Environments of deposition of lacustrine petroleum source rocks: an introduction 论文

摘要

F. A. Forel (1892-1902) established the scientific discipline of limnology with his integrated study of biology, chemistry, circulation and sedimentation in modern Lake Geneva. Subsequent literature on lakes is largely separate from geology in contrast to the historical development of marine geology. Strakhov (1970) is one exception and Pia (1933) another. Classic texts which summarize the limnological view of lakes include: F. Forel (1901), F. Ruttner (1963), G. E. Hutchinson (1957), D. Frey (1974), R. Wetzel (1983), and F. Taub (1984a). None of these however emphasize the burial and preservation of reactive organic carbon.<br />A lake may be defined as an inland body of standing water occupying a depression in the earth's crust. It is larger than a pond. As such, lakes can exhibit a wide range of possible settings, sizes, chemistries, concentrations and morphologies. The Greek 'Limne' which is at the root of the scientific disciplines Limnology and Limnogeology means marsh, lake or pool and by implication has been generally applied to freshwater environments. Thirteen of the world's 40 largest lakes, and innumerable smaller ones are however without outlets and commonly quite saline. Of the largest lakes, only 20 are deeper than 400 m but these hold most of the world's fresh lake water (23 000 km<sup>3</sup> in Baikal). Because traditionally the study of modern lakes is linked to securing water resources for man, only a minor emphasis has been given the brackish to hypersaline ecosystems. These, however, form important parts of the geological record of lake basins. Geology textbooks gloss over lakes as ephemeral geological features, but in recent years it has become increasingly obvious that vast lake deposits are preserved in the geological record and many of the ancient lake basins hold great promise for economic deposits including metals, salts and hydrocarbons. The situation is perhaps similar to the Dolomite Problem in the 1960s. Very skimpy data are available from modern systems to help formulate general models that can be useful in an exploration strategy. Wherever one begins; whether in palaeontology, petrology, geochemistry, seismic stratigraphy, or sedimentology, there is simply insufficient synthetic information on lake deposits. [...]