黄土高原上新世气候变化与气候事件的风尘沉积记录

Environment and climate changes during the Pliocene time in north China is not clear to date. The Red Clay deposit has offered a good record of the climate and environment changes. Samples from six Red Clay sequences and one lacustrine deposit of the Pliocene time are taken with higher time resolution, more than 10,000 samples are measured to investigate dust deposition process, atmospheric circulation and climatic changes during the Pliocene time. On the basis of the Paleomagnetic stratigraphy dating as well as vertebrate fossil excavated, the time frames are obtained. Grain size, Rubidium and Strontium content, magnetic susceptibility as well as the light of bulk samples and the grain size of the chemically extracted quartz, which can be employed as proxy index of the paleoclimate and the palaeoenvironment, are measured. Our results are : (1) Offering sedimentology evidences for aeolian origination of the Red Clay Deposit; (2) Climate in the Pliocene in the north China is relatively warmer and wetter, and, the East Asian monsoon system may be existed since then; (3) There are 104-105 year time scale variations of the palaeoclimate and palaeoenvironment in the north China during the 5.3-2.5 million years ago. We intend to examine the millennial time scale variation of the paleoclimate in this research. Because strongly modification of the Red Clay deposit and the low dust sedmentation rate which present low time resolution, paleoclimatic variations with short time scale are not confirmed. Futher investigations are needed.

对黄土高原六个上新世风成红粘土剖面进行系统采样，在较精确的时间标尺的基础上，测试化学提纯石英颗粒粒度、Rb和Sr含量、白度、磁化率等古气候代用指标。认识5.2-2.5MaBP仆粮咴蛲虻桨偻蚰瓴煌奔涑叨缺浠卣骱凸媛桑剿餮枪斓朗奔涑叨绕蚴录鲜抖枪偶痉缪莼鞒龉毕住