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1.
Heavy minerals in bottom-sediment samples of the lower Chesapeake Bay show distribution patterns and interrelationships that denote characteristic mineral suites associated with defined geographic provinces. The Baymouth province has a garnet—hornblende—pyroxene suite, which is largely attributed to the influx of littoral and shelf sediments; the Eastern Shore province has a similar suite, derived largely from coastal erosion of the Eastern Shore peninsula. The Northern and Combined River provinces have a zircon—tourmaline—staurolite assemblage, which reflects derivation from an Appalachian Piedmont—Atlantic Coastal Plain sourceland. The Western Shore province is associated with a zircon—epidote—staurolite assemblage, apparently derived jointly from tributary influx and coastal erosion of the western shore. Factor analysis identified two major factors that account for 63% of the total variation in the relative amounts of the seven most common heavy minerals. The dominant factor (44%) is based on a zircon—hornblende—staurolite—pyroxene relationship, which indicates that mineral stability, as influenced by sediment maturity, is a major contributing factor. The second factor (19%) based on a tourmaline—epidote—staurolite—garnet relationship indicates that provenance is another major cause of heavy-mineral variability within the lower bay. 相似文献
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大沽河泥沙来源的重矿物分析及其环境意义 总被引：1，自引：0，他引：1
应用矿物分析的方法研究大沽河下游泥沙的来源,研究表明,大沽河上游和小沽河流域的重矿物特征有很大的不同,大沽河上游段以高的普通角闪石含量为标志,绿帘石、钛铁矿具有较高的含量。小沽河和大沽河下游的重矿物组成以普通角闪石+绿帘石+透闪石+石榴石为主,重矿物特征相似性明显,其重矿物含量和主要重矿物相对含量都比较相似,数值相差不大,而且矿物的形态特征、矿物的种类也一致。这说明大沽河下游的泥沙主要来源于其支流小沽河,因此,小沽河流域的水土保持是大沽河河道以及胶州湾沉积环境整治的关键。 相似文献
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The coast of the State of Kuwait is characterized by a relatively wide intertidal flat area. At the north, where it is close to Shatt-al-Arab estuary, the intertidal sediments are mainly fluviomarine, while open marine sediments dominate the southern intertidal flat area. Samples were examined from the intertidal zone of deposition from the fluviomarine and open marine environments.The sediments consist mainly of carbonate minerals (low-Mg calcite, high-Mg calcite, aragonite and dolomite), quartz, feldspars, clay minerals and heavy minerals. The mineralogy of the clay fractions of the sediments is dominated by illite, mixed-layer illite—montmorillonite, montmorillonite, chlorite, kaolinite and palygorskite with only minor amounts of quartz. Heavy minerals are concentrated in the very fine sand fraction and are dominated by opaque minerals, amphiboles, pyroxenes, epidotes, garnet, kyanite and sillimanite. Zircon, tourmaline, andalusite, staurolite and rutile are present in subordinate amounts.Three main sources are suggested for the intertidal sediments of Kuwait: (a) Shatt-al-Arab fluviatile deposits, (b) aeolian dust fallout, and (c) direct chemical and biogenic precipitation from the Gulf water. 相似文献
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High quartz and low calcium carbonate percentages in the surface sediments of the Bay of Bengal adjacent to the Indian subcontinent result from the massive influx of terrigenous clastics. Fine-fraction (<2 ) mineralogy and heavy minerals in (turbidite) sands suggest that sediments of the western Bengal Fan (high in smectite, sillimanite, garnet) have been derived from peninsular Indian rivers; sediments of the rest of the fan (high in illite, hornblende, epidote) are derived from Himalayan rivers. The sediments on the Ninety East Ridge and in the deep southerly areas beyond the reach of fan deposition result from thein situ alteration of volcanics. 相似文献
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Heavy mineral studies of the nearshore placer deposits of the Konkan Coast reveal a dominant assemblage comprised of garnet and kyanite along with other accessory minerals like epidote, olivine and rutile. The heavy mineral assemblage of the study region shows a characteristic suite of 17 types of heavy minerals. Their abundance shows hardly any drastic variation in the four bays studied. Overwhelming presence of minerals like garnet and kyanite in the studied four bays points to the source as metamorphic rocks. The presence of etched garnets, overgrown zircons and etched kyanites corroborate the recycling of paleo-sediments into the bay. Characterization of opaques under the microscope also corroborates the influence of a metamorphic source, rather than the adjoining basaltic rocks. However, the absence of metamorphic rocks in the hinterland suggests the possibility of deposition of sediments predominantly from offshore. Factor analysis results also corroborate the overwhelming influence of metamorphic rocks in the present study region rather than the abutting basalts. 相似文献
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辽东湾表层沉积物碎屑矿物组合分布及其对物源和沉积物扩散的指示意义 总被引：1，自引：0，他引：1
对取自渤海辽东湾的128个表层沉积物样品进行了碎屑矿物鉴定,对矿物成分含量应用log-ratio法处理后进行统计分析。结果表明,研究区重矿物质量百分含量平均值为6.3%,高值区位于六股河口和湾西北近岸。共鉴定出7种轻矿物,38种重矿物,轻矿物以石英、斜长石和钾长石为主,重矿物以普通角闪石、绿帘石、磁铁矿、石榴子石、钛铁矿为主。根据碎屑矿物的组合分布特征,可将研究区划分为两个矿物组合区,其中又可细分为6个矿物亚区。六股河和湾西北近岸矿物亚区的碎屑矿物主要来源于六股河、湾西北入海小溪和海岸侵蚀物质,湾东北部矿物亚区沉积物主要来源于双台子河和大辽河,湾中部矿物亚区为多源混合区,湾南部矿物亚区受邻近海域和复州河沉积物影响大,湾东南部的辽东浅滩矿物亚区为潮流作用的产物。与河流入海沉积物相比,该区表层沉积物的石英/长石比值和ZTR指数明显增大。研究认为,物源是控制研究区碎屑矿物的组合与分布的主要因素,同时也受到海洋水动力和矿物性质等因素影响。 相似文献
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长江口北支表层沉积物重矿物分布和磁学特征 总被引：1，自引：0，他引：1
分析了长江口北支表层沉积物的重矿物分布,结合磁参数和粒度特征,探讨其在各沉积动力分区的分布特点及控制因素.研究表明:研究区重矿物以角闪石和绿帘石组合为主,其次为云母类和磁铁矿等.其中浅滩和潮流脊处水动力较强,沉积物颗粒较粗,重矿物以片状矿物-稳定矿物组合占优势,磁性参数相对较低;汉道和潮汐通道处水动力相对较弱,沉积物以... 相似文献
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长江水下三角洲沉积物的重矿物分布及组合 总被引：10，自引：0，他引：10
对2004年取自长江水下三角洲南部区域的145个表层样品进行了重矿物研究。结果表明,本区重矿物可划分为4个矿物组合区,即三角洲前缘南部矿物区(Ⅰ区)、三角洲前缘北部矿物区(Ⅱ区)、前三角洲主体矿物区(Ⅲ区)和前三角洲南部矿物区(Ⅳ区),它们代表了不同的沉积动力、沉积环境和风化作用条件;长江水下三角洲重矿物以普通角闪石-绿帘石为优势矿物组合,以低级变质来源的绢云母、白云母为特征矿物,局部富含普通辉石和氧化铁矿物;粉砂质砂和砂质粉砂中的重矿物组成比较稳定,基本可以代表长江物源。 相似文献
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Mustafa Ergin eref Keskin A. Umran Doan Yusuf Kaan Kad&#x;olu Zehra Karaka 《Marine Geology》2007,240(1-4):185-196
Backshore sediment samples from 22 beaches along the Antalya and Finike Gulfs have been studied for their grain size, chemical and heavy mineral composition. Data presented here suggest that well- to moderately-sorted (0.41 Φ–0.92 Φ) medium sand (1 Φ–2 Φ) represents dominant mean grain size in most beaches. In contrast, some beaches from the western part of the Gulf of Antalya (Göynük, Kemer-Kiriş and Beldibi) are composed of pebble- to boulder-size grained beaches which are located close to mouths of short and steep-gradient ephemeral rivers entering the sea from the Western Taurus Mountains. The heavy mineral assemblages are dominated by detrital opaque minerals (14–58% magnetite, chromite, and hematite), pyroxene (8–65% augite), amphibole (3–15% tremolite and actinolite), epidote (3–25%), garnet (2–9% pyrope and almandine) and micas (3–20 biotite, muscovite and chlorite). The very high concentrations of heavy minerals (up to 86% of bulk sediment) together with the significant concentrations of some elements found in beach sediments from the Gulf of Finike and western Gulf of Antalya (Fe: 18.40%; Cr: 10.00%; and Ti: 1.32%) are indicative of ultramafic origin, mainly derived from the ophiolitic rocks of the Antalya–Tekirova nappe on coastal hinterland. 相似文献
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对威海南部近岸泥质区WHZK01孔（孔深25.1 m）岩心开展重矿物分析，结果表明，WHZK01孔主要以普通角闪石（22.1%）、磁铁矿（20.0%）和绿帘石（17.7%）为主，晚更新世以来自下而上可分为3个矿物组合带。氧同位素3期晚期河流相沉积（DU3）主要矿物组合为普通角闪石-绿帘石。末次冰后期河漫滩-河口湾相沉积（DU2）主要矿物组合为普通角闪石-绿帘石-钛铁矿-褐铁矿。全新世滨-浅海相沉积（DU1）主要矿物组合为磁铁矿-绿帘石-片状矿物-自生黄铁矿。重矿物物源判别表明，DU3和DU2层沉积物主要来自山东半岛南部沿岸河流输入。DU1层沉积物主要来自沿岸流输运的大量黄河细粒物质，沿岸河流物质和岛屿侵蚀物也有少量贡献。 相似文献
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ZHANG Junqiang LIU Jian WANG Hongxi XU Gang QIU Jiandong YUE Baojing ZHAO Guangtao 《海洋学报(英文版)》2013,32(4):49-58
The previous studies of the sedimentology and chronology of sediment core SYS-0701, which was recovered from the western South Huanghai Sea (Yellow Sea), have revealed the changes in the sea-level and sedimentary evolution during the late Quaternary in the region. The present study used mineralogical data from the section of the core deposited since Marine Isotope Stage (MIS) 3, to decipher the provenance of sediments of the paleo-delta deposited during MIS 3 and MIS 1. Based on the lithologic features and the variations with depth of the concentrations of carbonates and both heavy and light minerals in bulk samples, the upper part of Core SYS-0701 can be divided into three units designated DU1, DU4, and DU5, in accord with previously used terminology. Sub-units of units DU1 (DU1-1 and DU1-2) and DU4 (DU4-1 and DU4-2) have also been identified. DU1 was deposited during MIS 1, and DU4 and DU 5 were formed during MIS 3. All data pertaining to dominant heavy mineral assemblages, diagnostic minerals, ratios of diagnostic minerals, light mineral associations, textural maturities, and carbonate contents, indicate that the sediments of Core SYS-0701 are comparable with Huanghe River (Yellow River) sediments. Moreover, the mineralogy of the sediment evidenced its dependence on supply rates and hydrodynamic conditions. Weak hydrodynamics (DU5 and DU4-2) and/or low sediment supply (DU1-2) led to sediment containing less hornblende and epidote, with a large specific gravity and high content of flaky minerals, and vice versa in cases of strong hydrodynamics (DU4-1) and very large sediment supply (DU1-1). 相似文献
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基于南极普里兹湾海域33个表层碎屑沉积物样品的碎屑矿物学分析,对该区的沉积环境与物质来源进行了分析。结果表明该区碎屑重矿物共17种,石榴子石、普通角闪石和磁铁矿为优势矿物,紫苏辉石和赤铁矿为特征矿物。根据矿物组合分布特征,普里兹湾可划分为4个矿物区:Ⅰ区为石榴子石含量占绝对优势、重矿物含量较高的弗拉姆浅滩矿物区;Ⅱ区为石榴子石、普通角闪石含量较高,磁铁矿为特征矿物的普里兹水道矿物区;Ⅲ区为紫苏辉石含量较突出的四女士浅滩矿物区;Ⅳ区为普通角闪石含量明显突出,石榴子石显著减少的深水陆坡矿物区。通过电子探针测试研究区石榴子石结果表明:碎屑石榴子石含有较高的Fe、Mg和较低的Ca、Mn,属主要来源于高级麻粒岩相副变质岩的A型石榴子石。普里兹湾海域的碎屑矿物分布特征是物质来源、海流系统以及冰川活动等多重因素综合作用的产物。 相似文献
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以东海内陆架S05-2孔沉积物为研究对象, 进行了加速质谱仪(AMS)14C年龄测定、粒度测试、粘土矿物及地球化学元素含量分析。研究表明: 东海内陆架泥质区南部水动力环境强, 沉积物主要以粉砂为主; 4870a BP以来研究区的物源以台湾岛河流物质为主, 长江和黄河物质在不同阶段存在间歇物质作用。通过元素比值、敏感粒级、粘土矿物含量比等季风气候指标, 指示了研究区的季风气候自4870a BP以来存在稳定、增强、减弱、再次增强的4个季风气候强度变化期。 相似文献
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U–Th decay series isotopes, δ18O and Si measurements in the river estuarine waters and sediments of the polluted Hooghly estuary as well as the surface waters of the Bay of Bengal, its high salinity end member, are reported. Dissolved Si indicates that there are probably two mixing regimes, dissolved U behaviour is nonconservative and δ18O behaves conservatively in the overall estuarine region. Isotopes of reactive elements, viz. 234Th and 210Po, are removed from the estuarine waters in <2 days and <1 month, respectively, which is due to high suspended matter (30–301 mg l−1). 228Ra and 226Ra are profusely released into the estuarine waters in the low to mid-salinity regions.As expected, the opposite trend is observed in the case of estuarine sediments and suspended matter. Reactive isotopes of Th, 210Pb and 210Po are enriched, whereas Ra isotopes are depleted with respect to their parent nuclides in the estuarine sediments and suspended matter. 232Th/Al ratio appears well suited to study the distribution and mixing of the bed load sediments of the Ganga–Brahmaputra (G–B) and the Hooghly rivers with those from other rivers on the Bay of Bengal floor. 相似文献
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冲绳海槽中南部不同环境表层沉积物质来源 总被引：1，自引：0，他引：1
对冲绳海槽中南部3种不同沉积环境(东海外陆架、东海陆坡和冲绳海槽)表层沉积物进行了稀土等元素地球化学分析,结果显示,冲绳海槽和陆坡表层沉积物具有与台湾物质来源类似的稀土元素配分模式,La/Sm-Gd/Yb散点图也显示海槽和陆坡沉积物主要分布在台湾物源端元区,表明冲绳海槽中南部海槽和陆坡表层沉积物主要来源于台湾,而外陆架沉积物明显的重稀土亏损与大陆河流(特别是长江、黄河)沉积物来源较为一致。为进一步判断外陆架表层沉积物来源,对外陆架沉积物重矿物进行分析鉴定,结果显示,外陆架沉积物重矿物以普通角闪石-绿帘石-石榴石-赤褐铁矿为组合特征,与长江沉积物重矿物组成特征类似,其明显缺乏台湾河流来源的典型重矿物锆石、黄河来源典型重矿物云母、浙闽沿岸来源典型重矿物磁铁矿,说明台湾、黄河和浙闽沿岸并非研究区外陆架表层沉积物主要物源。根据以往测年等研究成果,研究区外陆架沉积物年代较老,应为古长江物质经东海现代环流体系不断改造而成。 相似文献
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根据黄河下游干流高村以下河道50个断面底质样,尾闾清8断面到口门附近的104个表层沉积物样品,以及2000年7—9月黄河三角洲滨海区18个断面123个表层沉积物的粒度分析结果,结合动力条件和水深资料,探讨沉积物性质和粒度特征的分布和变化规律。结果表明,高村以下河道河床沉积物呈现由粗到细的变化趋势;黄河三角洲滨海区的沉积物分布显示出"侵蚀区砂多、堆积区泥多,近岸砂多、岸外泥多"的分布变化规律。进一步分析可知,20 m水深为黄河入海泥沙分选粗化的界线。 相似文献