Pan Mao, Yun Zukeng, Ma Mingliu, Zheng Chunjiang, Mo Dingxin
1992, 12(3): 202-209.
The Quaternary strata along the main reaches of the Beijiang River in Guangdong Province are poorly developed and less studied.The main characters can be summarized as being;(1) discontinuity in spatial distribution;(2) incompletion in time distribution;(3) small thickness;(4)lack of fossils.Through detailed field surveying,mainly by means of geomorphological correlation(terraces and caves),sediment analyses,14C and U-series timing,combined with drilling,a division scheme of the Quaternary strata in this region is put forward.
1.The red-clayey conglomerates on the third terrace in Shaoguan Basin may have been formed in Early Pleistocene(Q1) or earlier,while in Yingde Basin,the third terrace is under-developed,only developed the first and second tarraces, which can be correlated with their counterparts in Shaoguan Basin.The conglomerates on the second terrace were formed earlier than Maba Man fauna and later than Early Mid-Pleistocene(Q21).The yellow clayey silts on the first terrace were formed in Early Holocene(later than 18000-19000 a B.P.).2.Qingyuan Basin is significantly different from Shaoguan and Yingde Basins.There is no statum of Lower or Middle Pleistocene,Only a thin cover of late Pleistocene fluvial sediments(Q33)overlying on the weathering mantle of basic rocks.The Holocene strata of this basin developed well,whose thickness being 20-30 m,and geomorphologically being a wide fluvial plain.From bottom to top,the Holocene strata can be subdivided into four formations: Sanjiao Formation,Henglan Formation,Wanqinshan Formation and Denglongsha Formation.The time of each formation is respectively 7500~12000 a B.P.,5000-7000 a B.P.,2500-5000 a B.P.and 2500 a B.P.The sands and gravels at the bottom of Sanjiao Formation may belong to Upper Pleistocene.