凡纳滨对虾对东北碳酸盐型半咸水的适应性   总被引：2，自引：0，他引：2  

杨富亿  李秀军  杨欣乔  孙丽敏 《海洋湖沼通报》2005,(2):66-71

采用急性毒性实验法，研究了碱度和pH对凡蚋滨对虾幼虾的毒性效应，观察了幼虾在东北地区碳酸盐型半咸水水域的生存能力。结果表明，pH为8．03～8．37时，碱度对凡纳滨对虾幼虾的24，48和96h半致死浓度(LC50)分别为12．92，11．16和10．67mmol／L，生存的安全浓度(SC)为2．50mmol／L。碱度为5．37～42．06mmol／L时，pH对凡纳滨对虾幼虾的24，48，72和96h半致死值(LpH50)分别为9．26～8．64，9．14～8．62，9．10～8．80和9．00～8．80。幼虾在碱度为38．78mmol／L、pH为9．41、盐度为3．29的天然半咸水水域存活5～9h。认为高碱度、高pH是东北地区碳酸盐型半咸水水域移植凡纳滨对虾的主要障碍。  相似文献   

Microbial Shell Destruction in Deep-Sea Mussels, Florida Escarpment   总被引：2，自引：0，他引：2  

James E.  Hook Stjepko  Golubic 《Marine Ecology》1993,14(1):81-89

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Foraminifera in surface sediments of the Bering and Chukchi Seas and their sedimentary environment     

Meng Yi  Chen Ronghu  Zheng Yulong 《海洋学报(英文版)》2002,21(1):67-76

Based on a quantitative analysis of foraminifera in 39 surface samples of the Bering andChukchi Seas, the nearly absence of planktonic foraminifera in the surface sediments can be related to the low surface primary productivity and strong carbonate dissolution in the study area. It has been revealed that the surface primary productivity, and carbonate dissolution and properties of water masses related to the water depth mainly control the distribution of benthic foraminifera. The shelf of the Chukchi Sea is dominated by the Elphidium spp. assemblage and Nonionella robusta assemblage with low foraminiferal abundance and diversity, which is controlled by the coastal water mass of the Arctic Ocean. The slope of the Bering Sea is dominated by the Uvigerina peregrina - Globobulimina affinis assemblage with abundant N. robusta, and relatively high foraminiferal abundance and diversity, which is controlled by the intermediate and deep water masses of the Pacific Ocean. However, the Bering Sea has relatively sha  相似文献   

Fast reconnaissance of carbonate dissolution based on the size distribution of calcareous ooze on Walvis Ridge, SE Atlantic Ocean     

Jan-Berend W. Stuut  Maarten A. Prins  J. H. Fred Jansen 《Marine Geology》2002,190(3-4):581-589

We present a new index of carbonate fragmentation based on the size distribution of bulk sediments in core MD962094 from Walvis Ridge (SE Atlantic Ocean). The carbonate fragmentation index is constructed by taking a ratio of the two coarsest fractions in the grain size distributions of the bulk calcareous ooze. The coarsest two fractions (25–90 μm and >90 μm) of the bulk sediments consist primarily of complete shells and fragments of adult foraminifera shells, and juvenile foraminifera shells and fragments, respectively. The ratio of the proportions of the two fractions is interpreted as a measure of fragmentation of the foraminifera shells caused by carbonate dissolution. Downcore changes in our carbonate fragmentation index compare very well with those in the coarse-carbonate fragmentation index in sediments from a nearby core on Walvis Ridge. The latter commonly used fragmentation index is defined as a ratio of foraminifera fragments over whole foraminifera in the >150-μm fraction as seen with a light microscope. Fragmentation is relatively high during glacial stages and relatively low during interglacial stages during the last 300 kyr, caused by the combined effect of wind-driven upwelling of corrosive water and increased production of organic matter, decreasing the preservation potential of carbonates both during and after deposition. The carbonate fragmentation index we present here provides a precise and fast method to establish a downcore fragmentation record. It can be applied to bulk sediments that are carbonate-rich (CaCO₃>68%) and to all other deep-marine sediments of which the grain size distribution of the carbonate-free fraction is available.  相似文献   

Barium Increasing Prior to Opal during the Last Termination of Glacial Ages in the Okhotsk Sea Sediments     

Masayasu M. Sato  Hisashi Narita  Shizuo Tsunogai 《Journal of Oceanography》2002,58(3):461-467

Ba and Ti in a sediment core (10 m long) from the Okhotsk Sea, covering the last 120 kyrs, were measured. The authigenic Ba (Ba_ex) contents were calculated and compared with the opal. The correlation coefficient between Ba_ex and opal was quite small (r = 0.34), but it greatly grew larger (r = 0.90), if the Ba_ex contents were multiplied by a simple function increasing with depth, except for two intervals. This may be due to the gradual change in the sedimentation environment during the glacial ages. One of the exceptional interval is found at 60–170 cm in depth, corresponding to 10–17 calendar kyr ago, the last termination period of glacial ages, where the Ba_ex began to increase prior to opal. Since the calcium carbonate contents similarly increased prior to the opal increase, the Ba_ex may be also related to calcareous organisms besides siliceous ones. The other is the last interglacial period around 120 kyr ago when the opal contents were high, but those of the Ba_ex were not increased. This can be explained, if the Ba_ex was reduced to sulfide and dissolved away in a strongly anoxic environment during the biologically productive period. During the glacial ages, the mass accumulation rate (MAR) of lithogenic Ti was about twice the amount of that during the interglacial ages. For opal, however, the contrast between the glacial and interglacial ages was more remarkable in its MAR than in its concentration in sediments, due to the larger variation in the bulk sedimentation rates. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Cretaceous continental margin evolution revealed using quantitative seismic geomorphology,offshore northwest Africa     

Max Casson  Grme Calvs  Mads Huuse  Ben Sayers  Jonathan Redfern 《Basin Research》2021,33(1):66-90

The application of high‐resolution seismic geomorphology, integrated with lithological data from the continental margin offshore The Gambia, northwest Africa, documents a complex tectono‐stratigraphic history through the Cretaceous. This reveals the spatial‐temporal evolution of submarine canyons by quantifying the related basin depositional elements and providing an estimate of intra‐ versus extra‐basinal sediment budget. The margin developed from the Jurassic to Aptian as a carbonate escarpment. Followed by, an Albian‐aged wave‐dominated delta system that prograded to the palaeo‐shelf edge. This is the first major delivery of siliciclastic sediment into the basin during the evolution of the continental margin, with increased sediment input linked to exhumation events of the hinterland. Subaqueous channel systems (up to 320 m wide) meandered through the pro‐delta region reaching the palaeo‐shelf edge, where it is postulated they initiated early submarine canyonisation of the margin. The canyonisation was long‐lived (ca. 28 Myr) dissecting the inherited seascape topography. Thirteen submarine canyons can be mapped, associated with a Late Cretaceous‐aged regional composite unconformity (RCU), classified as shelf incised or slope confined. Major knickpoints within the canyons and the sharp inflection point along the margin are controlled by the lithological contrast between carbonate and siliciclastic subcrop lithologies. Analysis of the base‐of‐slope deposits at the terminus of the canyons identifies two end‐member lobe styles, debris‐rich and debris‐poor, reflecting the amount of carbonate detritus eroded and redeposited from the escarpment margin (blocks up to ca. 1 km³). The vast majority of canyon‐derived sediment (97%) in the base‐of‐slope is interpreted as locally derived intra‐basinal material. The average volume of sediment bypassed through shelf‐incised canyons is an order of magnitude higher than the slope‐confined systems. These results document a complex mixed‐margin evolution, with seascape evolution, sedimentation style and volume controlled by shelf‐margin collapse, far‐field tectonic activity and the effects of hinterland rejuvenation of the siliciclastic source.  相似文献   

泸州古隆起地区嘉陵江组层序特征及其对碳酸盐岩储层的控制   总被引：2，自引：1，他引：1  

乔占峰  李国蓉  李弢  王鑫  于海波  邓小江 《沉积学报》2008,26(1):92-99

在对研究区嘉陵江组沉积背景认识的基础上,通过对嘉陵江组岩性剖面结构的细致分析,将其划分为2个三级层序、6个四级层序和14个五级层序,认识到高频层序在海侵体系域和高水位体系域中有不同的岩性组合类型,建立了研究区嘉陵江组三级层序和高频层序格架。在研究区嘉陵江组储层特征认识的基础上,运用层序地层学原理,通过分析碳酸盐生长与相对海平面变化的关系,以及气候类型对高频层序演化的控制作用,建立了干旱气候背景下高水位体系域和海侵体系域中高频层序与溶蚀孔隙型储层形成的关系模式,并且层序表现出对溶蚀孔隙型储层和膏溶孔洞型储层发育分布具有重要控制作用;认为二级构造层序影响着岩溶缝洞型储层和裂缝—溶洞型储层的形成发育。总结出与各级层序相关的暴露期间大气水溶蚀作用（包括同生期和表生期）为研究区嘉陵江组储层形成的主要机制。  相似文献   

塔里木盆地深层碳酸盐岩中不同赋存形式芳烃化合物组成   总被引：1，自引：0，他引：1  

周世新  贾星亮  宋振响  王保忠  邹红亮  史基安 《沉积学报》2008,26(2):330-339

通过对塔参1井深层（＞5 700 m）碳酸盐岩游离有机质（氯仿沥青“A”）和包裹有机质（氯仿沥青“C”）中芳烃化合物组成和成熟度参数对比研究发现,芳烃化合物组成中菲和二苯并噻吩系列化合物较为丰富,菲和〖JX-*9〗〖XCQQ.TIF;%80%80〗〖JX*9〗等系列化合物丰度随埋深增加而增大,而二苯并噻吩、苯并萘并噻吩和芴等系列化合物丰度表现出相反的规律,这反映出不同芳烃系列化合物在高过成熟阶段热稳定性的差异。同一样品两种赋存形式芳烃化合物组成和成熟度参数明显不同,芳烃化合物成熟度参数和烷基化程度都反映出包裹有机质成熟度低于游离有机质,说明包裹有机质的热演化作用受到了抑制。在高过成熟阶段仍有部分芳烃参数仍可以用来表征深层有机质热演化程度,这些参数包括:菲系列烷基化指标（C1 P /C4 P、C1 P /C3 P、 C2 P /C4 P 、C2 P /C3 P）、以及二苯并噻吩系列化合物中MDR、C1/C3 DBT、2,4/1,4 DMDBT和4,6/1,4 DMDBT参数;虽然DBT/P比值被认为指示沉积环境的有效参数,但塔参1井深层样品研究表明,该参数与热演化程度关系密切,为高过成熟度阶段较好的成熟度参数。   相似文献   

Distribution of Chancelloriids in a Middle Cambrian Carbonate Platform Deposit, Taebaek Group, Korea     

HONG Jongsun  CHOH Suk-Joo  LEE Dong-Jin 《《地质学报》英文版》2016,90(3):783-795

The onset of the Cambrian witnessed the diversification of “small shelly fossils (SSF)”, which affected carbonate depositional system. One of the problematic SSF, chancelloriids, are common components of the early to middle Cambrian carbonate and shale, and their contributions toward Cambrian carbonates are not yet fully understood. This study assesses distribution patterns of chancelloriid sclerites in the Cambrian Series 3 Daegi Formation based on microfacies analysis and discusses their sedimentologic implications. In the lower part of the formation, partially articulated chancelloriid sclerites occur mainly in bioclastic packstone and grainstone facies, with isolated sclerite rays in nodular packstone to grainstone facies. In the middle part of the formation, chancelloriid fragments occur only sporadically in bioclastic wackestone to packstone, bioclastic grainstone and oolitic packstone to grainstone facies, whereas boundstone facies are nearly devoid of their fragments. There are no chancelloriid fragments in the upper part of the formation, which consists of oolitic packstone to grainstone facies. Chancelloriids are interpreted to have primarily occupied platform margin shoal environments, shedding their sclerites to surrounding areas, and thus contributed as sediment producers. The distribution of Daegi chancelloriid sclerites is similar to other Cambrian examples, with the exception of common chancelloriids in Cambrian Series 2 reefs and their apparent near absence in the Daegi and other Cambrian Series 3 reefs. This disparity resulted from changes in the ecologic niche of chancelloriids after the end-Cambrian Series 2 reef crisis, coupled with an overall decline of chancelloriids in the middle Cambrian.  相似文献   

Ocean Chemistry Revealed by Mineralogical and Geochemical Evidence at the Permian–Triassic Mass Extinction, Offshore the Persian Gulf, Iran     

Vahid TAVAKOLI 《《地质学报》英文版》2016,90(5):1852-1864

The Upper Permian Dalan Formation and the Lower Triassic Kangan Formation in the Persian Gulf area are mainly composed of shallow marine facies limestone and dolomite. Two subsurface-cored intervals were investigated in order to understand the original mineralogy and paleoceanic conditions. The decreasing trend of Sr concentration in these deposits shows that aragonite was precipitated during the Late Permian and then gradually changed to calcite toward the Permian–Triassic boundary (PTB). The dissolution rate of aragonite decreased from 60 m below the PTB toward the boundary, with the only exception at 10 m below the Permian-Triassic Boundary (PTB) due to the Permian–Triassic unconformity in this region. The increasing trend of Mg/Ca ratio in a global scale at the end-Permian time shows that the interpreted variation of mineralogy does not result from the change of this ratio. The increasing pCO2 and decreasing pH are considered to be the main controlling factors. The increase of Ca2+ at the end-Permian time due to the input of meteoric waters is too little to fully compensate this effect. A local maximum of the Si content just at the PTB confirms the input of runoff waters.  相似文献