Drainage spacing regularity on a fault-block: A case study from the eastern Ruahine Range

Abstract:  Recent research has indicated river basin outlets draining linear sections of large, uplifting mountain belts often show a regularity of spacing, transverse to the main structural trend. A morphometric analysis of part of the Ruahine Range, on the North Island was undertaken to test whether drainage regularity may exist in smaller, younger mountain ranges. The ratio, R , of the half-width of the mountain belt, W , and the outlet spacing, S , was used to characterize drainage networks on the eastern side of the range. The spacing ratio for the range of 1.31 is lower than R results from studies of larger mountain belts ( R  = 1.91–2.23). We suggest the cause of this lower ratio is related to eastward migration of the Ruahine drainage divide.     

吉尔嘎朗图凹陷宝饶洼槽下白垩统层序地层与沉积体系

运用高分辨率层序地层学原理和方法,通过对钻井和地震资料的综合分析,在二连盆地吉尔嘎朗图凹陷下白垩统中识别出1个超长期基准面旋回(二级层序)SSC1和5个长期基准面旋回(三级层序):LSC1,LSC2,LSC3,LSC4,LSC5,分析了各旋回的发育特征。识别出五种类型的沉积体系:滨浅湖近岸水下扇、较深水湖浊积扇、滨浅湖扇三角洲、滨浅湖辫状河三角洲和河流沉积体系,并在等时地层格架内分析了各基准面旋回的沉积体系构成和储层砂体的发育情况。综合分析生、诸、盖条件后认为,在垂向上,LSC3旋回为本区最有利的储集层段,在平面上,本区的油气勘探应主要寻找宝饶构造带辫状河三角洲前缘砂体,主要储层砂体类型为前缘分流水道砂和前缘席状砂。     

舞阳、襄城盐湖盆地未熟-低熟油成藏模式

舞阳、襄城凹陷下第三生活费为膏、盐岩相盐湖沉积。半咸水-咸水湖相、盐湖相是形成未熟-低熟油的良好环境，沉积旋回中期断坳式沉积形成了主要油源层系，其高丰度未熟烃类推岩体是形成未熟-低熟油藏的物质基础，中-高孔、中-高渗碎屑岩层构成了未熟-低熟油藏的重要储集层，并发育了较好的生储盖组合，这些有利条件为舞阳、襄城凹陷形成未熟-低熟油藏提供了重要保证。指出凹陷陡坡带为背斜、断鼻型油藏分布区，还可能有混合型油藏；中部洼陷带为岩性油藏、裂隙型油藏发育区；斜坡带主要发育断鼻型油藏。     

Lithium and lithium isotope profiles through the upper oceanic crust: a study of seawater-basalt exchange at ODP Sites 504B and 896A

Ocean Drilling Program (ODP) Hole 504B near the Costa Rica Rift is the deepest hole drilled in the ocean crust, penetrating a volcanic section, a transition zone and a sheeted dike complex. The distribution of Li and its isotopes through this 1.8-km section of oceanic crust reflects the varying conditions of seawater alteration with depth. The upper volcanic rocks, altered at low temperatures, are enriched in Li (5.6-27.3 ppm) and have heavier isotopic compositions (δ⁷Li=6.6-20.8‰) relative to fresh mid-ocean ridge basalt (MORB) due to uptake of seawater Li into alteration clays. The Li content and isotopic compositions of the deeper volcanic rocks are similar to MORB, reflecting restricted seawater circulation in this section. The transition zone is a region of mixing of seawater with upwelling hydrothermal fluids and sulfide mineralization. Li enrichment in this zone is accompanied by relatively light isotopic compositions (−0.8-2.1‰) which signify influence of basalt-derived Li during mineralization and alteration. Li decreases with depth to 0.6 ppm in the sheeted dike complex as a result of increasing hydrothermal extraction in the high-temperature reaction zone. Rocks in the dike complex have variable isotopic values that range from −1.7 to 7.9‰, depending on the extent of hydrothermal recrystallization and off-axis low-temperature alteration. Hydrothermally altered rocks are isotopically light because ⁶Li is preferentially retained in greenschist and amphibolite facies minerals. The δ⁷Li values of the highly altered rocks of the dike complex are complementary to those of high-temperature mid-ocean ridge vent fluids and compatible to equilibrium control by the alteration mineral assemblage. The inventory of Li in basement rocks permits a reevaluation of the role of oceanic crust in the budget of Li in the ocean. On balance, the upper 1.8 km of oceanic crusts remains a sink for oceanic Li. The observations at 504B and an estimated flux from the underlying 0.5 km of gabbro suggest that the global hydrothermal flux is at most 8×10⁹ mol/yr, compatible with geophysical thermal models. This work defines the distribution of Li and its isotopes in the upper ocean crust and provides a basis to interpret the contribution of subducted lithosphere to arc magmas and cycling of crustal material in the deep mantle.     

疏勒河流域昌马灌区泉水量预测分析

疏勒河流域农业灌溉主要采用地表水灌溉 ,泉水为该区农业灌溉的主要水源之一 ,该文利用 2 0世纪 90年代的测流资料 ,采用有限差分方法对疏勒河中游泉水量的变化趋势进行预测分析 ,结果显示 ,随着时间的延长 ,泉流量呈逐渐减小的趋势 ,但下降梯度逐渐变小 ,最终趋于稳定     

华南地区小流域水污染控制规划初探

随着经济和城市化进程的快速发展，华南地区小流域水环境污染日趋严重，因此以规划的方法控制该区小流域水污染成为了一种重要的途径。从水环境污染控制规划的基本定义出发，重点分析了小流域水环境污染控制规划的一般规范及其在实施中存在的一些问题，并就这些问题提出了相应的对策，指出小流域进行水环境污染控制时必须加强环境意识，提高环境工作者素质，结合自身实际，走出一条既符合中国国情更符合华南地区小流域的水污染控制规划道路，为华南地区的持续，快速发展创造条件。     

松潘-甘孜带：是弧前增生还是弧后消减?

根据多年在该区工作实践，认为松潘—甘孜造山带前身的巴颜喀拉盆地是羌塘—他念他翁晚古生代前缘弧之后的一系列多岛弧—盆系的一个大型弧后盆地。三叠纪时，围限此“三角形”盆地三条边缘的构造动力学作用方式具有不同的特征。其东侧为扬子西缘被动大陆边缘(D—T2)，中三叠晚期(拉丁期)转化为与华北和羌塘陆块有关的前陆盆地(T2—T3)，由于扬子陆块向西双向斜向俯冲作用，在其北侧和南侧边缘形成南昆仑和可可西里—甘孜—理塘俯冲消减杂岩。重建的地层层序和沉积地质特征显示巴颜喀拉盆地主体三叠系复理石沉积是周缘前陆盆地。     

甘肃北山公婆泉盆地中生代地层特征与砂岩型铀成矿条件分析

根据野外实地考察，综合前人的工作资料，从地层结构、层位、沉积体系、岩性及形成砂岩型铀矿的条件出发，概括了公婆泉盆地中生代地层的主要特征；确定了目的层并浅要分析了砂岩型铀成矿条件，对下一步铀矿找矿工作具有一定的现实意义。     

Groundwater transformation of a low-sulfur to a high-sulfur coal, the Harlem coal of the northern Appalachian basin

The Harlem coal is postulated to have been deposited in raised-bog settings. It was initially deposited as low-sulfur peat, but groundwater of a later origin altered portions of it to high-sulfur coal. The total sulfur content of 172 samples from 31 locations on a moisture- and ash-free basis have a quadrimodal distribution with two major modes at 0.75% S and 2.0%S. Multiple sampling and analyses at specific mine sites indicate that the addition of sulfur of a later origin occurred either laterally adjacent to sandstone channels or vertically adjacent to faults. Significant sulfur addition also occurred above clay partings at these sites. The original low-sulfur nature is preserved where the coal bed is isolated from descending groundwater by a thick impervious layer. Trace-element analyses show high concentrations of mobile elements such as Na and Mn in the high-sulfur coals.     

Reservoir Diagenesis Sequence and Framework in Intracontinent Rift Basin,East China

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