湘西凤凰大马地区中、晚寒武世三叶虫

我国湘西大马-亥冲口-峨梨塘地区有大量三叶虫化石产出，它是我国南方已知含丰富化石产地之一．此地同样也是我国寒武系地层出露最完整的地区之一．特别是黔东和湘西交界处，寒武系岩石出露相当好，未变形，易辩认．部分产自亥冲口剖面的多节类三叶虫由现作者近年出版在别处，本文重点介绍几个近年新发现产自大马剖面的三叶虫．     

Microstructure and functional morphology of the Early Cambrian problematical fossil Rhombocorniculum

Rhombocorniculum cancellatum from the Lower Cambrian of southern Shaanxi Province (South China) is represented by the dextral and sinistral tooth-like sclerites (both in nearly equal numbers), indicating that the body plan of the organism with these sclerites probably was bilaterian. The main feature of the microstructure of the sclerites is the presence of longitudinally arranged, mutually contiguous hollow tubules, the shared walls consisting of microcrystalline apatite. In transverse cross sections, the sclerite wall mainly exhibits a spongy structure, with pore size decreasing adapically. Functional morphological analysis indicates that the sclerites serve as a defensive rather than a grasping function.     

Early Cambrian eodiscoid trilobites of the Yangtze Platform and their stratigraphic implications

Analysis of the taxonomy and stratigraphic distribution of the Early Cambrian eodiscoid trilobites of the Yangtze Platform indicates that species of Tsunyidiscus and Hupeidiscus can be used for biostratigraphic correlation. T. aclis occurs only in the lower Qiongzhusian, T. armatus occurs in the lower and middle Qiongzhusian, while T. niutitangensis and T. tingi occur mainly in the middle and upper Qiongzhusian, with only T. tingi extending upward into the lower Canglangpuian. H. orientalis first appears in the upper Qiongzhusian, reaching peak abundance in the lower Canglangpuian and becoming extinct above the Drepanuroides Zone. Biostratigraphic and lithostratigraphic correlations indicate that the limestone in the lower part of the Mingxinsi Formation, the Upper Member of Jiumenchong Formation, and the upper part of the Middle Member of the Huangbailing Formation, can be correlated with each other as Hupediscus, an index fossil of the lower Canglangpuian, is abundant in all these units. The lower part of the Niutitang and Jiumenchong formations in eastern Guizhou, which mainly represent Qiongzhusian strata, can be correlated with the Lower Member of the Huangbailing Formation. The basal part of the Niutitang Formation, which may be equivalent to the Upper Meishucunian Shiyantou Formation in eastern Yunnan, is very condensed. Well-preserved sponge faunas and non-mineralized fossils in the lower part of the Niutitang and Hetang formations are not older than Qiongzhusian in age.     

Initial organic geochemical investigation on Late Neoproterozoic-Early Cambrian sediments in the Yangtze region, China

Totally 19 samples of typical Upper Proterozoic-Lower Cambrian sedimentary rocks were collected and analyzed for an organic geochemical investigation. Almost all these rocks have high TOCs, super-maturities and similar biomarker distribution. As an exception, however, the Sinian Nantuo Tillite shows much lower TOCs and little phytane and pristane in comparison with those in other strata, which implies a very faint photosynthetic process, and a restricted euphotic zone and quite limited sunlight within the sedimentary water column during the Sinian glaciation age in the western Yangtze region providing an evidence for palaeo-oceanic environment of the Neoproterozoic Snowball Earth age.     

Isotopic evolution of the terminal Neoproterozoic and early Cambrian carbon cycle on the northern Yangtze Platform, South China

Profound geotectonic, climatic and biological changes occur during the terminal Neoproterozoic and its transition into the early Cambrian. These are reflected in temporal variations of the chemical and isotopic composition of seawater. We are studying a sequence of sedimentary rocks at the Shatan section, northern Yangtze Platform, Sichuan Province of China. This succession comprises, in ascending stratigraphic order, predominantly calcareous sediments of the Sinian upper Dengying Formation and black shales of the lower Cambrian Guojiaba Formation (time equivalent of Niutitang Fm.). Paleoenvironmental setting represents shallow-water shelf deposits. The objective of our study is to provide temporal records for the isotopic compositions of organic and carbonate carbon throughout this time interval. Organic carbon isotope values display a range between -35.8‰ and -30.1‰ with clear stratigraphic variations. Carbonate carbon isotope data vary between -3.5‰ and +0.5‰. These secular variations are interpreted to reflect perturbations of the global carbon cycle, specifically changes in the fractional burial of organic carbon. However, local conditions have further affected the isotopic signals.     

岚皋大巴山岩溶地貌

认为岚皋大巴山岩溶地貌发育在寒武系石灰岩地层的高夷平面上，由于受岩性、地质构造、地貌和气候等自然条件的影响，地表、地下岩溶地貌发育不够均匀，但以溶洼丘峰为主，溶洼往往积水成湖，是我国南北方典型岩溶地貌的过渡类型区。     

多值Nemytskij算子的上半连续性

本文给出了作用在Ｍｕｓｉｃｌａｋ－Ｏｒｌｉｃａ－Ｆ空间上的多值Ｎｅｍｙｔｓｋｉｊ算子上半连续的充分条件。     

岷江上游干旱河谷区土壤水分含量及其动态

于2002年8月～2003年7月对四川西部理县干旱河谷区土壤水分状况进行了定位研究。结果表明：在理县干旱河谷区，不饲海拔高度0～50cm土层土壤平均含水量总的变化趋势是阴坡比阳坡高。而土壤水分空间异质性阳坡比阴坡大。同一坡向不同海拔的土壤含水量变化为2050m处的最高，1850m处的次之，1450m处再次之，1650m处最少，表明了在干旱区河谷的两岸坡面上部土壤水分状况最好，在坡面下部靠近河流处次之，中下坡水分条件最差。相同海拔高度，不同坡向土壤含水量都表现为随着土层深度的增加土壤含水量增加的趋势，且30～50cm土层的土壤含水量最高。     

Shenzhousia qilianshanensis gen. et sp. nov. (Protodonata, Meganeuridae), a giant dragonfly from the Upper Carboniferous of China

A new dragonfly of family Meganeuridae Shenzhousia qilianshanensis gen. et sp. nov., discovered from Ningxia Hui Autonomous Region in North China, is described in the present paper. It has an estimated wingspan of about 450?500 mm and may be the largest fossil insect in Late Carboniferous Namurian Stage discovered by far. The new species is referred to Meganeuridae because of the presence of the characteristic oblique vein between anterior branch of radius (RA) and posterior branch of radius (RP) near the base of RP2. It differs from other genera within the family in the following characteristics: Precostal area short and not extending to the midwing; posterior branch of subcostal vein short, merging into costal vein near the level of originating point of IR₂; RP forking earlier than anterior branch of media basally; RP_1＋2 and RP_3＋4 parallel and close to each other for a long distance, and then diverge gradually surpass midwing.     

一类含时滞反应扩散方程波前解的存在性

利用J.Wu和X.Zou(J.Dynam.Diff.Eqns.,2001,13(3):651～687.)建立的解的存在性理论,研究 2u1(x,t) u1(x,t) t=D1b1+a1u2(x,t-τ2)], x2+r1u1(x,t)[1-u1(x,t-τ1) u2(x,t) 2u2(x,t) t=D2b2+a2u1(x,t-τ4)], x2+r2u2(x,t)[1-u2(x,t-τ3)的行波解,其中x∈R,t∈R,ui(x,t)∈R,Di>0,ri>0,ai>0,bi>0,i=1,2,a1a2<1,τj>0,j=1,2,3,4,得到了这个系统波前解存在的充分条件.