Paleoclimate In Research. The Lantian Gongwangling Loess Profile

Some geoscience experts put forward a subject of "past global change"to settle the problem that what change will occur in the earth surface environment under the durative influence of the greenhouse effect. The subject is expected to provide a reference system to forecast the future global change through the study on the typical Quaternary climate gyration, especially the study on the climatic environment pattern of the calefacient period. "Past global change"is mainly carried out through the study of the Quaternary environment information carrier. Quaternary Period includes multiple ice age-interglacial gyrations, they were well memorized in deep ocean sediment, loess-ancient soil sequence and ice core, in which loess-ancient soil sequence is one of the several carrier studied in detail. This paper is based on the project of the national natural science fund, and it study mostly the eopleistocene climate evolvement of Early Pleistocene. Through the study on the grain size analysis and calcium carbonate content analysis of Gongwangling section, the paper infers the ancient climate and temporal sedimentary environment. The main results include: 1. The grain sizes of the Gongwangling section were analyzed, the samples were tested by advanced laser grain size instrument, and the depositional environments in different strata were gained. It is thought that the original sediment of the Gongwangling section was aeolian. 2. The content curve above 10μm well reflects the grain size characteristics of the area. Moreover, the curve is negatively correspond with the curve of the Luochuan section, a typical loess section. So, the content curve above 10μm is looked on as the effective substitute indication of the ancient climate in the paper. 3. The grain size curve is well corresponded with the strata. Based on the grain size analysis, it is considered that the area has undergone two great climatic fluctuations from dry, cold to warm, wet. 4. The conclusions based on the analysis of calcium carbonate content accorded with those based on the grain size analysis. And the calcium carbonate content can be regarded as a reference indication without confirming the cause of calcium carbonate in loess. 5. Compared with the magnetic susceptibility curve of the Luochuan section, a typical loess section, the criterions of the section in the paper are credible.