白垩纪早期陆相特殊沉积的分布特征及气候意义

通过对地质资料的系统总结,认为白垩纪存在有如下具有气候意义的陆相特殊沉积类型:钙质沉积、可燃性有机岩、蒸发岩、沙漠沉积体系、红土型风化壳、铁质沉积、含铜沉积、火山相关沉积、灰岩、白云岩和膨润土。利用所获得的早白垩世6个时期特殊沉积的分布图,可以对不同类型特殊沉积的时空分布特征进行讨论。结合特殊沉积所代表的气候意义,可归纳出如下气候指标:可燃性有机岩、与黑色(泥)页岩相伴生出现的黄铁矿及菱铁矿、膨润土是温暖潮湿气候的标志;红土型风化壳、三价铁质沉积是湿热-热气候的标志；石膏、灰岩反映了暖干气候。岩盐、钙芒硝、沙漠沉积体系、白云岩反映了干热环境。火山相关沉积可反映高温环境。钙质沉积、含铜沉积反映干旱-半干旱气候。根据特殊沉积的分布组合特征,可划分出6种气候类型:（1）暖湿气候;（2）暖湿-暖干气候;（3）暖干气候;（4）热干-干旱气候;（5）干热-暖干气候;（6）干热气候。气候区在BerriasianBarremian期主要表现以纬向分布为特点,Aptian期和Albian期体现出纬向和经向两种分布方式的叠加,同时在中东部地区的气候带类型增多。其中Hauterivian期最干热,Albian期最湿润。

Distribution characteristics and climate significance of continental special deposits in the Early Cretaceous

By systemically summarizing geological data,we have identified the following types of continental special deposits that may indicate the climate characteristics,namely,the calcareous deposit,flammable organic rock,evaporite,desert sedimentary system,lateritic weathering crust,ferruginous deposit,copper-bearing deposit,volcanic deposit,limestone,dolostone,and bentonite.On the basis of distribution maps of 6 periods of the Early Cretaceous,we are able to discuss the temporal and spatial distribution characteristics of different special deposits.Combined with climate significance of continental special deposits,we summarized the climate indexes as follows:the flammable organic rock,the pyrite and siderite associated with black shale,and the bentonite reflect warm and humid climate;the lateritic weathering crust and ferric deposit reflect humid and hot-hot climate;the gypsum and limestone reflect warm and dry climate;the rock salt,glauberite,desert sedimentary system and dolostone reflect hot and dry climate;the volcanic deposits reflect high temperature climate;the calcareous deposit and copper-bearing deposit reflect arid-semiarid climate.On the basis of distribution and assembly characteristics of special deposits,six climate types can be classified:(1)warm and humid climate;(2)warm and humid-warm and dry climate;(3)warm and dry climate;(4)hot and dry-arid climate;(5)hot and dry-warm and dry climate;(6)hot and dry climate.The distribution of different climate areas was latitudinal zoning from the Berriasian to the Barremian.The distribution manner changed to the overlapping of latitudinal distribution with meridional distribution in the Aptian and the Albian,and at the same time,the types of climate area increased in the East.The climate was hottest and driest in the Hauterivian and was most humid in the Albian.