The global control of silicate weathering rates and the coupling with physical erosion: new insights from rivers of the Canadian Shield

Millot, Romain; Gaillardet, Jérôme; Dupré, Bernard; Allègre, Claude J.

doi:10.1016/s0012-821x(01)00599-4

Cited by 408 publications

(253 citation statements)

References 38 publications

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“…If no regolith is present, chemical erosion of bedrock occurs at a rate 72 (T expose /1000) À0.71 mmol m À2 yr À1 , following the power law relationship defined by Blum (1997), Eq. (9) and supported by White and Brantley (2003) but modified to coincide with measurements of modern day silicate weathering rates determined by chemical fluxes from large river systems of the Canadian Shield (Millot et al, 2002). For T expose less than 1000-years-old, a maximum value of 72 mmol m À2 yr À1 corresponding to a 1000-year surface age is adopted.…”

Section: Article In Pressmentioning

confidence: 99%

“…The model domain encompasses 27% of the land surface excluding Antarctica. However, weathering rates are extremely variable around the world, with rates in volcanic provinces, for example, exceeding those in granitic terrains by up to a factor of 100 (Millot et al, 2002), so simply scaling weathering contributions by area is too simple an approach.…”

Section: Article In Pressmentioning

confidence: 99%

“…The model thus predicts that in the oldsoil limit, the Canadian Shield region would account for about 1.5% of global weathering. Modern observations of Canadian Shield weathering rate include $5 mmol m À2 yr À1 from the Slave province and $20 mmol m À2 yr À1 in the Grenville province (Millot et al, 2002). Using an intermediate value of $10 mmol m À2 yr À1 implies that the shield today accounts for about 6% of global weathering, within a range of 3-12%.…”

Section: Article In Pressmentioning

confidence: 99%

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The middle Pleistocene transition: characteristics, mechanisms, and implications for long-term changes in atmospheric pCO2

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Section: Article In Pressmentioning

confidence: 99%

Section: Article In Pressmentioning

confidence: 99%

Section: Article In Pressmentioning

confidence: 99%

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The middle Pleistocene transition: characteristics, mechanisms, and implications for long-term changes in atmospheric pCO2

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et al. 2006

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“…Though, the reverse argument also holds: thick soils require intense weathering and/ or a very long time. Several recent studies show a strong link between mechanical denudation [Millot et al, 2002] or tectonic activity inducing landscape rejuvenation [von Blanckenburg, 2005] and chemical weathering of silicates. In the absence of mechanical denudation and/or landscape rejuvenation, chemical weathering in low latitude areas will decrease through time.…”

Section: Consequences Of the Pangea Breakup On The Global Carbon Cyclementioning

confidence: 99%

A GEOCLIM simulation of climatic and biogeochemical consequences of Pangea breakup

Donnadieu¹,

Goddéris

Pierrehumbert

et al. 2006

Geochem Geophys Geosyst

126

127

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[1] Large fluctuations in continental configuration occur throughout the Mesozoic. While it has long been recognized that paleogeography may potentially influence atmospheric CO 2 via the continental silicate weathering feedback, no numerical simulations have been done, because of the lack of a spatially resolved climate-carbon model. GEOCLIM, a coupled numerical model of the climate and global biogeochemical cycles, is used to investigate the consequences of the Pangea breakup. The climate module of the GEOCLIM model is the FOAM atmospheric general circulation model, allowing the calculation of the consumption of atmospheric CO 2 through continental silicate weathering with a spatial resolution of 7.5°long Â 4.5°lat. Seven time slices have been simulated. We show that the breakup of the Pangea supercontinent triggers an increase in continental runoff, resulting in enhanced atmospheric CO 2 consumption through silicate weathering. As a result, atmospheric CO 2 falls from values above 3000 ppmv during the Triassic down to rather low levels during the Cretaceous (around 400 ppmv), resulting in a decrease in global mean annual continental temperatures from about 20°C to 10°C. Silicate weathering feedback and paleogeography both act to force the Earth system toward a dry and hot world reaching its optimum over the last 260 Myr during the Middle-Late Triassic. In the super continent case, given the persistent aridity, the model generates high CO 2 values to produce very warm continental temperatures. Conversely, in the fragmented case, the runoff becomes the most important contributor to the silicate weathering rate, hence producing a CO 2 drawdown and a fall in continental temperatures. Finally, another unexpected outcome is the pronounced fluctuation in carbonate accumulation simulated by the model in response to the Pangea breakup. These fluctuations are driven by changes in continental carbonate weathering flux. Accounting for the fluctuations in area available for carbonate platforms, the simulated G 3

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“…Dissolved organic nitrogen (DON) was calculated by subtracting inorganic nitrogen from TDN. Marine aerosol contribution to different elements was corrected by using molar ratios of different elements as reported in earlier studies (Keene et al 1986;McDowell et al 1990;Millot et al 2002;Bhatt and McDowell 2007). Marine aerosol contribution to pond waters was corrected for Na ?…”

Section: Methodsmentioning

confidence: 99%

Chemistry of Supraglacial Ponds in the Debris-Covered Area of Lirung Glacier in Central Nepal Himalayas

2015

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Glacial meltwater samples were collected from 15 supraglacial ponds at elevations ranging between 3989 and 4292 m above sea level in the debris-covered area of Lirung glacier in central Nepal Himalayas, from November 2010 to October 2011 on a bimonthly basis. We examined elevation trends, and their control by seasonality, dominant geochemical processes, and seasonal dynamics in these supraglacial ponds. Concentration of some parameters showed a decreasing trend with elevation but with high variability and modulation by seasons, being more prevalent in the post-monsoon. Sulfate is the only parameter showing significant elevation trends regardless of the season, although the trend is also affected by the monsoon. The concentrations of major chemical solutes were highest during post-monsoon season and lower in the pre-monsoon and monsoon seasons, indicating influence of seasonality on dissolution, dilution, and hydrological processes. Contribution to chemical loads from marine aerosols to these pond water appeared to be minor except for sodium and magnesium. Chemical weathering of carbonate and silicate minerals fueled by dissolution of pyrite appeared as the dominant geochemical processes.

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The global control of silicate weathering rates and the coupling with physical erosion: new insights from rivers of the Canadian Shield

Cited by 408 publications

References 38 publications

The middle Pleistocene transition: characteristics, mechanisms, and implications for long-term changes in atmospheric pCO2

The middle Pleistocene transition: characteristics, mechanisms, and implications for long-term changes in atmospheric pCO2

A GEOCLIM simulation of climatic and biogeochemical consequences of Pangea breakup

Chemistry of Supraglacial Ponds in the Debris-Covered Area of Lirung Glacier in Central Nepal Himalayas

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