LA-MC-ICP-MS Zircon U-Pb Ages of Kaikukang Formation and Their Tectonic Implications in Mohe Basin, Northeast China(PDF)
《地球科学与环境学报》[ISSN:1672-6561/CN:61-1423/P]
- Issue:
- 2018年第03期
- Page:
- 237-251
- Research Field:
- 基础地质与矿产地质
- Publishing date:
Info
- Title:
- LA-MC-ICP-MS Zircon U-Pb Ages of Kaikukang Formation and Their Tectonic Implications in Mohe Basin, Northeast China
- Author(s):
- YANG Xiao-ping; HU Dao-gong; LIU Xiao-jia; ZHANG Wen-long; WANG Yan; WANG Chao-qun
- 1. Shenyang Center of Geological Survey, China Geological Survey, Shenyang 110034, Liaoning, China; 2. Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China; 3. Qiqihar Branch, Heilongjiang Institute of Geological Survey, Harbin 150036, Heilongjiang, China
- Keywords:
- zircon U-Pb age; tuff; sandstone; Lower Cretaceous; Kaikukang Formation; intermountain basin; thrust-nappe structure; Mohe Basin
- PACS:
- P597
- DOI:
- -
- Abstract:
- Based on the geological investigation of “Upper Jurassic” Kaikukang Formation in the northeast of Mohe Basin, Northeast China, an unconformity is found between Kaikukang Formation and the underlying Ershierzhan Formation of Middle Jurassic. Meanwhile, the ages of sandstone on the interlayer and volcanic rocks in Kaikukang Formation were determined by LA-MC-ICP-MS zircon U-Pb dating. The youngest weighted average age of detrital zircon U-Pb is 159 Ma, indicating that the lower limit of deposition is not earlier than Early Cretaceous; the magmatic zircon 206Pb/238U ages obtained in the interlayer of volcanic rocks are (136.6±1.9)Ma and (137.5±2.5)Ma respectively, and they are in accordance with the age of reflection in the late fossil association of Coniopteris-Phoenicopsis flora and the early fossil association of Ruffordia-Onychiopsis flora in Kaikukang Formation. All these ages and fossils strata comparison results show that Kaikukang Formation forms in the early Early Cretaceous, rather than Late Jurassic classified by previous research. The structural unconformity between Kaikukang Formation and the underlying Ershierzhan Formation should be formed during 137-145 Ma according to the dating results, and this further restricts the formation time of Mohe thrust-nappe structure and the transformation age from Jurassic extensional basin to Cretaceous compresses intermountain basin after Mongolia-Okhotsk ocean closed. This redividing for Kaikukang Formation provides a new geological information for further studying the relationship between Mohe Basin and Mongolian-Okhotsk orogenic belt.
Last Update: 2018-06-05