西藏山南地区琼结南部上三叠统郎杰学群的沉积学岩相特征与浊积扇模式

西藏山南地区琼结南部上三叠统郎杰学群由轻微变质的泥质岩和碎屑岩组成,其中,砂岩主要为(岩屑)长石(杂)砂岩和(长石)岩屑(杂)砂岩,碎屑的分选和磨圆度较差,成分和结构成熟度较低,经历了压溶、交代及胶结等成岩作用;发育与浊积岩相关的层面、层理构造及沉积旋回发育。研究表明,按照宋热组、江雄组和姐德秀组地层层序,郎杰学群岩相总体呈现外—中扇砂板岩相向中—内扇砂板岩含砾岩相演化,向上变粗变浅,中源和近源/分支水道亚相增加;以姐德秀组下段中部为界可分为A和B两个层序,它们分属浊积扇演化的两个不同阶段;推测研究区及邻近地区可能存在一个较大规模向南迁移进积的舌状浊积扇。     

沿海冲积平原区土壤中元素含量特征及其影响因素研究

根据沿海冲积平原区地球化学调查方法技术研究试验研究结果，开展了土壤中元素含量变化特征及其影响因素的探索研究。研究结果表明，元素含量在不同地区和不同深度土壤层中的变化特征，除受土壤成壤母质的源岩影响以外，同时还受成壤母质所经历的风化作用及风化程度和由此所决定的土壤矿物组成特性等因素的影响。     

赣北双桥山群浅变质岩沉积学研究的新进展

通过对双桥山群单调岩性和沉积构造进行深入系统的研究,发现了大量不同类型的流水波痕,对条带状层理和复理石进行了细分,它们对识别环境变化、地层划分和对比、旋回沉积作用以及大地构造演化都具重要作用;系统提出了赣北双桥山群是个不断向上变厚、变粗的向海方进积的浊积扇体,反映其构造作用和海平面变化是比较剧烈的,而不是静止不动的。对造山带地区应更加强调构造与沉积学的紧密结合的研究方法。     

Asymmetrical valleys created by the geomorphic response of rivers to strike-slip fault

Offset fluvial valleys, including rivers beheaded and deflected by strike-slip faults, have long been used to estimate horizontal displacements on the faults. Larger rivers crossing such faults, however, sometimes show either no offset or only a small amount of offset compared to smaller rivers crossing the same faults. The larger rivers with higher erosional rates may widen their valleys asymmetrically downstream of strike-slip faults, rather than being beheaded or deflected. Examples are described from the Yellow River near the NE margin of the Tibetan Plateau. River beheading and asymmetrical widening are two end-members of a fluvial valley's response to strike-slip faulting, whereas deflection is a combination of both. Recognition of the formation of such asymmetrical valleys related to strike-slip faulting will help to understand fault activity better over longer time spans and enable a re-evaluation of many fault histories worldwide.     

Alluvial Fan-lacustrine Sedimentation and its Tectonic Implications in the Cretaceous Athgarh Gondwana Basin, Orissa, India

The Athgarh Formation is the northernmost extension of the east coast Upper Gondwana sediments of Peninsular India. The formation of the present area is a clastic succession of 700 m thick and was built against an upland scarp along the north and northwestern boundary of the basin marked by an E-W-ENE-WSW boundary fault. A regular variation in the dominant facies types and association of lithofacies from the basin margin to the basin centre reveals deposition of the succession in an alluvial fan environment with the development of proximal, mid and distal fan subenvironments with the distal part of the fan merging into a lake. Several fans coalesced along the basin margin, forming a southeasterly sloping, broad and extensive alluvial plain terminating to a lake in the centre of the basin. Aggradation of fans along the subsiding margin of the basin resulted in the Athgarh succession showing remarkable lateral facies change in the down-dip direction. The proximal fan conglomerates pass into the sandstone-dominated mid-fan deposits, which, in turn, grade into the cyclic sequences of sandstone-mudstone of the distal fan origin. Further downslope, thick sequence of lacustrine shales occur. The faulted boundary condition of the basin and a thick pile of lacustrine sediments at the centre of the basin suggest that tectonism both in the source area and depositional site has played an important role throughout the deposition of the Athgarh succession of the present area. The vertical succession fines upward with the coarse proximal deposits at the base and fine distal deposits at the top, suggesting deposition of the succession during progressive reduction of the source area relief after a single rapid uplift related to a boundary fault movement.The NW-SE trending fault defining the Son-Mahanadi basin of Lower Gondwana sediments are shear zones of great antiquity and these were rejuvenated under neo-tensional stress during Lower Gondwana sedimentation. The E-W-ENE-WSW trending fault of the Athgarh basin, on the other hand, define tensional rupture of much younger date. In the Early Cretaceous period, there was a reversal of palaeoslope in the Athgarh basin (southward slope) with respect to the Son-Mahanadi basin (northward slope). During the phase drifting of the Indian continent and with the evolution of Indian Ocean in the Early Cretaceous period, the tectonic events in the plate interior was manifested by formation of new grabens like the Athgarh graben.     

巴颜喀拉三叠纪沉积盆地岩相与古地理——以阿坝-若尔盖盆地为例

以阿坝－若尔盖盆地岩相与古地理研究为例,并结合区域上有关资料,认为巴颜喀拉三叠纪沉积盆地发育有世界上罕见的巨型浊流沉积,主要由一套大陆斜坡浊积扇相组合与深海盆地相组合等构成,而斜坡浊积扇,深海盆地的形成一发展和海平面的下降期与上升存在着对应关系,发育一系列叠复的浊积扇舌状体;浊流沉积物在陆源碎屑为主,伴有火山物质和碳酸盐岩的混合源型,物源主要来自北西侧与北侧的浅变质岩区;盆地属多阶段、多物源,不同     

ESTIMATIONS OF THE SHAPE AND VOLUME OF A STONY DEBRIS FLOW FAN

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冲洪积扇含水层地下水可开采量数值模拟——以文峪河冲洪积扇为例

依据钻孔岩性,水文地质资料,将文峪河冲洪积扇平原分为上游单一潜水区和中下游承压水区,中下游垂向划分为上部弱水含水层和下部较强承压水含水层,对上游潜水和中下游承压水用二维侧向流数学模型,对中下游弱潜水用一维垂向流数学模型,在计算了现状开采条件下的水资源基础上,进一步计算出,在扇上游集中采水时,按工业开采和农业开采,以地下水多年总补排均衡,水位长期稳定的约束条件地下水可开采量。     

Rational regime model of alluvial channel morphology and response

A theoretical model is developed for predicting equilibrium alluvial channel form. The concept of greatest relative stability, achieved by maximizing resistance to ?ow in the ?uvial system, is presented as the basis for an optimization condition for alluvial systems. Discharge, sediment supply (quantity and calibre) and valley gradient are accepted as independent governing variates. The model is used to de?ne a dimensionless alluvial state space characterized by aspect ratio (W/d), relative roughness (D/d), and dimensionless shear stress (τ*) or, equivalently, channel slope (S). Each alluvial state exhibits unique values of Froude number and sediment concentration. The range of alluvial states for constant values of relative bank strength (parameterized by an apparent friction angle, ?′) forms a single plane in the state space (W/d, D/d, τ* or S). The scaling relations produced by the model are consistent with laboratory channels exhibiting a range of bank strengths, and with the behaviour of natural channels. Copyright © 2004 John Wiley & Sons, Ltd.     

Strata反演技术在柳屯洼陷沙三2-3亚段储层描述中的应用

地震波阻抗反演技术已日益成为油气藏勘探、开发中储集层横向预测的重要手段。柳屯洼陷沙三^2-3亚段同时发育浊积砂体和厚层盐岩,横向相变剧烈。笔者论述了Strata反演的原理及其在该区的应用,在大量统计的基础上建立了不同岩性与波阻抗之间的解释标准。通过对反演剖面的解释,明确了深水浊积扇向盐湖相的渐变关系,做出了各体系域的砂体等厚图,描述了储层的空间展布特征。