Depositional Environments in Carbonate Rocks

1969 ◽  
Author(s):  
Gerald M. Friedman
2015 ◽  
Vol 45 (3) ◽  
pp. 415-429 ◽  
Author(s):  
Ana Carolina Tavares ◽  
Leonardo Borghi ◽  
Patrick Corbett ◽  
Jane Nobre-Lopes ◽  
Raphael Câmara

Lacustrine carbonate rocks form important hydrocarbon accumulations along the Brazilian continental margin, some of which are contained in oil fields in which coquinas are one of the main reservoirs (viz. Campos Basin). The complexity and heterogeneity of these deposits make them a challenge in terms of reservoir description. For the necessary classification and paleoenvironmental interpretation of the coquinas, it is essential to evaluate many aspects including biological (such as carbonate productivity), sedimentological (energy regime in the depositional environment, transport of bioclasts, terrigenous supply), taphonomic (fragmentation of shells, abrasion) and diagenetic processes. The facies analysis applied in this study is considered a more appropriate classification approach to understand these coquinas, since it is more flexible and comprehensive than the existing classifications for carbonate rocks. The material investigated here consists of rock samples of the coquinas from the Atol Quarry of the Morro do Chaves Formation (Barremian/Aptian), Sergipe-Alagoas Basin. These rocks that crop out in the Atol quarry complex can be considered as a case study for similar coquinas reservoirs found in the Brazilian continental margin basins. Six sedimentary facies were described, using the main taphonomic (fragmentation of shells) and compositional (presence of micrite and siliciclastic matrix) features as a diagnostic criteria. Two carbonate facies, two mixed carbonate-siliciclastic facies and two siliciclastic facies (mudstones) were identified. From the facies succession, combined with a review of the literature on the subject, the following depositional paleoenvironments were defined: high-energy lake platform, lacustrine delta in a high-energy lake platform and lake-centre. In this paper, a new facies model for the studied coquinas succession is proposed.


1983 ◽  
Vol 2 (2) ◽  
pp. 145-155
Author(s):  
Pamela Gore

The northern Appalachian Piedmont is underlain by metamorphosed sedimentary and igneous rocks. The sedimentary origin of many of these rocks was established during the late 1800's. Other rocks, particularly the massive inclusion-bearing metasediments (diamictites), were considered to be xenolithic granites until the 1940's or later. Relict sedimentary textures and structures are preserved in some Piedmonst metasediments despite sillimanite-grade metamorphism. Few sedimentary structures, other than bedding, were reported until the early 1960's, when graded bedding and sequences of sedimentary structures resembling the Bouma Cycle, characteristic of turbidity current deposits, were reported front metagraywackes in the Maryland Piedmont. The metagraywackes are now interpreted as submarine fan deposits. Few of the metasediments have been studied from a sedimentologic viewpoint. Most of our knowledge of the sedimentary structures and depositional environments has been contributed by igneous and metamorphic petrologists, primarily George W. Fisher and Clifford A. Hopson. Sedimentologists (Juergen Reinhardt and Gregory S. Gohn) working in the Piedmont have dealt primarily with lower metamorphic grade carbonate rocks in the western and northwestern Piedmont.


2018 ◽  
Vol 120 ◽  
pp. 77-107
Author(s):  
M.I. Tuchkova ◽  
S.D. Sokolov ◽  
T.N. Isakova ◽  
O.L. Kossovaya ◽  
T.V. Filimonova ◽  
...  

2021 ◽  
pp. 2580-2588
Author(s):  
Noor T. Altaee ◽  
Zaid A. Malak

The Early Jurassic (Liassic) sequence crops out in numerous anticlines of the high folded zone of north and north-east Iraq and in the Rutba subzone (including Ubaid Formation) in west Iraq. The present study deals with siliciclastic / carbonate rocks of the 58 m-thick Ubaid Formation at Zor Hauran valley in south western Iraq. The formation consists of two parts; the lower part is composed of pebbly coarse sandstone and greenish to yellowish soft marl alternated with marly dolostone, while the upper part is characterized by light brown, well bedded dolostone, with stromatolite structure in some locations. Oval, light to dark brown nodules of chert are also present.      A detailed field lithological description and facies analysis of the Ubaid Formation were performed for thin sections. It is composed of five main microfacies; dolomitized mudstone, dolomitized bioclastic wackstone, dolomitized pelloidal packstone, dolomitized oolitic grainstone, and bindstone, in addition to two lithofacies: marl and pebbly sandstone. These facies reflect the deposition from the environment of the lower supratidal to intertidal zone and the encompassing shallow scaffold secured shoal - marine environment with cautious water circulation.


Sign in / Sign up

Export Citation Format

Share Document