Carbonate sediments geologic history

Specifically, the isotopic composition of the carbon compounds in the oldest sediments supports the conclusion that the geochemical cycle of carbon evolved into a biogeochemical cycle by the time of the deposition of these rocks. Thus, a fully developed biogeochemical carbon cycle may date from 3.8 billion years ago. Also, the morphological record of microbial (prokaryotic) life has been shown to proceed over at least 3.5-3.8 billion years of geological history. 

Volcanic events have been frequent throughout most of geological history, yet there are few studies documenting their importance in sandstone diagenesis and carbonate cementation in particular. Is this related to difficulties in recognizing volcaniclastic sediments due to their rapid and extensive diage-netic alteration ... 

Collins, L.B. 1988. Sediments and history of the Rottnest Shelf, southwest Australia A swell-dominated, non-tropical carbonate margin. Sedimentary Geology, 60 15-50. 

Parameters influencing the distribution of calcium carbonate with increasing water depth in equatorial Pacific sediment. Note that fi is reported as a percentage (%). Source From van Andel, Tj. H., et al. (1975). Cenozoic History and Paleoceanography of the Central Equatorial Pacific Ocean, Geological Society of America, Boulder, CO, p. 40. 

Because sedimentary carbonates represent primarily chemical and biochemical precipitates from seawater, and because they make up 20% of the common sedimentary rock record, these rock types have been particularly good sources of chemical and mineralogical data for interpretation of the secular and cyclic evolution of the Earth s surface environment. This carbonate rock record as a function of geological age is now explored as are age trends in other rock types and sediment properties. With this information as background material, we can then discuss what these relationships tell us about the history of carbonates and the exogenic system throughout geologic dme. 

Fluctuations that have been measured in the 5 G values of sedimentary organic matter over the Earth s history (e g. Schidlowski 1988) can thus be interpreted in terms of the productivity in the water coltrrrm and the availability of DIG in a particular geological time period. In a study of sediments from the central equatorial Pacific Ocean spanning the last 255,000 years it has been demonstrated that the carbon isotopic composition of fossil organic matter depends on the exchange between atmospheric and oceanic GO. Ghanges with time can then be used to estimate past atmospheric carbon dioxide concentratiorrs (Jasper et al. 1994). 

---