川西北地区中三叠统顶部溶蚀型喀斯特特征及地质意义*

中三叠统顶部溶蚀型喀斯特在什邡金河剖面及四川盆地大部分地区已有报道。在近期的野外工作中,在川西北地区绵竹汉旺观音崖、江油黄莲桥和江油马鞍塘剖面天井山组近顶部、顶部也识别出这一古特提斯面,其形成与强烈的构造活动或全球海平面下降造成的岩层长时间的暴露有关。其表现形式主要为: (1)暴露溶蚀间断沉积面;(2)溶沟、溶缝及其内的碳酸盐、陆源碎屑充填物;(3)暴露期黏土层;(4)喀斯特角砾。其中暴露溶蚀间断沉积面上的沉积构造以鸟眼、层状孔洞构造最为典型,在绵竹汉旺观音崖剖面最为发育,孔、洞充填物主要为亮晶方解石和白云石;溶沟、溶缝及其内的碳酸盐、陆源碎屑充填物在江油马鞍塘、汉旺观音崖、什邡金河等剖面均有发育,这些溶缝、溶沟一般近于竖直发育,宽度及深度不一,被碳酸盐角砾、亮晶方解石、白云石或陆源黏土等所充填;暴露期黏土层主要见于江油黄莲桥剖面,共发育2套,厚5~20 cm,与铁质矿物共生,其上下发育深灰色潟湖沉积;喀斯特角砾主要见于汉旺观音崖剖面,喀斯特角砾最大可达15×20 cm大小,呈棱角状充填于富含泥质和有机质的暗色碳酸盐基质中。天井山组近顶部溶蚀型喀斯特的发现可为区域地层等时对比提供依据,与其有关的古岩溶作用可在天井山组(或雷口坡组)顶部碳酸盐岩中形成以溶蚀孔、洞、缝为主要储集空间的古岩溶型储集层。     

岩体结构面粗糙度系数JRC的定向统计研究

本文回顾了岩体结构面粗糙度系数ＪＲＣ的研究成果，分析了各种ＪＲＣ研究方法的应用范围。在野外实际结构面形态的详细调查和深入研究的基础上，发展了Ｂａｒｔｏｎ直边法，并提出按岩性定向统计研究结构面粗糙度系数ＪＲＣ的科学思想。     

Review of the Tropical Gyre in the Indian Ocean with Its Impact on Heat and Salt Transport and Regional Climate Modes

Due to the IO monsoon impact, the tropical IO circulation has significant seasonal variation, especially in the northern IO. However, in mean-state, a relatively closed current loop is established by eastward current along the equator and westward current south of equator, which is regarded as Tropical Gyre in the Indian Ocean. Based on this circulation system, relevant studies were reviewed. Its impact on heat and salt transports and regional climate changes were discussed.     

Prediction of open stope hangingwall stability using random forests

Natural Hazards - The prediction of open stope hangingwall (HW) stability is a crucial task for underground mines. In this paper, a relatively novel technique, the random forest (RF) algorithm, is...     

Groundwater management by riverbank filtration and an infiltration channel: the case of Obrenovac, Serbia

The Vi? Bare groundwater source is used to supply water to the population and industry of Obrenovac, one of the municipalities of Belgrade (the capital of Serbia). It is a typical riverbank filtration site; exploitation is performed through 30 drilled wells and two radial wells located in the meander of the Sava River. The established hydraulic connection between the river and tapped aquifer is so great that the river regime has a dominant influence on the aquifer. As a consequence of this, water-delivery reduction occurs in the dry months (summer–autumn), when the population needs water the most. Based on the data associated with the river’s gauges, precipitation, quantity of pumped water and groundwater-level fluctuation, a simulation of the groundwater regime for non-steady-state flow conditions has been undertaken through a numerical model. To overcome problems of water shortage during the dry season, the possibility of artificial recharge using an infiltration channel, made up of two connected parts, was analyzed. During the dry months, 80 % of the wells receive water partly from the infiltration channel. In this way, possibilities for extracting additional water are created. The application of this concept is discussed.     

Surface characterization of maize-straw-derived biochars and their sorption performance for MTBE and benzene

Biochars generated at various temperatures might show significant differences in sorption for organic contaminants. In this study, a series of biochars, generated from pyrolyzing maize straws at different temperatures, were systematically characterized. The characterization results showed that with increasing pyrolysis temperature, the surface areas, micropore areas and aromaticity of biochars were enhanced. Batch experiments were conducted to study methyl tert-butyl ether (MTBE) and benzene sorption to biochars. The results indicated that the sorption capacity of benzene to biochars was higher than that of MTBE. The higher pyrolyzed temperature of biochars resulted in a stronger sorption affinity for target compounds, and the dominant sorption mechanisms varied for biochars pyrolyzed at different temperatures. The sorption to biochars pyrolyzed at 700 and 800 °C performed a high adsorption capacity, which indicated that they might be a promising sorbent to remove MTBE and benzene from water. Biochar pyrolyzed at 400 °C showed transitional sorption mechanisms from partition to adsorption for MTBE and benzene. Pore-filling was a possible sorption mechanism to biochars pyrolyzed at high temperature.     

Atomistic simulation of the mechanisms of noble gas incorporation in minerals

Atomistic simulations have been carried out to investigate the mechanisms of noble gas incorporation in minerals using both the traditional two-region approach and the “supercell” method. The traditional two-region approach has been used to calculate defect energies for Ne, Ar, Kr and Xe incorporation in MgO, CaO, diopside and forsterite in the static limit and at one atmosphere pressure. The possibilities of noble gas incorporation via both substitution and interstitial mechanisms are studied. The favored mechanism varies from mineral to mineral and from noble gas to noble gas. In all minerals studied, the variation of the solution energies of noble gas substitution with atomic radius appears approximately parabolic, analogous to those for 1⁺, 2⁺, 3⁺ and 4⁺ trace element incorporation on crystal lattice sites. Noble gas solution energies thus also fall on a curve, similar to those previously observed for cations with different charges, but with much lower curvature.The “supercell” method has been used to investigate the pressure dependence of noble gas incorporation in the same systems. Results indicate a large variation of the solubility of the larger noble gases, Kr and Xe with pressure. In addition, explicit simulation of incorporation at the (0 0 1) surface of MgO shows that the solubility of the heavier noble gases may be considerably enhanced by the presence of interfaces.     

JRC修正直边法的数学表达

JRC是反映爬坡角力学效应的岩体结构面表面形态等效描述指标。本文在爬坡角力学效应机理研究基础上, 阐述了JRC直边法的物理意义；通过岩体结构面表面起伏幅度与金属表面粗糙度幅度对比分析, 肯定了直边法的合理性；考虑JRC的尺寸效应, 推导JRC修正直边法的数学表达式, 编译计算机常用程序。最后, 实例检验了JRC修正直边法数学表达式的合理性和可用性。     

沉降量约束下的黄骅裂谷形成的地球的动力学模式

在计算覆盖整个黄晔裂谷２００口人工井（包括少部分探井）沉降量的基础上，总结本区二种基本沉降曲线模式。统计出热沉降（Ｓｔ）与初始沉降（Ｓｉ）之比为０．６，依此为约束条件与大陆岩石圈伸展的地球动力学正演模式进行对比，与简单剪切模式预测的热沉降与初始沉降之比值及几何效应更接近。进一步证实黄骅裂谷以简单剪切机制形成的地球动力学模式更合理，这与著名的以纯剪模式形成的北海伸展盆地不同