红河断裂带中、越现代形变监测对比研究综述

利用现今大地形变测量资料,可分析研究得到现今地壳形变特征.大地形变场的建立,主要以精密水准测量监测大地区域垂直形变,以地面激光测距监测大地水平形变,以短基线、短水准测量等方法对断层活动性进行定点观测研究.20世纪90年代以后比较流行用GPS监测场区现代构造运动及断裂的地壳形变.本文主要通过分析对比中、越红河断裂带及其相邻地区的现代形变监测资料,得出现今红河断裂的形变特征.     

Downstream trends in sediment size and composition of channel-bed, bar, and bank deposits related to hydrologic and lithologic controls in the Llano River watershed, central Texas, USA

The downstream fining of fluvial sediments is a fundamental tenet of drainage systems and, for decades, has been the subject of considerable research. Most of this research has focused on variability in channel-bed material. Other sedimentological components such as channel bars and banks, however, represent distinctively different processes occurring at various flow magnitudes and durations and thus provide an opportunity to examine a more comprehensive set of controls on the larger fluvial system. This study analyses downstream patterns of sediment size and composition for channel-bed material, bars, and banks in the Llano River watershed (11,568 km²) in central Texas, USA.Fluvial deposits in the study area were characterized through field, laboratory, and statistical analyses and standard sedimentary indices (d₁₆, d₅₀, d₈₄, sorting) were computed. Two hundred thirty-eight sediment samples were collected at 15 sites along the main-stem channel with sampling occurring at the low-flow channel (thalweg), lateral bars, banks, and overbank locations. Channel-bar deposits are characterized by a downstream reduction in particle size, but low-flow-channel deposits have a substantially weaker trend, a discrepancy possibly attributed to uniformity and continuity of hydraulic sorting mechanisms during moderate and high flows. Channel-bar deposits reveal an abrupt downstream reduction in gravel size in the upper watershed, which is attributed to an increase in drainage area. Further, an abrupt gravel-to-sand transition occurs immediately downstream of a distinct lithologic change from mostly carbonate rocks to igneous and metamorphic rocks. The downstream decrease in channel-bar particle size occurs despite an increasingly constricted alluvial valley, commonly associated with greater unit stream power and relatively coarse sediment. Contrasting with channel-bed material, particle size of channel banks increases downstream, which is attributed to the addition of sand-sized sediment from igneous and metamorphic rocks. The consideration of distinctive sedimentological components of a dynamic fluvial system represents a more comprehensive and nuanced study of the topic of downstream sediment trends than prior studies, which is important to a range of engineering, biological, and planning issues at the watershed scale.     

鄂尔多斯盆地延长组高自然伽马砂岩储层特征

鄂尔多斯盆地延长组岩芯分析与测井特征研究表明,相对高自然伽马砂岩具有高长石、高Th、局部高U、K含量变化不大的共同特征,Th、U含量特征与凝灰岩极为相似;相对高自然伽马砂岩具有相对高自然伽马、高声波时差、低电阻率值的测井曲线特征,与凝灰岩测井曲线特征也极其相似;再者,从长6到长4+5油层组的各亚组,凝灰岩层逐渐不发育的同时,伴随相对高自然伽马砂岩发育程度依次增强;上述3项特征预示着延长组相对高自然伽马砂岩可能为同沉积期或较先期沉积的凝灰岩经搬运后作为砂岩组成部分再沉积形成的.四性关系研究表明：（1）依据自然伽马-自然电位曲线重叠图、声波时差-自然电位曲线重叠图,可快速识别相对高自然伽马砂岩;（2）相对高自然伽马砂岩具有相对发育的次生孔隙,非均质性强,一般物性越好,声波时差-自然电位曲线重叠图幅度差越大;（3）计算自然电位-自然电位曲线重叠图的幅度差,反映相对高自然伽马砂岩含油性,幅度差越大,表明其含油性越好.     

全球变化的地球物理测井研究

地球物理测井可以直接服务于全球变化的方面有;地球物理测井矿物分析（粘土矿物分析计算,碳酸盐含量分析计算,反射光谱计算分析）,地球物理测井岩性分析（粗细成分含量分析计算,平均粒度,层里一纹理类型,岩石孔隙度,渗透率）磁性地层测井分析（磁测试对比或计算后为全球变化问题间接斩有：同位素地层分析,旋回与层序地层划分,地层水化学成分分析;     

东南亚及哀牢山红河构造带构造演化的讨论

通过对东南亚和哀牢山红河构造带演化已有模式的分析,在近年来本区海上研究资料的了,结合滇西地质情况,认为东南亚的构造格局是由印度洋、太平洋和欧亚三大构造体系共同作用形成的。６０￣１５ＭａＢＰ,欧亚构造体系分别与太平洋和印度洋构造体系作用在东南亚东、西部形成两个弧后盆地扩张体系。两体系扩张强度和方向的不同,形成转换调节构造带－哀牢山红河构造带。东部较强的扩张作用使扬子板块向北运动,形成哀牢山以东的逆冲     

Enigma variations: the stratigraphy,provenance, palaeoseismicity and depositional history of the Lower Old Red Sandstone Cosheston Group,south Pembrokeshire,Wales

The Lower Devonian (Lochkovian‐Emsian) Cosheston Group of south Pembrokeshire is one of the most enigmatic units of the Old Red Sandstone of Wales. It consists of a predominantly green, exceptionally thick succession (up to 1.8 km) within the red c. 3 km‐thick fill of the Anglo‐Welsh Basin, but occupies a very small area (27 km²). Four formations—Llanstadwell (LLF), Mill Bay (MBF), Lawrenny Cliff (LCF) and New Shipping (NSF)—group into lower (LLF + MBF) and upper (LCF + NSF) units on stratigraphical and sedimentological criteria. Two palynostratigraphic associations (Hobbs Point and Burton Cliff) are recognised in the LLF. Overall, the Cosheston succession comprises a fluvial, coarsening‐upward megasequence, mostly arranged in fining‐upward rhythms. It is interpreted as the fill of an east‐west graben bounded by faults to the north and south of the Benton and Ritec faults, respectively. Both ‘lower Cosheston’ formations were deposited by east‐flowing, axial river systems draining a southern Irish Sea landmass. Drainage reversal, early in the deposition of the LCF, resulted in ‘upper Cosheston’ lateral, SW‐flowing rivers which carried predominantly second‐ and multi‐cycle detritus. The ‘lower Cosheston’ is characterized by an abundance of soft‐sediment deformation structures, probably seismically triggered by movements along the graben's northern bounding fault. A minimum average (≥ mesoseismic) earthquake recurrence interval of c. 4000 yr is estimated for the MBF. This and the correlative Senni Formation of south‐central Wales form a regionally extensive green‐bed development that represents a pluvial climatic interval. Copyright © 2006 John Wiley & Sons, Ltd.     

The Ridgeway Conglomerate Formation of SW Wales,and its implications. The end of the Lower Old Red Sandstone?

The Devonian Old Red Sandstone Ridgeway Conglomerate Formation crops out in Pembrokeshire, SW Wales. It was deposited as part of a dryland alluvial fan, axial fluvial valley deposystem. It conformably overlies the mid Lochkovian Freshwater West Formation and probably predates deposition of the Lower Cosheston Group Mill Bay Formation indicating an Early Devonian (latest Lochkovian to earliest Pragian) age, rather than a Middle Devonian age as suggested by previous workers. It therefore represents the youngest preserved formation of the Milford Haven Group south of the Ritec Fault. The Formation thickens drastically into the Ritec Fault, indicating its control on sedimentation. The half‐graben topography initiated deposition of a hangingwall alluvial fan that was sourced from a southerly Lower Palaeozoic/Precambrian provenance within the present‐day Bristol Channel. The Formation is heterolithic in nature, with deposits on the fan reflecting a mixture of processes. Conglomerates were deposited primarily by laterally extensive sheetfloods, and as bars in low‐relief, laterally accreted channels. Sandstones were also predominantly deposited by sheetfloods. Gritty mudrocks in comparison demonstrate deposition by cohesive debris flows. The fan prograded northward and interfingered with a low‐gradient, high‐sinuosity fluvial channel system dominated by inclined and non‐inclined heterolithic stratification. Thinly laminated mudstone and sandstone interbeds were deposited in ephemeral fan‐toe and axial valley lakes that may have developed during sub‐humid climatic episodes. The lacustrine heterolithic association has associated matgrounds and possible ‘algal roll‐up’ structures. Calcretized peetee structures and root traces comprise a lake margin calcrete association. Fan gravels prograded into the axial fluvial valley during periods of increased sediment flux that may represent semi‐arid conditions and/or episodes of tectonic activity. Calcretes of varying development were established in both the fan and axial valley zones. Calcretes with lower stages of development are more proximal to the Ritec Fault reflecting decreased soil residence times and high deposition rates within the axial valley. More strongly developed soil profiles on the fan may indicate sequence boundaries associated with low sediment flux, or increased soil residence time due to active fan‐channel migration (the pedofacies concept). Groundwater calcretes have sharp‐based and layer‐bound calcrete profiles. Gully‐bed cements are locally developed within the fan gravels. Copyright © 2007 John Wiley & Sons, Ltd.     

施洞口断裂带对金钟山断陷盆地沉积建造的制约研究

施洞口断裂位于贵州东部,曾作为贵州大地构造的分界,但马号段构造样式历有争议,为了探讨施秉县金钟山非典型丹霞地貌成因,即金钟山白垩纪断陷盆地及其“红层”非典型丹霞山体地貌形成的控制因素,对施洞口断裂带马号段、台盘段和舟溪段等多个重要剖面进行调查研究,结合区域地质资料,否定“巴团飞来峰构造”,认同1:20万镇远幅区域地质图划定的构造透镜体形式,同时查明了金钟山白垩系南东边界的沉积关系其实是断层接触,构成施洞口断裂马号地区较大规模构造透镜体的南东边界,使施洞口断裂在整体的平剖结构展布上呈现分支联合的构造透镜状普遍规律特征,另外认为马号—金钟山公路沿线寒武系白云岩为不整合沉积覆盖于青白口系之上,而东侧一带的青白口系又以逆冲断层“推覆”于寒武系白云岩之上,从而成为导致施洞口断裂带在马号段构造特征较为复杂的主要原因,据此本文对施洞口断裂构造特征进行了再次调查梳理,具有较重要的基础地质科学意义,并从地质演化角度解释了施秉金钟山白垩纪断陷盆地及其“红层”非典型丹霞地貌山体的形成,可为金钟山的旅游开发提供地学科普参考依据。     

红层软岩遇水作用的孔隙结构多重分形特征

红层软岩内部孔隙具有随机、多样化的分布特点,孔隙结构的变化是影响其宏观力学性能的关键所在。由SEM扫描电镜获取岩样不同饱水时间下的细观结构图像,根据盒维数法计算出孔隙的分形维数,发现随着饱水时间的加长,孔隙的分形维数呈现增大趋势。同时对孔隙的数量、大小进行统计分析,得出不同饱水时间下岩样内部孔隙的分布特征。基于多重分形理论,采用统计矩的方法对孔隙结构进行定量表征。结果表明,孔隙结构的分配函数与q阶次趋于线性关系,验证了该结构的自相似性与无标度性,由广义分形维数D(0)>D(1)>D(2)说明了孔隙具有多重分形特征,由多重分形谱参数分析了孔隙结构的不规则性与复杂程度,更好地表征孔隙大小各异的分布情况。结合孔隙结构的多重分形特征与岩样抗压强度,建立起孔隙结构变化与其力学性能的关联性,对研究红层软岩的损伤过程具有一定的指导意义。     

滇西哀牢山变质杂岩中含石墨岩石的变形-变质温度、构造特征及流变弱化意义

前人研究表明石墨化作用与变质温度具有良好的相关性,同时室内摩擦实验研究认为少量石墨就能够有效地降低断层摩擦阻力,进而被认为对断层弱化起着重要的固体润滑作用而开始受到大家的关注。但是由于技术手段的限制,我们对天然断裂带中含石墨岩石的宏观-微观构造、变形机制、变形-变质环境以及对岩石流变行为的贡献仍然还不是很清楚。本文在详细的野外地质观测的基础上结合室内实验分析,对新生代红河-哀牢山走滑断裂带内哀牢山深变质杂岩东南侧边界发育的含石墨岩石开展了深入的研究。其中主要侧重利用光学显微镜(OM)、扫描电镜(SEM)、电子背散射衍射(EBSD)以及拉曼光谱(Raman Spectra)技术方法和手段,对宏观及显微构造变形行为、石墨拉曼温度、矿物晶格优选定向(LPO)以及其变形-变质环境进行了综合分析。结果表明,含石墨岩石显微构造特征表现为典型的塑性到超塑性流动构造特征,通过石墨拉曼光谱地质温度计,获得了哀牢山杂岩东部边界与上盘未变质岩石接触的含石墨岩石变形-变质的石墨拉曼温度为462～505℃;而靠近深变质岩含石墨岩石的石墨拉曼温度在511～529℃。基质中强烈细粒化的石墨、石英及长石具有明显的晶格优选定向,其中石墨和石英均表现出强烈的(0001)a方向上的滑移系。细粒化的石墨滑移系的发育与长石、石英共同对岩石整体的晶质塑性变形起着重要的流变弱化作用。