%0 Journal Article
%T THE PROCESS AND ENVIRONMENT OF POLAEOKARST IN THE NORTHEAST AREA OF QINGHAI-XIZANG PLATEAR<br>青藏高原东北部古喀斯特过程与环境
%A Cui Zhijiu
%A Hong Yun
%A Gao Quanzhou
%A <br>崔之久
%A 陈怀录
%J 地理学报
%D 1996
%I 
%X The widespread distribution of karst landforms in the limestone area of Qinghai-Xizang Plateau in China has attracted attentions from geomorphologists. The preliminary study in the nonheast area of the Plateau indicates that the main types of karst include pinnacle karst, clints, limestone wall, cave and "widow-like cave", and etc.The results of fission track (FL) dating of recrystalized calcites in karst caves are 15.70 MaBP,12.19 MaBP,11.68 MaBP and 10.57 MaBP respectiwly(Tab. 4),Which are all in the mid-Miocene Epoch.The results from the analysis of relevant deposit,which is relic terra rossa or red regolith,reflect a kind of subtropical climate. The vahe of SiO2/Al2O3 is about 3.30 (Tab.2),which is similar to that of the soils under subtropical. climate. X-ray diffraction analysis indicates that the average content of kaolimte in caly minerals is over 20%(Tab.3),even over 50% in some samples(such as Hx and Lms-1 and Mc-2). The quartz sand grains were studied under the ebctronic scanning microscope(SEM), some chemical modification features (Fig.2) on the grain surface indicate that the terra rossa was formed under warm and humid climate.Two main reasons contribute to the karst evolution in this area, they are the uplift of QinghaiXizang Plateau and the northwards shift of latitudinal zone since the Pliocene. The karst evolutioncan be divided into 3 slages(Fig.3),the first stage:intense karst process,the second stage:coutinning karst process, and the third stage: mechanical weathering and relic karst process.
%K Qinghai-Xizang Plateau
%K Polaeokarst
%K Red regolith
%K Environment evolu tion<br>青藏高原
%K 古喀斯特
%K 风化壳
%K 环境演变
%K 喀斯特地貌
%U http://www.alljournals.cn/get_abstract_url.aspx?pcid=E62459D214FD64A3C8082E4ED1ABABED5711027BBBDDD35B&cid=869B153A4C6B5B85&jid=F7B5B947C24B9D649491012214E4BEF4&aid=D5FDF62DF45840C1&yid=8A15F8B0AA0E5323&vid=987EDA49D8A7A635&iid=94C357A881DFC066&sid=A53D7AA35F9929AF&eid=B6673406DE97CC60BBF0ECBD3B9B44BD&journal_id=0375-5444&journal_name=地理学报&referenced_num=3&reference_num=22