carbonate–silicate cycle

Reaction chain and net uptake

Record balanced reactions for the actual mineral assemblage. The idealised calcium-silicate pathway consumes CO2 during weathering and returns part during carbonate precipitation; its net reaction is CaSiO3 + CO2 → CaCO3 + SiO2. Treat this as an endmember rather than a universal rock composition. [NASA carbon-cycle overview](https://science.nasa.gov/earth/earth-observatory/the-carbon-cycle/)

1. Which silicate minerals, dissolved products and carbonate phases constitute the proposed pathway? definition
2. What net CO2 transfer follows after balancing weathering and downstream precipitation within the chosen boundary? measurement

Weathering is not automatically a sink

Record acid provenance and the silicate/carbonate contribution before assigning carbon uptake. Sulfide oxidation coupled to carbonate dissolution can supply CO2 over geological timescales. [Torres et al., 2014](https://www.nature.com/articles/nature13030)

1. Which observations distinguish carbonic-acid weathering from sulfide-derived sulfuric-acid weathering? provenance
2. How much of the measured solute flux represents silicate alteration, carbonate dissolution or other sources? measurement

Distinct weathering environments

Maintain separate continental and seafloor flux estimates and response laws. Geological inverse modelling has treated their contributions separately when constraining carbon-cycle feedback. [Krissansen-Totton and Catling, 2017](https://www.nature.com/articles/ncomms15423)

1. Which continental catchments and seafloor alteration environments are included, and which exchanges cross the model boundary? boundary
2. What observations constrain the flux assigned to each environment rather than merely their combined total? provenance

Conditional weathering feedback

Record temperature, runoff, CO2 and mineral-supply dependencies together with the range over which they apply. Do not assume identical feedback strength across continental and seafloor settings. [Krissansen-Totton and Catling, 2017](https://www.nature.com/articles/ncomms15423)

1. Which evidence identifies the dominant limitation on weathering under the conditions being assessed? measurement
2. Under the proposed perturbation, does weathering change enough to oppose atmospheric CO2 change, and over what interval? action

Transport and transformation budget

Record dissolved inorganic carbon, alkalinity and major-cation transfers separately, including transformations along the route. River transport links terrestrial weathering products to marine carbonate formation. [NASA carbon-cycle overview](https://science.nasa.gov/earth/earth-observatory/the-carbon-cycle/)

1. Which river, groundwater and ocean boundaries carry the weathering-derived dissolved products? boundary
2. What measured gains or losses occur between mineral dissolution and delivery to the receiving carbonate system? measurement

Net burial and secondary reactions

Record gross precipitation, subsequent dissolution and net burial separately. Include reverse weathering where relevant: marine authigenic silicate formation can affect ocean pH and carbon partitioning. [Isson and Planavsky, 2018](https://www.nature.com/articles/s41586-018-0408-4)

1. What fraction of carbonate production survives dissolution and crosses the specified burial boundary? measurement
2. Which evidence constrains alkalinity consumption through authigenic silicate formation in the receiving sediments? provenance

Storage, recycling and return pathways

Record retention, uplift and reweathering, subduction, and metamorphic or magmatic return as distinct pathways. Geological processing can release stored carbon as CO2; a specific buried parcel need not return within the assessment interval. [NASA carbon-cycle overview](https://science.nasa.gov/earth/earth-observatory/the-carbon-cycle/)

1. Which pathways connect the included carbonate stores to reweathering, deeper retention or CO2 release? definition
2. How is recycled carbonate carbon distinguished from other carbon contributing to measured geological degassing? provenance

Transient budget and identifiability

Record inventory changes, flux uncertainties and alternative parameter combinations before diagnosing equilibrium or feedback strength. Geological inverse modelling illustrates the need to constrain weathering and climate jointly. [Krissansen-Totton and Catling, 2017](https://www.nature.com/articles/ncomms15423)

1. Do carbon inputs, outputs and inventory changes close within uncertainty over the selected interval? measurement
2. Which additional observation would best distinguish changes in degassing, weatherability and climate sensitivity? action

Check these first

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these check these first hold for the sense of carbonate-silicate cycle this model covers, and on what evidence? provenance

Real-world use

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these real-world use hold for the sense of carbonate-silicate cycle this model covers, and on what evidence? provenance

Typical measurements

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these typical measurements hold for the sense of carbonate-silicate cycle this model covers, and on what evidence? provenance

Failure modes and hazards

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these failure modes and hazards hold for the sense of carbonate-silicate cycle this model covers, and on what evidence? provenance

Regional variation

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these regional variation hold for the sense of carbonate-silicate cycle this model covers, and on what evidence? provenance

Neighbouring kinds and how to tell them apart

Recalled without web access and unsourced; every item is a lead to verify.

1. Which of these neighbouring kinds and how to tell them apart hold for the sense of carbonate-silicate cycle this model covers, and on what evidence? provenance