Testing And Application Of Geochemical Lithogene

Based on the fact that the immobile elements retain the element attributes of the parent rock in the weathering products,Yan Taotao constructed a geochemical lithogene which was used to present the geochemical attributes of the rocks and weathering products.The sequence of the genetic elements was Al₂O₃?SiO₂?P?Ti?La?Fe₂O₃?Th?Zr?Nb?Y?U,and the geological samples can be identified by similarity of gene.In this paper,geological materials with three scales sourcing from the same granite in Lianyang area,Guangdong Province,China are selected to test the validity of the geochemical lithogene.By simulating the suspect's activities and the scene of obtaining criminal evidence,gene comparison between the collected soil stuck on the suspect's shoes and the stream sediments from the regional geochemical survey was carried out to recognize the source of the soil evidence on the geochemical lithogene.It is found that in the process of granite weathering,Ce anomaly increases with the enhancement of weathering degree?or the decrease of WIG?,and the sample with strong weathering shows positive Ce anomaly,from the bedrock to the weathering product.the geochemical lithogene show good heredity in the products from the bottom bedrock to the surface weathered soils,and good inheritance in samples from the surface soil to the bottom bedrock.The geochemical lithogene show good inheritance from stream sediments to residual slope soils and then to its parent rock in the soil profile of residual slope and alluvial sediments formed by granite weathering.In the stream sediments medium of1:200,000 regional geochemical survey,the stream sediments have good genetic similarities with soil and parent rocks of source area.Based on the test of three scale samples,it is considered that the parent rock tracer can be carried out on soil and stream sediment samples on the geochemical lithogene.Through scene simulation,the sole samples of the suspect were compared with those of the stream sediments from the regional geochemistry survey in the study area,it is found that the sole sample is similar to stream sediments in the exposed area of Lianyang granite.It is inferred that the soil evidence in sole may come from the exposed area of granite,which is coincide with the actual sampling site of the physical evidence scene simulation.Thus,based on regional geochemistry survey data,the geochemical lithogene can be used to trace the origin of the soil evidence in sole evidence,which may provide a new idea or technique for the study of forensic geology,especially the forensic geochemistry.