scholarly journals Authigenic carbonate precipitation at the end-Guadalupian (Middle Permian) in China: Implications for the carbon cycle in ancient anoxic oceans

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Masafumi Saitoh ◽  
Yuichiro Ueno ◽  
Yukio Isozaki ◽  
Takazo Shibuya ◽  
Jianxin Yao ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Middle Permian ◽  
Authigenic Carbonate ◽  
Carbonate Precipitation

scholarly journals Carbonate sedimentation and effects of eutrophication observed at the Kališta subaquatic springs in Lake Ohrid (Macedonia)

2010 ◽  
Vol 7 (3) ◽  
pp. 4715-4747 ◽  
Author(s):  
M. Matter ◽  
F. S. Anselmetti ◽  
B. Jordanoska ◽  
B. Wagner ◽  
M. Wessels ◽  
...  
Keyword(s):  
Sediment Traps ◽  
Authigenic Carbonate ◽  
Sidescan Sonar ◽  
Carbonate Content ◽  
Carbonate Precipitation ◽  
Lake Ohrid ◽  
Radiocarbon Dates ◽  
North West ◽  
The North ◽  
Spring Area

Abstract. To date, little is known about the role of spring waters with respect to authigenic carbonate precipitation in the shallow lacustrine setting. Lake Ohrid, located in Southeastern Europe, is a large lake fed to over 50% by karstic springs of which half enter subaquatically and influence significantly its ecology and species distribution. In order to evaluate how sedimentological processes are influenced by such shallow-water springs, the Kališta subaquatic spring area in the north west of Lake Ohrid was investigated by a sidescan sonar survey and with sediment traps and three transects of gravity short cores. Results indicate that sedimentation in the spring area is dominated by authigenic carbonate precipitation. High sedimentation rates and evidences for bio-induced precipitation processes were observed in the water column and in the sediments. Two distinct stratigraphic units characterize the shallow subsurface, both composed of carbonate silts with high carbonate contents of up to 96%, but differing in color, carbonate content and diatom content. A chronological correlation of the cores by radiocarbon dates and 137Cs activities places the transition between the two stratigraphic units after ~1955 AD. At that time, coastal sedimentation changed drastically to significantly darker sediments with higher contents of organic matter and more abundant diatoms. This change coincides with the recent human impact of littoral eutrophication.

scholarly journals New isotope constraints on the Mg oceanic budget point to cryptic modern dolomite formation

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Netta Shalev ◽  
Tomaso R. R. Bontognali ◽  
C. Geoffrey Wheat ◽  
Derek Vance
Keyword(s):  
Low Temperature ◽  
Carbon Cycle ◽  
Oceanic Crust ◽  
Isotope Fractionation ◽  
Hydrothermal Fluids ◽  
Carbonate Precipitation ◽  
Magnesium Isotopes ◽  
Conventional View ◽  
The Past ◽  
Dolomite Formation

AbstractThe oceanic magnesium budget is important to our understanding of Earth’s carbon cycle, because similar processes control both (e.g., weathering, volcanism, and carbonate precipitation). However, dolomite sedimentation and low-temperature hydrothermal circulation remain enigmatic oceanic Mg sinks. In recent years, magnesium isotopes (δ26Mg) have provided new constraints on the Mg cycle, but the lack of data for the low-temperature hydrothermal isotope fractionation has hindered this approach. Here we present new δ26Mg data for low-temperature hydrothermal fluids, demonstrating preferential 26Mg incorporation into the oceanic crust, on average by εsolid-fluid ≈ 1.6‰. These new data, along with the constant seawater δ26Mg over the past ~20 Myr, require a significant dolomitic sink (estimated to be 1.5–2.9 Tmol yr−1; 40–60% of the oceanic Mg outputs). This estimate argues strongly against the conventional view that dolomite formation has been negligible in the Neogene and points to the existence of significant hidden dolomite formation.

scholarly journals Carbonate sedimentation and effects of eutrophication observed at the Kališta subaquatic springs in Lake Ohrid (Macedonia)

2010 ◽  
Vol 7 (11) ◽  
pp. 3755-3767 ◽  
Author(s):  
M. Matter ◽  
F. S. Anselmetti ◽  
B. Jordanoska ◽  
B. Wagner ◽  
M. Wessels ◽  
...  
Keyword(s):  
Sediment Traps ◽  
Authigenic Carbonate ◽  
Sidescan Sonar ◽  
Carbonate Content ◽  
Carbonate Precipitation ◽  
Lake Ohrid ◽  
Radiocarbon Dates ◽  
North West ◽  
The North ◽  
Spring Area

Abstract. To date, little is known about the role of spring waters with respect to authigenic carbonate precipitation in a shallow lacustrine setting. Lake Ohrid, located in Southeastern Europe, is a large lake fed to over 50% by karstic springs of which half enter subaquatically and influence significantly its ecology and species distribution. In order to evaluate how sedimentological processes are influenced by such shallow-water springs, the Kališta subaquatic spring area in the north west of Lake Ohrid was investigated by a sidescan sonar survey and with sediment traps and three transects of gravity short cores. Results indicate that sedimentation in the spring area is dominated by authigenic carbonate precipitation. High sedimentation rates and evidences for bio-induced precipitation processes were observed in the water column and in the sediments. Two distinct stratigraphic units characterize the shallow subsurface, both composed of carbonate silts with high carbonate contents of up to 96%, but differing in color, carbonate content and diatom content. A chronological correlation of the cores by radiocarbon dates and 137Cs activities places the transition between the two stratigraphic units after ~1955 AD. At that time, coastal sedimentation changed drastically to significantly darker sediments with higher contents of organic matter and more abundant diatoms. This change coincides with the recent human impact of littoral eutrophication.

Reproducing Authigenic Carbonate Precipitation in the Hypersaline Lake Acıgöl (Turkey) with Microbial Cultures

2016 ◽  
Vol 33 (9) ◽  
pp. 758-773 ◽  
Author(s):  
Nurgül Balci ◽  
Meryem Menekşe ◽  
Nevin Gül Karagüler ◽  
M. Şeref Sönmez ◽  
Patrick Meister
Keyword(s):  
Authigenic Carbonate ◽  
Hypersaline Lake ◽  
Carbonate Precipitation ◽  
Microbial Cultures ◽  
Lake Acıgöl

Authigenic Carbonate and the History of the Global Carbon Cycle

Science ◽  
2013 ◽  
Vol 339 (6119) ◽  
pp. 540-543 ◽  
Author(s):  
Daniel P. Schrag ◽  
John. A. Higgins ◽  
Francis A. Macdonald ◽  
David T. Johnston
Keyword(s):  
Carbon Cycle ◽  
Carbon Isotope ◽  
Atmospheric Oxygen ◽  
Carbon Isotopic Composition ◽  
Minor Component ◽  
Authigenic Carbonate ◽  
Carbon Isotopic ◽  
History Of ◽  
A Minor ◽  
Global Carbon

We present a framework for interpreting the carbon isotopic composition of sedimentary rocks, which in turn requires a fundamental reinterpretation of the carbon cycle and redox budgets over Earth's history. We propose that authigenic carbonate, produced in sediment pore fluids during early diagenesis, has played a major role in the carbon cycle in the past. This sink constitutes a minor component of the carbon isotope mass balance under the modern, high levels of atmospheric oxygen but was much larger in times of low atmospheric O2or widespread marine anoxia. Waxing and waning of a global authigenic carbonate sink helps to explain extreme carbon isotope variations in the Proterozoic, Paleozoic, and Triassic.

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