期刊
MARINE GEOLOGY
卷 284, 期 1-4, 页码 86-95出版社
ELSEVIER
DOI: 10.1016/j.margeo.2011.03.010
关键词
carbonate diagenesis; carbonate mound; cold water corals; redox zonation; Rockall Trough
资金
- European Science Foundation (ESF)/Netherlands Organisation for Scientific Research (NWO)
- NWO through NEBROC (Netherlands-Bremen Cooperation in Oceanography) [800.08.290]
Piston cores from the summits of coral topped carbonate mounds at the south west Rockall Trough margin reveal that the sediments have undergone significant post-depositional modifications affecting the original geochemical signature and mineralogical composition of the sediments. This diagenetic imprint provides information about the geochemical processes within cold-water coral mounds. The most prominent result of diagenetic alteration of the primary sediment composition is the absence or poor preservation of aragonitic coral skeletons in certain depth intervals associated with lithification. This study focuses on the enrichment of redox-sensitive elements and the dissolution of primary magnetic ferric iron minerals in the depth interval below lithification levels. By combining the magnetic susceptibility with the XRF signal of Fe and Ti specifically, intervals with susceptibility variations related to the conversion of strongly magnetic into weakly magnetic iron species can be defined. In all three studied cores a succession is recognised with a lithified interval with aragonite dissolution and low-Mg calcite precipitates that is underlain by an interval of magnetite dissolution and of iron and manganese enrichment. For the most recent lithified interval it is demonstrated that initial lithification occurred before an erosional regime was in place, most likely near the end of interglacial or at the start of glacial periods. (C) 2011 Elsevier B.V. All rights reserved.
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