西澳大利亚豪特曼群礁复活节岛群全新世珊瑚礁的海底胶结作用          下载免费PDF全文

朱井泉  祝仲蓉ＬＢ．Ｃｏｌｌｉｎｓ 《地质科学》1996,(3):274

 对澳大利亚的位于海洋过渡带和高纬度的豪特曼群礁复活节岛群上的全新世珊瑚礁进行了海底胶结作用解剖研究。研究表明,该礁像热带珊瑚礁一样,也经历了相当程度的海底胶结。胶结物包括高镁方解石的和文石的共7种类型。由于所处地理位置和海洋环境条件,使得海底胶结物中强烈贫文石而富镁方解石(分别占4%和96%),造成镁方解石胶结物中的MgCO₃的摩尔含量规律性降低(8.47%-14.29%)。特有的生物组合及其竞争,不仅构成了迎风礁和背风礁的显着岩相差异(前者以藻类粘结岩为主,后者以珊瑚骨架岩占优),并导致海底胶结物在背风礁中的发育强度远大于迎风礁这一与热带珊瑚礁海底胶结物恰好相反的分布规律。  相似文献   

成藏体系中油气田母体的分布形式     

谌卓恒 《海相油气地质》1996,(2)

预测一个地区油气田的规模分布和数量,为经济分析和勘探决策提供定量依据,是油气资源评价中必不可少的一个部分。目前对成藏体系中油气田规模分布形式存在不同的看法,建立一个可信的母体分布模型是预测油气田规模分布的基础。为研究成藏体系油气田母体的规模的分布形式,本文收集了世界范围内近六十个成藏体系和含油气盆地已发现油气田规模分布的资料,以此分析油气田母体的分布类型。  相似文献   

Distribution and species composition of mass occurrences of large-sized sponges in the northeast Atlantic     

A.B. Klitgaard  O.S. Tendal 《Progress in Oceanography》2004,61(1):57-98

The geographic and bathymetric distribution of “ostur”, that is mass occurrences of large-sized astrophorid demosponges, first recognized at the Faroe Islands during the internordic BIOFAR programme (Marine Benthic Fauna of the Faroe Islands), are mapped for the northeast Atlantic. This is done on the basis of information obtained during the sampling of the BIOICE programme (Benthic Invertebrates in Icelandic Waters) as well as during cruises at Karmoy (southwest Norway), the Trondheim Fjord (middle Norway), the Koster area (southwest Sweden) and the Denmark Strait (southeast Greenland). In addition, information has been acquired from Nordic and German biologists and fishermen regarding the occurrence of “ostur”. These data together with the sparse information in the literature show that the geographic distribution of the “ostur” areas follows two band-shaped arcs, defined by the Norwegian Atlantic Current and the Irminger Current. The local occurrence of “ostur” is, however, to a great extent dependent on areas of variable topography where a hard bottom is present.The results show that two main types of “ostur” can be recognized in the northeast Atlantic. Firstly a boreal “ostur” which is dominated by Geodia barretti, Geodia macandrewi, Geodia atlantica, Isops phlegraei, Stryphnus ponderosus and Stelletta normani, and occurs around the Faroe Islands, Norway, Sweden, parts of the western Barents Sea and south of Iceland. Secondly a cold water “ostur” characterized by the same genera but represented by different species, viz. Geodia mesotriaena, Isops phlegraei pyriformis and Stelletta rhaphidiophora, which is found north of Iceland, in most of the Denmark Strait, off East Greenland and north of Spitzbergen. A number of hexactinellid species are also represented in the cold water “ostur”, the most frequently occurring being Schaudinnia rosea.Suggestions are given regarding the possible causes for observed changes in the distribution of “ostur” as well as to the biological importance of these areas.  相似文献   

莱州湾主要污染物来源及分布特征     

童钧安 《海洋科学进展》1994,(4)

本文在１９８８年至１９９２年大量调查资料的基础上，研究了莱州湾入海污染源及海水中污染物的分布特征。认为，莱州湾主要污染物质为石油类、ＣＯＤ，其主要来源为西南部沿岸河口，尤其是小清河和广利河；其次为无机氮、无机磷，其主要来源为黄河口，其次为南岸河口。小清河为本区主要污染源，占本区污染物总入海量的１／３强，治理小清河、广利河是改善本区环境质量的主要环节。  相似文献   

High gray whale relative abundances associated with an oceanographic front in the south-central Chukchi Sea     

B.A. Bluhm  K.O. Coyle  B. Konar  R. Highsmith   《Deep Sea Research Part II: Topical Studies in Oceanography》2007,54(23-26):2919

We describe gray whale (Eschrichtius robustus) distribution in the south-central Chukchi Sea in relation to environmental factors during two 5-day surveys in June and September of 2003. Whale counts per 10-min scan (an index of relative abundance) ranged from 0 to 41 in June and from 0 to 28 in September. CTD data showed an ocean front around 67.8°N with strong horizontal gradients in temperature, salinity, chlorophyll-a concentration and water-column stability. Highest whale abundance indices occurred in or near the front in both periods. Preliminary qualitative assessment of biological communities in the study area suggests that infaunal clams, echinoderms, euphausids, chaetognaths and Arctic cod were common, while ampeliscid amphipods, the previously abundant infauna (and likely prey) in the nearby Chirikov Basin feeding area, were not dominant. Euphausids may be a prey for gray whales in this area. We suggest that frontal systems may play an important role in eastern North Pacific gray whale foraging grounds. Further study is needed to fully describe the role of frontal systems in gray whale foraging grounds.  相似文献   

甘肃省主要河流径流时空分布规律及演变趋势分析   总被引：21，自引：0，他引：21  

胡兴林 《地球科学进展》2000,15(5):516-521

通过对甘肃省主要河流径流时空分布规律的分析研究,得出干旱缺水的主要原因是各河年径流丰水时段很短,一般只有2～3年;枯水时段很长,可达7～26年;祁连山区许多河流多年均值基本稳定。并预测从1998年开始至2009年,全省诸河水量从枯水年代转向平水到偏丰的年代;建议全省必须树立长期抗旱的思想,水资源利用必须进行系统分析优化配置。  相似文献   

Microbiotic crusts and their interrelations with environmental factors in the Gurbantonggut desert,western China     

Y. N. Chen  Q. Wang  W. H. Li  X. Ruan 《Environmental Geology》2007,52(4):691-700

Located in the Junggar Basin in Xinjiang, the Gurbantonggut Desert is the second largest desert in China. Microbiotic crusts consisting of animalcule, lichen, moss, and algae species develop extensively in the region. Their formation, species composition and distribution pattern are closely related to the environmental conditions along the different parts of sand dune. Analysis of microbiotic crust distribution and relationship to environmental factors shows that average microbiotic crust thickness is 0.05–0.1 cm at the tops dunes, 0.2–1.5 cm in the upper part, 1.5–2.5 cm in middle and lower parts of dunes, and 1.5–5.0 cm in interdune areas, while areal coverage is 30.5, 48.5, 55.5, and 75.5%, respectively. Microbiotic crust differentiation along dune slopes is a result of the development stage and converse-succession resistance of the different microbiotic crusts. The numbers of species, thickness and degree of development of microbiotic crusts increase from the upper part to the middle and lower parts of dune slopes. The development and differentiation of microbiotic crusts at various dune slope positions are a reflection of the ecological expression of the comprehensive adaptability and natural selection of different microbiotic crust species to the local environmental conditions, and are closely related to such ecological conditions as the physiochemical properties of soils and topsoil textural stability.  相似文献   

Reproductive characteristics of invasive gammarids in the Rhine-Main-Danube catchment, South Germany     

Axel Kley  Gerhard Maier   《Limnologica》2006,36(2):79-90

The gammarid composition at 25 sites in the rivers Danube, Main and the southern reaches of the Rhine were studied during the years 2002–2004. Dikerogammarus villosus and Echinogammarus ischnus were the most frequent species prevailing at 17 sites. Sympatric occurrence of D. villosus and E. ischnus was observed at 12 sites. Dikerogammarus haemobaphes was recorded at 7 sites; this species prevailed in the Danube, west of the Weltenburger Enge and in the Isar mouth where it co-existed with native species (Gammarus pulex and/or G. roeseli) at 6 sites. Dikerogammarus bispinosus and E. berilloni were found at only 1 site, where they co-existed with D. villosus and E. ischnus, and with D. villosus and native species, respectively. Investigation of reproductive characteristics at 3 sites showed that females of D. villosus and D. haemobaphes produced the biggest clutches with more than 100 eggs. Females of E. ischnus produced much smaller clutches (10–35 eggs on an average), but very big eggs. Clutch sizes and egg volumes of D. bispinosus and E. berilloni resembled those of native species. Our results suggest that the most successful invaders (D. villosus, D. haemobaphes and E. ischnus) display reproductive traits that facilitate their success. Both Dikerogammarus sp. allocate energy into production of many but small eggs, thus maximizing offspring number, while E. ischnus allocates its energy into production of fewer but large eggs which could be beneficial at sites where food is scarce.  相似文献   

WebGIS数据组织发展研究     

马少娟  孙绪新  陈景 《四川测绘》2003,26(2):64-67

本文论述互联网GIS数据组织的发展状况。首先介绍了在WebGIS环境下空间数据的特点及其管理上存在的困难，并分析了目前实现WebGIS数据组织的几种技术及其优缺点，最后说明ontologies和RDF在WebGIS数据组织中的具体应用。  相似文献   

晋江市规划区地下水调查初探     

叶建辉  黄蓬源 《福建地震》1998,(3)

本文通过在晋江市规划区开展抗震防灾基础调查工作中的地下水调查工作,总结在抗震防灾规划基础调查工作中对地下水专项调查的工作方法、重点及成果介绍。  相似文献