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.

scholarly journals Modeling the consequences on late Triassic environment of intense pulse-like degassing during the Central Atlantic Magmatic Province using the GEOCLIM model

2012 ◽  
Vol 8 (3) ◽  
pp. 2075-2110 ◽  
Author(s):  
G. Paris ◽  
Y. Donnadieu ◽  
V. Beaumont ◽  
F. Fluteau ◽  
Y. Goddéris
Keyword(s):  
Carbon Cycle ◽  
Carbon Isotope ◽  
Carbon Isotopic Composition ◽  
Late Triassic ◽  
Carbonate Production ◽  
Carbon Isotopic ◽  
Central Atlantic Magmatic Province ◽  
Igneous Provinces ◽  
Central Atlantic ◽  
Sedimentary Carbon

Abstract. The Triassic-Jurassic boundary (TJB) is associated with one of the five largest mass extinctions of the Phanerozoic. A deep carbon cycle perturbation and a carbonate production crisis are observed during the late Triassic. The Central Atlantic Magmatic Province (CAMP), one of the most important large igneous provinces of the Phanerozoic, emplaced at the TJB. To understand the carbon cycle perturbations observed at the TJB, we investigate the consequences of CO2 degassing associated to the CAMP emplacement on atmospheric and oceanic carbon cycle. The CO2 input within the atmosphere due to volcanism has been modeled using a global biogeochemical cycle box model (COMBINE) coupled with a climate model (FOAM). Weathering fluxes and CO2 equilibrium are constrained by the Rhaetian paleogeography and different scenarios of the CAMP emplacement are modeled. The study focuses (1) on the geological record and the carbonate productions crisis and (2) on the sedimentary carbon isotope record. For point (1), comparison of different modeling scenarios shows that a Gaussian CO2 emission distribution over the duration of the main activity phase of the CAMP fails in reproducing any of the geological observations, mainly the carbonate production crisis observed in the late Rhaetian sediments. Contrastingly, intense degassing peaks lead to successive decrease in carbonate production as observed in the geological record. For point (2), the perturbations of carbon cycle due to the degassing of CO2 with a mantellic carbon isotopic composition of −5‰ do not reproduce the intensity of the observed carbon isotope excursions. This was achieved in our model by assuming a mantellic carbon isotopic composition of −20‰. Even if this hypothesis requires further investigations, such low values may be associated to degassing of carbon from pools of light isotopic carbon located at the transition zone (Cartigny, 2010), possibly linked to setting of large igneous provinces (LIP's). Breakdown of biological primary productivity can also partially account for the sedimentary carbon isotope excursions and for the observed increase of atmospheric pCO2.

The stable carbon isotopic composition of organic material in platform derived sediments: implications for reconstructing the global carbon cycle

Sedimentology ◽  
2011 ◽  
Vol 59 (1) ◽  
pp. 319-335 ◽  
Author(s):  
AMANDA M. OEHLERT ◽  
KATHRYN A. LAMB-WOZNIAK ◽  
QUINN B. DEVLIN ◽  
GRETA J. MACKENZIE ◽  
JOHN J. G. REIJMER ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Isotopic Composition ◽  
Organic Material ◽  
Carbon Isotopic Composition ◽  
Global Carbon Cycle ◽  
Stable Carbon ◽  
Carbon Isotopic ◽  
Global Carbon

A geochronological framework for sedimentation and Mesoproterozoic tectono-magmatic activity in lower Belt–Purcell rocks exposed west of Kimberley, British Columbia

2015 ◽  
Vol 52 (7) ◽  
pp. 444-465 ◽  
Author(s):  
Christopher R.M. McFarlane
Keyword(s):  
British Columbia ◽  
Minor Component ◽  
Structural Level ◽  
Peraluminous Granite ◽  
Icp Ms ◽  
Ductile Shearing ◽  
History Of ◽  
Metamorphic Zone ◽  
A Minor ◽  
Plate Reconstruction

The Matthew Creek Metamorphic Zone (MCMZ) exposes what is inferred to be the lowest structural level of the lower Aldridge Formation in the Canadian portion of the Belt–Purcell Supergroup. Zircon, monazite, and titanite were dated using the U–Pb system by LA–ICP–MS. The detrital zircon populations of quartzite layers in these rocks define a provenance dominated by sources of Laurentian affinity with a minor component of non-North American ages between 1600 and 1490 Ma. Special attention was paid to monazite in sillimanite-grade metapelitic schists that was analyzed using in situ LA–ICP–MS techniques guided by BSE imaging and compositional mapping. Textural and geochronological evidence indicate that coupled dissolution–reprecipitation affected detrital monazite at 1413 ± 10 Ma. This was followed by prograde monazite growth at 1365 ± 10 Ma, synchronous with crystallization of the nearby Hellroaring Creek peraluminous granite at 1365 ± 5 Ma. Late-stage pegmatite emplacement and ductile shearing along the contact of the MCMZ and overlying rocks occurred at 1335 ± 5 Ma, interpreted as a period of post-collisional extension, core complex formation, exhumation, and decompression melting. The entire package was subsequently affected by a pervasive ∼1050 Ma hydrothermal overprint that partially reset U–Pb dates in monazite, zircon, and titanite contained in all lithologies examined. The lowermost Belt–Purcell stratigraphy in southeast British Columbia preserves a detailed record of sedimentary provenance and a long history of episodic collision and extension that must be reconciled with plate reconstruction models for the break-up of the Nuna supercontinent and assembly of Rodinia.

scholarly journals Carbon Isotopic Composition of Deep Carbon Gases in an Ombrogenous Peatland, Northwestern Ontario, Canada

Radiocarbon ◽  
1993 ◽  
Vol 35 (2) ◽  
pp. 271-276 ◽  
Author(s):  
Ramon Aravena ◽  
B. G. Warner ◽  
D. J. Charman ◽  
L. R. Belyea ◽  
S. P. Mathur ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Radiocarbon Dating ◽  
Carbon Isotopic Composition ◽  
Downward Movement ◽  
Terrestrial Biosphere ◽  
Carbon Isotopic ◽  
Northwestern Ontario ◽  
Global Carbon ◽  
Isotope Analyses ◽  
Carbon Gases

Radiocarbon dating and carbon isotope analyses of deep peat and gases in a small ombrogenous peatland in northwestern Ontario reveals the presence of old gases at depth that are 1000–2000 yr younger than the enclosing peat. We suggest that the most likely explanation to account for this age discrepancy is the downward movement by advection of younger dissolved organic carbon for use by fermentation and methanogens bacteria. This study identifies a potentially large supply of old carbon gases in peatlands that should be considered in global carbon models of the terrestrial biosphere.

scholarly journals The carbon cycle and carbon dioxide over Phanerozoic time: the role of land plants

1998 ◽  
Vol 353 (1365) ◽  
pp. 75-82 ◽  
Author(s):  
Robert A. Berner
Keyword(s):  
Organic Matter ◽  
Carbon Cycle ◽  
Vascular Plants ◽  
Global Climate ◽  
Carbon Isotopic Composition ◽  
Field Studies ◽  
Accelerated Weathering ◽  
Fossil Plants ◽  
Factors Affecting ◽  
Carbon Isotopic

A model (GEOCARB) of the long–term, or multimillion year, carbon cycle has been constructed which includes quantitative treatment of (1) uptake of atmospheric CO 2 by the weathering of silicate and carbonate rocks on the continents, and the deposition of carbonate minerals and organic matter in oceanic sediments; and (2) the release of CO 2 to the atmosphere via the weathering of kerogen in sedimentary rocks and degassing resulting from the volcanic–metamorphic–diagenetic breakdown of carbonates and organic matter at depth. Sensitivity analysis indicates that an important factor affecting CO 2 was the rise of vascular plants in the Palaeozoic. A large Devonian drop in CO 2 was brought about primarily by the acceleration of weathering of silicate rock by the development of deeply rooted plants in well–drained upland soils. The quantitative effect of this accelerated weathering has been crudely estimated by present–day field studies where all factors affecting weathering, other than the presence or absence of vascular plants, have been held relatively constant. An important additional factor, bringing about a further CO 2 drop into the Carboniferous and Permian, was enhanced burial of organic matter in sediments, due probably to the production of microbially resistant plant remains (e.g. lignin). Phanerozoic palaeolevels of atmospheric CO 2 calculated from the GEOCARB model generally agree with independent estimates based on measurements of the carbon isotopic composition of palaeosols and the stomatal index for fossil plants. Correlation of CO 2 levels with estimates of palaeoclimate suggests that the atmospheric greenhouse effect has been a major factor in controlling global climate over the past 600 million years.

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