南京市区降水酸度的初步研究

本文介绍了1979年11月至1980年7月期间南京市区降水酸度的测量结果。结果表明:南京市区降水的pH平均值为5.62,变化范围从4.10—7.93,其中,1980年1月份和7月份出现酸雨,pH的月平均值分别达到5.52和5.26。 测量结果还与日本、英国、美国的观测结果作了比较。     

1975—2015年甘肃省白龙江流域自然保护区生态系统服务价值及其时空差异

利用1975-2015年7期遥感数据重建甘肃省白龙江流域8个野生动物自然保护区的生态系统时空变化特征,并在对该研究区各类生态系统服务价值当量修订的基础上,采用生态系统服务价值评估模型和敏感性指数,对不同时期的生态系统服务价值进行评估。结果表明:(1)白龙江流域自然保护区以森林生态系统为主,研究期内生态系统格局总体稳定,农田和裸地生态系统面积减少,而森林、草地、水域和人工表面生态系统呈增加趋势,且在2000年后变化最活跃。(2)研究区生态系统服务价值由1975年的239.68×10^8元上升到2015年的243.58×10^8元,净增加3.90×10^8元,农田和裸地生态系统服务价值持续减少,而森林、草地和水域生态系统服务价值则呈增加趋势。(3)整体上,研究区南部生态系统服务价值呈增长趋势,而中北部地区则处于阶段性变化状态,文县大鲵自然保护区单位面积生态系统服务价值密度最高,多儿自然保护区价值密度最低,且为唯一衰退型保护区。(4)在不同生态系统服务类型中,调节服务居主导地位,且以气候调节服务价值最高。白龙江流域自然保护区生态系统服务价值缺乏弹性,水域生态系统面积变化对研究区生态系统服务价值的变化具有放大作用。     

STUDIES ON THE BHQ ICE CORE FROM THE LAW DOME, ANTARCTICA

The structure of the ice core varies with depth, Its surface layer is firn, followed by an ice layer with random fabric pattern (beginning at 28m depth), then transformed to a small circle girdle pattern (beginning at 147 m depth) through a transition layer, finally to a single-maximum pattern (beginning at 191 m depth). The stratigraphic profile of the ice core is similar to those of other cores on the Law Dome, For BHQ located in the middle of a flow line from the summit to the coast, the initial depth of every specific layer is less than that in the upstream and larger than that in the downstream. The ice was analyzed for trace elememts using instrumental neutron activation technique. No tendency towards a systematic increase or decrease in the element concentrations in the past 4000 years has been found. The mean concentrations of Na and Al over the past 4000 years are higher than those in the Vostok ice core by factors of 9 and 4, respectively.     

An Asian origin for Sinomastodon (Proboscidea,Gomphotheriidae) inferred from a new Upper Miocene specimen from Gansu of China

We report a fossil specimen referable to Sinomastodontinae gen. et sp. indet. from the Neogene strata at Yanghecun locality, Xihe County, Gansu Province, China. The specimen is characterized by a brevirostrine mandible, complete pretrite trefoils, and relatively simple posttrite half lophids, showing typical features of Sinomastodon. It differs from the other known species of Sinomastodon by the following features: relatively short and wide m3 due to fewer lophid numbers, less inflated pretrite accessory central conules, poorly developed secondary trefoils and cementum, and relatively strong cingulid. All of these features indicate a bias towards pleisiomorphies of Sinomastodon, implying that this specimen is more ancestral than any known species of Sinomastodon. The symphysis of the new specimen is relatively long, which differs from the typical brevirostrine Sinomastodon, and thus we consider it a gen. et sp. indet. in the Subfamily Sinomastodontinae. In addition, the horizon in which the present specimen was found probably represents the Upper Miocene because it is lower than Pliocene strata yielding Hipparion (Proboscidipparon) pater. Generally, Sinomastodon is considered to have migrated from North America at about the time of the Miocene/Pliocene boundary, and to have been derived from a certain clade of American gomphotheres. However, the discovery of the Yanghecun specimen verifies that Sinomastodon lived in East Asia during the Late Miocene, and probably derived from Old World gomphotheres (e.g., G. wimani). The similarity between the members of the Subfamilies Sinomastodontinae and those of Cuvieroniinae is suggested to have been the result of parallel evolution.     

Mineral isotope evidence for the contemporaneous process of Mesozoic granite emplacement and gneiss metamorphism in the Dabie orogen

Kinetics of isotopic equilibrium in the mineral radiometric systems of igneous and metamorphic rocks is an important issue in geochronology. It turns out that temperature is the most important factor in dictating isotopic equilibrium or disequilibrium with respect to diffusion mechanism. Contemporaneous occurrence of Mesozoic granites and gneisses in the Dabie orogen of China allows us to evaluate the thermal effect of magma emplacement and associated metamorphism on mineral radiometric systems. Zircon U-Pb, mineral Rb-Sr and O isotope analyses were carried out for a Cretaceous granite and its host gneiss (foliated granite) from North Dabie. Zircon U-Pb dating gave consistently concordant ages of 127 ± 3 Ma and 128 ± 2 Ma for the granite and the gneiss, respectively. A direct correspondence in equilibrium state is observed between the O and Rb-Sr isotope systems of both granitic and gneissic minerals. Mineral O isotope temperatures correlate with O diffusion closure temperatures under conditions of slow cooling, indicating attainment and preservation of O isotope equilibrium in these minerals. The mineral Rb-Sr isochron of granite, constructed by biotite, feldspar, apatite and whole-rock with the O isotope equilibrium, yields a meaningful age of 118 ± 3 Ma, which is in accordance with the mineral Rb-Sr isochron age of 122 ± 1 Ma for the host gneiss. The consistency in both U-Pb and Rb-Sr ages between the granite and the gneiss suggests a contemporaneous process of crystallizing the zircons and resetting the Rb-Sr radiometric systems during magma emplacement and granite foliation. Whereas the zircon U-Pb ages for both granite and gneiss are interpreted as the timing of magma crystallization, the young Rb-Sr isochron ages record the timing of Sr diffusion closure during the slow cooling. Protolith of the gneiss crystallized shortly before intrusion of the granite, so that it was able to be foliated by voluminous emplacement of coeval mafic to felsic magmas derived by anatexis of orogenic lithospheric keel. Therefore, extensional collapse of collision-thickened crust at Early Cretaceous is suggested to trigger the post-collisional magmatism, which in turn serves as an essential driving force for the contemporaneous high-T deformation/metamorphism.     

前陆沉积与变形对郯庐断裂带同造山运动的制约

郯庐断裂带两侧的前陆沉积及其变形现象,揭示了该断裂带同造山活动的大量信息。合肥盆地东侧的郯庐断裂带旁,侏罗系沉积时出现了沉降中心与边缘相,显示这期间郯庐断裂带所处的张八岭隆起已移位至盆地东侧。砂岩的端元组份分析与碎屑白云母的电子探针分析显示,下扬子地区弧形展布的黄马青群与象山群前陆沉积的物源区为大别——苏鲁造山带,属于原地沉积,表明造山期郯庐断裂带已经出现。大别与苏鲁造山带周边都出现了强烈的前陆褶皱冲断带。合肥盆地前侏罗系基底上印支期的逆冲断层,在郯庐断裂带旁侧明显增多,指示该断裂带曾发生过同造山活动。下扬子地区前陆构造走向向郯庐断裂带方向偏转,反映它们形成时受到了郯庐断裂带左旋走滑运动的影响。这一系列前陆沉积与变形特征,指示郯庐断裂带在华北与华南板块的碰撞造山中以陆内变换断层的型式出现。该断裂带造山期运动中,东盘为主动盘,并发生了显著的逆时针旋转。独特的徐宿弧形逆冲——推覆构造,表明造山期郯庐断裂带左行平移幅度达350km。在该断裂带早白垩世的第二次平移中,断裂带向北延伸,又发生了约200km的左行平移。     

贵州省金沙煤田龙潭组岩煤层测井对比方法

龙潭组是金沙井田的主要含煤地层，含煤达12~15层，其中7、8、9、11、12五层煤较稳定，为主要可采煤层。根据测井物性曲线与地质岩心的对比分析，总结出该组煤岩层的共有测井物性规律：低密度、中低电阻率、较高中子孔隙度和较低的纵波速度，以及其特有规律如：5、6、7、8、9煤层的低自然伽马，11、12煤层较高的自然伽马等特征。结合煤层测井曲线形态特征及其与顶、底板以及和煤层上、下标志层间组合关系，进行了全煤系地层的对比，揭示了该井田煤层的分岔、合并、冲刷、沉缺、煤层厚度等变化规律。     

上海市地热资源地质条件及开发利用潜力分析

受多种因素制约,上海市近年来陆续实施的地热资源勘查效果都不理想.本文在汇总整理本市有关地热资料的基础上,对区内热源、热储、热盖和通道等地质条件进行了分析,并划分了12个地热资源远景区.热盖为上侏罗统、松散层区域性热盖和上白垩统-古近系、下古生界陆源碎屑岩局部性热盖.热储具有下古生界和白龙港玄武岩层状热储和断裂破碎带带状热储.热源主要为正常的地温增温,断陷盆地盆缘断裂和主要断裂具有深部导热作用.     

前陆盆地斜坡带勘探丛式平台优选评价——以厄瓜多尔奥连特盆地TW区块为例

针对南美前陆盆地斜坡带圈闭规模小、热带雨林地貌勘探投资大、丛式平台优选难的问题,以厄瓜多尔奥连特盆地TW区块为例,在圈闭地质风险评价后,进行平台控圈闭群经济性评价,最终实现丛式平台优选评价。评价方法流程包括：1）圈闭地质风险评估和圈闭资源量评价（传统六要素评价）;2）丛式平台经济评价,设计N个平台（每个平台控制圈闭不同）,对单一平台控制范围内的圈闭进行经济性评价,包括投资（钻井、平台建设、道路及管线建设、射孔费用、地表植被复原费等）和收益（原油出售）,剔除没有经济价值的圈闭后重新对单一圈闭的经济性进行评价,直至单一平台内所有圈闭均具有经济价值;3）丛式平台和圈闭优选：根据单一平台控制圈闭总经济价值大小,优选出最优的丛式平台,按照经济价值大小对最优平台控制圈闭进行优选获得圈闭排序;4）新一轮平台和圈闭优选,删除已选出的圈闭后重新进行步骤2）-3）,最终获得研究区的平台及圈闭优选排序。运用该方法提出TW区块平台建设和圈闭钻探建议,实施效果良好。