This book starts with a review of sedimentologic principles governing the large scale anatomy of reefs and platforms. It then looks at sequence and systems tracts from a sedimentologic point of view, assess the differences between siliciclastics and carbonates in their response to sea level, evaluates processes that compete with sea level for control on carbonate sequence and finally presents a set of guidelines for application of sequence stratigraphy to reefs and carbonate platforms.
Sedimentology and stratigraphy are neighbors yet distinctly separate entities within the earth sciences. Sedimentology searches for the common traits of sedimentary rocks regardless of age as it reconstructs environments and processes of deposition and erosion from the sediment record. Stratigraphy, by contrast, concentrates on changes with time, on measuring time and correlating coeval events. Sequence stratigraphy straddles the boundary between the two fields. This book, dedicated to carbonate rocks, approaches sequence stratigraphy from its sedimentologic background. This book attempts to communicate by combining different specialities and different lines of reasoning, and by searching for principles underlying the bewildering diversity of carbonate rocks. It provides enough general background, in introductory chapters and appendices, to be easily digestible for sedimentologists and stratigraphers as well as earth scientists at large.
Sequence stratigraphic principals can be applied to carbonate rock sequences. Typical tropical shallow-water carbonate shelves lead to sequence boundary exposure across carbonate platforms, and carbonate deep water deposits during highstands. Rapid carbonate sedimentation across a shelf leads to vertical accretion during the TST and progradation during the HST. Reef-bound shelf margins tend to evolve into escarpment margins with megabreccia development on the slope. Examples are the Devonian of the Canning Basin and the Cretaceous of Mexico. Carbonate ramps typically develop lowstand prograding complexes. Cool-water carbonates develop ramp morphology, independent of light with no framework reefs, and parallel the sequence stratigraphic framework of siliciclastics. The cool water sediments of the Great Australian Bight is an example Mud mound sequences as seen in Morocco are generally independent of sea-level changes, so most sequence stratigraphic concepts are not applicable. In mixed carbonate-siliciclastic situations reciprocal sedimentation results with HST carbonates dominating in the basin and LST clastics dominating in the basin. Sequence stratigraphic concepts are generally not applicable to lacustrine carbonates, but lake dessication cycles present a similar stratigraphic framework as seen in the Tertiary Green River of the Western United States.
"Offering a solid introduction to the principles and applications of sedimentology and stratigraphy, author Richard A. Davis Jr. emphasizes the integration of these two areas and covers both modern and ancient depositional environments using modern examples and excellent illustrations. The Second Edition presents updated technical information, and offers a major reorganization of chapters to promote greater clarity and to place greater emphasis on more current topics. Additional content highlights: provides new approaches to basic analysis, including sequence stratigraphy; integrates genetically related depositional environments that share a common thread in concurrent chapters; discusses topics such as sedimentary processes and structures, the desert system, the fluvial system, the delta system, the barrier island system, reefs and the carbonate platform system, the deep ocean system, and much more." --
This IAS Special Publication #27 contains 17 of the papers presented at the IAS International Workshop on Reefs and Carbonate platforms in the Pacific and Indian oceans held in Sydney (July 1995). This is the first book to summarize the current state of knowledge about reefs and carbonate platforms in these oceans, where there is a great diversity of carbonate systems in various tectonic settings. Papers concern both processes operating in reefs and carbonate platforms and case histories (platform and oceanic reef case histories). Case histories range from the Lower Cretaceous to modern reefs and most fossil carbonate platforms concern outcomes from recent ODP legs in the Pacific. The book covers a broad spectrum of disciplines related to carbonate geology: sedimentology, geochemistry, geophysics, reef ecology and modeling. If you are a member of the International Association of Sedimentologists, for purchasing details, please see: http://www.iasnet.org/publications/details.asp?code=SP25
Sequence stratigraphy has advanced considerably since the early applications of the concepts on seismic data. It attempts to discern the migration of facies re sulting from changes in a combination of factors such as, sea level, tectonics, climate and sediment flux, and integrates it with a meaningful chronostratigraphy. The stratigraphic record is envisioned as a framework of repetitive packages of genetically-related strata, formed in response to the shifting base level, in which the locus of deposition of various sediment types may be anticipated. This attribute is rapidly promoting sequence stratigraphy as an indispensable tool for prediction of facies in exploration and production geology. In hydrocarbon exploration the application of sequence stratigraphy has ranged from anticipating reservoir- and source-rock distribution to predicting carbonate diagenesis, porosity and permeability. The capability to anticipate vertical and lateral distribution of facies and reservoir sands in the basinal, shoreface, incised valley-fill and regressive settings alone has been a great asset for exploration. In frontier areas, where data are often limited to seismic lines, sequence-stratigraphic methodology has helped determine the timing and of types of unconformities and anticipate transgressive- and regressive-prone intervals. In production it is aiding in field development by providing improved source and seal predictions for secondary oil recovery. A recognition of stratigraphic causes of poor recovery through improved understanding of internal stratal architecture can lead to new well recompletions and enhanced exploitation in existing fields. The sequence-stratigraphic discipline is in a state of rapid expansion.
