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1.
新疆叶城地区第四纪粗砂砾层沉积及其与昆仑山隆起的关系* 总被引：2，自引：0，他引：2
采用粒度分析、岩石岩性分析、砾石统计等方法,本文认为新疆叶城地区第四纪粗砂砾层为冲积-洪积类型。沉积物的组分结构及其空间分布呈带状变化规律。沉积物分布受昆仑山强烈隆起的控制,反映了昆仑山隆起的时代和阶段性。 相似文献
2.
新疆叶城地区第四纪粗砂砾层沉积及其与昆仑山隆起的关系 总被引：1，自引：0，他引：1
采用粒度分析、岩石岩性分析、砾石统计等方法,本文认为新疆叶城地区第四纪粗砂砾层为冲积-洪积类型。沉积物的组分结构及其空间分布呈带状变化规律。沉积物分布受昆仑山强烈隆起的控制,反映了昆仑山隆起的时代和阶段性。 相似文献
3.
阿尔泰山大罗坝地区第四纪沉积物覆盖面积较大,平均厚度超过3m。沉积物分选性很差,其重矿物组成中以较稳定矿物和不稳定矿物为主。沉积物类型较复杂,初步划分有:残坡积、洪积、冲洪积、冲积和沼泽沉积。其中以冲积物和冲洪积物与砂金关系最为密切,含金量较高,其分布范围是砂金相对富集区,这是该地区沉积物的成因所决定的。 相似文献
4.
萨拉乌苏河地区粘土矿物组合分析与古气候的关系 总被引：6，自引：1，他引：5
萨拉乌苏河嘀哨沟湾剖面中晚更新统下部萨拉乌苏组,晚更新统上部的城川组中部,全新统中下部河湖沉积或黑垆土中的粘土矿物组合以伊利石为主,但伴有少量的高岭石类矿物;而晚更新统上部的城川组上下部,全新统上部嘀哨沟湾组以风成沙为主的粘土矿物组合均以伊利石-绿泥石为主,并有少量的蒙脱石。萨拉乌苏河雷家咀子、马达渠以北西北部梁地的第四纪地层中的粘土矿物组合与萨拉乌苏河嘀哨沟湾剖面的结果基本吻合。这表明本区第四纪风成沙与黄土是在相对干冷气候下沉积的,而河湖相、湖沼相及古土壤是在相对暖湿的气候下形成的。由本区第四纪地层中的粘土矿物组合,反映自晚更新世以来,本区气候曾经历暖湿→干冷→温湿→干冷→暖湿→干冷的多次更替,大体与北半球的玉木——里斯间冰期、前玉木冰期、玉木间冰阶、玉木主冰期、冰后转暖期和新冰期气候变化趋势一致。 相似文献
5.
西宁盆地晚始新世泥岩地层粒度特征及其古环境指示意义 总被引：1，自引：0，他引：1
《亚热带资源与环境学报》2017,(1)
西宁盆地较为完整地保存着一套新生代(约55~17 Ma)地层,盆地内的水湾村附近出露的晚始新世石膏-红色泥岩旋回沉积序列,是研究晚始新世气候演变的理想地质记录。关于这套地层的沉积环境存在不同的观点,尤其是关于其中泥岩地层成因的争论颇多,主要有洪积扇远端沉积、咸水深湖沉积和风积成因3种观点,差别甚大,至今没有统一的认识。沉积物的粒度可以用来反演其形成时的沉积动力及沉积环境,为了明确该段地层中泥岩的沉积环境,本研究选取水湾剖面代表性泥岩样品进行了系统的粒度测量及分析,结果表明,西宁盆地晚始新世泥岩沉积与黄土高原典型黄土-古土壤粒度特征类似,应为风积地层,而不是洪积扇远端或咸水深湖沉积。西宁盆地晚始新世风积地层的发现为盆地区域构造和古气候演化研究提供了新的研究视角。 相似文献
6.
《山地学报》2017,(6)
本文通过对银川平原深达900米的YE07钻孔沉积物进行粒度分析,结合其他钻孔的研究资料,探讨了银川平原中更新世以来沉积环境的演化过程,发现银川平原沉积环境的变化主要受气候和构造因素的影响,其演化过程表现出一定的区域特点,主要经历了以下的演化阶段:722~664 ka B.P.属于湖沼相沉积;664~126 ka B.P.沉积环境以河流相沉积为主,水动力条件较强,沉积动能较高;126~11 ka B.P.的沉积环境是以河流相为主的河湖交替相;11 ka B.P.以来沉积环境主要表现为河湖相沉积。银川平原沉积环境的研究为其水文地质研究和第四纪地层划分提供新的理论依据。 相似文献
7.
为了探讨粒度特征所指示的环境意义,对西藏定结地区现代沙丘进行采样,分析不同类型沙丘表层沉积物的粒度特征。结果表明：（1）流动沙丘和爬坡沙丘粒度组成相似,灌丛沙堆与二者粒度组成差异较大。流动沙丘和爬坡沙丘表层沉积物主要以细砂和中砂为主,而灌丛沙堆表层沉积物以极细砂、细砂和粉砂为主。（2）不同类型沙丘粒度参数呈现不同变化趋势,流动沙丘和爬坡沙丘表层沉积物分选较好,近对称,中等尖锐,灌丛沙堆表层沉积物分选中等,正偏,很尖锐。（3）流动沙丘和爬坡沙丘频率分布曲线呈近似对称的单峰分布,灌丛沙堆频率分布曲线呈双峰分布;不同类型沙丘表层沉积物概率累积曲线差异较为明显。（4）不同类型沙丘表层沉积物沉积环境主要以风成沉积为主,少数为河流沉积。（5）不同类型沙丘表层沉积物粒度特征对比可知,粒度特征的差异主要是沙源、植被覆盖度和风况共同作用的结果。 相似文献
8.
珠江三角洲及其附近地区河流阶地的分布与特征——广东河流阶地研究之二 总被引：4，自引：1，他引：3
依据珠江三角洲及其附近地区超过24条河流、80处河流阶地、97个沉积物年龄等情况,可知本区第一级半埋藏阶地具有天然堤地貌和加积型特征,与全新世河漫滩组成冲积平原.山前半埋藏洪冲积阶地与全新世洪冲积扇组成山前倾斜平原.这两种平原地貌衔接过渡,沉积物同期异相,全新统通常是上更新统阶地面被蚀低后的补偿性沉积.多项证据显示新构造运动趋势:在中更新世以间歇性构造抬升为主,自晚更新世以来却变成间歇性下沉或稳定.自晚更新世以来包括珠江三角洲及其汇入的各大河流中下游地区一起构造下沉,所以珠江三角洲不是断块型三角洲;横穿广从断裂和瘦狗岭断裂的众多小河河谷地貌在该断裂处无显著变化,显示自晚更新世这些小河河谷形成以来该两断裂无明显造貌运动. 相似文献
9.
天山北麓河流下游冲积平原与古尔班通古特沙漠交汇带，沉积环境独特，对全球气候变化响应敏感。囿于年代校正不确定性、代用指标的多解性以及地形地貌格局等因素的影响，该区域全新世时期沉积环境演变过程和气候演化模式研究，尚存在不同认识。重建该区域的中晚全新世环境演变历史及其对气候变化的响应过程，有助于加深对天山北麓冲积平原沉积环境演化时空特征的认识。本文选取天山北麓中部河流下游冲积平原四个典型冲积-湖积-风积地层剖面为研究材料，以光释光(OSL)测年确定地层绝对年代，综合沉积构造特征、沉积物粒度参数和石英砂表面微结构特征分析，探讨河流下游中晚全新世冲积-湖积平原沉积序列的演变过程和驱动因素。结果表明：(1)研究剖面主要由黏土、粉砂和极细砂含量较高的河湖相沉积构成，靠近北部沙漠边缘以极细砂、细砂为主的风成砂层明显增多，形成以冲积相、湖沼相和风沙相交替叠覆的沉积序列，其沉积相组合具有明显的时空变化特征；(2)沉积物石英颗粒表面常见冰川、流水、风力等多种外营力作用的痕迹，表明河流下游平原沉积物主要来源于山区冰川搬运、磨蚀的碎屑物质，并经流水和风力分选后成为古尔班通古特沙漠的重要物源；(3) 7.59～6... 相似文献
10.
库姆塔格沙漠粒度分布特征及环境意义 总被引：22，自引：10，他引：12
库姆塔格沙漠位于中国西北干旱区,被称为我国第六大沙漠。粒度分析在区分沉积环境、判定物质输运方式、判别水动力条件和分析粒径趋势等方面具有重要作用。对库姆塔格沙漠中北部、北缘、西部、中间及南部、东南缘5组20个沙样粒度分析结果表明：其粒度组成差异很大;粒度参数具有以下特征值：平均粒径Mz=1.55～2.92 Φ;标准偏差σ1=0.41～1.11;偏度SK1=-0.11～0.31;峰态KG=0.77～1.23。同时,粒度频率曲线呈单峰态和多峰态共存状态;大部分沙样的偏度近于对称。分析结果说明库姆塔格沙漠沉积物的沉积环境复杂多样,有风力沉积、河湖沉积、河流冲积(洪积)等。 相似文献
11.
A vast bajada consisting of coalescing low-gradient (< 0.3°) alluvial fans exceeding 100 km in length formed along the southwestern margin of the Oman Mountains. It comprises an old fan sequence of inferred Miocene to Pliocene age termed Barzaman Formation, diagenetically highly altered to dolomitic clays, and a thin veneer of weakly cemented Quaternary gravels. A combination of remote sensing, lithological analyses and luminescence dating is used to interpret the complex aggradation history of the Quaternary alluvial fans from the interior of Oman in the context of independent regional climate records. From satellite imagery and clast analysis four fans can be discerned in the study area. While two early periods of fan formation are tentatively correlated to the Miocene–Pliocene and the Early Pleistocene, luminescence dating allows the distinction of five phases of fan aggradation during the Middle–Late Pleistocene. These phases are correlated with pluvial periods from Marine Isotope Stage (MIS) 11 through 3, when southern Arabia was affected by monsoonal precipitation. It is concluded that the aggradation of the alluvial fans was triggered by the interplay of increased sediment production during arid periods and high rainfall with enhanced erosion of hillslopes and transport rates during strong monsoon phases. However, the lack of fine-grained sediments, bioturbation and organic material implies that although the Quaternary fans are sourced by monsoonal rains they formed in a semi-arid environment. Thus, it appears that, in contrast to the Oman Mountains, the interior was not directly affected by monsoonal precipitation. 相似文献
12.
野外调查、室内样品分析及区域地层对比表明,广布于甘肃白银盆地的巨厚层发育大型交错斜层理的浅黄色固结砂岩是典型的沙丘岩,主要沉积于中新世末至上新世初,代表弱固定性沙漠,风系属行星西风,但盛行古风向分为SW至WNW两支,既不同于早白垩世鄂尔多斯盆地盛行NE向信风及W向行星西风,也不同于现代本区在东亚季风环流影响下盛行N、NNE及NE向冬季风的情况.这可能指示当时青藏高原已经隆升到海拔1 000～3 000 m,引起西风环流在高原南北两侧发生季节性摆动绕流,而同期蒙古高压系统的作用不明显. 相似文献
13.
Climatic and halokinetic controls on alluvial–lacustrine sedimentation during compressional deformation,Andean forearc,northern Chile 
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下载免费PDF全文 Laura A. Evenstar Adrian J. Hartley Stuart G. Archer Joyce E. Neilson 《Basin Research》2016,28(5):634-657
The Salar de Atacama forms one of a series of forearc basins developed along the western flank of the Central Andes. Exposed along the northwest margin of the basin, a salt‐cored range, the Cordillera de la Sal, records the Mid‐Miocene to recent sedimentological and structural development of this basin. Sediments of the Mid‐Miocene Vilama Formation record the complex interaction between regional/local climate change, halokinesis and compressional deformation. This study reveals how these factors have controlled the facies development and distribution within the Salar de Atacama. Detailed sedimentary logging, cross‐sections and present day geomorphology through the northern Cordillera de la Sal have been used to establish a lithostratigraphy, chronostratigraphy and the regional distribution of the Vilama Formation. The Vilama Formation documents an increase in aridity with a hiatus in sedimentation from Mid‐Miocene to 9 Ma with initial uplift of the Cordillera de la Sal. From 9 Ma to 8.5 Ma deposition of a meandering fluvial system is recorded followed by a rapid decrease in sedimentation till 6 Ma. From 6 to 2 Ma, the deposition of extensive palustrine carbonates and distal alluvial–mudflat–lacustrine demonstrates the existence of an extensive lake within the Salar de Atacama. Post 2 Ma, the lake decreased in size and braided alluvial gravels associated with alluvial fans were widespread through the region suggesting a final shift to hyperarid conditions. By comparing the Vilama Formation with similar age facies throughout northern Chile and southern Peru, several shifts in climate are recognized. Climate signatures within northern Chile appear to be largely diachronous with the last regional event in the Mid‐Miocene. Since that time, humid events have been restricted to either Precordillerian basins or the Central Atacama. Within the Central Atacama, the final switch to hyperarid conditions was not till the earliest Pleistocene, much later than previously estimated within the region. 相似文献
14.
图解法计算沉积物粒度参数在沉积学研究中被广泛应用,但需要通过手工作图求累积曲线,是一项相当繁杂的劳动。通用计算软件Origin拥有很强的函数计算和绘图功能,不仅可以批量计算图解粒度参数,同时还可以直接绘制（分段）概率累积曲线图;其实施过程操作简单,仅需点击菜单命令,无需编写任何语句,有利于不懂编程的沉积分析人员进行数据分析,有很大的应用价值。文章随机选取10个不同沉积环境下形成的松散沉积物样本,利用Origin求解各样本粒度累积曲线的百分位数,在其内嵌的Excel表格中计算粒度参数,并用Origin的制图功能绘制粒度概率累积曲线与沉积组分分段直线图。Origin与手工作图计算的结果之间的差值（绝对值平均）及方差都很小（0.004 2~0.018 6）。计算结果表明Origin在粒度参数计算方面完全可以代替手工作图,不仅操作简单,而且精度非常高。 相似文献
15.
Foreland basin strata provide an opportunity to review the depositional response of alluvial systems to unsteady tectonic load variations at convergent plate margins. The lower Breathitt Group of the Pocahontas Basin, a sub‐basin of the Central Appalachian Basin, in Virginia preserves an Early Pennsylvanian record of sedimentation during initial foreland basin subsidence of the Alleghanian orogeny. Utilizing fluvial facies distributions and long‐term stacking patterns within the context of an ancient, marginal‐marine foreland basin provides stratigraphic evidence to disentangle a recurring, low‐frequency residual tectonic signature from high‐frequency glacioeustatic events. Results from basin‐wide facies analysis, corroborated with petrography and detrital zircon geochronology, support a two end‐member depositional system of coexisting transverse and longitudinal alluvial systems infilling the foredeep during eustatic lowstands. Provenance data suggest that sediment was derived from low‐grade metamorphic Grenvillian‐Avalonian terranes and recycling of older Palaeozoic sedimentary rocks uplifted as part of the Alleghanian orogen and Archean‐Superior‐Province. Immature sediments, including lithic sandstone bodies, were deposited within a SE‐NW oriented transverse drainage system. Quartzarenites were deposited within a strike‐parallel NE‐SW oriented axial drainage, forming elongate belts along the western basin margin. These mature quartzarenites were deposited within a braided fluvial system that originated from a northerly cratonic source area. Integrating subsurface and sandstone provenance data indicates significant, repeated palaeogeographical shifts in alluvial facies distribution. Distinct wedges comprising composite sequences are bounded by successive shifts in alluvial facies and define three low‐frequency tectonic accommodation cycles. The proposed tectonic accommodation cycles provide an explanation for the recognized low‐frequency composite sequences, defining short‐term episodes of unsteady westward migration of the flexural Appalachian Basin and constrain the relative timing of deformation events during cratonward progression of the Alleghanian orogenic wedge. 相似文献
16.
依据广东西部超过18条河流、39处河流阶地、至少35个14C、热释光的冲积层测龄数据等情况,可知粤西最多有4级河流阶地(不包括湛江组和北海组阶地);多数河流最高阶地靠近现代主河床分布,深切曲流中有河流阶地,反映近数十万年来河床改道不大;西江在封开有广东高度最高(76 m)的河流阶地,而广东高度最高的地下河阶地是111 m,大致显示出地面与地下剥蚀强度的差异;通常山区河流长度越大,河漫滩和河流阶地的高度越大,河流阶地的级数和级别也常增加;在河流上游的下段和中游的上段,河流阶地的高度最大且级数也最多;在晚更新世之前与后,河谷中下游地区的新构造运动趋势由上升变为稳定或沉降;连滩盆地是广东全新世构造沉降最典型的山间盆地。 相似文献
17.
The Quaternary evolution and the morpho-sedimentary features of some of the most important rivers in Spain (Ebro and Tagus rivers among others) have been controlled by subsidence due to alluvial karstification of the evaporitic bedrock. The subsidence mechanism may range from catastrophic collapse to slow sagging of the alluvium by passive bending. In the Ebro Basin, the mechanisms and processes involved in karstic subsidence were studied through the analysis of present-day closed depressions as well as through old subsidence depressions (palaeocollapses and solution-induced basins) and associated deformations recorded in the Quaternary alluvial sediments. The Gállego–Ebro river system is presented as a case study of channel adjustments and geomorphic and sedimentary evolution of fluvial systems in dissolution-induced subsidence areas. In this fluvial system, evaporite dissolution during particular Quaternary time intervals (namely early and middle Pleistocene) have lead to the development of a solution-induced basin, approximately 30 km-long by 8 km-wide, filled by Quaternary deposits with a total thickness in excess of 190 m. The main river response to balance the subsidence in the alluvial plain was aggradation in the central reach of the subsiding area, and degradation both in the upstream reach and in the valley sides where alluvial fans and covered pediments may prograde over the fluvial sediments. The main sinking areas are recognized in the sedimentary record by anomalous thickenings in the alluvial deposits and fine-grained sediments deposited in backswamp and ponded areas. 相似文献
18.
Rare earth element, major and trace element and mineralogy in the sediments representing last 50 cal kyr BP from the summer precipitation fed paleolake San Felipe identify the different association of minerals and selective transportation of different grain size fractions and relate them to the variation in pluvial discharge into the basin as well as aeolian activities in the western Sonora Desert. Period of lower pluvial discharge during 14–48 cal kyr BP is contemporary to the regime of dominant winter storms in the region. Transportation of coarser quartz and plagioclase during 40–48 cal kyr BP and dominant finer fractions during 14–40 cal kyr BP possibly mirror the variation in the frequency of winter storms. During 3–14 cal kyr BP, higher catchment erosion (sedimentation increased 4–12 times) and transportation of REE bearing heavy minerals into the basin indicate higher pluvial discharge. We relate this period to a regime of dominant summer precipitation associated with the North American Monsoon and tropical cyclones. Geochemical and mineralogical signatures of the sediments deposited during ca. 8, 12–13 and >48 cal kyr BP suggest selective mobilization of quartz and plagioclase from the surrounding sand dunes by the aeolian processes. 相似文献
19.
《Basin Research》2018,30(2):249-278
The Turonian‐Coniacian Smoky Hollow Member of the Straight Cliffs Formation in the Kaiparowits basin of southern Utah records a stratigraphic transition from isolated fluvial channel bodies to increasingly amalgamated channel belts capped by the Calico bed, a sheet‐like sand‐gravel unit. Characteristics of the Smoky Hollow Member are consistent with a prograding distributive fluvial system including: up‐section increases in average grain size, bed thickness, channel‐body amalgamation, a fan‐shaped planform morphology and a downstream increase in channel sinuosity. The system prograded to the northeast based on thickness and facies patterns, and palaeocurrent indicators. This basin‐axial sediment‐dispersal trend, which was approximately parallel to the fold‐thrust belt at this latitude, is supported by provenance data including detrital zircons and modal sandstone compositions indicating sediment derivation mainly from the Mogollon Highlands and Cordilleran magmatic arc to the southwest, with episodic input from the more proximal Sevier fold‐thrust belt to the west. Progradation occurred during a eustatic still‐stand, relatively stable climatic conditions, and continuous tectonic subsidence, thus suggesting increased extrabasinal sediment supply as a primary control on basin‐fill. Progradation of the Smoky Hollow Member fluvial system culminated in a ~2–3 My hiatus at the top of the lower Calico bed. Correlation with the Notom delta of the Ferron Sandstone, 80 km northeast in the Henry basin, is proposed on the basis of facies relationships and geochronology. The Calico bed unconformity is linked to regional tectonically driven tilting and erosion observed in both basins. 相似文献
20.
V. Bracone A. Amorosi P. P. C. Aucelli C. M. Rosskopf F. Scarciglia V. Di Donato P. Esposito 《Basin Research》2012,24(2):213-233
A basin‐scale, integrated approach, including sedimentological, geomorphological and soil data, enables the reliable reconstruction of the infilling history of the southern Apenninic foredeep, with its subsequent inclusion in the wedge‐top of the foreland basin system. An example is shown from the Molise‐Apulian Apennines (Southern Italy), between Trigno and Fortore rivers, where the Pleistocene tectono‐sedimentary evolution of the basin is framed into a sequence‐stratigraphic scheme. Specifically, within the traditional subdivision into Quaternary marine (Qm) and Quaternary continental (Qc) depositional cycles, five third‐order depositional sequences (Qm1, Qm2, Qc1, Qc2 and Qc3) are identified based on recognition of four major stratigraphic discontinuities. The lower sequence boundaries are represented by angular unconformities or abrupt facies shifts and are generally associated with distinctive pedological and geomorphological features. Three paleosols, observed at top of depositional sequences Qm2, Qc1 and Qc2, represent pedostratigraphic markers that can be tracked basinwide. The geomorphological response to major tectono‐sedimentary events is marked by a series of paleosurfaces with erosional, depositional and complex characteristics. Detailed investigation of the relationships between stratigraphic architecture and development of unconformities, paleosols and paleosurfaces suggests that the four sequence boundaries were formed in response to four geomorphological phases/tectonic events which affected the basin during the Quaternary. The first three tectonic events (Lower‐Middle Pleistocene), marking the lower boundaries of sequences Qm2, Qc1 and Qc2, respectively, are interpreted to be related to the tectonic regime that characterized the last phase of thrusting recorded in the Southern Apennines. In contrast, sequence Qc3 does not display evidence of thrust tectonics and accumulated as a result of a phase of regional uplift starting with the Middle Pleistocene. 相似文献