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1.
曲林岩体位于冈底斯带中段的南缘,为渐新世-中新世复合岩体,主体为粗粒花岗斑岩,被后期煌斑质、花岗闪长质和花岗质岩脉切割,是多期岩浆作用的产物,出露面积约8km2。花岗斑岩两组样品（T0849-PG和T0849-G）的锆石U-Pb定年结果分别为29.7±0.1Ma和30.0±0.2Ma。花岗斑岩为高钾,准铝质,低MgO,高度富集轻稀土元素（LREE）和大离子亲石元素（LILE）,亏损重稀土元素（HREE）和高场强元素（HFSE）。此外具有高Sr、Sr/Y、（La/Yb）N;低Y和Yb,弱Eu负异常等特征。岩体内发育一系列近南北向展布的花岗闪长玢岩脉,其中两组样品的锆石U-Pb定年结果分别为15.5±0.1Ma（T0848-PY）和14.4±0.1Ma（T0850）。两条花岗闪长玢岩脉具有与岩体主体相似的稀土和微量元素分布模式,同样富集轻稀土及大离子亲石元素,亏损重稀土及高场强元素。花岗斑岩的87Sr/86Sr（i）=0.706102~0.706202,εNd（t）=-0.6~+0.6,锆石εHf（t）=+4.9~+7.9;花岗闪长玢岩脉的87Sr/86Sr（i）=0.705429~0.705474,εNd（t）=-1.4~-0.2,锆石εHf（t）=+2.6~+7.6。本文数据和文献数据结果表明：曲林花岗斑岩与花岗闪长玢岩脉均来源于加厚南拉萨下地壳的部分熔融,很可能与增厚的深部岩石圈的拆沉或俯冲印度岩石圈的撕裂诱发软流圈上涌有关。 相似文献
2.
本文以华北陆块东部早白垩世滁州闪长玢岩和管店石英闪长岩为研究对象,报道了新的全岩地球化学（主量元素、微量元素以及Sr-Nd同位素）以及锆石U-Pb年代学和Hf同位素的综合研究结果,进而约束其岩石成因和构造意义。滁州闪长玢岩中锆石发育振荡环带,管店石英闪长岩中锆石具条痕状吸收的特点,它们均为岩浆成因。锆石LA-ICP-MS U-Pb定年结果显示,滁州和管店闪长质锆石年龄分别为128±1Ma和130±2Ma,表明二者均形成于早白垩世。地球化学特征显示,滁州和管店闪长质岩石具有类似的主量元素和微量元素组成,整体具中等的SiO2含量（58.55%~60.12%）和富MgO（4.43%~5.10%,Mg#=57~61）的特征,Na2O/K2O比值为1.20~1.47,属于高钾钙碱性系列岩石;富集轻稀土元素和大离子亲石元素（如Rb、Ba）,亏损重稀土元素和高场强元素（如Nb、Ta、Zr、Hf）,并具不同程度的Eu负异常（δEu=0.85~0.93）。它们具高的Sr（575×10-6~1035×10-6）和低的Y含量（10.2×10-6~15.3×10-6）以及高的Sr/Y比值（57~69）,属于埃达克质岩石。此外,滁州和管店闪长质岩石具有类似的Sr-Nd以及锆石Hf同位素的特征,滁州闪长玢岩的87Sr/86Sr初始比值介于0.7061~0.7066之间,εNd（t）值为-17.7~-16.9,锆石εHf（t）值变化于-23.1~-19.1之间,而管店石英闪长岩的87Sr/86Sr初始比值为0.7046~0.7059,εNd（t）值为-18.7~-15.8,锆石εHf（t）值为-25.6~-20.0。综合上述,滁州和管店闪长质岩石均属于高镁埃达克质岩石,起源于拆沉的加厚下地壳部分熔融的熔体与地幔橄榄岩反应的产物,形成于早白垩世华北东部陆块拆沉作用下的伸展背景。 相似文献
3.
苗儿山岩体位于湘西南与桂北交界处,为由晋宁期、加里东期、印支期和燕山期花岗岩组成的复式岩体。其中,加里东期花岗岩构成该复式岩体的主体,可划分为六个侵入次。本次通过锆石LA-ICP-MS测年,获得第一、第二、第六侵入次的年龄分别为（428.1±3.6）Ma、（420.3±3.4）~（421.3±3.2）Ma和（408.3±3.5）Ma。加里东期花岗岩的（87Sr/86Sr）i为0.71765,εNd（t）为-9.7,δ18O值为9.8‰,总体属壳源弱过铝-强过铝质花岗岩,形成于碰撞挤压峰期之后挤压减弱、应力松弛的后碰撞构造环境,其早期和晚期的源区岩石类型和形成温度有所区别：早期花岗岩的上地壳源区成分较为复杂,不仅存在泥岩,还有砂屑岩和/或变质火成岩,其形成温度较高（>875℃）;晚期花岗岩的源岩为上地壳泥岩,属典型的S型花岗岩,其形成温度较低（<875℃）。 相似文献
4.
辽西义县盆地早白垩世义县组陆相湖盆沉积中常发育多个薄层碳酸盐岩沉积层,碳酸盐岩地球化学的研究对揭示湖盆沉积古环境具有重要理论意义。义县组砖城子层英窝山剖面湖相碳酸盐岩分析结果显示,岩石δ13C值为-3.44×10-3~0.27×10-3,均值为-1.21×10-3;δ18O值为-15.73×10-3~-9.93×10-3,均值为-10.88×10-3。盐度Z值变化范围114.78~122.39。碳酸盐岩主量元素分析表明,w（CaO+MgO+LOI）=53.38%~97.04%,均值71.15%;陆源组分w（Al2O3+SiO2+Fe2O3）=2.19%~44.87%,均值为27.77%;x（Mg）/x（Ca）摩尔比介于0.92~1.01。碳酸盐岩微量元素地球化学提供了古湖泊学的古盐度、氧化还原和古气候证据。w（Sr）=110.4×10-6~1360.2×10-6,w（Ga）=0.152×10-6~14.13×10-6,w（Sr）/w（Ba）=0.34~131.49（多数>1）,指示沉积湖泊水体为咸水环境;氧化-还原指标w（V）/w（V+Ni）＝0.51~0.83,w（V）/w（Cr）＝1.59~8.28（多数>2.0）,w（U）/w（Th）=0.39~10.24,且变化范围较大,指示为半封闭—封闭的缺氧还原强分层水体沉积环境;w（Sr）/w（Cu）=54.94~1260.71,均值为213.79,反映炎热干旱气候类型。义县组砖城子层沉积期湖泊为干旱古气候背景下的半咸水—咸水、缺氧还原强分层的半封闭—封闭型。 相似文献
5.
在柴北缘东段识别出早古生代埃达克岩-富Nb玄武岩的火山岩组合。埃达克岩富Na2O、贫K2O,K2O/Na2O比值介于0.14~0.43之间;高Sr（614×10-6~1043×10-6）,但亏损Y（3.26×10-6~14.1×10-6）和Yb（0.33×10-6~1.46×10-6）,具有高的Sr/Y比值（44~282）;富集Sr、Ba等大离子亲石元素,亏损Nb、Ta、Ti等高场强元素及Cr、Ni、Co、V等相容元素。富Nb玄武岩富Na2O、贫K2O、高TiO2,其Nb含量较高,介于16.9×10-6~17.9×10-6之间,具有高的Nb/Ta、Nb/U、（Nb/La）N比值,同时富集高场强元素。埃达克岩锆石U-Pb定年得到453±4Ma和457±4Ma的结晶年龄。锆石εHf（t）范围较大,介于3.40~13.23之间,对应的二阶段模式年龄tDM2介于1059~566Ma之间,显示以新生物质为主的特征。综合研究表明柴北缘东段埃达克岩可能为岛弧环境下俯冲的南祁连大洋板片部分熔融的产物。板片来源的埃达克质熔体交代或与上覆地幔楔橄榄岩反应,导致被交代的地幔橄榄岩部分熔融而形成富Nb玄武质岩浆。柴北缘东段埃达克岩-富Nb玄武岩火山岩组合的厘定表明南祁连洋可能直到~455Ma之前并未完全闭合,同时表明俯冲大洋板片的部分熔融可能是柴北缘早古生代地壳增生的一种重要方式。 相似文献
6.
中新世是青藏高原隆升、增厚的重要时期,并且在这一时期内拉萨地块广泛发育碰撞后岩浆岩。本文对南拉萨地块米拉山地区的钙碱性钾质火山岩进行了锆石U-Pb年代学、Lu-Hf同位素和全岩主量、微量元素的测定与系统研究。米拉山中新世火山岩为粗面英安岩、英安岩和流纹岩（SiO2=59.89%~71.78%）。锆石U-Pb定年结果为16.1±0.2Ma~20.4±0.3Ma,表明其喷发时代为中新世。岩石具有较高的Al2O3含量（13.54%~16.31%）,低MgO（0.46%~1.95%）、高Sr（388×10-6~804×10-6）、低Y（6.55×10-6~11.20×10-6）和Yb（0.70×10-6~1.07×10-6）的特征,具有较高的Sr/Y值（51~80）、低相容元素（Cr=4.26×10-6~32.53×10-6,Ni=4.16×10-6~25.75×10-6）和弱Eu负异常。岩石具有轻稀土元素和Rb、Th、U、K等元素富集、重稀土元素和高场强元素Nb、Ta、Ti亏损的特征。米拉山中新世火山岩显示出埃达克质岩石的地球化学特征,可能来自于的镁铁质加厚下地壳的部分熔融,推测下地壳源区是石榴石角闪岩。锆石εHf（t）值为+2.2~+7.8,表明源区为新生地壳物质,有俯冲板片熔体加入。米拉山中新世火山岩的喷发时代与米拉山断裂活动时间一致,二者可能同为拉萨地块岩石圈拆沉的结果。 相似文献
7.
塔里木克拉通前寒武纪构造演化,特别是早前寒武纪构造演化一直是地质学家讨论的焦点。本文通过对阿尔金北缘新太古代TTG片麻岩进行详细的野外调查、岩相学观察、地球化学分析以及锆石SHRIMP U-Pb定年来揭示该岩石的成因以及探讨塔里木克拉通早前寒武纪构造演化。锆石SHRIMP U-Pb定年结果显示阿尔金北缘TTG片麻岩的形成年龄为2740±19Ma,而后经历了新太古代（2494±53Ma）混合岩化作用和古元古代（1962±78Ma）麻粒岩相变质作用。阿尔金北缘英云闪长质片麻岩显示低的MgO含量（1.33%~3.08%）和Mg#（37~52）,具有高Sr（469×10-6~764×10-6）含量、低Y（4.72×10-6~13.5×10-6）和Yb（0.37×10-6~0.99×10-6）含量的特点,它们的Sr/Y比值可达到41~99。岩石的这些特征与基性下地壳部分熔融形成的TTG相同。并且,该新太古代TTG片麻岩还具有正的εNd（t）值（0.2~3.6）、高的Nd同位素初始值（0.509088~0.509260）和古太古代两阶段模式年龄（3.62~3.70Ga）。因此,阿尔金北缘新太古代TTG片麻岩可能来源于基性下地壳部分熔融,并且岩浆源区有石榴石、角闪石和金红石的残留。综合前人的研究成果,对比相邻区域TTG的形成时代,变质事件的记录以及太古宙地壳增生差异都指示阿尔金北缘和敦煌-库鲁塔格地区可能来源于不同的大陆块体。 相似文献
8.
云南保山金厂河铁铜铅锌多金属矿床Rb-Sr等时线测年及其地质意义 总被引：7，自引：2，他引：5
金厂河铁铜铅锌多金属矿床位于保山地块北部、NS向保山-施甸复背斜与NNW向澜沧江断裂锐角交汇部位的南部。矿体呈层状、似层状产于寒武系核桃坪组金厂河背斜的层间裂隙中,受NW向、NE向断裂交汇处的控制。选取闪锌矿及其共生的方铅矿、黄铜矿、石英样品,应用Rb-Sr同位素测年方法,获得闪锌矿等时线年龄为（118.9±5.9） Ma,闪锌矿+方铅矿等时线年龄为（119.3±1.7） Ma,闪锌矿+黄铜矿等时线年龄为（120.3±5.1） Ma,闪锌矿+石英等时线年龄为（117.0±2.4） Ma,闪锌矿+方铅矿+石英等时线年龄为（118.7±1.5） Ma,闪锌矿+方铅矿+黄铜矿等时线年龄为（119.6±1.6） Ma,闪锌矿+方铅矿+黄铜矿+石英等时线年龄为（118.9±1.4） Ma。Rb-Sr定年结果表明,金厂河铁铜铅锌多金属矿床的成矿时代为117~120 Ma,为早白垩世。热液矿物组合的 （87Sr/86Sr）i平均值为0.713?885,与保山地块内志本山岩体的（87Sr/86Sr）i值接近,指示其成矿物质主要来源于地壳,成矿作用与保山地块内燕山晚期花岗岩岩浆活动有关,结合矿区重力负异常特点,推测矿区内存在隐伏的中-酸性岩体。通过地球动力学背景探讨,认为该矿床的形成可能是对中特提斯洋闭合过程中腾冲地块与保山地块碰撞造山作用的响应,与地块内部受碰撞影响而导致地壳深熔所产生的岩浆作用有关。 相似文献
9.
钱台子金矿床是一个产于皖东蚌埠隆起区东端的石英脉型小型矿床,矿体主要赋存于变质结晶基底五河岩群中,受张扭性断裂控制。本文通过对不同阶段石英进行系统的包裹体岩相学观察、显微测温、激光拉曼探针及氢氧同位素分析,探讨了该矿床的流体来源及矿床成因。结果表明,钱台子金矿床流体包裹体有纯CO2型、CO2—H2O型和H2O—NaCl型3种,包裹体均一温度集中在286~385℃,w(NaCl, eqv)=4.80%~12.56%,平均8.29%;不同阶段石英的δ18OV-SMOW变化范围为9.0×10-3~15.2×10-3,对应的δ18O水变化范围为2.12×10-3~9.70×10-3;各成矿期流体密度集中于0.63~0.84 g/cm3之间,均一压力为163~178 MPa,成矿深度＜6 km;成矿早期流体属于中高温、低盐度、低密度的CO2—H2O—NaCl变质流体,后期有岩浆水参与。钱台子金矿床形成于扬子克拉通沿NW方向俯冲于华北克拉通之下的造山期后持续伸展背景下的拆沉作用和壳幔相互作用所导致的大规模岩浆活动。 相似文献
10.
湖相碳酸盐岩是一种分布极其广泛的陆相碳酸盐岩。中国湖相碳酸盐岩沉积始于二叠纪—三叠纪,经侏罗纪—白垩纪发展,鼎盛于古近纪,具有沉积时间跨度长、分布面积广的特征。碳酸盐岩发育方式多样,常以多个单层、薄夹层状、互层状、韵律沉积为主,也见以结核状或钙质微体化石等薄层赋存于泥岩、页岩等细粒碎屑岩中。湖相碳酸盐岩δ13C值介于-10.0×10-3~+10.0×10-3之间,多数为-5.0×10-3~+5.0×10-3,正负值均有。二叠系—三叠系δ13C发生负偏,侏罗系—白垩系先正向漂移随后负偏,古近系—新近系再次正偏,达最大值约+5.0×10-3。氧同位素δ18O值介于-20.0×10-3~+2.0×10-3之间,多数为-15.0×10-3~-0.0×10-3,几乎全部为负值。二叠系—三叠系、侏罗系—白垩系碳酸盐岩δ18O值在-15.0×10-3~-3.0×10-3之间变化,古近系—新近系δ18O值明显正偏移,多数位于-10.0×10-3~0.0×10-3。中国湖相碳酸盐岩碳氧同位素相关性分析表明,δ13C与δ18O密切相关,且δ13C值多正值或轻微负值,指示湖泊为封闭型咸水—半咸水环境;δ13C和δ18O不相关,δ13C值为负值,指示湖泊为开放型淡水环境。 相似文献
11.
Police, politics, and the right to the city 总被引：1，自引：0，他引：1
Mustafa Dikeç 《GeoJournal》2002,58(2-3):91-98
Space and spatiality have recently been at the core of debates concerning the political possibilities of the city. The arguments advanced in this paper might be seen as an attempt to contribute to these debates through a reflection on the spatiality of (in) justice, politics, and the right to the city. The case of French urban policy, with its focus on distressed urban areas, and the `suburban problem' in France are used as examples to make arguments more concrete. 相似文献
12.
I. M. Gorokhov M. A. Semikhatov M. M. Arakelyants E. A. Fallick N. N. Mel’nikov T. L. Turchenko T. A. Ivanovskaya T. S. Zaitseva E. P. Kutyavin 《Stratigraphy and Geological Correlation》2006,14(3):260-274
Clay subfractions (SFs) of <0.1, 0.1–0.2, 0.2–0.3, 0.3–0.6, 0.6–2 and 2–5 μm separated from Middle Riphean shales of the Debengda Formation are studied using the TEM, XRD, K-Ar and Rb-Sr isotopic methods. The oxygen and hydrogen isotope compositions in the SFs are studied as well. The low-temperature illite-smectite is dominant mineral in all the SFs except for the coarsest ones. The XRD, chemical and isotopic data imply that two generations of authigenic illite-smectite different in age are mixed in the SFs. The illite crystallinity index decreases in parallel with size diminishing of clay particles. As compared to coarser SFs, illite of fine-grained subfractions is enriched in Al relative to Fe and Mg, contains more K, and reveals higher K/Rb and Rb/Sr ratios. The Rb-Sr age calculated by means of the leachochron (“inner isochron”) method declines gradually from 1254-1272 Ma in the coarsest SFs to 1038-1044 Ma in finest ones, while the K-Ar age decreases simultaneously from 1225–1240 to 1080 Ma. The established positive correlation of δ18O and δD values with dimensions of clay particles in the SFs seems to be also consistent with the mixing systematics. The isotopic systematics along with data on mineral composition and morphology lead to the conclusion that mixedlayer illite-smectite was formed in the Debengda shales during two periods 1211–1272 and 1038–1080 Ma ago. The first period is likely close to the deposition time of sediments and corresponds to events of burial catagenesis, whereas the second one is correlative with the regional uplift and changes in hydrological regime during the pre-Khaipakh break in sedimentation. 相似文献
13.
E. M. Prasolov S. A. Sergeev B. V. Belyatsky E. S. Bogomolov K. A. Gruzdov I. N. Kapitonov R. Sh. Krymsky V. O. Khalenev 《Geochemistry International》2018,56(1):46-64
This paper reports the first results of a study of 11 isotope systems (3He/4He, 40Ar/36Ar, 34S/32S, 65Cu/63Cu, 62Ni/60Ni, 87Sr/86Sr, 143Nd/144Nd, 206–208Pb/204Pb, Hf–Nd, U–Pb, and Re–Os) in the rocks and ores of the Cu–Ni–PGE deposits of the Norilsk ore district. Almost all the results were obtained at the Center of Isotopic Research of the Karpinskii All-Russia Research Institute of Geology. The use of a number of independent genetic isotopic signatures and comprehensive isotopic knowledge provided a methodic basis for the interpretation of approximately 5000 isotopic analyses of various elements. The presence of materials from two sources, crust and mantle, was detected in the composition of the rocks and ores. The contribution of the crustal source is especially significant in the paleofluids (gas–liquid microinclusions) of the ore-forming medium. Crustal solutions were probably a transport medium during ore formation. Air argon is dominant in the ores, which indicates a connection between the paleofluids and the atmosphere. This suggests intense groundwater circulation during the crystallization of ore minerals. The age of the rocks and ores of the Norilsk deposits was determined. The stage of orebody formation is restricted to a narrow age interval of 250 ± 10 Ma. An isotopic criterion was proposed for the ore-bearing potential of mafic intrusions in the Norilsk–Taimyr region. It includes several interrelated isotopic ratios of various elements: He, Ar, S, and others. 相似文献
14.
Influences of the unsaturated,saturated, and riparian zones on the transport of nitrate near the Merced River,California, USA 总被引：1，自引：0，他引：1
Joseph L. Domagalski Steven P. Phillips E. Randall Bayless Celia Zamora Carol Kendall Richard A. WildmanJr Janet G. Hering 《Hydrogeology Journal》2008,16(4):675-690
Transport and transformation of nitrate was evaluated along a 1-km groundwater transect from an almond orchard to the Merced River, California, USA, within an irrigated agricultural setting. As indicated by measurements of pore-water nitrate and modeling using the root zone water quality model, about 63% of the applied nitrogen was transported through a 6.5-m unsaturated zone. Transport times from recharge locations to the edge of a riparian zone ranged from approximately 6 months to greater than 100 years. This allowed for partial denitrification in horizons having mildly reducing conditions, and essentially no denitrification in horizons with oxidizing conditions. Transport times across a 50–100-m-wide riparian zone of less than a year to over 6 years and more strongly reducing conditions resulted in greater rates of denitrification. Isotopic measurements and concentrations of excess N2 in water were indicative of denitrification with the highest rates below the Merced River. Discharge of water and nitrate into the river was dependent on gradients driven by irrigation or river stage. The results suggest that the assimilative capacity for nitrate of the groundwater system, and particularly the riverbed, is limiting the nitrate load to the Merced River in the study area. 相似文献
15.
扬子北缘马元铅锌矿床闪锌矿微量元素及S-Pb-He-Ar-C同位素地球化学研究 总被引：7，自引：3，他引：4
马元铅锌矿床是近年扬子陆块北缘铅锌找矿的新突破。矿体呈层状、似层状产于碑坝隆起翼部震旦系灯影组角砾状白云岩层间构造带中,围岩蚀变很弱。矿石中硫化物以闪锌矿、方铅矿为主,中粗粒晶质结构,充填于白云岩角砾间。闪锌矿富集Cd、Ge、Ag,贫In、Tl、Se,Ga/In为6~132,Ge/In多1000,成矿温度以中-低温为主。金属硫化物ε~(34)S值相对集中,为12.9‰~19.4‰,平均为17.4‰,来自于海相硫酸盐的还原。铅同位素组成稳定,~(206)Pb/~(204)Pb为17.858~17.918:~(207)Pb/~(204)Pb为15.603~15.694;~(208)Pb/~(204)Pb为37.756~38.046,具有造山带和上地壳铅的特征,震旦系可能提供了金属成矿物质。闪锌矿中流体包裹体的~3He/~4He为0.03Ra~1.05Ra,~(40)Ar/~(36)Ar为326.1~765.1,~(38)Ar/~(36)Ar为0.183~0.204,表明成矿流体主要为地壳流体和饱和大气水(大气降水或海水)的混合。闪锌矿内流体包裹体挥发分δ~(13)C_(CH_4)值为-36.01‰~-28.80‰,δ~(13)C_(C_2H_6)值为-27.72‰~-22.44‰,δ~(13)C_(CO_2)值为-23.24‰~-9.68‰,表明有机流体参与了成矿作用。石英、方解石的H-O同位素结果表明具有海水和有机水混合的特征。可见,成矿流体具有两种流体混合的特征,一为蒸发海水与围岩反应所形成的盆地卤水,二为有机流体。推测矿区可能存在一个古油气藏,由于TSR生成一高硫气藏,为区内还原性有机流体的主要来源。当富含Pb、Zn等成矿物质的成矿流体运移至富含CH_4和H_2S的还原性流体的矿区角砾岩带时,两种流体混合,Pb、Zn等遇到H_2S发生反应而沉淀成矿,并伴生热液白云石等,形成了马元铅锌矿床。综上所述,我们认为马元矿床属MVT型铅锌矿床。 相似文献
16.
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18.
Over the past decade researchers working on the rocks of the Beaufort Group in the main Karoo Basin of South Africa have vastly increased our understanding of this important Permo-Triassic sequence. Many new fossil forms have been discovered, allowing for breakthroughs into the biodiversity, biogeography and biostratigraphy of the group. Taxonomic and phylogenetic advances are many and varied, and cover most of the vertebrate taxa, but with emphasis placed on the temnospondyl amphibians, archosauriforms and non-mammalian synapsids, in particular the anomodontia. Biostratigraphic breakthroughs have centered on the Middle Permian Eodicynodon and Tapinocephalus assemblage zones, the Late Permian Dicynodon Assemblage Zone, and the Triassic Lystrosaurus and Cynognathus assemblage zones. Correlation of these biozones with better dated sequences in Europe, Russia and China has allowed for many chronostratigraphic refinements, which are in turn vital for sequence stratigraphical analysis of the basin fill. Based on fossil data, both the lower (Ecca–Beaufort) and upper (Beaufort–Molteno) contacts of the group have been proved to be highly diachronous. The refined chronostratigraphic framework has also allowed for a better analysis of the basin evolution through time, particularly in terms of the correlation of external stimuli that affect basin sedimentation patterns. 相似文献
19.
Delivery of Trace Metals (Al,Fe, Mn,V, Co,Ni, Cu,Cd, Ag,Pb) from the Trinity River Watershed Towards the Ocean 总被引：2，自引：0，他引：2
The Trinity River (Texas, USA) contains in its watershed 23 different reservoir lakes, the largest one being Lake Livingston
situated in the lower Trinity River watershed and two potentially polluting metroplexes, Dallas and Houston. In order to determine
fluxes of nutrients and trace metals to Galveston Bay, a survey that included 24 discreet samples collected over a year and
at various stages of discharge was carried out during 2000–2001. Geochemical (i.e., sorption by Fe oxyhydroxides), biological
(i.e., seasonal uptake by sinking algae in Lake Livingston), and hydrological (i.e., dilution effects by increasing flow rates)
controls were found to be mainly responsible for variations in dissolved trace metal concentrations rather than pollution
sources. The Trinity River loads of suspended sediments and pollutant trace metals entering Galveston Bay at Anahuac were
<20% of those reaching Lake Livingston, and only a few percent of the total upstream trace metal load is entering the Gulf
of Mexico. Thus, during the transit through the 23 man-made lakes and an estuary, >96% of the pollutant trace metal load is
lost to sediments. 相似文献