渭河阶地全新世成壤环境演变的高分辨率研究

对秦岭北麓渭河阶地全新世土壤剖面进行的高分辨率分析研究，揭示了该地区全新世土壤剖面的黄土-古土壤序列，是由于季风气候变化引起的以风尘堆积占优势的成黄土期和以生物风化作用占优势的成壤期相互更迭造成的。马兰黄土堆积所代表的晚更新世，气候冷干，当地为半荒漠环境；全新世初期是气候转暖转湿的过渡时期；全新世中期(85003100 a B．P．)发育的古土壤S0成壤作用最为强烈，为褐色土类型，分析研究表明其中既有淋溶淀积作用，又有粘化作用发生；各项分析指标也都表明S0反映了全新世中期的温暖湿润气候；在该土壤层形成初期，就有属于老官台文化(7500～7000 a B．P)时期的人在当地从事耕作活动。此后，新石器时代中晚期也有人类开发利用当地的土地资源。全新世晚期从3100 a B．P开始，西北季风增强，气候恶化，但当地降水量的减少似乎滞后于降温，所以先周和西周时代在沣河西岸建立都城的时期，当地土壤湿度似乎较大，而之后则显著干旱化。

High-resolution study on pedogenic environmental change of the Weihe river terrace in the Holocene

A high-resolution Holocene loess-soil sequence of the Weihe Terrace at the pediment of the Qinling Mountains was studied multi-disciplinarily. It indicates that this loess-soil sequence has been developed by Eolian dust deposition and the bio-pedogenesis controlled by monsoonal climatic changes. The Malan Loess was deposited by dust storms in a cold and dry semi-desert environment before 11500 a B.P. The transitional layer between the Holocene soil and the Malan Loess was developed in the early Holocene between 11500~8500 a B.P. when a climatic amelioration occurred. Very strong bio-pedogenesis occurred during the mid-Holocene between 8500~3100 a B.P. when a fertile Cinnamon soil was developed with leaching and argillic processes. All of the climatic proxies indicate this soil was formed in response to the warm and moister Holocene Megathermal. The Neolithic cultural remains identified in the soil profile show that arable cultivation was initiated between 7500~7000 a B.P. the land has been continuously cultivated during the whole Neolithic period. A climatic decline took place during the late Holocene from 3100 a B.P. The intensified Northwest monsoon and dust storms has caused a degradation of soil and land resources. A newly deposited loess has buried the mid-Holocene soil which is presented as a palaeosol in the profile now. The climatic aridity caused the people of the Zhou Dyansty to relocate their capital city from the higher loess tableland to this lowland of river terraces where the soil humidity remained relatively high, which is favorable for the arable farming. But, thereafter, the climate became remarkably dry.