Limestone Microfacies Research Articles

Microbialitic structures in the Sarmatian carbonate deposits from Şimleu Basin, Romania

The Sarmatian deposits from the Şimleu basin are developed in two facies: terrigenous and calcareous. An attempt to distinguish the main types of Sarmatian limestone microfacies was made by Bucur et al. (1992). The present study provides more detail of the sedimentary facies and fabrics of these limestones, emphasizing the essential contribution of microbialites to their formation. The following types of microbialite and microbial structure were found: (1) thrombolites with clotted fabric and fenestral structures; (2) microbial crusts on bioclasts; (3) peloidal microbialites (4) agglutinated microbialites; (5) stromatolites and laminoid-fenestral structures. All these structures played an important role in the accretion of the Sarmatian carbonate deposits in the area studied.

Limestone Microfacies and Sequence Stratigraphy: Eagle Ford Group, North-Central Texas Outcrops : ABSTRACT

Limestone Microfacies and Sequence Stratigraphy: Eagle Ford Group, North-Central Texas Outcrops : ABSTRACT

Microfacies of Cambrian Limestones in Jordan

The limestones of the Wadi Nasb Formation of the uppermost Lower Cambrian of Jordan are under- and overlain by massive sandstones of a near-shore facies. Facies analysis is based on samples from an outcrop at the northeastern shore of the Dead Sea and two oil test wells in the Wadi Sirhan Depression in eastern Jordan. Limestones were deposited in the shallow sea and within the coastal tidal area. Cyanobacteria, algae, echinoderms, trilobites and hyoliths have contributed the bulk of the carbonate and phosphatic material composing the Wadi Nasb limestone. Fine-grained facies types are composed of peloidal carbonate muds with laminar and nodular algal and cyanobacterial mats. They formed within a quiet tidallagoonal environment. The coarse grained facies types consist of carbonate sands with layers of sheell debris deposited in crossbeds in an environment with a rich endobenthic fauna. Here most particles were coated by cyanobacterial crusts. Ooids, oncoids and various coated grains are present. Consolidated sediments were commonly eroded within or near to this environment and their remains were integrated within the sands. Diagenesis is reconstructed step by step with deposition, first cementation, aragonite dissolution, compaction, pore filling, formation of pressure solution, growth of dolomite and anhydrite within the calcitic limestone and final fissure formation and filling.

Las microfacies carbonatadas neógenas en un sector occidental de la depresión del Bajo Guadalquivir

It sets up limestone microfacies (microfacies A to G) in the neogene calcarenitic materials of Carmona, Alcala de Guadaira and Arcos de la Frontera-Bornos, localizated in the occidental sector of the Guadalquivir Basin. Their analysis allow to define the implantation of a mixed shelf environment, a carbonate ramp in a open marine ambient, during Upper Miocene-Lower Pliocene, in such sectors. The composition of these limestones represents the «Foramol» lithofacies. More closely, «molechfor» (Carmona-Alcala de Guadaira) and «bryomol» (Arcos de la Frontera-Bornos). Minimum and medium temperature were < 15 and < 180 oC. Salinity varied between 30-40 ‰ (marine normal salinity). It diferenciates the standard microfacies types SMF 9 and SMF 11 and the facies zone FZ 2 and FZ 6 that respond to shallow waters with open circulation in (or below) wave base and winnowed shelf edges with constant wave action in (or above) wave base, in the Carmona area platform. Ambient energy varied between intermitent (microfacies A) and moderated (microfacies B-C). In Alcala de Guadaira and Arcos de la Frontera-Bornos sectors have been stablished SMF 11, SMF 12 (Shelf edges) and FZ 6. These microfacies are deposited in moderated (microfacies D,E,F) and strongly agitated water (microfacies G). Two shallow subtidal zones with lower boundary at about 30 m (microfacies B-e and F-G) have been delimitated. Limestones are temperate-polar carbonates. Exactly, the carbonate platform is «cold temperate ».

Introduction to the Petrology of the Oil-Shale Group Limestones of West Lothian and Southern Fifeshire, Scotland

ABSTRACT Five distinctive limestone micro-facies (oolitic, oolitoid, micro-conglomeratic, shelly, and nodular) are recognised, each of which may be present within one individual bed. They generally indicate shallow water, restricted lagoonal conditions inimical to organic life. Sometimes the conditions were modified, allowing organisms such as worms and ostracods to proliferate; rarely, a widespread linkage of adjacent lagoons allowed a more comprehensive fauna to develop. The limestones are invariably associated with shales into which they normally sharply grade.