1999 Vol. 5, No. 4

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SOME CONSIDERATIONS ON THE ENVIRONMENTAL GEOSCIENCE AND LAND IMPROVEMENT IN THE YELLOW RIVER BASIN
WU Xi-hao, JIANG Fu-chu, LEI Wei-zhi
1999, 5(4): 3-12.
Abstract (107) PDF (88KB)(5)
Abstract:
In this paper, a comprehensive description of the environmental geoscience background of the hanging river and the streamflow break in the lower reaches of the Yellow River is made from a combination of geology and geography, meteorology and climatology, hydrology and sediment, vegetation and soil, as well as human and population. The history of the change of course of the Lower Yellow River and its present state are analysed from an integration of flood and dam defence, dam breach and change of course, distributary and canal, as well as hanging river and flow break. It is proposed that countermeasures against water depletion and the resulting streamflow break flood, environmental deterioration etc. be immediately taken to improve the land in the Middle and Upper Yellow River Valley including observation of the natural law, reorientation of thoughts on water/soil conservation increase of local ponds to impound water control of surface evaporation and gully/valley development and stream-harnessing.
PLEISTOCENE ENVIRONMENTAL MEGAEVOLUTION AS INDICATED BY THE SPOROPOLLEN FLORAS IN CHINA
TONG Guo-bang, CHEN Yun, WU Xi-hao, LI Zheng-hua, YANG Zhen-jing, WANG Shu-bing, CAO Jia-dong
1999, 5(4): 13-23.
Abstract (174) PDF (315KB)(10)
Abstract:
By an analysis of the sporopllen time sequences from samples of 38 sections, a discussion of the vegetational and environmental megaevolution in China during the time of 1.6MaBP~0.8MaBP was made, with the result that we have 2 zones of the sporopollen assemblages and 2 palynoclimate events. It is pointed out that it was the period of the worst environment in the pleistocene, during which vegetation was very sparse, with dominantly forest-steppe and steppe in northern China, desert or desert-steppe in northwestern China and forest and shrub-steppe in southern China. It has been shown that the climate was then cold and dry, with a of 15~17℃ temperature drop and decrease En precipitation of 300~500mm. As a result no reappearance of subtropical plant has since occurrred in North China and further north, but an initial form of the present vegetation cover. There after there was a more frequent and larger flora fluctuation. The change of spruce pollen in Qaidam Basin shows that the Qinghai-Tibetan Plateau had then been uplifted to a height that could cause a transformation of the vegetation.
STUDY ON MAGNETOSTRATIGRAPHY IN QINGHAI-TIBETAN PLATEAU IN LATE CENOZOIC
QIAN Fang
1999, 5(4): 24-36.
Abstract (116) PDF (214KB)(6)
Abstract:
In this paper, the polarity epochs of some twenty and more sections or boreholes in Qinghai-Tibetan plateau in Late Cenozoic are discussed in detail, and thence we have the ages of the sediments involved. The Qiangtang Formation at Kunlun pass has an age of 3.1MaBP~0.65MaBP, the Hipperion sp. contained in it being of an age of 2.08MaBP.The Gongba Formation at Dingri county 2.31MaBP~1.90MaBP, the Zhada Formation and Xiangzi Formation in the Zhada Basin 6.15MaBP~3.40MaBP and 3.40MaBP~1.25MaBP respectively, and Jiawa Formation at Litang 1.24MaBP~0.43MaBP. And the age for the Hipperion guizhongensis sp. from Jilong is 5.0MaBP. The age of early Quaternary glaciation is obtained as well. Thus a chronological scale is provided for the study of the time, and rate of the uplifting of the Plateau as well as the consequent environmental changes.
ON THE AGE OF LOESSAL SEDIMENT AROUND QIAOJIA IN THE JINSHAJIANG RIVER VALLEY
JIANG Fu-chu, WU Xi-hao, WANG Shu-bing, TIAN Guo-qiang, LIU Ke
1999, 5(4): 37-42.
Abstract (151) PDF (139KB)(12)
Abstract:
There is a wide distribution of thick loessal sediment around Qiaojia in the Jinshajiang River valley, especially near the Huatan area, Ningnan county, Sichuan province on the left bank.The sediment is very thick, rich in calcareous concretions, and with no clear bedding.A detailed magnetostratigraphic study combined with thermoluminescence dating of seven sections of the sediment shows that it was deposited during the late Brunhes normal epoch, and has a geologic age of Late Pleistocene to Holocene.
THE NEOTECTONIC SETTING OF LATE QUATERNARY TRANSGRESSIONS ON THE EASTERN COASTAL PLAIN OF CHINA
WANG Qing, TIAN Guo-qiang
1999, 5(4): 43-50.
Abstract (199) PDF (198KB)(11)
Abstract:
The study of boreholes in the subsided coastal plain and in offshoe area in China shows that at the most part of Quaternary sea water had been blocked from invading the Yellow Sea Basin and Eastern China Sea Basin as a result of the uplifting of Fujian-Lingnan when the Qinghai-Tibetan Plateau was rising at an unprecedented rate.The subsidence of most of Fujian-Lingnan uplift to the sea floor since Late Quaternary had kept the isostatic balance between the Qinghai-Tibetan Plateau and Japan-Ryukyu Island Arc.As sea water entered into the East China Sea and Yellow Sea Basins since about Late Pleistocene, China continent became closely linked to the sea, due to the crustal deformation of the subsidence of continental basins and the corresponding uplifting of the Qinghai-Tibetan Plateau.Since then there has occurred complex land-sea interaction between the Yangtze River, Yellow River, Luanhe River and transgressions caused by the eustatic changes.
TECTONIC CLIMATE RESPONSE IN THE GEOMORPHOLOGY OF THE WEIHE RIVER VALLEY AROUND BAOJI, SHAANXI PROVINCE
CHEN Yun, TONG Guo-bang, CAO Jia-dong, LI Zheng-hua, JIA Yan-kun, XU Jian-ming, YANG Zhen-jing
1999, 5(4): 51-58.
Abstract (169) PDF (150KB)(8)
Abstract:
There have been developed five stages of terraces, formed in 1.2MaBP, 0.8MaBP, 0.5MaBP, 0.13MaBP, 0.009MaBP, respectively, in the Weihe river around Baoji, Shaaxi Province.Each of these stages is considered to be the response to the corresponding large up lifting and consequent climatic changes during the rising of Qingzang Plateau's since middle period of early Pleistocene, witnessing tectonic climatic cycles and subcycles of a period of about 0.4Ma and 0.1Ma.Such scale tectonic climatic cycles well agrees with the astroclimatic circles recorded by loess-paleosol sequence.This shows that there may be some causative relation between them. A knowledge of the relation will be helpful to the undertanding of the environmental evolution of the region.A preliminary discussion on the age of the passage of the Weihe river through the Longshan Mt.and the formation of a unified drainage system of it.
A STUDY ON THE AGE OF SANMEN GROUP IN SANMENXIA AREA
WANG Shu-bing, JIANG Fu-chu, WU Xi-hao, WANG Su-min, TIAN Guo-qiang, XUE Bin, ZHENG Hong-bo
1999, 5(4): 59-67.
Abstract (199) PDF (169KB)(9)
Abstract:
The lacustrine deposits of the ancient Sanmen Lake have been preserved in good condition in the Huangdigou profile which is located at the north of Sanmenxia Reservoir in Pinglu County of Shaanxi province.From a study of the magnetostratigraphy, the deposition of the ancient Sanmen Lake is known to have started in the middle of Gilbert reversal polarity chron, about 5MaBP, and ended in the late of Brunhes normal polarity chron, about 150kaBP. Since the sedimentary sequence has persisted from the early Pliocene of Neogene to the end of middle Pleistocene of Quaternary, it is referred to as the Sanmen group.Based on the lithological characters, the sequence can be subdivided into three members, the upper member consisting dominantly of sand layers, the middle member of clay layers and the lower member of basal gravel.The series is now known to have the longest period of deposition that commenced earlier and terminated later than all the others.
RECORD OF PALEOENVIRONMENTAL CHANGES IN PINGDINGCUN SECTION, HEBEI PROVINCE
CHI Zhen-qing, MIN Long-rui
1999, 5(4): 68-74.
Abstract (134) PDF (319KB)(5)
Abstract:
From field observation, sporopollen analysis and 14C dating of samples collected from the Pingdingcun Section, Hebei province, the sediments involved are determined to have formed from Late Pleistocene to Early Holocene.According to an estimate of the temperature then prevailing by Fe3+/Fe2+ ratio and an analysis of the change of CaCO3 content, the paleoclimate of the Yangyuan area has obviously experienced four stages in the period, i.e. warm-humid, cold-dry, cold-humid and warm-dry stages.The sporopollen assemblages reflect that a change in vegetation from forest to grass land has occurred.
A STUDY OF PALEOCLIMATIC FLUCTUATIONS IN THE LAST 2600 YEARS IN THE NINGJIN LAKE AREA,HEBEI PROVINCE
GUO Sheng-qiao, SHI Ying, YANG Li-juan, CAO Jia-dong, ZHANG Wen-qin, ZHANG Jing, LIN Fang, HE Jian-xin
1999, 5(4): 75-81.
Abstract (141) PDF (153KB)(8)
Abstract:
Based on the data of sporpollen assemblages, clay minerals, and grain size of the Nanwangzhuang section in the Ningjin lake area, and the timescale established from the age/grain size model by Porter et al, the climatic fluctuations in the last 2600 years are brought out to light as reflected by the seven sporopollen zones.Zone Ⅰ representing a cold and dry climate was ca.200~630 aBP in age, Zone Ⅱ formed in a warm and humid climate in ca.630~1010 aBP, Zone Ⅲ indicative of a cold and humid climate was of an age of ca.1010~1165 aBP, Zone Ⅳ again warm and humid in ca.1165~1350 aBP, Zone Ⅴ, being characteristic of a slightly cool and dry climate was ca.1350~1790 aBP old, Zone Ⅵ, warm and a little dry in ca.1790~2250 aBP, Zone Ⅶ cold and dry in ca.2250~2580 aBP.Such climatic fluctuations well accord with the historical records and may be of a global significance.
AGES OF THE YELLOW RIVER DELTA IN SHELF REGIONS OF THE YELLOW SEA AND THE BOHAI SEA
YU Hong-jun
1999, 5(4): 82-90.
Abstract (202) PDF (219KB)(11)
Abstract:
There are two different opinions for the formation history of the Yellow River, one postulates that the Yellow River might have come into existence before Tertiary, the other supposes that it joined up into a long river only in the late stage of Upper Pleistocene.The presence of the whole course of the Yellow River is believed to be closely related to the uplifting of the Tibetan Plateau.It is not likely that it would come into being before the high elevation river head was formed.Today's Yellow River is not known to occur during the recession of sea in glacial periods.In the last glacial stage, the climate was very harsh in the area north of the modern estuary of the Changjiang River, that some areas were permafrost and the others barren-deserts.At that time, the aeolation was the major exogenic force on the exposed shelf.Begining from 12ka BP, the global climate became warm, resulting in gradual disappear ance of continental glaciers retreat of mountain glaciers, and rise of sea level. Consequently, the Yellow River was replenished with water to become the modern river system.With continued rising of sea level, the Yellow River delta moved continuously towards the west and ushered in the history of human beings.
SINGLE ALIQUOT REGENERATIVE/ADDITIVE METHOD IN GLSL DATING OF QUARTZ
LAI Zhong-ping, ZHOU Jie, LU Yan-chou, A K Singhvi
1999, 5(4): 91-95.
Abstract (150) PDF (84KB)(8)
Abstract:
The most recent development in OSL dating is the single-aliquot method.It has a big advantage over the conventional multiple-aliquot technique.The sensitivity change in the repeated luminescence measurements is the crucial problem for this protocol.The singlealiquot regenerative/additive (SARA)method, using the regeneration and additive dose method together, can allow for the sensitivity change in the repeated luminescence measurements.In the present study, the SARA method was applied to the GLSL dating on quartz extracted from the aeolian samples from loess/desert transitional zone in China.The SARA results were in agreement with the results of the single-aliquot regenerative-dose (SAR) method and the conventional multi-aliquot additive dose method.