共查询到11条相似文献,搜索用时 46 毫秒
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从大陆海底边缘、海底山脉和海岛这 3个不同的环境来研究海洋磷块岩中的锰和钼。1 大陆海底边缘的磷块岩和沉积物 对采自纳米比亚内陆架的现代含磷酸盐沉积物硅藻软泥的 1 2个样品的分析显示 ,它们都富含生物质蛋白石、二氧化硅 (平均为61 57% )、有机碳 (平均为 5 0 7% )和磷 (平均为 1 1 2 %P2 O5)。在这些沉积物中钼的含量为2 6~ 1 2 0 (平均为 53 ) g/t,锰为 3 0~ 3 60 (平均为1 2 8) g/t,Mo/Mn比值为 0 1 2~ 1 1 6(平均为0 1 4 )。以上系列的 5个样品采自 3个海底岩心 ,每个的重量约 1 50kg。经过冲洗后从其中取出砂、砾… 相似文献
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海洋沉积物中黏土矿物的两种提取方法的对比 总被引:1,自引:0,他引:1
黏土矿物作为海洋细粒陆源碎屑沉积物中最重要的组成部分,在海洋沉积物来源、洋流搬运、古环境演化研究中发挥了重大的作用。因此,如何正确而高效地从沉积物中分离出黏土矿物组分成为开展黏土矿物研究工作的先决条件。介绍了两种提取海洋沉积物中黏土矿物的方法——沉降法和离心法,并将两种方法所得黏土矿物分析结果进行了对比。其中,黏土矿物平均含量的配对t检验结果显示,两种方法所得黏土矿物含量相关系数为0.96,Sig.值远大于0.05,结果不具有显著差异性;ODP1146站样品两种方法所得蒙脱石含量及伊利石含量分别在0.01水平上显著相关,ZK001孔样品高岭石含量在0.01水平上显著相关;两者之间黏土矿物含量在时间序列上的总体变化趋势也非常相近;粉末样XRD扫描结果显示两种方法所提取颗粒所含矿物均主要为黏土矿物,且两者之间矿物含量非常接近;另外粒度分析表明,沉降法与离心法所提取的颗粒大小均小于2 μm。分析结果表明与沉降法相比,离心法提取黏土矿物同样可以准确地获取黏土矿物中蕴含的重要信息,而且提取效率较传统沉降法更高,其在海洋沉积物黏土矿物中的研究亟待得到推广。 相似文献
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第一次测定铼 ( Re)在底质中含量的是 O-laffson J和 JP Riley( 1 972 )。在 8个北大西洋钙质软泥样品中他们发现了 1 .7~ 6.8ng/ g铼 ,其中 1个样品中为 1 9.4ng/ g,而在 2个非钙质软泥样品中该元素的含量分别为 3 .7ng/ g和 1 1 .3 ng/ g。后来查明 ,这些结果被大大提高了。按现代的资料 ,除铁锰结核和结壳之外 ,氧化的海洋沉积物 (某些含矿沉积物除外 ) ,含铼 0 .0 2~ 0 .5ng/ g。而大陆边缘和一系列内陆海 ,包括黑海的还原沉积物含铼量要高出若干个数量级。此外 ,较高的铼含量还见于秘鲁陆架还原沉积物的磷块岩标本中。因此 ,查明… 相似文献
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Oceanology - The interaction of modern (Holocene) phosphorite nodules with solutions imitating pore waters of sediments of highly productive ocean regions with a high carbonate alkalinity was... 相似文献
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对沉积矿床的成因问题历来存在着不同的说法。例如,磷块岩的成因问题开始时与海洋生物作用相联系,然后与细菌作用、磷酸钙从海水中的化学沉淀、生物化学反映、火山作用过程、成岩过程以及沉积物沉积后的反复冲洗作用相联系。近年来在一系列努力下,恢复了微生物假说。该假说的原 相似文献
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Submersible investigations with the ROV Victor 6000 of some pockmark structures on the seafloor of the Congo deep-sea fan
have shown that they are active venting sites of methane-rich fluids, associated with abundant fauna and carbonate crusts.
Moreover, methane hydrates have been observed both outcropping and deep in the sediments in the centre of the “Regab” giant
pockmark. Authigenic carbonates, mostly calcite sometimes mixed with aragonite, are cementing the sedimentary matrix components
and fauna; diatoms are abundant but only as moulds, indicating that biogenic silica dissolution occurred in situ synchronous
with carbonate precipitation. The occurrence of diagenetic barite and pyrite in some carbonate crusts demonstrates that they
can be formed either within the sulphate/methane transition zone or deeper in sulphate-depleted sediments. The oxygen isotopic
compositions of the diagenetic carbonates (3.17–6.01‰ V-PDB) indicate that precipitation occurred with bottom seawater mixed
with a variable contribution of water from gas hydrate decomposition. The very low carbon isotopic compositions of the diagenetic
carbonates (−57.1 to −27.75‰ V-PDB) demonstrate that carbon derives mostly from the microbial oxidation of methane. 相似文献
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M. D. Kravchishina A. Yu. Lein A. S. Savvichev L. E. Reykhard O. M. Dara M. V. Flint 《Oceanology》2017,57(1):174-191
Authigenic minerals were studied in Holocene shelf sediments of the Laptev Sea (cold methane seep site, water depth 71 m). The study presents the first finds of large hard carbonate concretions with Mg-calcite cement in recent sediments of the Arctic shelf seas. These concretions differ from previously reported glendonites and concretions from bottom sediments of the White Sea, Kara Sea, Sea of Okhotsk, etc. A study of the morphology, microstructure, and composition of these newly reported concretions revealed the multistage formation of carbonates (structural varieties of Mg-calcite and aragonite). It was shown that organic matter played an important role in the formation of authigenic carbonates, i.e., in the formation of sedimentary–diagenetic Mg-calcite. The role of methane as a possible source for authigenic carbonate formation was estimated. It was found that methane-derived Mg-calcite accounts for 17–35% of concretion materials. Mg-calcite had δ13С-Сcarb values between–24 and–23‰ and δ13С-Сorg values between–44.5 and–88.5‰. 相似文献
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为了探讨甲烷通量或SMT对自生碳酸盐岩埋深和水合物饱和度的影响,综述了第六届国际水合物论文集中的相关论文得出如下结论:海底发生富含甲烷的孔隙水渗漏和甲烷气的排出,有利于海底自生碳酸盐岩的沉积;甲烷通量和海底侵蚀可能控制了自生碳酸盐岩和SMT的埋深,然而,甲烷通量或SMT埋深是否控制沉积物中水合物的饱和度目前尚无定论。 相似文献