DOI: 10.1016/j.palaeo.2013.01.012
论文题名: Methane-derived authigenic carbonates from modern and paleoseeps on the Cascadia margin: Mechanisms of formation and diagenetic signals
作者: Joseph C. ; Campbell K.A. ; Torres M.E. ; Martin R.A. ; Pohlman J.W. ; Riedel M. ; Rose K.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2013
卷: 390 起始页码: 52
结束页码: 67
语种: 英语
英文关键词: Anaerobic methane oxidation
; Barkley Canyon
; Carbonate diagenesis
; Cascadia margin
; Fluid flow
; Hydrate Ridge
; Methane-derived authigenic carbonate
英文摘要: Authigenic carbonate precipitation occurs within marine sediments where sulfate-dependent anaerobic methane oxidation occurs. Geochemical and isotopic analyses of authigenic carbonates are commonly used as indicators of carbon sources and environmental conditions present during carbonate formation, but burial diagenesis and recrystallization can overprint these signals. Plane polarized light (PPL) and cathodoluminescent (CL) petrography allows for detailed characterization of carbonate phases and their subsequent alteration. Petrographic, isotopic, and geochemical characteristics of modern offshore authigenic carbonates from central and northern Cascadia are compared with Oligocene-Pliocene fossil seep carbonates uplifted on the Olympic Peninsula. Coupled analyses show the value and complexity of separating primary vs. secondary signals with relevance to understanding fluid-burial history in methane seep provinces on tectonically active convergent margins. The modern, offshore, near-seafloor diagenetic environment (S. Hydrate Ridge and Barkley Canyon) is dominated by acicular and microcrystalline aragonite and high-Mg calcite (HMC, >12mol % Mg). PPL and CL data illustrate that aragonite and HMC phases recrystallize to intermediate-Mg calcite (IMC, 5-12mol% Mg) during burial and diagenesis and eventually to low-Mg calcite (LMC, <5mol% Mg). This diagenetic progression is accompanied by a decrease in Mg/Ca and Sr/Ca ratios. Typically an increase in Ba/Ca is consistent with a high-barium content of the methane-bearing pore fluids that drive recrystallization. CL images also discern primary carbonates with high Mn/Ca ratios, including biogenic peloids, from secondary phases related to deep fluid migration through high permeability conduits. In the secondary phases, the Mn/Ca reflects Mn-enrichment that characterizes deep sourced fluids venting at Barkley Canyon. Mn-enrichment is accompanied by depletion in 18O attributable to elevated fluid temperatures during recrystallization. © 2013 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/69585
Appears in Collections: 过去全球变化的重建
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作者单位: Oregon State University College of Earth, Ocean, and Atmospheric Sciences, United States; University of Auckland, School of Environment, New Zealand; Burke Museum, Seattle, WA, United States; United States Geological Survey, United States; Natural Resources Canada, Geological Survey of Canada-Pacific, Canada; U.S. Department of Energy National Energy Technology Laboratory, United States
Recommended Citation:
Joseph C.,Campbell K.A.,Torres M.E.,et al. Methane-derived authigenic carbonates from modern and paleoseeps on the Cascadia margin: Mechanisms of formation and diagenetic signals[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2013-01-01,390