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Formation of Authigenic Low-Magnesium Calcite from Sites SS296 and GC53 of the Gulf of Mexico
Huang, Huiwen1; Gong, Shanggui2; Li, Niu2; Birgel, Daniel3; Peckmann, Jorn3; Jin, Meng1; Cheng, Ming; Roberts, Harry H.; Chen, Duofu2,5; Feng, Dong2,5
2019
Source PublicationMINERALS
ISSN2075-163X
Volume9Issue:4Pages:251
AbstractAuthigenic low-magnesium calcite (LMC)a mineral phase that should precipitate in calcite seas rather than today's aragonite seawas recently discovered at the seafloor of the Gulf of Mexico (GoM) at water depths of 65 m (site SS296) and 189 m (site GC53). This study investigates the mineralogical, petrographic, and geochemical characteristics of LMC from both sites to reveal its formation process. The O-18 values of LMC from site SS296 cluster in two groups (-0.6 parts per thousand to 1.7 parts per thousand; 6.3 parts per thousand to 7.5 parts per thousand) and the presence of cone-in-cone texture in the samples with lower O-18 values suggest precipitation at higher temperatures and greater depth. Low O-18 values of LMC from site GC53 ranging from -9.4 parts per thousand to -2.5 parts per thousand indicate an influence of meteoric waters during formation. LMC at both sites reveals a wide range of C-13 values (-17.4 parts per thousand to 2.6 parts per thousand), indicating various carbon sources including seawater and/or organic matter. This interpretation is further supported by the C-13 values of organic carbon extracted from the LMC lithologies (C-13(org): from -26.8 parts per thousand to -18.9 parts per thousand). Relatively low Sr concentrations of LMC samples regardless of variable Sr-87/Sr-86 ratios, ranging from 0.707900 to 0.708498 for site GC53 and from 0.709537 to 0.710537 for site SS396, suggest the exchange of Sr between pore fluids and ambient sediments/rocks. The observed wide range of Sr-87/Sr-86 ratios and the enrichment of Fe and Mn in LMC is in accordance with pore fluids deriving from the dissolution of Louann salt. Overall, this study reveals that the formation of LMC at sites SS296 and GC53 was favored by the presence of low Mg/Ca ratio pore fluids resulting from salt dissolution in subsurface environments when sufficient dissolved inorganic carbon was available. These results are essential for understanding the formation of marine LMC at times of an aragonite sea, highlighting the role of formation environmentsopen environments close to or at the seafloor vs. confined subseafloor environments typified by pore waters with a composition largely different from that of seawater.
DepartmentOMG
Keywordlow-magnesium calcite aragonite sea carbonates salt diapirs Gulf of Mexico
DOI10.3390/min9040251
Citation statistics
Document Type期刊论文
Identifierhttp://ir.scsio.ac.cn/handle/344004/17966
Collection中科院边缘海地质重点实验室
Affiliation1.Chinese Acad Sci, South China Sea Inst Oceanol, CAS Key Lab Ocean & Marginal Sea Geol, Guangzhou 510301, Guangdong, Peoples R China
2.Univ Chinese Acad Sci, Beijing 100049, Peoples R China
3.Shanghai Ocean Univ, Coll Marine Sci, Shanghai Engn Res Ctr Hadal Sci & Technol, Shanghai 201306, Peoples R China
4.Univ Hamburg, Ctr Earth Syst Res & Sustainabil, Inst Geol, D-20146 Hamburg, Germany
5.Roberts, Harry H.] Louisiana State Univ, Coll Coastal & Environm, Coastal Studies Inst, Baton Rouge, LA 70803 USA
6.Qingdao Natl Lab Marine Sci & Technol, Lab Marine Mineral Resources, Qingdao 266061, Shandong, Peoples R China
Recommended Citation
GB/T 7714
Huang, Huiwen,Gong, Shanggui,Li, Niu,et al. Formation of Authigenic Low-Magnesium Calcite from Sites SS296 and GC53 of the Gulf of Mexico[J]. MINERALS,2019,9(4):251.
APA Huang, Huiwen.,Gong, Shanggui.,Li, Niu.,Birgel, Daniel.,Peckmann, Jorn.,...&Feng, Dong.(2019).Formation of Authigenic Low-Magnesium Calcite from Sites SS296 and GC53 of the Gulf of Mexico.MINERALS,9(4),251.
MLA Huang, Huiwen,et al."Formation of Authigenic Low-Magnesium Calcite from Sites SS296 and GC53 of the Gulf of Mexico".MINERALS 9.4(2019):251.
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