Glaciers show direct linkage between erosion rate and chemical weathering fluxes

Anderson, Suzanne P.

doi:10.1016/j.geomorph.2004.07.010

Cited by 121 publications

(104 citation statements)

References 48 publications

Supporting

Mentioning

102

Contrasting

Order By: Relevance

“…Under the assumptions of a chemical steady state and a dilute input source, Anderson (2005) implemented a forward modelling approach by conceptualizing the flow-through reactor as…”

Section: Geochemical Modelling Methodsmentioning

confidence: 99%

Clay mineral precipitation and low silica in glacier meltwaters explored through reaction-path modelling

et al. 2015

View full text Add to dashboard Cite

ABSTRACT. The subglacial chemical weathering environment is largely controlled by low temperatures and the presence of freshly comminuted minerals with a high surface area. These characteristics are believed to promote dissolution processes that give rise to low silica and high Ca 2+ fluxes emanating from glacierized basins. We test an alternative hypothesis, that mineral precipitation reactions in the subglacial environment play an equally important role in controlling the water chemistry in glacierized basins. We analyze borehole and proglacial water chemistry from a subarctic polythermal glacier, complemented by mineral XRD analysis of suspended sediment, till and bedrock samples. In conjunction with a thermodynamic analysis of the water and mineral chemistry, we use reactionpath modelling to study the chemical enrichment of water through the glacier system. We find that the high pH of the subglacial environment is conducive to secondary mineral precipitation, and that it is not possible to balance the water chemistry using dissolution reactions alone. We show that low silica can be explained by standard weathering reactions without having to invoke mineral-leaching reactions. Our results suggest that subglacial weathering intensity may be significantly underestimated if the production of secondary minerals is not considered.

show abstract

“…Under the assumptions of a chemical steady state and a dilute input source, Anderson (2005) implemented a forward modelling approach by conceptualizing the flow-through reactor as…”

Section: Geochemical Modelling Methodsmentioning

confidence: 99%

Clay mineral precipitation and low silica in glacier meltwaters explored through reaction-path modelling

et al. 2015

View full text Add to dashboard Cite

show abstract

“…The directionality of long-term glaciation-weathering feedbacks depends on the extent to which glacial weathering is a net source or net sink of CO 2 to the atmosphere, which in turn depends on the balance of sulfide vs. silicate mineral weathering. A growing number of studies have explored various aspects of glacial weathering by analyzing the chemical composition of glacial runoff, often focusing on specific case studies, and in some cases synthesizing global datasets (13,26,27). Here, we assemble an expanded compilation of glacial weathering data and use this compilation to identify characteristic features of present-day glacial weathering, including the relative roles of sulfide-carbonate vs. silicate mineral weathering compared with rivers not dominated by glacial processes.…”

Section: Significancementioning

confidence: 99%

Glacial weathering, sulfide oxidation, and global carbon cycle feedbacks

Torres

Moosdorf

Hartmann

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

159

171

View full text Add to dashboard Cite

Connections between glaciation, chemical weathering, and the global carbon cycle could steer the evolution of global climate over geologic time, but even the directionality of feedbacks in this system remain to be resolved. Here, we assemble a compilation of hydrochemical data from glacierized catchments, use this data to evaluate the dominant chemical reactions associated with glacial weathering, and explore the implications for long-term geochemical cycles. Weathering yields from catchments in our compilation are higher than the global average, which results, in part, from higher runoff in glaciated catchments. Our analysis supports the theory that glacial weathering is characterized predominantly by weathering of trace sulfide and carbonate minerals. To evaluate the effects of glacial weathering on atmospheric pCO 2 , we use a solute mixing model to predict the ratio of alkalinity to dissolved inorganic carbon (DIC) generated by weathering reactions. Compared with nonglacial weathering, glacial weathering is more likely to yield alkalinity/DIC ratios less than 1, suggesting that enhanced sulfide oxidation as a result of glaciation may act as a source of CO 2 to the atmosphere. Back-of-the-envelope calculations indicate that oxidative fluxes could change ocean-atmosphere CO 2 equilibrium by 25 ppm or more over 10 ky. Over longer timescales, CO 2 release could act as a negative feedback, limiting progress of glaciation, dependent on lithology and the concentration of atmospheric O 2 . Future work on glaciation-weathering-carbon cycle feedbacks should consider weathering of trace sulfide minerals in addition to silicate minerals.weathering | carbon cycle | glaciation | oxidation | sulfide E pisodes of glaciation represent some of the most dramatic changes in the history of Earth's climate. Basic questions remain unanswered about why the planet has occasionally but not always supported glaciers, about why some glaciations have been more intense than others, and about how glaciers have shaped Earth's landscapes, chemical cycles, and climate. Before the Phanerozoic (i.e., before ∼540 Mya), several glaciations are thought to have approached complete or near-complete planetary ice cover ("Snowball Earth" events; ref. 1). In contrast, more recent glaciations, including the Quaternary glaciations of the last million years, have been characterized by oscillating climate with ice extent limited to high latitudes even during glacial maxima (2). The formation of ice cover has long been known to fundamentally alter Earth's environment, changing albedo (3), influencing atmospheric and ocean circulation (4), and reshaping landscapes (5). These diverse effects may contribute to planetary-scale feedbacks that influence the transition to and the evolution of glaciation.Chemical weathering influences the composition of the atmosphere by releasing ionic species from minerals that alter the alkalinity and redox condition of the ocean-atmosphere system. Weathering of silicate minerals produces alkalinity, removing carbon from the at...

show abstract

“…This is particularly the case in glacial settings because glaciers are highly efficient at eroding landscapes (e.g. Hallet et al, 1996;Koppes & Montgomery, 2009) and produce 15 highly-reactive and easily-weathered sediments (Anderson et al, 1997;White & Brantley, 2003;Anderson, 2005). Moreover, glaciers can create large overdeepenings that are subsequently filled with sediments isolated from interactions with surface processes.…”

Section: Introductionmentioning

confidence: 99%

“…Based on the argument above, these sediments are exposed to water in the proglacial system before deposition in the moraine. Authors such as Anderson (2005) have shown that proglacial en-5 vironments favor weathering. Since weathering rate is a time dependent parameter (e.g.…”

mentioning

confidence: 99%

U-Th and <sup>10</sup>Be constraints on sediment recycling in proglacial settings, Lago Buenos Aires, Patagonia

Cogez¹,

Herman²,

Pelt³

et al. 2017

Preprint

View full text Add to dashboard Cite

Abstract. The estimation of sediment transfer times remains a challenge to our understanding of sediment budgets and the relationships between erosion and climate. Uranium (U) and Thorium (Th) isotope disequilibria offer a means of more robustly constraining sediment transfer times. Here, we present new Uranium and Thorium disequilibrium data for a series of nested moraines around Lago Buenos Aires in Argentine Patagonia, as well as a refined glacial chronology for the area using in situ cosmogenic 10Be analysis from 5 corresponding glacial outwash. Sediment transfer times within the periglacial domain were estimated by comparing the deposition ages of moraines to the theoretical age of sediment production, i.e. the comminution age inferred from U disequilibrium data and recoil loss factor estimates. Our data show first that the classical comminution age approach must include weathering processes, accounted for by measuring Th disequilibrium. Second, our combined data suggest that the pre-deposition history of the moraine sediments 10 is not negligible, as evidenced by the large disequilibrium of the youngest moraines despite the equilibrium of corresponding glacial flour. Monte Carlo simulations suggest that weathering was more intense before the deposition of the moraines and that the transfer time of the fine sediments to the moraines was on the order of 100-200 ka. Long transfer times could result from a combination of long sediment residence times 1 Earth Surf. Dynam. Discuss., https://doi

show abstract

Glaciers show direct linkage between erosion rate and chemical weathering fluxes

Cited by 121 publications

References 48 publications

Clay mineral precipitation and low silica in glacier meltwaters explored through reaction-path modelling

Clay mineral precipitation and low silica in glacier meltwaters explored through reaction-path modelling

Glacial weathering, sulfide oxidation, and global carbon cycle feedbacks

U-Th and <sup>10</sup>Be constraints on sediment recycling in proglacial settings, Lago Buenos Aires, Patagonia

Contact Info

Product

Resources

About

Glaciers show direct linkage between erosion rate and chemical weathering fluxes

Cited by 121 publications

References 48 publications

Clay mineral precipitation and low silica in glacier meltwaters explored through reaction-path modelling

Clay mineral precipitation and low silica in glacier meltwaters explored through reaction-path modelling

Glacial weathering, sulfide oxidation, and global carbon cycle feedbacks

U-Th and &lt;sup&gt;10&lt;/sup&gt;Be constraints on sediment recycling in proglacial settings, Lago Buenos Aires, Patagonia

Contact Info

Product

Resources

About

U-Th and <sup>10</sup>Be constraints on sediment recycling in proglacial settings, Lago Buenos Aires, Patagonia