蜀南地区飞仙关组高精度层序地层研究     

廖明光  周素彦  罗冰  李凌  牟晓慧  夏吉文  周小刚  冯钰 《地层学杂志》2010,34(4)

针对四川盆地下三叠统飞仙关组层序地层存在多种不同划分方案,以高精度层序地层学理论与方法为指导,以蜀南地区飞仙关组台地相碎屑岩和碳酸盐岩为研究对象,以野外露头剖面、岩芯、钻井、测井、地震等资料为基础,综合应用岩性突变面、沉积相转换面、沉积物空间堆积样式的变化、早期成岩变化、电测井曲线特征以及地震反射特征等标志,识别出不同级次的11个层序界面,据此将本区飞仙关组划分为2个三级层序(TSQ1和TSQ2)和10个四级层序,其中TSQ1可细分出6个四级层序,TSQ2可再分出4个四级层序,并将其与传统地层单位进行对比:三级层序TSQ1和TSQ2分别对应于飞一段+飞二段地层和飞三段+飞四段地层。通过层序地层对比和层序地层格架的建立,指出这些层序在全区均具有良好的可对比性和等时性,每个层序均具有快速海侵到缓慢海退的特点,均由海侵体系域和高位体系域构成,未发现低位体系域和凝缩段。层序与储层关系的研究表明,四级层序Ⅲ和Ⅷ是台内鲕滩这种有利储集相带的主要发育层位,所形成的滩相鲕粒灰岩储层与高位体系域的向上变浅序列和早期暴露及其所导致的大气淡水淋溶改造有关,平面上集中分布于中东部地区。  相似文献   

Laminated sediments from the central Peruvian continental slope: A 500 year record of upwelling system productivity, terrestrial runoff and redox conditions   总被引：1，自引：1，他引：0  

A. Sifeddine  D. Gutirrez  L. Ortlieb  H. Boucher  F. Velazco  D. Field  G. Vargas  M. Boussafir  R. Salvatteci  V. Ferreira  M. García  J. Valds  S. Caquineau  M. Mandeng Yogo  F. Cetin  J. Solis  P. Soler  T. Baumgartner 《Progress in Oceanography》2008,79(2-4):190

Sedimentological studies including X-ray digital analyses, mineralogy, inorganic contents, and organic geochemistry on cores of laminated sediments accumulated in the oxygen minimum zone of the central Peruvian margin reveal variable oceanographic and climate conditions during the last 500 yr. Coherent upcore variations in sedimentological and geochemical markers in box cores taken off Pisco (B0405-6) and Callao (B0405-13) indicate that variability in the climate proxies examined has regional significance. Most noteworthy is a large shift in proxies at 1820 AD, as determined by ²¹⁰Pb and ¹⁴C radiometric dating. This shift is characterized by an increase in total organic carbon (TOC) in parallel with an abrupt increase in the enrichment factor for molybdenum Mo indicating a regional intensification of redox conditions, at least at the sediment water interface. In addition there was lower terrestrial input of quartz, feldspar and clays to the margin. Based on these results, we interpret that during several centuries prior to 1820, which corresponds to the little ice age (LIA), the northern Humboldt current region was less productive and experienced higher terrestrial input related to more humid conditions on the continent. These conditions were probably caused by a southward displacement of the inter-tropical convergence zone and the subtropical high pressure cell during the LIA. Since 1870, increases in TOC and terrigenous mineral fluxes suggest an increase of wind-driven upwelling and higher productivity. These conditions continued to intensify during the late 20th century, as shown by instrumental records of wind forcing.  相似文献   

Reduction of a Model Describing Ozone Oscillations in the Troposphere: Example of an Algorithmic Approach to Model Reduction in Atmospheric Chemistry     

Leonid V. Kalachev  Richard J. Field 《Journal of Atmospheric Chemistry》2001,39(1):65-93

We consider a simplified reaction mechanism from tropospheric chemistryconsisting ofsix chemical species involved in ten dynamic processes. The concentrations of all six speciesundergo temporal oscillation for some parameter values. An asymptoticapproach to reduction of the original six-variable model to a four-variable version is considered together with detailed explanation of the procedure as well as discussion of conditions under whichthe reduction is possible. The reduced system nearly quantitatively represents the oscillating behavior of thefull model and allows elucidation of its basic dynamical features. This approach also can be used to compare various small models of atmospheric chemistry, and to determine their underlying dynamic structure. The method can be systematically appliedto larger atmospheric models.  相似文献   

A Program to Analyze Aquifer Test Data and Check for Validity with the Jacob Method     

Malcolm S. Field 《Ground water》1993,31(2):316-320

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From food security to food insecurity: The case of Iraq, 1990–91     

John Osgood Field 《GeoJournal》1993,30(2):185-194

The article explains Iraq's precipitous decline into food insecurity following its military invasion of Kuwait. Food security and insecurity are defined and then examined in the Iraqi context. Five vulnerabilities are identified that were activated by international retaliation against Iraq, including the UN Security Council's embargo on trade between Iraq and the rest of the world and the Gulf War itself. The emergence and intensification of food insecurity are analyzed step by step, followed by consideration of how food security might be restored in Iraq. An Appendix assesses whether Iraq experienced famine in 1991.  相似文献   

Geochemistry of molybdenum in some stream sediments and waters     

Dawn S. Kaback  Donald D. Runnells 《Geochimica et cosmochimica acta》1980,44(3):447-456

Elevated concentrations of Mo are present in both the waters and sediments of Tenmile Creek, downstream from the large Mo deposit at Climax. Colorado. Concentrations of Mo reach a maximum of 10mg/1 in the water and 384μ/g in the (?) 80 mesh fraction of the sediment. The Mo anomaly extends for more than 80 km downstream from Climax, and results from the mining and milling at Climax. Background Mo concentrations in the nearby mountainous area are < 10μg/l (water) and < 5μg/g (sediment). Immediately below three small unmined Mo-rich orebodies elsewhere in Colorado < 3μg/l Mo are present in the waters and 20–30μg/g Mo in the fine fraction of the sediments.The Mo in the sediment of Tenmile Creek is chiefly adsorbed on coatings of amorphous Fe oxyhydroxide. and is similar to its form below two small, unmined Mo deposits. Mining has not changed the character of the chemical processes responsible for Mo dispersion from the Climax site.A modified version of the WATEQF computer program (Plummeret al., 1976) predicts that Tenmile Creek is undersaturated with respect to ferrimolybdite. molybdenite, powellite, and ilsemannite. The Mo in the stream water occurs as the molybdate ion which can be adsorbed on amorphous Fe oxyhydroxides. These predictions are supported by the absence of Mo minerals in the sediment of Tenmile Creek.  相似文献   

Rare-earth and LIL element fractionation in high-grade charnockitic gneisses,south Norway     

D Field  S.A Drury  D.C Cooper 《Lithos》1980,13(3):281-289

High-Fe, intermediate-acid, charnockitic gneisses in the Arendal-Tromøy area of the Svecofennian terrain of southeast Norway comprise two chemically contrasting zones - one with normal large-ion-lithophile (LIL) element characteristics, and the other IIL-deficint. The noramal -LiLL-deficient varitties also have low ΣEEE, commonly with positive Eu anomalies. The normal-LIL rocks are enriched in ?REE, exhibit fractionated patterns and have negative Eu anomalies. Modelling shows that both the LIL and REE patterns are consistent with an essentially primary fractionation process involving the separation of cumulus (LIL-deficient) phases from andesitic-dacitic magma emplaced directly under the high-grade conditions, with the normal-LIL rocks crystallising from the residual melt. This process is interpreted as a deep-seated component of the magma system which culminated in the emplacement of some higher level rapakivi granite late in the Svecofennian event. The model presented does not require anorthosite to be part of the same magma system.  相似文献   

The chemistry and origins of Proterozoic low-potash,high-iron,charnockitic gneisses from Tromøy,south Norway     

D.C. Cooper  D. Field 《Earth and Planetary Science Letters》1977,35(1):105-115

New major and trace element data for 79 acid-intermediate charnockitic gneisses (the Tromøy gneisses) and 16 associated metabasites from the island of Tromøy show that this part of the 1200–900-m.y. Sveconorwegian zone is occupied by rocks of unusual composition. Overall values for K and Rb are the lowest yet reported for any granulites, and K/Rb ratios are very high. Cs and Th are also low and, abnormally for granulites, so are Ba, Sr and Zr. Ba/Sr ratios are similar to those in other suites, but K/Ba and K/Sr are higher. These features may partially be reflecting unusual pre-metamorphic lithologies, but it is considered more likely that they are largely the product of metamorphically induced depletion processes involving metasomatism. There is some indication that the Na₂O/CaO and normative Ab/An ratios may also have been modified during metamorphism.Data for the presumed relatively immobile elements Cr, Co, Ni and V support an igneous origin for the Tromøy gneisses, but the presence of a paragneiss component cannot be ruled out. A characteristic of the gneisses is their high iron content, and spatial and temporal considerations point towards a genetic link with the iron-rich, intrusive rapakivi suites of Finland, Sweden and south Greenland. If the Tromøy gneisses do represent material of this type, it would seem to follow that potash fractionation has been extreme.  相似文献   

Evaluation of lead movement from the abiotic to biotic at a small-arms firing range     

Michael P. Labare  Michael A. Butkus  Dawn Riegner  Nick Schommer  Jason Atkinson 《Environmental Geology》2004,46(6-7):750-754

An investigation to characterize the extent and speciation of lead contamination in water, soil, and surrounding biota was conducted at a small-arms firing and skeet range in West Point, New York. Specifically, lead concentrations were examined in sediment, soil, water, plants, fish and invertebrates. There is an elevated concentration of lead in the soil and sediment up to 11,000 g/g and 340 g/g and also evidence of bioconcentration of the lead by the surrounding biota. Earthworms had up to 90% higher concentrations of lead while tadpoles showed 20% higher concentrations compared with their controls. Lead uptake by indigenous plants gave varying results. Two species bioconcentrated lead 20 and 55 times greater than the control plants. These differences were significant (P <0.05 level) when tested by the students t test. Further studies show that the total leachable lead was highest in the invertebrates and vertebrates but not in the plants.  相似文献   

烃源岩非均质性的控制因素研究--以东营凹陷为例   总被引：12，自引：1，他引：11  

朱光有  金强  张水昌  张林晔 《矿物岩石》2003,23(4):95-100

下第三系沙河街组是东营凹陷最重要的生储组合。通过对沙河街组烃源岩的研究,发现厚度大、分布广的沙四段和沙三段烃源岩在有机质组成和岩性等方面存在多种尺度的非均质性。从宏观到微观系统分析烃源岩的非均质性后发现,沙河街组烃源岩的非均质性明显受其体系域、沉积相带、有机质保存务件和古生产力等多种因素控制。其中,不同的体系域和沉积相带控制了烃源岩的岩性和岩相组合及生、排烃能力,高的古生产力是有机质富集的前提,缺氧还原环境使有机质能够保存的决定因素,同时,局部环境下发育的火山活动,对优质烃源岩的形成也具有重要作用。  相似文献