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1.
对东海外陆架中部表层沉积物34个样品,南部两个岩心75个样品的沉积物特征和重矿物特征进行了分析,计算了其中有用重矿物砂的品位。东海外陆架晚更新世残留沉积中有用的重矿物砂来源于中国大陆,其含量与细砂含量、重矿物总量、沉积物的粒度和分选性呈正相关关系。重矿物砂赋存在海退层位中,形成于滨岸带,并经过后期海侵过程的改造和进一步富集,主要分布在水深100～200 m范围内。外陆架中部有用重矿物砂高品位异常区面积达1.2×10.4 km锆石和石榴石品位达到Ⅰ级异常。南部岩心中异常品位的有用重矿物砂的厚度1.5～2 m,锆石品位达到工业边界品位,研究区钛铁矿普遍出现Ⅱ级和Ⅱ级以上的异常品位。东海外陆架区浅海砂矿成矿条件较好,具有较大的资源潜力,值得进一步调查研究。 相似文献
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利用在海南岛西南部海域调查的最新资料,对2014年该区域采集的445个站位的表层沉积物样品进行了重砂矿物研究,计算了钛铁矿、锆石、金红石、磁铁矿4种有用重砂矿物的品位,分析了海南岛西南部海底有用重砂矿物品位异常值分布范围,在此基础上讨论了钛铁矿、锆石、金红石、磁铁矿品位状况及其形成条件。结果表明,钛铁矿品位异常值主要富集在沿岸带及研究区中南部,分布范围较广,有良好的成矿远景;其他3种有用重砂矿物主要富集在研究区中东部;认为重砂矿物的分布与海南岛母岩、水动力、沉积物底质类型密切相关,最终在海南岛西南部海域划分了3个潜在的有用重砂矿资源成矿远景区,都在可采水深范围之内,具有找矿意义,为将来开发提供了科学依据。 相似文献
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通过全国资源潜力评价,结合各省自然重砂资料和全国重砂资料汇总成果,对85个常见自然重砂矿物进行统计分析。研究表明,中国自然重砂矿物复杂多样,重砂矿物分布具有明显的区域性特点。造山带中自然重砂矿物产出数量相对较多且密度较大,而稳定地区重砂矿物相对较少。不同的自然重砂矿物及其组合具有明显的找矿信息,单矿物自然重砂可能来源于相对单一的矿石或岩石,其异常范围表明与其相关的矿产可能具有较好的成矿远景;矿物组合常显示出有关矿床的成因信息。自然重砂矿物与源区岩石或矿石具有密切的成因联系,对指导矿产勘查与研究具有十分重要的意义。 相似文献
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海南岛海砂资源丰富,质量较好,储量位居全国前列,其中钛铁矿、锆英石和独居石是海南岛的优势滨海砂矿资源。根据其用途主要分为3类: 锆钛砂矿、石英砂矿和建筑用砂矿。通过资料收集和整理,分别研究了海南岛不同类型海砂资源的分布范围、勘查程度、资源储量、形成环境和资源潜力等。研究结果表明: 锆钛砂矿开发程度最高,主要分布于琼东沿海及水下阶地一带的全新统,规模较大,品位较高,开发条件较好; 琼西则以建筑用砂矿和石英砂矿为主,海砂质量好,杂质含量较低; 位于浅海区的潮流沙脊和河口三角洲,工作程度不高,但其海砂分布广、厚度大、砂质好,是今后海砂勘查的重点区域,具有良好的资源开发前景。总结海南岛海砂资源的主要成矿特点为: ①分布广泛,规模巨大,开发条件好; ②主要产于全新世地层; ③沉积厚度较大,纵向连续性好; ④海砂质量较好,并富含重矿物。 相似文献
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莫桑比克东濒印度洋,沿海岸线赋存丰富的具有世界级规模的滨海砂矿资源,具有较好的勘探和开发投资前景。通过野外地质调查和室内综合研究,对莫桑比克中北部滨海砂矿的成矿地质背景、矿体特征、矿石特征及矿床成因进行总结。本区滨海锆钛砂矿赋存于第四系粉细砂层中,地貌上多为起伏砂地和平坦砂地,矿体沿海岸线呈条带状分布,延展连续性较好,形态较规则。沿倾向矿石品位较连续,矿体厚度总体上变化不大,各重矿物在矿体中的含量变化呈正相关关系。重矿物以钛铁矿为主,其次为锆英石、金红石、独居石,多以单矿物颗粒的状态散布在矿石中,粒度主要为0.096～0.15 mm,属易分选型矿石。矿床类型属滨海相机械沉积型矿床,其形成受成矿物质来源、气候和水动力、海岸地貌、构造运动与海岸变迁等多种因素影响,主要经历三个阶段,即重矿物原生赋存阶段、运移阶段和富集成矿阶段。本工作揭示了滨海砂矿形成规律,为莫桑比克中北部滨海砂矿矿床勘探和开发提供了参考。 相似文献
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《矿物学报》2016,(3)
对南海西北部近海陆架273个站位表层沉积物稀有金属矿物进行了研究,并结合沉积物粒度和沉积物类型,及与之相关的稀有金属元素分析,探讨了研究区稀有金属矿物的分布特征及主要影响因素。结果表明,本区沉积物中稀有金属矿物的分布主要受沉积物物源、沉积物类型和水动力条件等因素的控制,稀有金属矿物与相关元素的分布存在较大差异,不能仅凭沉积物中相关元素的质量分数分布来确定金属砂矿的有利富集或成矿区。根据沉积物中稀有金属矿物质量分数的分布特征及沉积环境分析,初步划分出5个稀有金属矿物富集区,分别对应于水东湾及附近海域、珠江口南外海、上下川岛与海陵岛之间外海、湛江湾及附近海域和海南岛东南近岸海域,且每个海域富集的稀有金属矿物种类有所不同,有望成为本区不同种类稀有金属砂矿的有利成矿区,其中钛铁矿、锆石和白钛石是本区最有成矿潜力的稀有金属矿种。 相似文献
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福建近海砂矿资源极为丰富，目前已发现各类近海砂矿10余种，初步探明具有工业价值的有回填用砂（建筑用砂）、石英砂（型砂、玻璃砂、标准砂等）和稀有、稀土砂（锆石、钛铁矿、金红石、独居石和磷钇等）9个矿种，各类矿床（点）42个，成因类型有海积、风积、冲洪积和洪积等。近海砂矿主要分布在闽江口及其以南近海地区，是福建极为重要的矿产资源。 相似文献
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江苏宁芜北段自然重砂异常特征及其对铜金矿的响应 总被引：2，自引：0，他引：2
宁芜火山岩盆地是长江中下游成矿带中重要的铁、硫、铜、金成矿区。基于宁芜北段自然重砂建库数据,通过ZSAPS2.0软件GIS平台,选择与火山热液充填型铜金矿相关的特征矿物,圈定了自然重砂组合异常。通过自然重砂组合异常特征发现,铜矿物(黄铜矿、斑铜矿、蓝铜矿、辉铜矿、孔雀石)、自然金、黄铁矿、重晶石等重矿物组合对火山热液充填型铜金矿响应明显。在组合异常的基础上,圈定自然重砂综合异常,以成矿地质条件、与已知矿床的对应关系、异常强度、异常规模、重砂异常套合程度等为指标,对综合异常进行评价,从而为宁芜火山岩盆地北段铜金矿找矿远景区的划定提供依据。 相似文献
9.
为进一步探索砂矿中金刚石的来源,寻找湖南地区原生金刚石,利用水系自然重砂方法在湖南桃江马迹塘地区共采集自然重砂测量样品250件,金刚石指示矿物种类较齐全,数量较多。其中发现金刚石12颗,类型较单一,粒径0.3mm左右,黄绿色、六-八面体;指示矿物铬尖晶石8864颗,黑色-灰黑色,磨损较强烈,呈浑圆粒状;钛铁矿2403颗,黑色-灰黑色,磨损较弱。通过区内金刚石及指示矿物分布特征,在区内划分出14个异常区,其中Ⅰ级异常区5个,Ⅱ级异常区5个,Ⅲ级异常区4个。金刚石及指示矿物分布广泛,但无定向富集,北部地区数量多、南部地区数量少,时间上老地层出露区数量多,新地层出露区数量少。通过金刚石及指示矿物对比研究发现,其晶形、颜色、粒度与桃江江石桥辉绿岩中的金刚石及宁乡钾镁煌斑岩中发现的金刚石特征相似,推测其来自区内尚未被发现的辉绿岩/钾镁煌斑岩等类型的岩体中。 相似文献
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11.
This paper extends earlier work on sand erosion and presents an attempt to couple sand erosion to mechanical damage of rock around a wellbore. Porosity which evolves in time and space as surface erosion progresses, is chosen as the coupling parameter. Both rock elasticity and strength (cohesion) are assumed to depend on porosity in such a way that the material becomes weaker with increasing porosity. The mathematical model, consists of erosion equations, mixture flow equations and stress equilibrium equations, is solved numerically by Galerkin finite element method. Numerical results suggest that erosion, resulting in sand production, is high close to the free surface. Erosion is accompained by changes in porosity and a significant permeability increase. Erosion in the vicinity of the wellbore induces alterations in the mechanical behaviour of the medium. Weakening of rock stiffness leads to severe alteration of both effective stresses and pore pressure near the cavity. Since cohesion decreases with increasing porosity, one can also identify the time instant at which rock mechanical failure starts. © 1998 John Wiley & Sons, Ltd. 相似文献
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13.
济阳坳陷东部埕北地区Ng上段曲流河沉积相及砂体展布研究 总被引：1，自引：0，他引：1
埕北地区Ng~上段主要为曲流河沉积,储油砂体微相为由流河冲积平原亚相的曲流砂坝。由于它的单层薄,横向上变化大,分布复杂,直接影响到对它的勘探开发和储量计算。通过研究取芯井段的岩相、岩相组合、垂相沉积层序及各种电测井资料等,将Ng~上段曲流河沉积砂体划分为三种亚相,并建立了由流河沉积砂体的剖面结构和平面分布模式,进一步又以沉积小层和砂层组为单元研究了曲流河砂体的平面分布特征及纵向演化规律等,为下一步的精细油藏描述研究打下了可靠的基础。 相似文献
14.
A sand production model was developed for volumetric sand production predictions that take into account the effects of the external stresses and fluid flow rate. The model couples the poro‐mechanical behaviour of the solid–fluid system with the erosion behaviour of the solids due to fluid flow. It predicts reasonably experimental volumetric sand production data from a hollow cylinder test on a weak sandstone. The test results show that in weak and compactive sandstones, sand production is associated with decohesioning and plasticification of a zone around the inner hole which can then be mobilized by the hydrodynamic forces of the fluid flow. The sand production rate increases both with external applied stress and fluid flow rate but it is constant with time under constant external stress and fluid flow rate. In both cases a critical lower limit has to be exceeded for sand production initiation. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
15.
Bi-weekly multi-track sonar surveys collected along a 2-km reach of the estuarine South Arm of the Fraser River, British Columbia, Canada, during seasonal high flows document the initiation, development and interaction of dune and bar morphologies. Bedforms of several scales developed in well-delineated fields. Bedforms that appear to fit accepted equilibrium depth-scaling developed in the main channel during rising discharge when there was little local aggradation. During the rising stage, a bar also formed along the tidal shelf of the channel, migrated downstream and expanded into the main channel. Dunes that formed along the bar crest, a region of rapid deposition, lagged flow conditions and were larger than expected based on depth-scaling relations. The larger dunes developed simultaneously, although bar growth lagged dune development and was initially partially obscured by the more rapidly developing dune field. It appears that rapid deposition enhances dune development along the channel tidal shelf to dimensions larger than would be expected by simple depth-scaling rules. Smaller dunes that fit equilibrium depth-scaling relations re-established themselves throughout the study area during falling discharge when there was again little or no aggradation. Bed-material transport rates estimated from the migration rates of the large dunes suggest that, at high flows, the dunes transport the majority of the material found within the bar. 相似文献
16.
The cone penetration test (CPT) is widely used, and although initially developed as a stratigraphic logging tool its excellent repeatability and accuracy offers a benchmark quantitative test for sand in particular. A continuing difficulty, however, is that the CPT does not measure any soil property directly, so that parameters of interest must be recovered from solution of an inverse boundary value problem, which is difficult. To date most CPT interpretations in sand have been based on very limited calibration testing carried out in large chambers on a few sands from which mappings are developed. But there are differences in the CPT response from one sand to another leaving the interpretation imprecise (and arguably even speculative) because these differences remain poorly understood. In this paper we use the familiar spherical cavity expansion analogy to the CPT including large strains and a good, critical-state-based, soil model to develop a pattern of behaviour which we then compare to some of the reference chamber test data. We find that one of the issues of dispute in the empirical interpretation methods, the so-called stress-level effect, is caused by neglect of elasticity and that there are several additional parameters of first-order significance to cavity expansion in sands. More generally, we show that the difference in CPT response between various chamber sands in predicted. Our results are cast in dimensionless form and the inversion illustrates that extreme care is required in interpreting CPT data if the in situ sand state is to be determined with precision approaching that suggested as achievable by the repeatability of the CPT data itself. Aspects requiring particular care in interpreting CPT data in sand are discussed. © 1998 John Wiley & Sons, Ltd. 相似文献
17.
川中地区上三叠统须四段砂体沉积过程中,由于构造活动强弱的变化,导致物源供应速率与可容纳空间增长之间关系的变化,须四段厚层砂体自下而上由水退式、加积式和水进式3种不同成因类型的砂组纵向叠合而成.水退式砂组主要由高能削截式河道、削截式河口坝和远砂坝组成,加积式砂组主要包括冲蚀下切式河道和高能削截式河道,水进式砂组主要包括低能河道、低能削截式河道、完整式河口坝和下缺式河口坝.不同砂组中砂体类型不同,颗粒大小分异不同,水动力强弱的差异,不同成因砂体间形成了不同的成岩相和储集相,加积式砂组以绿泥石衬边和溶蚀成岩相为主,物性好,为好的储集体;水进式砂组由压实和胶结相为主,物性较差;水退式砂组中溶蚀相和胶结相发育,物性较好,为中等的储集体.须四段三种成因砂组中,加积式砂组中发育高能削截式河道,形成了在平面上广泛分布的高能水道,砂体厚度大,延伸长,发育有利的成岩相,物性较好,为油气的富集提供了足够的空间;同时加积式砂组与水退式砂组呈沉积不整合相接触,呈现相嵌关系,对天然气的运移起到通道作用,加积砂组向上的水进式砂组容易发生储层致密化,形成有利的盖层,使加积式砂组发育区成为川中天然气富集的有利部位. 相似文献
18.
Slump-initiated and controlled syndepositional sandstone remobilization: an example from the Namurian of County Clare, Ireland 总被引：1，自引：0，他引：1
Lorna J. Strachan 《Sedimentology》2002,49(1):25-41
Remobilization of sandstones can dramatically reconfigure original depositional geometries and results in very unusually shaped sandstones, which resemble little, if any, of the original geometry. A number of deformational sandstone bodies, dykes and volcanoes from the upper part of the Carboniferous Ross Formation are described, which offer the opportunity to examine a suite of field-scale reconfigured sandstones. These structures are located in close proximity to the Ross Slide, which outcrops along a 2-km section on the northern coast of the Loop Head Peninsula, County Clare, Ireland. Dome- and ridge-shaped deformational sandstone bodies, dykes and volcanoes are interpreted to be the product of remobilization of a turbiditic sandstone. Liquification and remobilization were triggered by translation, cessation and loading of the underlying turbiditic sandstone by the Ross Slide. Deformational sand body, dyke and volcano development occurred in an asynchronous fashion with deformational sand bodies formed during slump translation. Sand dykes and volcanoes developed after the cessation of slump movement. During slump translation, the minimum principal stress (σ3 ) was orientated vertically and the slump behaved in a `ductile' manner. After slump arrest, the minimum principal stress was oriented horizontally, and the unit regained shear strength to behave in a `brittle' manner. The relative change in rheological states with changing applied shear stress is indicative of thixotropic-like behaviour within the slump mass. Ridge-shaped deformational sand bodies are aligned parallel to slump folds, and their morphology is inferred to be controlled by compressional slump deformation associated with heterogeneous cessation of slump movement that was initiated by frontal arrest of the translating mass. 相似文献
19.
横山地区位于盆鄂尔多斯盆地北部,上古生界下石盒子组盒8期处于辫状河三角洲平原与三角洲前缘过渡区。由于地形平缓、间歇性水流供给使得河流频繁改道。不同形态与规模的河道砂体交错叠置,加大连续沉积砂体的寻找难度。通过连井剖面追踪主河道内的单一砂体,揭示其空间展布规律,多条砂体追踪得到不同厚度砂体的空间延伸形态,其结果表明连续沉积越厚的砂体,其延伸距离越远。基于砂泥叠置关系与砂体发育规模确定优势砂体为多期次叠加的且隔夹层较少的具有一定规模的整套砂体。优势砂体空间延伸较远、沉积厚度较大、岩性较为均一,为理想的储集砂体。确定优势砂体的平面发育情况,为优势储层的寻找奠定基础。 相似文献
20.
Clastic injection and surface expression of subsurface sediment remobilization is a phenomenon which is becoming increasingly recognized. However, understanding of the physical mechanisms that control these features remains limited, dominated by inference from outcrop and seismic studies. Here, this limitation is addressed through a set of experiments focused on the development and evolution of fluidization features in non‐cohesive bedded sequences. Fluidization and the onset of piping are shown to occur progressively through a sequence of discrete phases, with initial void formation, development of infiltration horizons, rupture and finally pipe formation. Critically, the style of piping, the stability of piping and the temporal evolution of venting are shown to exhibit considerable variability. In particular, pipes may either be stable or very mobile, migrating laterally over large distances; these produce deposits that are typically interpreted in outcrop as being the product of en masse liquefaction rather than localized, dynamic fluidization. These differing elements are synthesized to produce a model of sand extrudites. In addition, the implications of this model are explored. 相似文献