Depositional sedimentary environments with reference to terrigenous clastics / Условия осаждения осадочных пород применительно к терригенным обломкам

Geologists are mainly concerned with the study of the lithosphere. The sedimentary and metasedimentary rocks, although they constitute only 5 % of the lithosphere by volume, they occupy 75% of the exposed land area (PETTIJOHN, 1957). Thus, the study of sedimentary rocks is the major problem of geology. An obvious question arises in the study of sedimentary rocks: Under what conditions and by which processes were the sedimentary rocks in question deposited.
PETTIJOHN (1957) pointed out that geology is primarily history-a history of the earth. The study of sedimentary rocks concerns the history of sedimentary rocks. PETTIJOHN adds, further, that the history of any given sedimentary rock unit involves determining the source area and source rocks, determining the environment of deposition the physical, chemical, and biological milieu in which the sediment accumulated, and finally, lithification the study of post-depositional changes.
Excluding the process of lithification, the sediment can be regarded as a product of source and environment (PETTIJOHN, 1957). Discovering the origins and reconstructing the environment that produced the sedimentary rock is a difficult task. A thorough knowledge of sedimentary processes that cause the production, transportation, and deposition, is most important in environmental reconstruction. Most important for such purposes are primary structures and textures, together with the biological and chemical aspects of the sediment. In this book, mainly primary structures and textures have been considered. However, biological factors, as far as they are important in sedimentation processes and environmental interpretation, have been covered. A short account of mineralogical and chemical factors is also given. <...>