Lithologic Controls on Silicate Weathering Regimes of Temperate Planets

Hakim, Kaustubh; Bower, Daniel J.; Tian, Meng; Deitrick, Russell; Auclair-Desrotour, Pierre; Kitzmann, Daniel; Dorn, Caroline; Mezger, Klaus; Heng, Kevin (2021). Lithologic Controls on Silicate Weathering Regimes of Temperate Planets. The planetary science journal, 2(2), p. 49. IOP Publishing 10.3847/PSJ/abe1b8

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Weathering of silicate rocks at a planetary surface can draw down CO2 from the atmosphere for eventual burial and long-term storage in the planetary interior. This process is thought to provide essential negative feedback to the carbonate-silicate cycle (carbon cycle) to maintain clement climates on Earth and potentially similar temperate exoplanets. We implement thermodynamics to determine weathering rates as a function of surface lithology (rock type). These rates provide upper limits that allow the maximum rate of weathering in regulating climate to be estimated. This modeling shows that the weathering of mineral assemblages in a given rock, rather than individual minerals, is crucial to determine weathering rates at planetary surfaces. By implementing a fluid-transport-controlled approach, we further mimic chemical kinetics and thermodynamics to determine weathering rates for three types of rocks inspired by the lithologies of Earthʼs continental and oceanic crust, and its upper mantle. We find that thermodynamic weathering rates of a continental crust-like lithology are about one to two orders of magnitude lower than those of a lithology characteristic of the oceanic crust. We show that when the CO2 partial pressure decreases or surface temperature increases, thermodynamics rather than kinetics exerts a strong control on weathering. The kinetically and thermodynamically limited regimes of weathering depend on lithology, whereas the supply-limited weathering is independent of lithology. Our results imply that the temperature sensitivity of thermodynamically limited silicate weathering may instigate a positive feedback to the carbon cycle, in which the weathering rate decreases as the surface temperature increases.

Item Type:

Journal Article (Original Article)

Division/Institute:

10 Strategic Research Centers > Center for Space and Habitability (CSH)
08 Faculty of Science > Institute of Geological Sciences

UniBE Contributor:

Hakim, Kaustubh; Bower, Daniel James; Tian, Meng; Deitrick, Russell John; Auclair-Desrotour, Pierre Bernard Roger; Kitzmann, Daniel; Mezger, Klaus and Heng, Kevin

Subjects:

500 Science > 520 Astronomy
500 Science > 550 Earth sciences & geology

ISSN:

2632-3338

Publisher:

IOP Publishing

Funders:

[18] European Research Council ; [4] Swiss National Science Foundation ; [UNSPECIFIED] NCCR PlanetS

Language:

English

Submitter:

Kaustubh Hakim

Date Deposited:

06 Apr 2021 16:23

Last Modified:

11 Apr 2021 03:07

Publisher DOI:

10.3847/PSJ/abe1b8

ArXiv ID:

2008.11620

BORIS DOI:

10.48350/153806

URI:

https://boris.unibe.ch/id/eprint/153806

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