中国第四纪地层

本文综述了中国第四纪沉积类型及第四系的划分，并与国际第四系划分进行了对比。指出中国第四纪沉积物分布广泛，种类繁多，以陆相沉积为主。按其成因主要有风成黄土堆积、河一湖相沉积、冲一洪积堆积、冰川沉积、洞穴堆积、风化壳残积（红土）、火山堆积和海相沉积等。各种沉积物都有很好的剖面，尤其是黄土和河一湖相沉积更为连续完整。按中国第四纪地层发育的实际情况，第四系的底界应置于松山一高斯极性转换界线（Ｍ／Ｇ，２．６ＭａＢ，Ｐ，）；第四系内部划分为更新统（Ｑ_ｐ）和１４新统（Ｑ_ｈ），界线在１１０００ａＢ，Ｐ，。更新统进一步划分为下、中和上３个阶(Ｑ_ｐ１， Ｑ_ｐ２， Ｑ_ｐ３)， Ｑ_ｐ２／Ｑ_ｐ１的界线为布容一松山极性转换界线（Ｂ／Ｍ； ０．７８ＭａＢ，Ｐ，）；Ｑ₍ｐ３_／Ｑ_ｐ２的界线为本次间冰期的起始时间（０．１２８ＭａＢ，Ｐ，）。

QUATERNARY STRATIGRAPHY IN CHINA

Quaternary sediments in China are mainly consisting of aeolian sediments, lacustrine sediments, glacial sediments, weathering crust sediments, biotic deposits, cave deposits, volcanic deposits, and sea faces sediments. Among them, loess and lacustrine sediments are characterized by their vast distribution, tremendous thickness, almost complete sequence, and long term continuity. Loess-paleosol sequence is typical Quaternary stratigraphy in China, which can be subdivided in to three units named Wucheng Huangtuan, Lishi Huangtuan and Malan Huangtuan from the bottom to the top in the fifth edition of International Geological Time Table. Quaternary in China was used to be divided into four parts: Early Pleistocene (Q1), Middle Pleistocene (Q2), Late Pleistocene (Q3), and Holocene (Q4). This division is unconformity with international dichotomy of Pleistocene (Q1), and Holocene (Q2). To avoid confusion, we propose to substitute Qp for Q1 (Pleistocene), including Chinese Q1, Q2 and Q3, and substitute Q2 for Q2 (Holocene). Pleistocene can be further divided into Lower Qp1, Middle Qp2, and Upper Qp3. The present Pleistocene / Pliocene boundary is at the top of the Olduvai normal subchron, corresponding to the bottom of MIS 62 and bottom of paleosol S24 in China loess--paleosol sequence. International Geological Time Table adopts 1.8--l.6MaB. P. as start--age of Quaternary. Some Chinese scientists suggest that the Pleistocene/Pliocene boundary is fit lower to Matuyama/Gauss reversal (2.6MaB.P.),which is corresponding to the boundary of loess/red clay and the end of the MIS 104. Qp2 / Qp1, boundary locates at Brunhes/Matuyama reversal (0.78MaB.P.), corresponding to the lower Part of loess L8 and the end of MIS 19. Qp3,/Qp2 boundary is 0.128MaB.P., corresponding to the bottom of paleosol S1 and the beginning of MIS 5e. Qh/Qp boundary is 0.01 IMaB.P., corresponding to the bottom of paleosol S0 and the end of MIS 1.