scholarly journals Tracing Silicate Weathering Dynamics in a Shale-Dominated Hillslope Using Lithium Isotopes in a Reactive Transport Framework

2020 ◽  
Author(s):  
Jon Golla ◽  
Marie Kuessner ◽  
Julien Bouchez ◽  
Daniella Rempe ◽  
Jennifer Druhan
Keyword(s):  
Reactive Transport ◽  
Silicate Weathering ◽  
Lithium Isotopes

Lithium isotopes tracing weathering processes in a time series through soil porewaters

2020 ◽  
Author(s):  
David Wilson ◽  
Philip Pogge von Strandmann ◽  
Gary Tarbuck ◽  
Jo White ◽  
Tim Atkinson ◽  
...  
Keyword(s):  
Time Series ◽  
Chemical Weathering ◽  
Silicate Weathering ◽  
Lithium Isotope ◽  
Lithium Isotopes ◽  
Drip Water ◽  
Weathering Processes ◽  
Li Isotope ◽  
Clay Formation ◽  
Isotope Measurements

<p>Chemical weathering is a key process that controls Earth’s geochemical cycles and global climate, yet at present the climate-weathering feedback is poorly understood. Lithium (Li) isotopes are sensitive to silicate weathering processes [1] and can be applied in a range of settings to improve our understanding of weathering mechanisms and timescales, and hence to quantify the role of weathering in the global carbon cycle. While marine carbonates [2] and speleothems [3] are suitable for recording changes over million year and thousand year timescales, respectively, it is equally important to assess how weathering operates over seasonal [4] and shorter [5] timescales.</p><p>In order to explore seasonal variability in a natural system, we analysed Li isotopes and major/trace elements in a time series of cave drip-water samples from Ease Gill and White Scar caves (Yorkshire Dales, U.K.). Since the drip-waters are sourced from the overlying soil porewaters, these measurements provide a record of the evolving weathering fluid chemistry at approximately monthly intervals. Our data reveal striking temporal variations in ∂<sup>7</sup>Li of 4 to 8 permil, hinting at rapid changes in weathering processes over monthly to seasonal timescales. We assess the sources of Li using isotope measurements on local rocks and soils, which enables a first order quantification of the temporal changes in Li removal by clay formation. Comparison to records of temperature, precipitation, drip rates, and drip-water chemistry allows the local controls on weathering to be assessed and indicates that a dominant control is exerted by the fluid residence time.</p><p>These data are further complemented by batch reactor experiments, which were conducted to replicate rock weathering over timescales of hours to weeks. In combination, the time series and experiments contribute to a better understanding of weathering changes over short timescales and their influence on Li isotopes. In addition, results from the drip-waters provide key ground-truthing for interpreting our ongoing Li isotope measurements on speleothems, which will provide new records of weathering changes over longer timescales in response to regional climate forcing.</p><p>[1] Pogge von Strandmann, P.A.E., Frings, P.J., Murphy, M.J. (2017) Lithium isotope behaviour during weathering in the Ganges Alluvial Plain. GCA 198, 17-31.</p><p>[2] Misra, S. & Froelich, P.N. (2012) Lithium isotope history of Cenozoic seawater: changes in silicate weathering and reverse weathering. Science 335, 818-823.</p><p>[3] Pogge von Strandmann, P.A.E., Vaks, A., Bar-Matthews, M., Ayalon, A., Jacob, E., Henderson, G.M. (2017) Lithium isotopes in speleothems: Temperature-controlled variation in silicate weathering during glacial cycles. EPSL 469, 64-74.</p><p>[4] Liu, X.-M., Wanner, C., Rudnick, R.L., McDonough, W.F. (2015) Processes controlling δ<sup>7</sup>Li in rivers illuminated by study of streams and groundwaters draining basalts. EPSL 409, 212-224.</p><p>[5] Pogge von Strandmann, P.A.E., Fraser, W.T., Hammond, S.J., Tarbuck, G., Wood, I.G., Oelkers, E.H., Murphy, M.J. (2019) Experimental determination of Li isotope behaviour during basalt weathering. Chemical Geology 517, 34-43.</p>

scholarly journals Lithium and Lithium Isotopes in Earth’s Surface Cycles

Elements ◽  
2020 ◽  
Vol 16 (4) ◽  
pp. 253-258 ◽  
Author(s):  
Philip A.E. Pogge von Strandmann ◽  
Simone A. Kasemann ◽  
Josh B. Wimpenny
Keyword(s):  
Climate Change ◽  
Atmospheric Co2 ◽  
Silicate Weathering ◽  
Lithium Isotope ◽  
Climatic Warming ◽  
Pore Waters ◽  
Lithium Isotopes ◽  
Weathering Processes ◽  
Isotope Evidence ◽  
Clay Formation

Lithium and its isotopes can provide information on continental silicate weathering, which is the primary natural drawdown process of atmospheric CO2 and a major control on climate. Lithium isotopes themselves can help our understanding of weathering, via globally important processes such as clay formation and cation retention. Both these processes occur as part of weathering in modern surface environments, such as rivers, soil pore waters, and groundwaters, but Li isotopes can also be used to track weathering changes across major climate-change events. Lithium isotope evidence from several past climatic warming and cooling episodes shows that weathering processes respond rapidly to changes in temperature, meaning that weathering is capable of bringing climate back under control within a few tens of thousands of years.

scholarly journals Tracing silicate weathering processes in the permafrost-dominated Lena River watershed using lithium isotopes

2019 ◽  
Vol 245 ◽  
pp. 154-171 ◽  
Author(s):  
Melissa J. Murphy ◽  
Don Porcelli ◽  
Philip A.E. Pogge von Strandmann ◽  
Catherine A. Hirst ◽  
Liselott Kutscher ◽  
...  
Keyword(s):  
Silicate Weathering ◽  
Lithium Isotopes ◽  
Lena River ◽  
River Watershed ◽  
Weathering Processes

scholarly journals PALEOCLIMATE CONSTRAINTS ON TERRESTRIAL HYDROCLIMATE, SILICATE WEATHERING, AND THE CARBON CYCLE

2018 ◽  
Author(s):  
Daniel Enrique Ibarra
Keyword(s):  
Carbon Cycle ◽  
Land Surface ◽  
Reactive Transport ◽  
Water Cycle ◽  
Climate System ◽  
Silicate Weathering ◽  
Earth System ◽  
Evolution Of Life ◽  
Paleoclimate Records ◽  
Lake Systems

Maintenance of a habitable planet requires connections and balance among Earth’s biogeochemical cycles. Further, the strength of the feedbacks and couplings determines the stability of conditions in the surface climate system necessary for the evolution of life. Records of Earth’s past climate, paleoclimate records, provide constraints beyond the reach of the instrumental record on the directionality, strength and co-evolution of key Earth system cycles. This includes the geologic carbon cycle, the water cycle and the planet’s energy balance. Crucially, the geography, topography and lithology of Earth’s continents have two important features that are the focus of this dissertation. First, the continents provide boundary conditions that determine global circulation and hydroclimate patterns that couple Earth’s water and carbon cycles (Chapters 1 and 2). Second, the land surface provides a stabilizing negative feedback in the form of silicate weathering fluxes (Chapters 3 and 4, and Appendix E), balancing the long-term carbon cycle through alkalinity and solute delivery to the oceans, and subsequent carbonate burial. In this dissertation I use data, observations and modeling to place mechanistic constraints on how interactions between Earth’s surface and long-term biogeochemical cycles maintain balance and habitable conditions in our climate system conducive for the evolution of life. Fundamental to understanding our climate system is predicting the anticipated sign of terrestrial hydroclimate change during periods of climatic change. To this end I have investigated the regional response of hydroclimate change using paleoclimate records from mid-latitude lake systems. First, in Chapter 1, I have developed an inverse model to quantify how a mid-latitude lake system in Asia, the Songliao Basin, responded to a transient warming event during the Cretaceous. This model was also applied to a Holocene ostracod record from Lake Miragoane, Haiti. Second, in Chapter 2, I compile spatial distributions and size estimates of pluvial lake systems in western North America during the Pliocene-Pleistocene. By imposing mass and energy balance constraints (sensu Budyko) I forward modeled lake area distributions to demonstrate that now-arid western North America was wetter during both past colder and warmer periods during the Pliocene-Pleistocene, a result not predicted for future warming scenarios. Geologic observations primarily suggest wetter conditions globally during warmer-than-present periods. Importantly, this observation is a requirement for the operation of the stabilizing negative feedback between silicate weathering and climate. Understanding the factors that control silicate weathering rates is fundamental to constraining the evolution of Earth’s carbon cycle over geologic timescales. One challenge for reconstructing past weathering rates is determining the reactivity of Earth’s surface. In Chapter 3 I have quantified the reactivity of modern basalt and granite catchments using a process-based solute production model and concentration-discharge weathering relationships. This approach provides mechanisms that link runoff (i.e., terrestrial hydroclimate changes that were the focus of Chapters 1 and 2) with the distribution of global sub-aerial silicate lithologies. In Chapter 4 I utilize an emerging metal isotope system, lithium isotopes, to investigate the terrestrial weathering response to a large perturbation in the carbon cycle during the Cretaceous. We determine that the background-state of the Cretaceous weathering system was more congruent and, hence, more sensitive to perturbations in the carbon cycle than during the Neogene. Finally, in Appendix E I have quantified how step-wise geologic evolution of land plants strengthened the silicate weathering feedback over the Phanerozoic. I have developed a new reactive transport framework for evaluating the relative plant-controlled roles of hydrologic versus thermodynamic mechanisms that influence the coupling between the water cycle and silicate weathering fluxes on a continental scale. The results described in this dissertation constrain links between two connected portions of the exogenic Earth system. I have provided constraints for how the land surface records past changes in regional atmospheric circulation patterns, as well as regional water and energy balances. Further, using reactive transport modeling, I have placed new constraints on the role of plants and lithology in determining the coupling between terrestrial hydroclimate and weathering. Collectively these results suggest that the surface Earth system, our planet’s fluid envelope, has been progressively tuned by the advent of continents and the evolution of life. [Note: this is the non-embargoed portion of my dissertation]

scholarly journals Lithium isotopes in speleothems: Temperature-controlled variation in silicate weathering during glacial cycles

2017 ◽  
Vol 469 ◽  
pp. 64-74 ◽  
Author(s):  
Philip A.E. Pogge von Strandmann ◽  
Anton Vaks ◽  
Miryam Bar-Matthews ◽  
Avner Ayalon ◽  
Ezekiel Jacob ◽  
...  
Keyword(s):  
Silicate Weathering ◽  
Glacial Cycles ◽  
Lithium Isotopes ◽  
Temperature Controlled

scholarly journals Tracing silicate weathering in estuaries using lithium isotopes

2021 ◽  
Author(s):  
Chunyao Liu ◽  
Philip Pogge von Strandmann ◽  
Kevin Burton ◽  
Ed Hathorne
Keyword(s):  
Silicate Weathering ◽  
Lithium Isotopes
Sign in / Sign up

Export Citation Format

Share Document