Discovery of Sand Wedge/Ice Wedge Cast of Last Glaciation in Wuhai Basin and Its Paleoclimatic Significance(PDF)
《地球科学与环境学报》[ISSN:1672-6561/CN:61-1423/P]
- Issue:
- 2016年第03期
- Page:
- 410-419
- Research Field:
- 水资源与环境
- Publishing date:
Info
- Title:
- Discovery of Sand Wedge/Ice Wedge Cast of Last Glaciation in Wuhai Basin and Its Paleoclimatic Significance
- Author(s):
- LI Da-wei; LI De-wen; SHEN Xiao-ming; SUN Chang-bin; KANG Yan-rui; ZHANG Ya-jiao
- Key Laboratory of Crustal Dynamics, Institute of Crustal Dynamics, China Earthquake Administration, Beijing 100085, China
- Keywords:
- periglacial phenomenon; sand wedge; ice wedge cast; paleoclimate; last glaciation; OSL dating; grain size analysis; Wuhai Basin
- PACS:
- P931.4
- DOI:
- -
- Abstract:
- The periglacial phenomena like sand wedge/ice wedge cast have been discovered with the paleoclimatic and paleoenvironmental significances in the northern China. But most of them are dated to the late stage of last glaciation. The periglacial phenomenon discovered firstly in Wuhai Basin was reported. Characteristics of morphology, grain size analysis of filler and OSL dating were applied to identify the origin and age, including that the early primary sand wedge encompasses a set of structures almost parallel with the wall around it, and the late ice wedge cast (including its formation, melt and fill) is superposed on the sand wedge. The ice wedge cuts through and damages the structure of the primary sand wedge, and the wedge is characterized with bend and irregular boundary as a whole. OSL dating results show that the primary sand wedge is formed during the early last glaciation ((62.69±6.81)-(66.45±7.08)ka B.P., MIS4), and may go down to MIS3b; the filler of ice wedge cast is formed during the Middle Holocene ((5.95±0.61)-(6.62±0.73)ka B.P.). Because the filling of ice wedge cast is later than the formation of ice wedge, it is probably that the formation of ice wedge is during the late last glaciation. Based on the formation process of sand wedge/ice wedge cast and their environmental requirement, it is estimated that the annual mean temperature has dropped 12.1 ℃-13.6 ℃ from the formation of sand and ice wedges to present, and the annual precipitation is of no significant difference from the formation of sand wedge (the early stage of last glaciation) to present. The discovery of sand wedge/ice wedge cast in Wuhai Basin could provide a basis for studying the distribution of permafrost and the paleoclimate during the last glaciation (especially the early stage) in the northern China.
Last Update: 2016-06-02