海南岛三亚三井珊瑚礁中稀土元素地球化学特征及其古气候意义

本文对海南岛三亚三井全新世形成的珊瑚礁中稀土元素进行了系统分析研究。结果表明，稀土元素具有明显分布特征：１．在井深４—７ｍ范围内，ΣＲＥＥ变化频繁；２．ＬＲＥＥ／ＨＲＥＥ的比值增大；３．Ｃｅ出现相对大的负异常。这些特征表明，在井深４—７ｍ范围内，珊瑚礁成岩环境频繁受到古气候变化的影响，径流和风化作用增强，并且出现了相对强的氧化环境。而径流和风化作用的增强及相对强的氧化环境的形成，通常由暧湿的古气候所致。说明珊瑚礁中稀土元素对古气候变化有良好的指示作用     

Increase in Cliona delitrix Infestation of Montastrea cavernosa Heads on an Organically Polluted Portion of the Grand Cayman Fringing Reef

Abstract. A marked increase in the biomass of Cliona delitrix infesting Montastrea cavernosa substrate occurred in a portion of the Grand Cayman fringing reef affected by the discharge of untreated fecal sewage. It is suggested that the six-fold increase in bacteria biomass (both "coliforms" and natural marine bacterioplankton) in reef waters receiving the sewage effluent is linked to a five-fold increase in sponge biomass at the polluted site relative to a control site. The elevated density of C. delitrix biomass signifies a similar increase in the amount of M. cavernosa skeleton that has been eroded by this sponge and reduced to silt-sized sediment. Thus, the proliferation of a bioeroding organism in the sewage-stressed environment has caused a shift in the carbonate balance on the reef.     

中沙群岛春季珊瑚礁鱼类资源组成的初步研究

2003年5月采用延绳钓和底层刺网在中沙群岛珊瑚礁水域进行了1个航次的鱼类资源调查。两种作业投入的捕捞努力量分别为延绳钓5620钓、底层刺网16120m,单次作业努力量延绳钓80~600钓、底层刺网600~1200m。捕获鱼类105种,渔获量1067尾2645.76kg,其中延绳钓34种计134尾2294.32kg,底层刺网共86种计933尾351.44kg。按岛礁平均,渔获率和单位捕捞努力量渔获量(CPUE)延绳钓为2.38尾.(100钓)-1、40.82kg.(100钓)-1,底层刺网为57.88尾.(1km)-1、21.80kg.(1km)-1。捕获的主要经济种类有鲨鱼、裸胸鳝、石斑鱼、笛鲷、裸颊鲷、鱼参科鱼类和大眼鲷等。     

Community structures of coral reefs around Peninsular Malaysia

Coral community structures at eleven fringing reef sites were investigated along the coast of Peninsular Malaysia. Estimated coverage of coral communities is examined by applying quantitative digital image analysis to the line transect method. Four coral community types were characterized by dominant genera and lifeforms: Acropora branching community, Montipora-Acropora community, Porites massive community, and Heliopora community. Live coral coverage in all study sites ranged from 17.9% to 68.6%. Most reefs were in “fair” condition while some reefs were shown to be in “poor” condition. Coral community structures among the study sites were divided into the west coast of Peninsular Malaysia with a dominant Porites massive lifeform, and the east coast with a variety of lifeform categories of Montipora and Acropora. Physical effects such as the monsoon wind regime and sedimentation are likely to influence the formation of dominant coral communities around Peninsular Malaysia.     

Tethya (Porifera,Demosponglae) Species Coexisting in a Maldivian Coral Reef Lagoon: Taxonomical,Genetic and Ecological Data

Abstract. Tethya microstella, T. orphei, T. robusta, and T. seychellensis live in sympatry in a Maldivian coral reef lagoon (Gangehi Island, Ari Atoll). A morphological, morphometric, and electrophoretical study of these species show that their Maldivian populations are well separated morphologically and genetically. The genetic distances and the other data are more consistent with an immigration than with a local speciation hypothesis. Their coexistence may be explained by a differentiation in ecological requirements. The four species inhabit the shallow water biotope of the lagoon among the rubble of dead corals. Our data show that T. orphei and T. seychellensis occupy the upper rubble layer, T. microstella and T. robusta the lower one. This distinction agrees with the different morpho-functional features of the two pairs of species.     

Palaeoceanographic controls on reef deposition: the Messinian Cariatiz reef (Sorbas Basin, Almería, SE Spain)

The Cariatiz section lies at the toe of the palaeoslope of the Messinian Cariatiz fringing reef, at the northern margin of the Neogene Sorbas Basin in SE Spain. Distal-slope reef deposits in the upper part of the section can be traced laterally to the reef core of the last episodes of reef progradation. The underlying deposits are alternating diatomitic marl, marl and silty marl that intercalate with sandstone beds. Combined lithological changes, variations in proportions of warm-water planktic foraminifera and δ 18O values suggest that at least seven, probably precessional, cycles are recorded throughout the Cariatiz section. The correlation of seven cycles in the pelagic deposits to seven reef progradation cycles, and associated vertical shifts in reef facies, indicates relative sea-level oscillations of several tens of metres. Biostratigraphic and palaeomagnetic data suggest that both the Cariatiz section and the fringing reef formed during the reverse polarity Chron C3r. Surface-water temperatures seem to be the major factor controlling carbonate production in the reef system. Deposition of bioclastic calcirudite and calcarenite, with no active coral growth, took place at the lowest sea-level within each reef cycle during temperature minima within each precessional cycle. Porites framework and reef-slope deposits with Halimeda gravel, in contrast, formed during temperature rises and thermal maxima within precessional cycles.     

礁滩复合型气藏物质聚集分布及储层特征研究——以川东北地区普光气田长兴组—飞仙关组为例

四川盆地普光气田在近期获得重大突破,普光气田礁滩复合型气藏物质聚集模式及储层特征的深入研究对于川东北地区乃至整个四川盆地的碳酸盐岩有利勘探区的预测具有一定的指导意义。受开江—梁平台盆(inter-platform basin)的控制,普光地区长兴组—飞仙关组在台盆东侧发育了类似于威尔逊相模式的碳酸盐岩沉积体系,主要发育台地蒸发岩、局限台地、开阔台地、台地边缘礁滩、斜坡和台盆沉积相,但陆棚相不甚发育。古地理的分异主要围绕开江—梁平台盆的发育、发展及填平补齐的过程而演化。储层沉积微相及微观地质特征研究表明,台地边缘礁滩相为该区储层发育最有利的相带,海绵障积白云岩、海绵骨架礁灰岩、鲕粒白云岩及残余鲕粒白云岩等为最主要的储集岩类型。优质储层的发育主要受沉积相带展布,后期的白云石化、溶蚀作用以及构造作用的控制。     

华南大陆沿岸珊瑚礁的特点与分析

华南大陆沿岸不乏造礁石珊瑚生长,但能成礁的仅在西部广西涠洲岛、斜阳岛和广东雷州半岛西南海岸,均为岸礁,累计礁体长约63 km,约占华南大陆(含近岸岛屿)岸线的1%,礁厚1~4 m,总面积约45 km2。礁体在全新世中期形成,胶结程度差,内礁坪部分已被沿岸泥沙覆盖,活珊瑚种类较少。进入全新世晚期,环境条件发生变化,冬季表层平均水温略低,沿岸泥沙运动活跃,人类生产活动对水质的影响等,珊瑚礁发育受到制约。但在西部海岸局部地方造礁珊瑚仍然顽强地生长,礁体向海拓展。预测未来冬季水温升高,更有利于珊瑚礁自然恢复。     

Estimating the uncertainty of coral isochron U–Th ages

Recently, alternative models to estimate the age of diagenetically altered fossil reef corals have been presented based on either redistribution of U or its immediate daughters ²³⁴Th and ²³⁰Th. Here, we present three methods to estimate the uncertainty of ages derived using an amended version of our coral isochron method [Scholz et al., 2004. U-series dating of diagenetically altered fossil reef corals. Earth and Planetary Science Letters 218, 163–178], which is based on addition/loss of U. The obtained uncertainties are substantially larger than those previously published and should, in general, be more reliable. The isochron method yields larger uncertainties than alternative models based on Th redistribution due to -recoil processes. However, comparison of model open-system ages based on such redistribution of U-series daughters for different sub-samples from an individual coral specimen shows that the smaller errors derived with these models cannot account for the observed variability. We recognise that none of the available models is applicable to all corals, probably reflecting different diagenetic processes even in different sub-samples from one coral specimen. To better understand the diagenetic processes and precisely constrain the uncertainties of the ages derived from diagenetically altered corals, the application of all available models is recommended.     

Coral δO records as an indicator of winter monsoon intensity in the South China Sea

We have used correlative analysis between mean December-January-February winter wind velocities, measured at the Xisha Meteorological Observatory (16°50′N, 112°20′E) in the middle of the South China Sea, and mean δ¹⁸O data for the corresponding month from Porites lutea coral, collected in Longwan waters (19°20′N, 110°39′E), to obtain a linear equation relating the two datasets. This winter wind velocity for the South China Sea (WMII_scs) can then be correlated to the coral δ¹⁸O by the equation WMII_scs = −1.213-1.351 δ¹⁸O (‰ PDB), r = −0.60, n = 40, P = 0.01. From this, the calculated WMII_scs-δ18O series from 1944 to 1997 tends to decrease during the 1940s to the 1960s; it increases slightly during the 1970s and then decreases again in the 1980s and 1990s. The calculated decadal mean WMII_scs-δ18O series had a obvious decrease from 5.92 to 4.63 m/s during the period of 1944-1997. The calculated yearly mean WMII_scs-δ18O value is 5.58 m/s from 1944 to 1976 and this decreases to 4.85 m/s from 1977 to 1998. That is the opposite trend to the observed yearly mean SST variation. The yearly mean SST anomaly is −0.27° from 1943 to 1976 and this increases to +0.16° from 1977 to 1998. Spectral analysis used on a 54-year-long calculated WMII_scs-δ18O series produces spectral peaks at 2.4-7 yr, which can be closely correlated with the quasibiennial oscillation band (QBO band, 2-2.4 yr) and the El Ñino southern oscillation band (ENSO band, 3-8 yr). Hence most of the variability of the winter monsoon intensity in the middle of the South China Sea is mainly constrained by changes in the thermal difference between the land and the adjoining sea area, perhaps due to global warming.