Microbial production of CO2 in red soil in Stone Forest National Park

Lunan stone forest is a kind of typical karst in China, which is mainly developed under red soil. In the winter of 1999, three study sites were chosen in stone forest national park according to vegetation cover, geomorphologic location and soil types. CO2 concentration was measured with Gastec pump at different depths of soil (20, 40, 60 cm) and at the same time soil samples were gathered and soil properties such as soil moisture, pH, soil organic content were analyzed and the total number of viable microbes were counted in laboratory. In the study, dependent variable was chosen as the mean soil log (PCO2), and soil properties were chosen as the independent variables. Multiple stepwise regression analysis showed that the total amount of microbes and soil moisture are the best indicators of the CO2 production, with the equation LOG(PCO2) = - 0.039(TNM) - 0.056(Mo) + 1.215 accounting for 86% of the variation of the soil CO2 concentration, where TNM is the total number of microbes in the soil and Mo is the moisture of soil sample.     

长江中下游晚中生代中基性岩的铅同位素特征:富集地幔的证据

长江中下游东段庐枞、怀宁、繁昌、铜陵和宁芜地区的中基性岩属于碱性系列 ,具有高的U ,Th含量和Th/Pb ,U/Pb比值 ,分别平均为 2 .82× 10 -6,9.5 6× 10 -6和 0 .6 35 ,0 .184。样品的初始铅同位素 (130Ma)组成为 :(2 0 6Pb/ 2 0 4Pb) i=17.6 5～ 18.6 0 ,(2 0 7Pb/ 2 0 4Pb) i=15 .4 2～ 15 .5 0 ,(2 0 8Pb/ 2 0 4Pb) i=37.6 7～ 38.0 4。形成中基性岩的原始岩浆来源于富集的岩石圈地幔 ,具有EMⅠ和EMⅡ ,且以EMⅡ为主的特征。和长江中下游西段黄石地区以及大别地块西南部玄武岩的比较表明 ,长江中下游地区岩石圈地幔高的Th/Pb和U/Pb比值可能和俯冲板片析出流体的交代有关。晚中生代时期 ,华北板块岩石圈地幔以EMⅠ特征为主 ,华南板块岩石圈地幔以EMⅡ特征为主 ,岩石圈地幔性质的区域性分布与印支期扬子板块深俯冲事件密切相关。虽然中国东部新生代玄武岩因岩石圈大规模减薄表现了亏损特征 ,但残留的富集岩石圈地幔在中国东部新生代玄武岩的Pb同位素中仍有所反映     

板块下的构造及地幔动力学

最新的全球地幔地震层析资料揭示了岩石圈板片可以俯冲到核幔边界，超地幔羽可以从核幔边界上升到地壳上部形成热点。在大陆板块汇聚边界，地幔地震层析图像不仅显示了岩石圈板片的超深俯冲，还保存了拆沉的岩石圈“化石”残片的重要信息。从地幔深部所获取的新资料为全地幔“单层对流“的新模式提供了依据。在介绍上述全球构造研究新动向的基础上，本文强调了研究岩石圈板块必须了解板块下的构造，探索岩石圈板块的驱动力应该从“岩石圈动力学”升华到“地幔动力学”，并提出了大陆板块汇聚边界地幔动力学研究的新思考。     

Cascaded Evolution of Mantle Plumes and Metallogenesis of Core- and Mantle-derived Elements

Mineral deposits are unevenly distributed in the Earth's crust, which is closely related to the formation and evolution of the Earth. In the early history of the Earth, controlled by the gravitational contraction and thermal expansion, lighter elements, such as radioactive, halogen-family, rare and rare earth elements and alkali metals, migrated upwards; whereas heavier elements, such as iron-family and platinum-family elements, base metals and noble metals, had a tendency of sinking to the Earth's core, so that the elements iron, nickel, gold and silver are mainly concentrated in the Earth's core. However, during the formation of the stratified structure of the Earth, the existence of temperature, pressure and viscosity differences inside and outside the Earth resulted in vertical material movement manifested mainly by cascaded evolution of mantle plumes in the Earth. The stratifications and vertical movement of the Earth were interdependent and constituted the motive force of the mantle-core movement.