黄土中古土壤淀积类型

作者在西安附近发现了第１、４层古土壤的双层淀积和第５、８层古土壤多层淀积现象。资料表明，双层淀积、多层淀积和厚度异常大的ＣａＣＯ３淀积层是土壤具多元发生过程或受后期淋溶的产物，它们常代表两个或两个以上的成壤期。第１层古土壤下部的两层结构均不属古土壤组合部分，该层土壤为中、酸性森林土壤。第８层古土壤特殊的厚层淀积代表了气候的多次变化和多个成壤期。第４、５层古土壤具不连续ＣａＣＯ３和Ｆｅ２Ｏ３、Ａｌ２     

Progress of loess research in China

Progress in Chinese loess research made in recent 15 years was introduced in this paper, including mainly distribution and paleoenvironment significance of Chinese loess, new development of loess formation age, red-brown paleosol types and environmental change, loess-paleosol sequence and climate cycles, monsoon strength change during last interglacial and last glacial periods in the Loess Plateau, climate events, and source areas of loess and material.     

环境变化中土壤的响应与反馈

文章从古土壤及其环境信息、人类文明以来的土壤变化以及未来土壤环境变化的一些趋势3方面进行综述。指出土壤不仅是个历史自然体,而且是有自身发展变化规律的地球系统的一个圈层,土壤随地球系统的发展而不断演化;列举了我国主要埋藏古土壤和残余古土壤后指出,研究古土壤可揭示许多环境信息,发现未来变化的主要趋势;阐述了人类文明以来之土壤变化,包括建立了人为土,与此同时也引起了土壤退化。面对工业化与城市化以来出现的土壤环境问题,从土壤学角度提出了有关环境保护和农业可持续发展的对策和建议。     

Middle Terrace Deposits of the Tagus River in Alpiarça, Portugal, in Relation to Early Human Occupation

The stratigraphy and sedimentology of the Q3 middle terrace alluvial sequence in the lower Tagus river valley, Portugal, were studied near the village of Alpiarça, approximately 40 km upstream from the estuarine area. Two main stratigraphic units were recognized, separated by an important uncomformity. The Lower Gravels unit (LG) consists of intercalations of medium to coarse gravel deposits, mainly quartzitic, with coarse sandy matrix, organized in tabular bodies. The overlying Upper Sands unit (US) consists of tabular sandy channel deposits and overbank fines, the latter containing well-developed paleosols and backswamp deposits, showing a general aggrading trend, apparently with varying rates; available data indicate that deposition of the US took place under temperate climatic conditions. Within US deposits are several paleolithic archaeological sites, the lower ones in the alluvial stratigraphy being Middle Acheulian, whereas those embedded in overlying deposits are, from bottom to top, Upper Acheulian and Micoquian. Some of these sites have been recently excavated. The quartzite artifacts were apparently abandoned by early humans on the flood plain surface during deposition of the US unit and were subjected to limited reworking during their incorporation in the alluvium. TL/OSL dating of sandy-silty sediments, though imprecise, support archaeological evidence pointing to an age of 150,000 to 70,000 yr B.P. for the US unit.     

古红土的发育与演变

分布于江南丘陵地的第四纪红色粘土,通常由均质红土质、网纹层和砾石层所构成,它是第四纪初期的沉积物,但在一定程度上又具有成土作用的特征,故称为古红土。深厚的红色风化壳、酸性和高度富铝化是古红土的特点,而古红土上发育的红壤继承、保留了古红土的原有特征,又在生物作用和人为活动共同作用下形成生物富集的、表层复硅的、高度风化、发育的特征。因此,人有昔日和现在环境双重特征的地表红壤是由古红土发育、演变而成的典     

碱式水解法提取红土分子化石: 以安徽宣城更新世网纹红土为例

红土中种类丰富的分子化石为红土古生态研究提供了直接证据, 但较低含量的分子化石限制了传统索氏抽提方法的推广应用.本次研究尝试性地运用碱式水解法提取安徽宣城更新世红土中的分子化石, 在25g样品中检测到了含量明显、种类丰富的有机物, 且该方法可以显著地降低空白污染, 这说明碱式水解法在分子化石含量低的地质体(如红土) 研究中具有一定的应用潜力.本次研究检测出除了传统索式抽提得到的正构烷烃、脂肪酸、脂肪醇等以外, 还提取到了二元羧酸这一重要化合物, 它的存在为网纹红土可能形成于多水环境提供了新的证据.测试样品中各类分子化石组合信息显示出红土有机物以微生物为主的来源特征, 表明网纹红土形成过程受到了微生物活动的影响, 同时伴有大量低等菌、藻来源有机质的输入, 初步结果为红土形成环境研究提供了新的证据.      

内蒙古及东北地区古冻土及古环境考察研究新进展

中国北方地区保留了晚更新世以来大量的冰缘遗迹. 在气候变化背景下, 在寒区和干旱区分别出现冰缘地貌、正逆向沙化等问题, 综合不同区域的地质遗迹, 从时间上的对应关系可进一步分析气候环境变化问题. 2008年5-7月调查中, 在鄂尔多斯和大同地区分别发现了新的砂楔和土楔;在大兴安岭生态定位研究站设立了8个钻孔和2套自动气象站, 开启了冻土、湿地、 积雪研究以及现代陆面过程对下伏冻土影响的研究;在黄岗梁地区新发现了一个冻融褶皱;调查了松嫩沙地古沙丘及古土壤活动与冻土进退的关系;发现小兴安岭地区冻土退化显著, 岛状冻土散布于海拔相对较高的地区;三江平原西部农业开发强烈改变了地表覆盖, 冻土温度升高显著, 冻土上限下降明显, 甚至厚度较薄的冻土消失. 后期工作希望通过综合、集成分析以上结果, 探讨我国北方地区晚更新世/全新世的冻土南界及环境变迁.     

济源上三叠统古土壤及其意义

河南省济源地区上三叠统曲流河体系中发现赋存于洪泛平原和天然堤沉积中的古土壤,湖泊体系中则发现滨岸泥滩和湖泊淤浅古土壤。本文总结了其野外识别标志,探讨其成因,并讨论了将其应用于地层对比、层序地层学研究、盆地和沉积环境分析等方面的前景。     

Geochemistry of sericite deposits at the base of the paleoproterozoic aravalli supergroup, Rajasthan, India: Evidence for metamorphosed and metasomatised precambrian paleosol

Fine grained sericite deposits occur at the interface between Archean Mewar Gneiss Complex and the Proterozoic Aravalli Supergroup independent of shearing. They show a gradational contact with the basement granites and gneisses and a sharp contact with the overlying quartz pebble conglomeratic quartzites. Rip-up clasts of these sericite schists are found in the overlying conglomerates. The sericite schists are rich in sericite towards the top and contain chlorite towards the base. The sericite in these schists was formed by metasomatic alteration of kyanite and not from the feldspars of the basement granitoids and gneisses. Uni-directional variations of SiO₂ and Al₂O₃, high Al₂O₃ content (>30%), positive correlation between Al₂O₃ and TiO₂, Ti/Al and Ti/Zr ratios, high pre-metasomatic chemical indices of alteration (> 90), and enrichment of heavy rare earth elements relative to the parent granites and gneisses—all these chemical characteristics combined with field evidence suggest that the sericite schists are formed from a paleosol protolith, which developed on Archean basement between 2.5 and ~2.1 Ga in the Precambrian of Rajasthan. The superimposed metasomatic alteration restricts the use of Fe²⁺/Ti and Fe³⁺/Ti ratios of these paleosols for interpretation of PO₂ conditions in the atmosphere.     

中国黄土研究进展

1ThedistributionandpaleoenvironmentsignificanceofloessinChinaIn the world, the loess in China has most extensive distribution, the largest thickness and the most complete times. The distribution area is over 448,000 km2 (Liu, 1985), the thickness is about 505 m (Lei, 1995) and the times began from the Tertiary (Zhao, 1989; Ding etal, 2000; Guo etal., 2002). The loess in China is mainly distributed in the middle reaches of the Huanghe (Yellow) River, and concentrated in the east of Gansu p…