The Thermal Structure of the Upper Mantle in Eastern China——Inferred from the Petrological Model

Cenozoic basalt in eastern China contains abundant ultramafic xenoliths which are specimens of pyrolitesreleased during basaltic magma eruption. A total of 405 P-T data of pyroxene in the ultramafic rocks have beencollected, which present a more precise pyroxene geotherm. The average geothermal gradient in the upper man-tle represented by the pyroxene geotherm is about 3.3℃ / km, which is much less than that derived from theconductive thermal model (≈14℃ / km), implying the great significance of convective heat transfer. The calcu-lation shows that the contributions of convective and conductive heat transfers are 79% and 21%, respectively.The perturbation in the thermal structure of the upper mantle is an important manifestation of thetectonothermal event of Cenozoic continental rifting and intense basaltic volcanism in eastern China. Based onthe pyroxene geotherm and its comparison with the current geothermal field derived from the measurements ofthe surface heat flows, it is suggested that the Moho may be a secondary thermal boundary. The currentgeothermal field and the thermal structure of the lithosphere in eastern China may mainly reflect the result ofthe tectonothermal disturbance in the Neogene-Quaternary, in other words, the lithosphere has just begun toCool.

QβstructureofthecrustanduppermantleintheeasternSino┐Koreanparaplatform

Based on the long period surface wave data recorded by the China Digital Seismograph Network (CDSN), the Q R of fundamental mode Rayleigh wave with periods from 10 s to 146 s is determined for the eastern Sino Korean paraplatform in this paper. The Q β models of the crust and upper mantle are respectively obtained for the 4 paths, with the aid of stochastic inverse method. It shows that in the eastern Sino Korean paraplatform, the average crustal Q β is about 200, and that there exists a weak attenuation layer in the middle crust (about 10～20 km deep) which is possibly related to earthquake prone layer. A strong attenuation layer (low Q ) of 70 km thick extensively exists in the uppermost mantle, with the buried depth about 80 km. The average Q R of fundamental mode Rayleigh wave is between the value of stable tectonic region and that of active tectonic region, and much close to the latter.

Abnormality of thermal structure and current in the upper western tropical Pacific Ocean and its effect on subtropical high

-Mainly on the basis of the data obtained during PRC/US bilateral TOGA cruises, abnormal variation occurred during the 1986/1987 El Nino is shown in this paper about the thermal structure and circulation of the upper western tropical Pacific Ocean. The effects of the abmormal variation on the subtropical high over the Northwest Pacific Ocean are discussed. During the El Nino: (1) In the east part of the western tropical Pacific Ocean (the subsurface temperature data on the 165° E section are taken as an example), the water wanner than 29 C in the upper layer spread on the longitudinal section and positive temperature anormalies appeared in a large area of the sea surface. (2) In the west part of the western tropical Pacific Ocean (the subsurface temperature data on the 137°E section are representative ), the cross section occupied by the upper layer warmer water ( T >28 ℃ ) became shrunk, and the sea surface temperature showed negative amomalies. (3) The eastward flows in the upper layer of the 165°E section strengthened. (4)The northward flow volume of warm water from the origin area of Kuroshio, i. e. , the tropical oceanic area south of 18?0' N and from the west of 130?E to the Philippine coast, decreased. When those kinds of abnomal variation occurred, air divergence on the low level (1 000 hPa) over the Northwest Pacific Ocean was intensified, favourable to the strengthening of subtropical high over the Northwest Pacific Ocean.

Differences of Hydrocarbon Enrichment between the Upper and the Lower Structural Layers in the Tazhong Paleouplift

The Tazhong paleouplift is divided into the upper and the lower structural layers, bounded by the unconformity surface at the top of the Ordovician carbonate rock. The reservoirs in the two layers from different parts vary in number, type and reserves, but the mechanism was rarely researched before. Therefore, an explanation of the mechanism will promote petroleum exploration in Tazhong paleouplift. After studying the evolution and reservoir distribution of the Tazhong paleouplift, it is concluded that the evolution in late Caledonian, late Hercynian and Himalayan periods resulted in the upper and the lower structural layers. It is also defined that in the upper structural layer, structural and stratigraphic overlap reservoirs are developed at the top and the upper part of the paleouplift, which are dominated by oil reservoirs, while for the lower structural layer, lithological reservoirs are developed in the lower part of the paleouplift, which are dominated by gas reservoirs, and more reserves are discovered in the lower structural layer than the upper. Through a comparative analysis of accumulation conditions of the upper and the lower structural layers, the mechanism of enrichment differences is clearly explained. The reservoir and seal conditions of the lower structural layer are better than those of the upper layer, which is the reason why more reservoirs have been found in the former. The differences in the carrier system types, trap types and charging periods between the upper and the lower structural layers lead to differences in the reservoir types and distribution. An accumulation model is established for the Tazhong paleouplift. For the upper structural layer, the structural reservoirs and the stratigraphic overlap reservoirs are formed at the upper part of the paleouplift, while for the lower structural layer, the weathering crust reservoirs are formed at the top, the reef-flat reservoirs are formed on the lateral margin, the karst and inside reservoirs are formed in the lower part of the paleouplift.

ARCH STRUCTURE OF TRABECULAE OF THE UPPER FEMORAL END AND ITS BIOMECHANICAL SIGNIFICANCE IN HIP FRACTURES

We studied ultrastructurally the cancellons bone tissues of the upper femoral ends, collected from 12 patients undergoing endoprostbesis replacement for fractures of the femoral neck and from 7 fresh cadavers. The bone tissues were composed of meshwork of trabeculae, that constituted tier upon tier of anisotropic arch structures of different diameters and sizes. The arch structures of the cancellous bone tissues in the femoral heads assumed round or roundish configurations, whereas those of the femoral head-neck junctions revealed oval outlines and those of the femoral necks showed narrow oval profiles. The fine structures of the trabecnlae in the femoral head could be divided into superficial zone, central zone, and transitional zone. Under weight-bearing, the central zone suited to sustain the load, while the superficial zone could produce elastic deformation lest fracture of the trabecaulae should ensue. The long axes of the oval arch structures of the femoral head-neck junction and the narrow oval arch structures of the femoral neck coincided with those of the femoral neck, thereby facilitating weight-bearing under physiological conditions. However, external violence in the form of either adduction or abduction force would act in a horizontal direction on the long axes of the oval and narrow oval arches so as to produce subcapital or transverse fracture of the femur in the aged.