On Study Of Continental Special Deposits And Paleocilmate In The Earlier Cretaceous In China

By systemically summarizing geological data, the following types of continental special deposits which can indicate climate character can be identified:calcare ous deposit, flammability organic rock, evaporite, desert sedimentary system, lateritic weathering crust, ferruginous deposit, copper-bearing deposit, volcanic deposit, limestone, dolostone, bentonite, the climate characteristics reflected can by generalized:flammability organic rock, pyrite goes with coal, pyrite nodules and siderite nodules reflect the warm and humid climate. Lateritic weathering crust, ferruginous deposit reflects the hot and hot～humid climate. Gypsum and limestone reflect the warm dry climate. Rock salt, calcium Glauber, desert depositional system and dolomite reflect the hot and dry environment. Volcanic-related deposit may reflect the high-temperature environment; calcium deposit, copper deposit, bentonite reflect the arid～semi-arid climate. on the basis of distribution map of 6 periods of the earlier Cretaceous, we found that calcium deposits distribute widely in the northwest, central and eastern regions, particularly in Hauterivian～Albian, the distribution significantly exceed that in previous period; Volcanic-related deposits are mainly distributed in Northeast China, Inner Mongolia and eastern regions, volcanic deposits in Valanginian reduced relatively in the eastern coastal areas, AFTER THAT, the distribution area gradually increase. In the northeast region, the distribution is the most intensive in Aptian. Coal mainly distributes in the northeast, Inner Mongolia, Gansu province and eastern regions. The distribution areas in Berriasian grow at the beginning and then gradually narrowed to some extent; the oil shale mainly distributes in Inner Mongolia, northeast China, from Aptian on, the distribution was processing a sharp contraction. Only in Heilongjiang and Jilin provinces can we see sporadical distribution; gypsum and rock salt mainly distribute in the northwest, especially in Gansu, Inner Mongolia, Ningxia, Qinghai. From Aptian on, distribution areas in Inner Mongolia began to decline sharply; Limestone mainly distributes in the eastern and northwestern regions. From Barremian on, we could find Limestone in coastal areas, and the distribution gradually expands; dolomite distribution area is very small, generally found in the eastern coastal regions; bentonite distributes in western Inner Mongolia and Fujian province, in Berriasian～Hauterivian, the areas of distribution gradually expand, later gradually shrink, so even to Albian, we did not find a bit of them. The distribution areas of Pyrite and siderite are very small, and we only find them in southeastern of Gansu province and in mid-west of Shaanxi province. Desert deposits in western Xinjiang survive all the time. But until Aptian, it began to appear in Sichuan province; trivalent iron deposit appears in the mid-south region and Hainan Province, but the distribution area is limited. According to the distribution and combination characteristics of the Special Deposits,6 kinds of weather can be figured out.①warm and humid climate;②warm and humid-warm and dry climate;③warm and dry climate;④hot and dry-arid climate;⑤hot and dry-warm and dry climate;⑥hot and dry climate. Based on the characteristics of the climatic zone in six periods, seeing on the view of space, the Early Cretaceous climatic zone reads in the geographical map of China:this line, dry heat～arid climate zone in Kashgar Golmud-Chengdu, is the center of the climate zone. Moving to the north east, Southwest sides, the climate become relatively warm and humid, showing an inverted "V". Climatic zone is the superposition of zonal and meridional distribution, which is obviously embodied in Berriasian-Barremian. From the standpoint of time, comparing Aptian-Albian with the next period, climate types in the eastern area are less than that before; In Hauterivian, the distribution area of warm and humid climate was relatively smaller, while the distribution area of arid climate zone of warm～warm and dry climate, warm and dry climate zones and dry heat～arid climate zones is the largest. At the same time, in Ningxia, eastern Gansu, Shaanxi, southeastern of Liaoning, east of Hebei and north of Shandong, there are two dry and hot climate areas, reflecting the driest and hottest period in the earlier Cretaceous. The distribution area of the warm and humid climate, warm and humid climate zone in Albian was the largest, reflecting the increase of humid climate in this period. This feature represented here may be related to the global sea level rise which is one of the largest transgression in the entire Cretaceous period.Further analysis shows that the climate in the Earlier Cretaceous of China is closely related to the patterns of basin shaped by Yanshan movement and the Cretaceous transgressive events. The uplift of series of mountains caused by Yanshan movement blocked the ancient Pacific Ocean warm and humid monsoon, resulting in keeping the hot and dry status in inland areas; The Earlier Cretaceous marine transgression events reflected in northeast China is because of the direct impact of ocean climate, sp the humid climate zone goes further expansion.