
Geological Bulletin of China
基金
中国地质调查局<I48C001001(临夏市幅)
I48C001002(定西县幅)1:25万数字区域地质调查>项目(编号:200413000007)
高等学校全国优秀博士学位论文作者专项资金项目<造山带混杂岩区非史密斯地层研究>(编号:200228)资助
关键词
风暴岩
早三叠世江里沟组
古地理
西秦岭
tempestite
Early Triassic Jiangligou Formation
palaeogeography
West Qinling
