摘要
根据在庐山山上和庐山东麓采集的基岩和沉积物砾石标本薄片鉴定，发现山上基岩和山麓沉积物在岩性之间没有必然的联系。山麓大多数沉积物在岩性和沉积相上类似于白砂井组，作者认为该沉积物主要是古赣江上游搬运来的物质。论证了网纹红土主要是中更新世初湿热低平地形下形成，而庐山现今１０００－１２００ｍ高度存在着变位网纹红土，由此推论，庐山在网纹红土形成后（中更新世中期以来）的新构造运动中，山体抬升了约６００－８００ｍ。
Since 1930′s, the genesis of the Quaternary sediments in the east piedmont of the Lushan has been argued. J. S. Lee had ever taken the Quaternary sediments from Gutang (poyang Lake shore) at the moraine of the first glaciation──'Poyang Glaciation' . Lithology investigation and the source analysis for the hilltop and the piedmont is an important aspect for revealing Quaternary depositional environment on the Lushan Mountain. According to the lithology identification of 24 thin-sections (the sample selected from the hilltop and piedmont). the author finds that there is not an obvious relationship of erosion, transportation, sedimentation. For instance. on the hilhop and the a slope, there are not red quartzite. yellow metamorphic quarzose sandstone in Gutang, white quartzite, gray gneissoid quartzite in Jiangpochang. gray-yellow quartzite in Dapailin. and lessmetamorphic muscovite quartzose-sandstone. gray-yellow quartz-schist. red quartzite in Jindingshan. Besides, the piedmont sediments have a feature of binary sediment, their gravel has a very well psephicity and weathering ratio. In lithology and sedimentary facies, their features are very similar to the Bashajing Formation of the Poyang Lake. According to his own and other colleagues′testing results of paleomagnetic, the author finds that the reticulate pattern ground of the east piedmont are mainly located in plus polarity zone of Brunhes normal epoch. Combining the analysis of the stratigraphic sequence, he considers that the sediments were formed in the Middle Pleistocene and were mainly transported from the former Gan River.More and more facts have proved that the reticulate pattern ground were formed in the early period of the Middle Pleistocene. At that time. the climate was humid-hot and pluvial. its annual mean air-temperature war 18-28℃. and its precipitation was about 1000-3000 mm.At present, the upper limit of reticulate pattern ground is about 400 m a. s. l. on the piedmont of the Lushan Mountain, but we can see the shift reticulate pattern ground in Dajiaochang, the west valley and the central valley between 1000-1200 m a. s. 1. At this elevation, its present annual mean air-temperature is only 11. 4℃or so.So we can deduce that the shift ground should be formed during the uplifting neotectonic period.The maximum uplift period for the Lushan block shold be in the middle period of the Middle Pleistocene after the formation of the ground, and it shouldn′t be in the early period of the Middle Pleistocene as the former researcher said. The Lushan block has been uplisted about 600- 800 m since the middle period of the Middle Pleistocene.
出处
《地理学报》
CSSCI
CSCD
北大核心
1995年第1期41-50,T002,共11页
Acta Geographica Sinica
基金
国家博士后科学基金
关键词
庐山
第四纪
沉积物
新构造运动
Lushan Mountain
Guaternary sediments
Neotectonics
