南秦岭金龙山微细浸染型金矿成矿时代

 金龙山金矿带是南秦岭新发现的卡林型金矿带,主要产于上泥盆统南羊山组细碎屑岩—碳酸盐岩建造中,在上泥盆统冷水河组、下石炭统碳酸盐建造中也有产出,可分为明显受断裂控制的脉型金矿化和受有利岩性及小规模断裂、节理控制的浸染型矿化。     

南江县铁炉坝地区含金丰度及金矿化围岩蚀变特征

对四川省南江县铁炉坝地区各类岩石和土壤的含金丰度进行了阐述，对金矿化的围岩蚀变特征进行了较详细的论述，指出黄铁矿化一电气石化-硅化的蚀变组合是该区金成矿的指示性标志。     

Parameter estimation for a karst aquifer with unknown thickness using the genetic algorithm method

The combination of ecological fragility and agricultural activity in the loess hilly–gully regions of western China has received broad environmental concerns. In this region, rainfall and soil moisture can fatally influence crop production under dry land farming. In this study, field experiments were conducted, from March 2001 to September 2005, to demonstrate the variation of soil moisture and fertilizer contents at different depths in slope and terraced lands, and to evaluate the ecological impacts and economic benefits in the terraced land of Loess Plateau. The results of both field test and Grey model (GM) calculation show that the terraced land, as compared to the sloping land, in the agricultural area of the Loess Plateau tends to store and retain much water, promoting more favorable interactions between water and fertilizer. During the months from March to June of the year with less rainfall, the water supply for crop growth is mainly derived from the deep storage of soil moisture accumulated from July to September of the previous year. The field experiments indicate that the crop yield of the 3-year-old terraced lands was 27% higher than that of the sloping lands with slopes greater than 10°, and that the crop yield can increase by 27.07 to 52.78% in the following cultivation years. In particular, potato was found to be more drought-resistant than winter wheat, thus it is more suitable for the arid and semi-arid Loess Plateau regions.     

华南燕山晚期构造-岩浆事件与成矿作用——来自广西大瑶山龙头山金矿床的地球化学约束

广西贵港大瑶山成矿带位于华南东南沿海成矿带西南端,对矿带内龙头山金矿黄铁矿化斑岩进行定年的结果为96.1±3.0 Ma,与区域内邻近的平天山侵入岩体(96.2±0.4 Ma)相同.龙头山矿床的Sr同位素组成与其锆石的REE特征表明,成矿作用伴随有大量的流体参与;矿化斑岩与区内侵入相岩石相同的形成时代以及矿化斑岩中锆石C...     

辽西义县组与冀北大店子组、西瓜园组的对比

辽西义县组与冀北大店子组、西瓜园组的对比关系一直存有分歧.综合分析前人生物地层学资料,并结合同位素年代学,提出老公沟层、业南沟层、尖山沟层和冀北滦平盆地大店子组1~2段及3~4段下部相当,大康堡层可与大店子组3~4段上部对比,金刚山层与西瓜园组大致相当.     

Characteristics of the Two Types of Granits at Sikongshan in the Eastern Part of the Dabieshan Mountains

It has been shown from petrologic,geochemical,trace element and REE evidence that the gran-ite intrusions at Sikongshan,Anhui Province,can be assigned to two distinct types which are radically different in age and origin.The Precambrian gneissic granited resulted from remelting of old continental crust while the Mesozoic granites were derived ,also through remelting,from low-Rb/Sr rocks at greater depths.Granite masses at Tiantangzhai and Zhoujiawan in the Dabieshan Mountains are also dicussed.     

Gas accumulation from oil cracking in the eastern Tarim Basin: A case study of the YN2 gas field

Oil and gas exploration in eastern Tarim Basin, NW China has been successful in recent years, with several commercial gas accumulations being discovered in a thermally mature to over-mature region. The Yingnan2 (YN2) gas field, situated in the Yingnan structure of the Yingjisu Depression, produces gases that are relatively enriched in nitrogen and C₂₊ alkanes. The δ¹³C₁ (−38.6‰ to −36.2‰) and δ¹³C₂ values (−30.9‰ to −34.7‰) of these gases are characteristic of marine sourced gases with relatively high maturity levels. The distributions of biomarkers in the associated condensates suggest close affinities with the Cambrian–Lower Ordovician source rocks which, in the Yingjisu Sag, are currently over-mature (with 3–4%Ro). Burial and thermal maturity modeling results indicate that paleo-temperatures of the Cambrian–Lower Ordovician source rocks had increased from 90 to 210 °C during the late Caledonian orogeny (458–438 Ma), due to rapid subsidence and sediment loading. By the end of Ordovician, hydrocarbon potential in these source rocks had been largely exhausted. The homogenization temperatures of hydrocarbon fluid inclusions identified from the Jurassic reservoirs of the YN2 gas field suggest a hydrocarbon emplacement time as recent as about 10 Ma, when the maturity levels of Middle–Lower Jurassic source rocks in the study area were too low (<0.7%Ro) to form a large quantity of oil and gas. The presence of abundant diamondoid hydrocarbons in the associated condensates and the relatively heavy isotopic values of the oils indicate that the gases were derived from thermal cracking of early-formed oils. Estimation from the stable carbon isotope ratios of gaseous alkanes suggests that the gases may have been formed at temperatures well above 190 °C. Thus, the oil and gas accumulation history in the study area can be reconstructed as follows: (1) during the late Caledonian orogeny, the Cambrian–Lower Ordovician marine source rocks had gone through the peak oil, wet gas and dry gas generation stages, with the generated oil and gas migrating upwards along faults and fractures to form early oil and gas accumulations in the Middle–Upper Ordovician and Silurian sandstone reservoirs; (2) since the late Yanshanian orogeny, the early oil accumulations have been buried deeper and oil has undergone thermal cracking to form gas; (3) during the late Himalayan orogeny, the seals for the deep reservoirs were breached; and the gas and condensates migrated upward and eventually accumulating in the relatively shallow Jurassic reservoirs.     

吉林延边汪清县蛤蟆塘盆地白恶纪地层划分及其演化

通过１∶５万区调填图（１９８８～１９９０）,笔者将蛤蟆塘盆地白垩纪地层划分为大拉子组、富兴屯砾岩、龙井组。其中大拉子组下部为山麓冲积扇沉积,上部为湖相沉积;富兴屯砾岩为河流—扇三角洲相沉积;龙井组为浅盆广湖相沉积,其中产有Ｎｉｇｅｒｅｓｔｈｅｒｉａｓｐ等化石,属早白垩世,与延吉盆地等有明显时代差异,具有穿时性。     

Hydrocarbon Generating Potential of Mineral—Bituminous Matrix in Source Rocks

Mineral-bituminous matrix(MBM) makes up a major part of source rocks,but its potential in hydrocarbon generation is uncertain,Mineral and organic (Maceral and kerogen) compositions,organic maturity and fluorescence of MBM are studied based on source rock samples from eastern Jiuquan(Jiudong)Basin.The results show that MBM is dominated by inorganic minerals and among the small percentage of organic components those of secondary origins are predominant over the primary species.This strongly indicates that the significance of MBM in hydrocarbon generation is limited.