柴达木盆地西部更新统砂砾型深层卤水钾矿成矿模式与找矿方向探讨

通过对柴达木盆地西部大浪滩-黑北凹地、察汗斯拉图凹地、昆特依凹地和马海凹地发现的新类型砂砾型深层卤水钾盐矿床进行卤水化学成份和微量元素系统测试和分析、相关同位素测试,经综合分析和研究后认为,砂砾型深层卤水钾盐矿床为溶滤-沉积成因类型,其形成受第四纪砂砾层和古近纪以来古岩盐层的控制.其成矿模式为:盆地西部从始新世至上新世...     

澳大利亚凹凸棒石（坡缕缟石）粘土矿床的分布、类型、特征及成因

本文旨在介绍凹凸棒石（坡缕缟石）粘土矿床在澳大利亚的分布、矿床类型、典型矿床特征及成因,以求国人了解和借鉴。     

柴达木盆地北缘中新生代地层的磁组构特征及其沉积-构造学意义

柴达木盆地沉积地层记载着青藏高原东北部的构造演化信息.对该盆地路乐河地区上中生界-新生界地层系统采样,获得千余块定向岩心样品.岩石磁学研究表明样品中的磁性矿物主要为赤铁矿和磁铁矿;磁组构研究表明为初始沉积磁组构特征.磁组构特征指示了自中侏罗统大煤沟组（J₂d）至早中新统下油砂山组（N₂¹y）7个地层单位沉积时期,古水流方向共经历了4次阶段性的变化,表明柴达木块体相应地发生了4次旋转.在中-晚侏罗世块体逆时针旋转约22°;至早白垩世,块体又顺时针旋转约65°;在65.5~32 Ma期间块体旋转方向再次改变,逆时针旋转约63°;到32~13 Ma阶段块体又发生约50°的顺时针旋转.柴达木块体的旋转及其方向的转换,可能与其南的羌塘块体、拉萨块体和印度板块阶段性北向碰撞挤压紧密相关.拉张环境与挤压环境的多次转换可能与中特提斯的关闭、新特提斯的张开和闭合、高原快速隆升后其边部松弛相联系.

     

A new model of back-arc spreading in the Parece Vela Basin, northwest Pacific margin

Abstract Swath bathymetric data, single-channel seismic reflection profiles, magnetic and gravity anomalies in the northern part of the Parece Vela (West Mariana) Basin were obtained by comprehensive surveys conducted by the Hydrographic Department of Japan. The central zone of the Parece Vela Basin is characterized by the north-south trending chain of depressions in a right-stepping en echelon alignment. The morphology of these depressions is diamond shaped and bordered by steep escarpments of 1000-1500 m relative height. These fault escarpments extend northeastward and southwestward from the depressions into the surrounding basin floor and then gradually fade out. These escarpments have an S-shaped trend, and their geometry seems to be symmetric about the depressions. Minor ridges and troughs trending orthogonal to these escarpments are recognized. It is concluded that these depressions and escarpments are the topographic expression of extinct spreading axes and S-shaped transform faults, respectively. The age of the central depressions seems to be young, although details of tectonic processes forming them remains unsolved. The western province of the basin floor and basement is extremely rugged and characterized by minor ridges and troughs trending in a north-south direction. Although magnetic anomalies of the basin are very weak, magnetic lineations trending parallel to the topographic trend are recognizable in the central and western parts of the basin. Based on updated geomorpholog-ical features and magnetic anomalies revealed by the present survey, together with the previously published data including drilling results, it is proposed that the evolution of Parece Vela Basin took place in four stages of opening and tectonic activity: rifting, east-west spreading, northeast-southwest spreading with counter-clockwise rotation of spreading axes, and post-spreading deformation and volcanism. This proposed spreading model of the Parece Vela Basin is similar to that of the adjacent Shikoku Basin. The spreading axes of both basins were segmented and gradually rotated counter-clockwise in a later phase of the basin evolution, after the cessation of relatively uniform spreading nearly in an east-west direction.     

Carbon isotope characteristics,origin and distribution of the natural gases from the Tertiary salty lacustrine facies in the West Depression Region in the Qaidam Basin

Since the Meso-Cenozoic, controlled by paleoclimate, a series of fresh to brackish water basins and salt to semi-salt water basins were developed in wet climatic zones and in dry climate zones in China, respectively[1]. The geological and geochemical char…     

青海湖及柴达木盆地地区现代湖泊沉积物中长链烯酮的分布特征

研究了我国青海湖和柴达木盆地地区不同类型湖泊表层沉积物中的长链烯酮。结果表明该地区湖泊中可能广泛存在长链烯酮,多数淡水湖、咸水湖现代沉积物中C37／C38〉1,而盐湖中C37／38〈1。根据文献中报道的湖泊环境下长链烯酮不饱和度U^K＋37与温度的方程,估计的温度在青海湖地区处于实际温度范围内,而在柴达木盆地低于实际温度,结果亦显示在青海湖和柴达木盆地地区,长链烯酮的含量在咸水湖中要明显的高于淡水湖和盐湖,最高含量出现在咸水湖（盐度为103.2g／L）尕海中,高达86.09μg／g;这种含量和分布特征可能表明生产长链烯酮的藻类应该更喜欢生长于具有一定盐度的环境;长链烯酮含量的变化可能指示咸水或淡水环境。     

Characteristics,genesis and accumulation history of natural gas in Hetianhe gasfield,Tarim Basin,China

Hetianhe gasfield in Bachu region of the Tarim Basin is mainly composed of three reservoir-caprock assembly,namely regional caprock of upper mudstone,middle mudstone and lower mudstone of the Carboniferous and reservoir of Bachu bioclastic limestone,glutenite and the Ordovician carbonate buried hill.Natural gas in Hetianhe gasfield sourced from the Cambrian source rock.It is thought that gases in Ma4 well block in the east of Hetianhe gasfield are mainly crude-oil cracked gases,while those in Ma3 and Ma8 well blocks in the west are the mixture gases of kerogen cracked gases and crude-oil cracked gases.Natural gas is rich in H2S and accumulated in multiply stages as the result of TSR.The accumulation history is divided into three stages,namely accumulation and breakage in the late Caledonian-early Hercynian,migration and dissipation in the late Hercynian and accumulation in Himalayan. The main accumulation of reformed gas reservoir is in Himalayan.     

柴达木盆地航磁资料微弱信息增强技术研究及在线性构造识别中的应用

目的利用重磁异常数据微弱信息增强技术识别线性构造的方法,并介绍其实现过程.方法文中提出了一种梯级带滤波增强非线性滤渡技术与Tilt梯度及其水平导数的有效结合,增强放大微弱信息再识别提取线性构造,利用数字图象显示技术成图.结果识别出柴迭木盆地线性构造多条,分析对比柴达木盆地区域地质构造资料及重力解释成果,具有较好的吻合性.为深入研究该地区线性构造、成矿特征、寻找勘探靶区补充了新的证据.结论该方法提取了区域航磁异常资料中的微弱信息,弥补传统方法的不足,对断层边界及异常的边界划定更为准确.梯级带滤波增强技术与Tilt梯度及其水平导数相结合取得良好的解释效果.     

柴达本盆地沙下盐湖的卤水化学及矿物沉积特征——以察尔汗盐湖区北部外围地带为例

对柴达木盆地察尔汗盐湖区外围沙下盐湖的卤水及沉积进行了综合研究。沙下盐湖卤水化学组成与地表径流和开放性盐湖卤水之间存在明显的差异性,具有高Na⁺+Cl^-、低Mg²⁺+Ca²⁺+SO₄^2-、贫K⁺+CO₃^2-+HCO₃^-等特征。沙下盐湖析盐层位含有新生矿物并夹带碎屑矿物,其盐类矿物组合为:石盐+羟氯镁铝石+光卤石。25℃等温蒸发相图表明,其卤水演化方向往光卤石析出区迁移,在穿越上覆盖层通道中卤水发生的物理化学反应与独特的沉积特征,可以作为继续寻找沙下盐湖的指导。     

柴达木盆地尕斯库勒盐湖地表水-地下水的转化与铀的补给通量

流域范围内地表水和地下水转化对盐湖成盐元素的运移和富集具有十分重要的意义.本文通过尕斯库勒盐湖盆地内流域水体的水化学和B同位素特征识别了地表水和地下水之间的定量转化关系,在此基础上估算了流域中铀的补给通量.结果表明,流域水体中离子的分异除了蒸发浓缩作用之外,还受重力分异及掺杂作用的影响;上游库拉木勒克萨伊河和阿特阿特坎河水体在出山口附近转入地下并在中游补给地表水和地下水,其补给率分别占48.8%和51.2%,年均补给量分别为1.08×108和1.13×108m3/a;在中游至尾闾盐湖段,阿拉尔河和侧向补给对盐湖卤水的补给率占55.2%,深部水体的补给占44.8%;至少从5.7 ka以来,上游水体对盐湖卤水中铀的补给通量为4.11×103t,在湖积平原黏土沉积带以及祁漫塔格山前局部还原带可能具有较大规模的铀矿.研究结果有助于建立盐湖盆地水循环模式、揭示卤水资源形成机制;同时为尕斯库勒盐湖盆地水资源的高效利用和寻找铀矿提供理论依据和技术支持.     

Wind erosion on the north‐eastern Tibetan Plateau: constraints from OSL and U‐Th dating of playa salt crust in the Qaidam Basin

The arid Qaidam Basin is the largest (~3.88 × 10⁴ km²) basin on the north‐eastern Tibetan Plateau. Wind erosion in the area has been regarded as an important trigger for intra‐basin tectonic balance upheaval, geomorphologic development and as a major supplier of dust to the Chinese Loess Plateau downwind. An initial estimate of the rate of wind erosion (Kapp et al., 2011) based on geological cross‐sections has suggested up to 3.2 × 10⁴ km³ of sediments has been deflated over the past 2.8 Ma, lowering the landscape by an average of 0.29 mm/yr. In this paper we re‐evaluate this estimate by dating surface crusts present on three playas within the basin. Understanding the development of these playas is crucial to assessing the overall role of the wind in shaping the regional landscape because they are typically capped with a thick salt crust which effectively protects them from wind erosion. Optically stimulated luminescence (OSL) and U‐series dating from a pit section and from the top of a deep drill core, together with results from magnetostratigraphy and a climate proxy record correlated to the marine oxygen isotope record, are used here to determine the age of the playa plains and suggest that the salt crusts have an age of c. 0.1 Ma. This young age and the wide distribution of resistant thick salt crusts of the playa plains indicate a much lower degree of wind erosion than previously suggested. The crusts protect the surface from significant surface erosion (including sediment exhumation and unloading) and whilst some wind erosion does occur, it is unlikely to be sufficient to trigger tectonic uplift of the basin or to be a major dust source for the Loess Plateau as previously suggested. Copyright © 2013 John Wiley & Sons, Ltd.