L. Hinnov February 15, 2012 Global carbonates Reading list: Feeley, R.A., Sabine, C.L., Lee, K., Berelson, W., Kleypas J., Fabry, V.J., and Millero, F.J., 2004, Impact of anthropogenic CO2 on the CaCO3 system in the oceans, Science, v. 304, pp., Markello, J.R., Koepnick, R.B., Waite, L.E., and Collins, J.F., 2007, The carbonate analogs through time (CATT) hypothesis and the global atlas of carbonate fields -- a systematic and predictive look at Phanerozoic carbonate systems, in Controls on Carbonate Platform and Reef development, SEPM Special Publication no. 89; and chart. Ridgwell, A. and Zeebe, R.E., 2005, The global carbonate cycle in the regulation and evolution of the Earth system, Earth and Planetary Science Letters, v. 234, pp Stanley, S.M., and Hardie, L.A., 1998, Secular oscillations in the carbonate mineralogy of reef-building and sediment-producing organisms driven by tectonically forced shifts in seawater chemistry, Palaeogeography, Palaeoclimatology, Palaeoecology, v. 144, pp

Surficial reservoir: Geologic reservoir: Atmosphere Oceans Biosphere Soils “Exchangeable sediments” Sediments Crust Mantle EARTH’S CARBON RESERVOIRS Cycling between reservoirs: (a) Precipitation/burial of CaCO 3 (b) Weathering/geologic cycling

CARBONATE ENVIRONMENTS (b) Pelagic zone (a) Neritic zone Shallow marine organisms: Corals Benthic shelly animals Algae Planktonic organisms: Coccolithophores Foraminifera Pteropods (pelagic bivalves)

(a) Surficial to geologic reservoir (b) Geologic to surficial reservoir 1.Bioprecipitation by pelagic organisms (calcite) 2.Carbonate reaching ocean bottom 3.Bioprecipitation by neritic organisms (aragonite) 4.Carbonate precipitation results in higher pCO 2 at surface and CO 2 to atmosphere 5. Erosion of uplifted carbonate 6. Decarbonation of carbonate (CO 2 release in interior) 7. Weathering of silicate rocks (CO 2 consumption) 8. CO 2 emission from decarbonation GLOBAL CARBONATE CYCLE

Calcite - a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO 3 ). Crystal system: Trigonal; specific gravity 2.71g/cm 3 ; Aragonite - a carbonate mineral and the second most common calcium carbonate (CaCO 3 ). Crystal system: Orthorhombic; specific gravity 2.95g/cm 3 ; CARBONATE MINERALS Today is the prevalent mineral precipitated mainly by pelagic organisms (except pteropods) Today is a common mineral precipitated mainly by neritic organisms (also high-Mg calcite) Iceland spar

Feeley et al. (2004)

Scholle et al., 1983 CARBONATE SATURATION STATE OF OCEANS Lysocline -->  = 0.8 More older water; more metabolic CO 2

Sea level - e.g., coral reef hypothesis: shelf flooding, coral reef colonization increased marine CaCO 3 precipitation, caused ppm rise in pCO 2 during Holocene. Pelagic calcifiers did not arise until the start of the Mesozoic Era (250 Ma). Observed (shaded bars) vs. modeled [Ca 2+ ] in the world ocean. (Controlled by changes in mid-ocean ridge volume.) ARAGONITE v. CALCITE SEAS (next slide) Deep-sea-carbonate: percent occurrence of carbonates in ophiolite complexes. Shallow-marine-carbonate: changes in the total area of shallow marine carbonates. Figure from Ridgwell and Zeebe, 2005

Aragonite v. Calcite Seas Stanley and Hardie, 1998

Markello et al. (2007) “Carbonate Analogs Through Time” (CATT): High-confidence, age-specific predictive models and concepts for ancient carbonate systems and carbonate reservoirs in terms of occurrence, composition, stratal attributes, and reservoir properties can be developed by summing the ambient conditions of the carbonate processes and Earth processes at any geologic age. The summations are termed age-sensitive patterns or themes. Graphically, the CATT hypothesis can be expressed as: The petroleum geologists perspective:

Markello et al. (2007) From left to right: