西菲律宾海沉积物稀土元素地球化学

对取自西菲律宾海区3个沉积物柱样（WP1、WP2和WP40）的32个样品的稀土元素（REE）地球化学行为进行了系统的研究。区内沉积物表现出以下特征：①稀土元素含量及总量（ZREE）较低，WP1、WP2和WP40孔的ΣREE依次为72．91×10－6，54．15×10－6和54．18×10－6，REE在粘土粒级中得到了较大富集；②REE球粒陨石标准化的分布模式曲线表现为负斜率，富集轻稀土，WP1、WP2和WP40孔LREE／HREE比值平均值为37．36，26．33和17．16，页岩标准化曲线大致呈水平；③与球粒陨石和页岩相比，Ce都表现为强烈的亏损；以球粒陨石为标准，WP40孔表现为弱的Eu正异常，其他两孔表现为弱的Eu负异常；以页岩为标准，皆显示Eu正异常；④ΣREE纵向变化曲线与CaCO3旋回曲线有良好的对应关系。上述特征表明：①沉积物的来源复杂，有陆源、火山源、生物源和自生源，在所研究的三个孔中，WP1孔含有较多的陆源物质，WP2和WP40含有较多的火山物质；②被粘土吸附是本区REE重要的存在形式；③沉积物形成环境为氧化条件；④据ΣREE的纵向变化曲线与CaCO3旋回曲线，将本区沉积物自下而上划分为末次冰期亚间冰期沉积、冰期最盛期沉积和全新世沉积。     

楚雄盆地铜、盐、有机质相互作用与砂岩铜矿生成

矿床的有机地球化学研究表明:楚雄盆地含煤、含铜和含膏盐建造中的有机质在来源、类型和成熟度上是不一致的。成岩期干酪根降解形成的短链羧酸是矿源层中铜活化的重要因素,石油烃是矿质搬运的重要载体。改造成矿期,天水淋滤膏盐展形成富SO_4~(2-)的下渗氧化性流体,为改造成矿提片供了硫源。另一方面,来自基底的含矿流体沿同生断裂上涌,混染煤系地层形成还原性流体,沿次级断裂进入到高渗透的砂岩储集层。当两种流体在砂岩中相遇时,发生氧化-还原作用而形成改造期矿体。     

The Uplift of the Longmenshan Thrust Belt and Subsidence of the West Sichuan Foreland Basin

Based on fission track dating of apatite, and measurement of vitrinite reflectance of rock samples from the Longmenshan (Longmen Mountain)area and the West Sichuan foreland basin and computer modelling it is concluded that (l)the Songpan-Garze fold belt has uplifted at least by 3-4 km with an uplift rate of no less than 0.3-0.4 mm/a since 10 Ma B.P.; (2) the Longmenshan thrust nappe belt has uplifted at least by 5-6 km with an uplift rate of more than 0.5- 0.6 mm /a since 10 Ma B.P.; (3) the Longmenshan detachment belt has uplifted by 1 - 2 km at a rate of 0.016-0.032 mm/a since 60 Ma B.P.; (4) the West Sichuan foreland basin has uplifted by 1.7-3 km at a rate of 0.028-0.05 mm/a since 60 Ma B.P.; (5) the uplift rate of the area on the west side of the Beichuan-Yingxiu-Xiaoguanzi fault for the last 10 Ma is 40 times as much as that on its east side; (6) the uplifting of the the Songpan - Garze fold belt and the subsidence of the West Sichuan foreland basin 60 Ma ago exhibit a mirro-image correlation, i.e     

The transition from passive to active margin tectonics: a case study from the zone of Samedan (eastern Switzerland)

The Zone of Samedan is part of a fossil, early Mesozoic rift system originally situated in the distal, Lower Austro-Alpine domain of the Adriatic passive continental margin. An early Mesozoic configuration of asymmetrical rift basins bounded by relative structural highs compartmentalized Late Cretaceous active margin tectonics; Jurassic half-grabens were folded into arcuate synclines, whereas relative structural highs engendered thin, imbricated thrust sheets. West-directed thrusting and folding initiated at the surface and continued to depths favoring mylonitization under lower greenschist-facies conditions. At this time Liguria-Piemontese ophiolites were accreted to Lower Austro-Alpine units directly underlying the Zone of Samedan. Late Cretaceous orogenic collapse of the Adriatic active margin involved the reactivation of west-directed thrusts as low-angle, top-to-the-east, normal faults. These faults accommodated extensional uplift of Liguria-Piemontese ophiolites and Lower Austro-Alpine units beneath and within the Zone of Samedan. During Paleogene collision, some Late Cretaceous faults in the Zone of Samedan were reactivated under lower anchizonal conditions as north-directed thrusts. The latter stages of this early Tertiary thickening were transitional to brittle, high-angle normal faulting associated with top-to-the-east extension and spreading above the warm, uplifting Lepontine dome.     

Subduction,mega-shear systems and Late Palaeozoic basin development in the African segment of Gondwana

 Basins within the African sector of Gondwana contain a Late Palaeozoic to Early Mesozoic Gondwana sequence unconformably overlying Precambrian basement in the interior and mid-Palaeozoic strata along the palaeo-Pacific margin. Small sea-board Pacific basins form an exception in having a Carboniferous to Early Permian fill overlying Devonian metasediments and intrusives. The Late Palaeozoic geographic and tectonic changes in the region followed four well-defined consecutive events which can also be traced outside the study area. During the Late Devonian to Early Carboniferous period (up to 330 Ma) accretion of microplates along the Patagonian margin of Gondwana resulted in the evolution of the Pacific basins. Thermal uplift of the Gondwana crust and extensive erosion causing a break in the stratigraphic record characterised the period between 300 and 330 Ma. At the end of this period the Gondwana Ice Sheet was well established over the uplands. The period 260–300 Ma evidenced the release of the Gondwana heat and thermal subsidence caused widespread basin formation. Late Carboniferous transpressive strike-slip basins (e.g. Sierra Australes/Colorado, Karoo-Falklands, Ellsworth-Central Transantarctic Mountains) in which thick glacial deposits accumulated, formed inboard of the palaeo-Pacific margin. In the continental interior the formation of Zambesi-type rift and extensional strike-slip basins were controlled by large mega-shear systems, whereas rare intracratonic thermal subsidence basins formed locally. In the Late Permian the tectonic regime changed to compressional largely due to northwest-directed subduction along the palaeo-Pacific margin. The orogenic cycle between 240 and 260 Ma resulted in the formation of the Gondwana fold belt and overall north–south crustal shortening with strike-slip motions and regional uplift within the interior. The Gondwana fold belt developed along a probable weak crustal zone wedged in between the cratons and an overthickened marginal crustal belt subject to dextral transpressive motions. Associated with the orogenic cycle was the formation of mega-shear systems one of which (Falklands-East Africa-Tethys shear) split the supercontinent in the Permo-Triassic into a West and an East Gondwana. By a slight clockwise rotation of East Gondwana a supradetachment basin formed along the Tethyan margin and northward displacement of Madagascar, West Falkland and the Gondwana fold belt occurred relative to a southward motion of Africa. Received: 2 October 1995 / Accepted: 28 May 1996     

鄂西震旦系上统含磷岩系的划分与对比

上震旦统陡山沱组是鄂西地区最具工业价值的含磷地层。著名的磷矿有荆襄磷矿、宜昌磷矿、兴(山)神(农架)保(康)磷矿。迄今已有20多年的勘探史,但由于各矿区研究程度不一,又缺古生物依据,亦不能依靠同位素年龄来作划分对比,故在地层及磷矿层的划分、对比上认识不一。笔者结合磷矿特征及含磷岩系岩类组合、剖面结构特点、稀土元素特征等,将本区划分为4个磷矿分布区,将陡山沱组划分为3个岩性段、5个含磷层位。     

滇西变泥质岩的白云母b_0值及其构造－地层意义

据３３３个白云母ｂ０值，结合区域地层和构造的研究成果，提出：（１）原称昌宁－孟连变质带解体为西盟－勐统变质带（加里东期中压变质带）和澜沧双变质带的高压亚带，两期高压变质作用分别与海西－印支期的洋壳消减和陆－陆碰撞有关；（２）石鼓变质带是三个逆冲岩片的叠置，各岩片内岩石的变质作用各具特色；（３）金沙江洋盆为地块间小洋盆，其消减及嗣后的弧－弧碰撞可能不产生高压变质作用。在此基础上探讨了白云母ｂ０值在造山带研究中的意义。     

松辽盆地第三系可地浸砂岩型铀矿找矿方向

松辽盆地是在兴蒙－吉黑海西褶皱带上发育起来的中、新生代大型陆相沉积盆地，基底主要为古生界浅变质岩，盖层主要是白垩系杂砂岩－有机页岩建造和新生界疏松碎屑堆积。笔者通过对前人资料分析研究后认为：松辽盆地具有良好的成矿地质条件和找矿前景；第三系是寻找可地浸砂岩型铀矿的主要目的层之一，层间氧化带型铀矿是主要寻找类型；盆地的西部和西南部是寻找可地浸砂岩型铀矿远景区。     

新疆伊犁盆地侏罗纪煤岩特征及煤相

应用煤岩学方法，探讨了新疆伊犁盆地侏罗纪煤的煤岩特征及煤相划分，将煤相划分为９种类型即干燥森林沼泽相，潮湿森林沼泽相，草木混生型沼泽相或芦苇沼炭沼泽相。通过煤相分析，为伊犁盆地成煤环境的研究提供了佐证。     

广州珠江西航道,流溪河有机污染特征与感潮作用

珠江西航道和流溪河在广州市区上游，为广州市主要水源区。由于感潮作用，受市区严重污染的水体因涨潮上溯而上游传输。严重影响上游水质。因此，弄清感潮作用对广州水源区水质的影响程度和范围，对水源保护与利用有重要意义。本研究从下游到上游，对水源区底泥中有机物特征进行了分析，结果表明：（１）从上游到上游，受感潮作用影响逐渐减小，污染程度逐渐减轻；（２）水源区有机物特征呈有规律变化。从靠近城市的下游到远离城市的