To accurately identify the reservoir characteristics and main controlling factors of the Cambrian Niutitang black shale in the southeast Chongqing,a series of systematic measurements were conducted on core samples from Well Yuke-1 and Well Youke-1.The measurements include clay mineral analysis,XRD analysis,petrophysical properties,specific surface area,pore diameter and TOC,as well as R_(o) and maceral compositions.The Niutitang shale reservoir contains detrital minerals and clay minerals averagely of 51.34%and 32.74%,respectively.The average effective porosity and permeability are 1.2%and 8.0×10^(-3)mD,respectively,typically of ultra-low porosity and permeability.Mesopores are dominant,accounting for approximately 73%of the total pore volume.The average BET specific surface area is 7.75m^(2)/g and the average pore diameter is 5.3nm.The average TOC is 2.29%and the average R_(o) is 3.12%,indicating that the organic matter is in over-maturity stage.Statistical analyses of the measurements show that the micropore volume is positively correlated with TOC but negatively correlated with the total content of clay minerals;the mesopore volume is positively correlated with TOC,the total content of clay minerals and the content of carbonate minerals;the macropore volume is positively correlated with TOC and the content of carbonate minerals,weakly positively correlated with the content of detrital minerals but negatively correlated with the total content of clay minerals.The porosity and TOC of the Niutitang shale are computed using the conventional well-logging method for the Yuke-1 and Youke-1 wells,and the porosities are quite consistent with the core analysis resultsr,but in the shallow reservoir that contains no oil and gas,the TOC exhibits no correlation with the core analysis results.
In recent years the Lower Cretaceous red beds of southwestern China have yielded more than 20 significant dinosaur-dominated tracksites. More than half occur in the Jiaguan Formation with the remainder in the Feitianshan and Xiaoba formations. Collectively these sites provide evidence of at least 13 distinct dinosaurian trackmaker morphotypes, in addition to two avian theropod(bird)morphotypes and pterosaur and turtle tracks. Together these total 17 morphotypes provide a data base of 479 potential trackmakers, probably representing the same number of individuals. Such an ichnological database provides a useful proxy paleoecological census of tetrapod communities in the area during the Early Cretaceous, and is especially significant given the complete absence or scarcity of skeletal remains reported from these formations.The composition of ichnofaunas in all three formations is heavily saurischian(theropod and sauropod) dominated with a high diversity of distinctive theropod morphotypes,mostly assignable to known ichnogenera. Moreover, ichnofaunal data from multiple sites are generally consistent between sites and an indication of the reliability and repeatability of track census data. Such regionally-widespread data are rapidly superseding the information available from the skeletal record in the corresponding area, and must therefore be considered of high paleontological value.
The genus Sciadopitys, containing a single species (S. verticillata), is the only extant representative of the Family Sciadopityaceae (Coniferales), and is a remarkable living fossil. Although some leafy fossils have been ascribed to Sciadopityaceae, fossil xylem material with a close affinity to this family is very rare, and there have been no fossils found showing both pith and primary xylem structures, which are of great importance for wood identification. Thus, it has been difficult to use fossils for the understanding of wood anatomy evolution in the sciadopityaceous plants over geological time. In this note we briefly report on Sciadopitys-like fossil wood found in the Middle Jurassic of western Liaoning, which bears well-preserved Protosciadopityoxylon-type secondary xylem, endarch primary xylem and heterogeneous pith. This is the first report of fossil specimens of the Sciadopityaceae with such detailed preservation of wood structures. The discovery provides precise anatomical evidence for reconstructing the evolu- tionary history and geographical distribution of Sciadopityaceae, as well as contributing to understanding of the fossil diversity of the Jurassic Yanliao Flora in northern China.
JIANG ZiKunWANG YongDongZHENG ShaoLinZHANG WuTIAN Ning
