Glacial advances and ESR chronology of the Pochengzi Glaciation,Tianshan Mountains,China   总被引：2，自引：0，他引：2  

ZHAO JingDong  LIU ShiYin  WANG Jie  SONG YouGui & DU JianKuo State Key Laboratory of Cryospheric Sciences  Cold  Arid Regions Environmental  Engineering Research Institute  Chinese Academy of Sciences  Lanzhou  China  Key Laboratory of Western China’s Environmental Systems  Lanzhou University  Institute of Earth Environment  Xi’an 《中国科学:地球科学(英文版)》2010,(3)

The Pochengzi Glaciation is a typical glaciation in Quaternary in the Tianshan Mountains. The glacial landforms comprise several integrated end moraines, like a fan spreading from the north to the south at the mouth of the Muzhaerte River valley and on the piedmont on the southeastern slope of the Tumur Peak, the largest center of modern glaciation in the Tianshan Mountains. The landforms recorded a complex history of the ancient glacier change and contained considerable information of the glacial landscape evolution, and dating these landforms helps us understand the temporal and spatial shifts of the past cryosphere in this valley and reconstruct the paleoenvironment in this region. Electron spin resonance (ESR) dating of the glacial tills in the upper stratum from a well-exposed section, end moraines, and associated outwashes was carried out using Ge centers in quartz grains, which are sensitive to the sunlight and grinding. The results could be divided into three clusters, 13.6–25.3, 39.5–40.4 and 64.2–71.7 ka. Based on the principle of geomorphology and stratigraphy and the available paleoen- vironmental data from northwestern China, the end moraines were determined to deposit in the Last Glaciation. The landforms and the three clusters of ages demonstrate that at least three large glacial advances occurred during the Pochengzi Glaciation, which are corresponding to marine oxygen isotope stage 4 (MIS4), MIS3b and MIS2. The landforms also indicate that the gla- ciers were compound valley glacier in MIS2 and MIS3b and piedmont glacier in MIS4, and the ancient Muzhaerte glacier were 94, 95 and 99 km at their maximum extensions in these three glacial advances.  相似文献   

2005年西藏波密古乡沟泥石流暴发成因分析   总被引：9，自引：3，他引：6  

鲁安新  邓晓峰  赵尚学  王丽红  张盈松  蒋熹 《冰川冻土》2006,28(6):956-960

青藏高原是我国滑坡泥石流等自然灾害最严重的地区之一,位于西藏波密县的古乡泥石流沟是川藏公路上重大灾害之一.在经过1966-2004年的弱活跃期后,古乡沟于2005年7月30日上午10:00左右、7月30日晚和8月6日上午8:00分别暴发了不同规模的大型冰川泥石流.淤积在公路面上的泥石流堆积物厚度达2 m左右,宽20多米,土方量约2×10⁴m³,多次中断交通运营,对川藏公路的畅通和当地人民的财产造成巨大的损失.通过实地调查研究和分析,发现这3次泥石流暴发的原因与1953年相似,均是由集中降雨和持续高温共同作用的天气所致.  相似文献   

A New Age Constraint on Sturtian Glaciation: SHRIMP U-Pb Zircon Geochronology Of Neoproterozoic Altungol Formation in Tarim Basin, NW China     

ZHOU Xiaobei  LI Jianghai  LI Wenshan  WANG Honghao 《《地质学报》英文版》2013,87(Z1):617-619

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Radiometric and stratigraphic constraints on terminal Ediacaran (post-Gaskiers) glaciation and metazoan evolution     

Craig L. Hebert  Alan J. Kaufman  Sarah C. Penniston-Dorland  Aaron J. Martin 《Precambrian Research》2010

Radiometric constraints on mid-Ediacaran Period glaciation (Gaskiers) in Newfoundland narrowed the known temporal gap between widespread ice ages and the evolution of complex metazoans to several million years. To further evaluate this claim we studied an Ediacaran glacial diamictite at the base of the Fauquier Formation of northern Virginia, and discovered a conformable relationship between the post-glacial cap carbonate and overlying volcanic rocks of the Catoctin Formation. U/Pb zircon age constraints for the rift-related volcanic flows suggest initial emplacement around 571 million years ago. Application of the Catoctin age to the Fauquier succession indicates the occurrence of an ice age about 10 million years younger than the 582 Ma Gaskiers event, supporting the view of multiple Ediacaran Period glaciations. Furthermore, the age constraint from eastern Laurentia falls within radiometric uncertainty of fossiliferous strata in Avalonia, indicating that the Fauquier glaciation was coincident with early metazoan evolution.  相似文献   

A note on the glacial and late glacial history of caithness     

Derek Flinn 《Geological Journal》1981,16(3):175-179

It is generally accepted that in the last glaciation Scottish ice from the Moray Firth flowed to the northwest across Caithness depositing shelly drift. Examination of striae along the east coast of Caithness shows that some were formed by ice flowing into and not out of the Moray Firth. It is argued that the flow into the Moray Firth may have occurred in the last glaciation and that the shelly drift may be a relic of an earlier glaciation. The cliffs of Caithness were formed during the Loch Lomond Readvance and have since been raised isostatically and so have been protected from further marine erosion by their own wave-cut platform which can be traced into Orkney where it intersects the present level.  相似文献