世界石油的总贮量

现在世界石油的日产量约为5,700万桶,将来即使没有什么新发现,日产量也可增长到6,600万桶。如加上新发现的部分,则可增长到9,000万桶。     

隐伏矿床普查中如何确定钻进深度

为了确定矿田的剥蚀切割深度,必须掌握两个数值:一是被剥蚀的岩石距离成矿时期存在的地表的厚度,二是矿化区间的深度.例如,假定剥蚀切割为500米,这个数值对矿化区间为300～1000米的矿床来说,相当于中等深度的切割值;而对生成深度为1500～3000米的矿床则相当于矿体上部的浅部切割深度.任何一个区域范围内,同类成因的矿床在围岩地质纵剖面上的分布受正态法则支配,并且具有矿化的固定最大值和矿化边缘     

http://www.sciencedirect.com/science/article/pii/S1674987112001259

The eastern Pontides orogenic belt provides a window into continental arc magmatism in the Alpine-Himalayan belt.The late Mesozoic-Cenozoic geodynamic evolution of this belt remains controversial.Here we focus on the nature of the transition from the adakitic to non-adakitic magmatism in the Kale area of Gumushane region in NE Turkey where this transition is best preserved.The adakitic lithologies comprise porphyries and hyaloclastites.The porphyries are represented by biotite-rich andesites,hornblende-rich andesite and dacite.The hayaloclastites represent the final stage of adakitic activity and they were generated by eruption/intrusion of adakitic andesitic magma into soft carbonate mud.The non-adakitic lithologies include basaltic-andesitic volcanic and associated pyroclastic rocks. Both rock groups are cutting by basaltic dikes representing the final stage of the Cenozoic magmatism in the study area.We report zircon U-Pb ages of 48.71±0.74 Ma for the adakitic rocks,and 44.68±0.84 Ma for the non-adakitic type,suggesting that there is no significant time gap during the transition from adakitic to non-adakitic magmatism.We evaluate the origin,magma processes and tectonic setting of the magmatism in the southern part of the eastern Pontides orogenic belt.Our results have important bearing on the late Mesozoic-Cenozoic geodynamic evolution of the eastern Mediterranean region.     

加州帕克菲尔德附近微震序列的破裂方向性

破裂扩展方向是影响地震引发地震动方式的重要因素。因此,表征促进潜在破裂扩展方向的因素是极其重要的。本文分析了加州帕克菲尔德附近圣安德烈斯断层上反复发生的地震序列的地震方向性。同一序列中的所有地震都有非常相似的波形并有重叠的地表破裂。我们说明,普通序列地震之间传递函数的微妙变化可以被认为是视破裂持续时间的改变。计算了所有可用台站的成对地震事件以及每个序列的相对视破裂持续时间。我们反演这些测量结果,得到了序列中各单一事件相对于参考事件的视破裂持续时间的估计值。视破裂持续时间随方位的变化证实了破裂方向性。我们说明,大多数所分析的微震显示为东南向破裂。我们还说明,在给定的重复序列中,大多数地震往往显示出相同的破裂方向。     

A comparison of two stochastic inverse methods in a field-scale application

Inverse modeling is a useful tool in ground water flow modeling studies. The most frequent difficulties encountered when using this technique are the lack of conditioning information (e.g., heads and transmissivities), the uncertainty in available data, and the nonuniqueness of the solution. These problems can be addressed and quantified through a stochastic Monte Carlo approach. The aim of this work was to compare the applicability of two stochastic inverse modeling approaches in a field-scale application. The multi-scaling (MS) approach uses a downscaling parameterization procedure that is not based on geostatistics. The pilot point (PP) approach uses geostatistical random fields as initial transmissivity values and an experimental variogram to condition the calibration. The studied area (375 km2) is part of a regional aquifer, northwest of Montreal in the St. Lawrence lowlands (southern Québec). It is located in limestone, dolomite, and sandstone formations, and is mostly a fractured porous medium. The MS approach generated small errors on heads, but the calibrated transmissivity fields did not reproduce the variogram of observed transmissivities. The PP approach generated larger errors on heads but better reproduced the spatial structure of observed transmissivities. The PP approach was also less sensitive to uncertainty in head measurements. If reliable heads are available but no transmissivities are measured, the MS approach provides useful results. If reliable transmissivities with a well inferred spatial structure are available, then the PP approach is a better alternative. This approach however must be used with caution if measured transmissivities are not reliable.     

Relative importance of dissolved and food pathways for lead contamination in shrimp

The relative importance of dissolved and food pathways and the influence of food type in the bioaccumulation and retention of lead in the shrimp Palaemonetes varians were examined using a radiotracer method. Shrimp were exposed to ²¹⁰Pb-labelled seawater or fed two types of ²¹⁰Pb-labelled food, viz. mussels or worms. The amount of radiotracer accumulated by shrimp was examined over a 7-day period, followed by a 1-month and a 7-day depuration period for the dissolved and food source, respectively. Steady state in the uptake was reached after 2 days exposure to dissolved lead, with a resultant estimated concentration factor of 98 ± 3. Transfer factors following ingestion of contaminated mussels and worms were lower than unity for both food types, with lead transfer from worms being significantly higher than that from mussels. Accumulation of dissolved Pb by shrimp was found to occur mainly through adsorption on the exoskeleton with a minor accumulation in the internal tissues probably resulting from the intake of seawater for osmoregulation. In contrast, lead taken up from contaminated food was readily absorbed and bound in the internal tissues of P. varians. Although the transfer of lead to P. varians through the ingestion of contaminated food was low (TF < 1%), it still represented 4 to 8% of the lead content in the prey which is a significant additional contribution of lead to the shrimp body burden. Independent of food type, following ingestion of contaminated food, approximately 23–27% of total lead accumulated in shrimp was located in the edible parts (e.g. muscle). Therefore, the food pathway is suggested to be a significant contributor to the lead transfer to humans through ingestion of contaminated shrimp. After exposure to contaminated food, lead loss kinetics were described by a two-component model, whereas Pb loss following direct uptake from seawater was best described by a three-component model. The additional compartment representing 64% of total Pb retained and characterized by a turnover < 10 min, corresponded to lead weakly adsorbed on the exoskeleton and incorporated in the hepatopancreas. Nevertheless, a significant fraction of lead accumulated from the dissolved (2%) and food (52–57%) pathways remained irreversibly retained in the tissues, suggesting that this organism could also serve as an effective long-term bioindicator of lead contamination in marine waters.