The Eruptive Timing of Permian Basalts in Keping Area, the Northwest Margin of Tarim Basin, China: Evidence from Detrital Zircons(PDF)
《地球科学与环境学报》[ISSN:1672-6561/CN:61-1423/P]
- Issue:
- 2017年第03期
- Page:
- 301-325
- Research Field:
- 基础地质与矿产地质
- Publishing date:
Info
- Title:
- The Eruptive Timing of Permian Basalts in Keping Area, the Northwest Margin of Tarim Basin, China: Evidence from Detrital Zircons
- Author(s):
- LI Jin-yi; LIU Jian-feng; ZHENG Rong-guo; FENG Qian-wen; ZHENG Pei-xi; ZHU Zhi-xin; WANG Li-jia; ZHANG Xiao-wei; SONG Biao
- 1. Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China; 2. Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, Xinjiang, China; 3. Xinjiang Mineral Resources Research Center, Chinese Academy of Sciences, Urumqi 830011, Xinjiang, China; 4. College of Earth Sciences, Jilin University, Changchun 130061, Jilin, China
- Keywords:
- tectonics; Permian; basalt; stratum; detrital zircon; eruptive timing; Keping area; Tarim Basin
- PACS:
- P588.14+5
- DOI:
- -
- Abstract:
- Permian basalts in Keping area, the northwestern margin of Tarim Basin, as part of Tarim large igneous province, consist of two interlayers in Permian sedimentary sequences. Up to now, there are two different viewpoints on the eruptive timing of those basalts in publications, one is 270-290 Ma, another one is about 290 Ma, which are controversial each other and discordant with biostratigraphy of the area. The eruptive timing of the basalts based on the sedimentary ages of Permian strata holding these basalts, which are constrained by detrital zircon dating data of 7 samples from 3 sections obtained by LA-ICP-MS zircon U-Pb dating method, was discussed. Three sandstone samples from sedimentary sequences under the lower basalts contain a moderate numbers of zircons with the ages of 275-290 Ma, implying that the oldest deposition age of the sandstone is not earlier than the late of the Early Permian. One sample (Kp10-1) from the sedimentary interlayer of the lower basalts contains 11 younger zircons with the ages of 270-279 Ma, and 20 grains with the ages of 280-289 Ma among 94 zircons. Three samples from sedimentary sequences between lower and upper basalts yield a big number of zircons with the ages of 260-280 Ma. These younger detrital zircon ages show that the depositing timing of Permian strata holding the basalts in Keping area is not early than the late of Early Permian, probably from Middle Permian to the early of Late Permian. Thus, it is impossible that the eruption of basalts in the area took place during Early Permian. Considering the fossils in the sedimentary sequences between two layers of basalts and above the upper basalts, and the long time from crystallisation through uplifting, denudation, and transportation to deposition of the detrital zircons, it is speculated that the eruption of basalts in Keping area took place in Middle-Late Permian, which means that the eruption of Keping basalts is possibly simultaneous with Emeishan basalts in South China.
Last Update: 2017-06-05