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Theme 7

Evolutive and Integrative Earth Surface Processes

Paul Bierman, Vermont,
Jacques Schott, Toulouse,
Teofilo Abrajano, Reensalear,

Co-hosted sessions

SESSIONS

7a. The Art of weathering: A symposium in honor of Art White

(co-hosted by Themes 7 and 19)

Co-convenors:
Heather Buss (University of Bristol) - h.bussbristol.ac.uk
Marjorie S. Schulz (US Geological Survey) - mschulzusgs.gov

The rates and mechanisms of chemical weathering processes are important to understanding a variety of environmentally and economically important issues including water quality, the cycling of mineral nutrients, soil fertility, environmental contamination, the evolution of landforms, and the long-term drawdown of atmospheric CO₂. Following the recent retirement of Art from the US Geological Survey, this session will celebrate Art's significant scientific contributions to field of geochemistry. We invite presentations pertaining to the rates and mechanisms of chemical weathering processes and their application to natural systems. While submissions from Art's former collaborators and colleagues are particularly encouraged, contributions from all researchers who share Art's interest in chemical weathering are welcome.

Keynote speaker:
Sue Brantley (Penn State University), brantleygeosc.psu.edu
Invited speakers:
Susanne Anderson (University of Colorado), suzanne.andersoncolorado.edu
Kate Maher (Stanford University), kmaherstanford.edu
Jérôme Gaillardet (Institut de Physique du Globe, Paris), gaillardetipgp.fr
Sigurdur Gislason (University of Iceland), sigrgraunvis.hi.is
Jennifer Harden (USGS- Menlo Park, CA), jhardenusgs.gov
Arjun Heimsath (Arizona State University), arjun.heimsathasu.edu
Roland Hellmann (CNRS- Université de Grenoble), roland.hellmannobs.ujf-grenoble.fr
Oliver Chadwick (UC Santa Barbara), oacgeog.ucsb.edu

7b. The dynamics of continental weathering

Co-convenors:
Yves Goddéris (GET, CNRS Toulouse) - yves.godderisget.obs-mip.fr
Kate Maher (Stanford University) - kmaherstanford.edu

Weathering of the continental surfaces is a dynamic process, sensitive to many forcing functions at various timescales. Given that continental weathering is a major process in many biogeochemical cycles, describing its dynamic response to various forcings is a key challenge. This session encourages submission of abstracts dealing with the evolution of the weathering processes in response to changes in tectonics, erosion rates, biological forcings, climate changes, land uses (the list being non-exhaustive) from the hourly to the multi-million year timescale. This encompasses field studies collecting time series and exploring hourly to decadal changes in weathering rates connected to environmental changes. Included are also past reconstructions of weathering rates, and numerical modeling of the dynamic of weathering.

Keynote speaker:
Peter Raymond (Yale University), peter.raymondyale.edu

7c. Accessory minerals in chemical weathering

Co-convenors:
Jason Price (Millersville University, USA) – Jason.Pricemillersville.edu
Jean-Jacques Braun (India Institute of Science, Bangalore) – brauncivil.iisc.ernet.in

The chemical weathering of reactive bedrock accessory minerals is capable of asserting a major influence on the mineralogy, major element, trace element (e.g., REEs, U, Th, Zr, Nb, Sr, and P), and isotopic abundances of both regolith and water. Trace elements at the whole rock- or regolith-scale are often major elements in accessory minerals. Major and trace elements and their isotopes, are widely applied as tracers of weathering processes. Therefore, the presence and weathering of accessory minerals needs to be considered when interpreting critical zone chemical data. The importance of these phases on biogeochemical budgets is often ignored because of their relatively low abundance of ≤2% by volume. Their scarcity may also result in lack of recognition in both parent and weathered materials. This session welcomes experimental and field-based contributions addressing the role of primary and secondary accessory minerals on biogeochemical budgets from atomic- to global-scales, for regolith and water, and addressing both silicate and nonsilicate minerals.

Keynote speaker: TBD

7d. Records of climate change from terrestrial archives: palaeosols and loess

(Co-hosted by Themes 7, 10 and 11)

Co-convenors:
Mohammed Rafi G. Sayyed (Poona College, Pune, India) - mrgsayyedyahoo.com
Martine Gerard (IMPMC, Paris) - Martine.Gerardimpmc.upmc.fr

The driving forces of evolution of Earth’s climate, from cold snowball Earth to warm greenhouse state, can be revealed and quantified by palaeoclimate studies. Nowadays fragile global environmental conditions demand urgent improving of the understanding of paleoclimates to better predict climate change. The physical, chemical and biological composition of ancient soils or more polygenetic buried soils hold great potential as proxies for regional palaeoclimate and palaeoatmospheric circulation patterns as well as palaeoatmospheric pCO₂ variations for intervals of Earth’s history characterized by extreme and abrupt environmental perturbations. More understanding of the mechanisms that influence biogeochemical data preservation in the proxies is needed to avoid biases of interpretation. Once these issues are addressed, the geochemistry of palaeosols can provide both qualitative and semi-quantitative information about the changing redox state of the atmosphere since the Precambrian times. Palaeosol-loess sequences also have a great potential for the evolution of climate throughout Earth’s history as they have preserved detailed climatic records of stepwise terrestrial climate change. We invite contributions that investigate various biogeochemical proxies of the evolution of the climate system from Precambrian to Holocene as well as on extreme events (e.g. LIPs related to catastrophic global climate impacts and mass extinctions events).

Keynote speaker:
Steven Driese (Baylor University, Texas), Steven_Driesebaylor.edu

7e. The global weathering thermostat

(co-hosted by Themes 7 and 10)

Co-convenors:
Heather Buss (University of Bristol) - H.Bussbristol.ac.uk
Rich Pancost (University of Bristol) - r.d.pancostbristol.ac.uk)
Andy Ridgwell (University of Bristol) andy.ridgwellbristol.ac.uk

This session brings together the chemical weathering and palaeoclimate communities to discuss and debate fundamental issues in how the Earth’s climate is regulated. One of the most important over long-term timescales is the carbon dioxide – temperature – chemical weathering feedback. It is ingrained in biogeochemical models and is thought to be the key relationship that has governed the Earth’s climate stability and, therefore, habitability for billions of years. However, other factors, such as plant evolution and tectonics, are also important regulators of climate – weathering feedbacks, and the relative importance of these controls on different timescales remains unclear. Much work in investigating contemporary or Holocene chemical weathering and geomorphological processes underscore the difficulty in ascribing specific reaction rates to climatic, tectonic or biological controls. They particularly highlight the challenge of applying rates determined in the lab or in non-steady state systems to long-term climate dynamics. We invite submissions that grapple with these issues either via modern investigations, numerical modelling or proxies for past climate and weathering, and especially encourage integrative presentations that cross over disciplinary boundaries. We also welcome submissions that address related processes such as erosion, sediment transport and associated organic matter oxidation or burial.

Keynote speaker:
Lou Derry (Cornell University), lad9cornell.edu
Invited speakers:
Friedhelm von Blanckenburg (GFZ-Potsdam), fvbgfz-potsdam.de
Amanda Olsen (The University of Maine), amanda.a.olsenmaine.edu
Joshua West (University of Oxford, UK), joshuawearth.ox.ac.uk

7f. Critical zone processes: their role in ecology and evolution

(co-hosted by Themes 7, 12 and 15)

Co-convenors:
Elisabeth Bui (CSIRO, Australia) - Elisabeth.Buicsiro.au
Martin B. Goldhaber (US Geological Survey) - mgoldusgs.gov
Geoffrey Abbott (University of Newcastle) –
Sylvie Derenne (Université Pierre et Marie Curie, Paris) -

The soil and its underlying parent material are generally neglected  in current studies of biodiversity and predictive modelling of  biological responses to global warming that focus on climate variables. The geochemistry of the edaphic factor is key in  driving the distribution of microbes, plants and organisms they support-this has been demonstrated in wetlands, in serpentine ecosystems, in saline ecosystems, and in phosphorus-poor ones. Yet  there has been little work examining the combined impact of climate, substrate geochemistry, and nutrient cycling on microbial and plant distributions and ecosystem function. This session aims to bring together geochemists, ecologists, and molecular biologists interested in synthesis studies that advance our knowledge of the role of biogeochemistry in geoecology.

Keynote speakers:
Stephen D. Hopper (Royal Botanic Gardens, Kew, UK), s.hopperkew.org
Nishanta Rajakaruna (College of the Atlantic, Maine), nrajakarunacoa.edu
Fatima Laggoun-Défarge (Université d’Orléans), Fatima.Laggoun-Defargeuniv-orleans.fr

7g. The organic biogeochemistry of peatlands: adaptation or vulnerability to global climate change?

(co-hosted by Themes 7 and 10)

Co-convenors:
Geoffrey Abbott (University of Newcastle) – Geoff.abbottnewcastle.ac.uk
Sylvie Derenne (Université Pierre et Marie Curie, Paris) - sylvie.derenneupmc.fr

SESSION MERGED with 7f

7h. Weathering of sediments – from natural processes to underground CO₂ storage

(co-hosted by Themes 7, 12 and 19)

Co-convenors:
Matthias Haeckel (GEOMAR, Kiel, Germany) - mhaeckelifm-geomar.de
Judith Schicks (GFZ, Potsdam, Germany) - judith.schicksgfz-potsdam.de
Giovanni Aloisi (Université Pierre et Marie Curie, Paris) - Giovanni.Aloisi locean-ipsl.upmc.fr

The weathering of silicate minerals exposed on the continents is known to be the main natural sink of CO₂ from the atmosphere. Detrital silicates derived from the physical denudation of the continents are also a major component of marine sediments and it has recently been shown that CO₂-induced weathering is a common process in marine sediments. Nevertheless, their geochemical behaviour and reaction rates are poorly understood. The same weathering processes are the final and long-term trapping mechanisms for underground CO₂ storage, one of the options to mitigate our anthropogenic CO₂ emissions. Nevertheless, reaction rates at those high-CO₂ conditions and the geochemical behaviour in the natural storage formation are difficult to predict and hence the risks and/or safety of the CCS technology difficult to assess.

Furthermore, only very limited data is available from natural analogues with high CO₂ concentrations, e.g. volcanic/hydrothermal CO₂ seeps.

This session aims at bringing together experts for the naturally-occurring weathering processes and those involved in CCS projects in order to exchange know-how as well as identify knowledge gaps on both sides. In this context we would like to invite contributions presenting field work, experimental investigations as well as thermodynamic and transport-reaction modeling studies.

Keynote speaker:
Sigurdur Reynir Gislason (University of Iceland), sigrgraunvis.hi.is

Co-hosted sessions:

Please note that for abstract submission purposes, the following sessions and their respective descriptions appear in their primary Theme assignments (numbers in red or before the title).

17f.- Frontiers in U-Series as tracers and chronometers of environmental processes and paleoclimatic archives

Co-convenors: Pierre Deschamps/CEREGE, Francois Chabaux/LHyGeS, Strasbourg, Andrea Dutton/University of Florida and Bassam Ghaleb, GEOTOP-UQAM
(co-hosted by Themes 17, 7 and 10)

17g.- Traditional and novel isotopes as tracers of weathering processes

Co-convenors: Jérôme Gaillardet/IPG-Paris, Sophie Opfergelt/Oxford, Thomas Bullen/USGS and Friendhelm von Blanckenburg/Postdam
(co-hosted by Themes 17, 7 and 10)

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