Facies models of a shallow-water carbonate ramp based on distribution of non-skeletal grains (Kimmeridgian, Spain)

Abstract

The internal facies and sequence architecture of a Late Jurassic (Late Kimmeridgian) shallow carbonate ramp was reconstructed after the analysis and correlation of 17 logs located south of Teruel (northeast Spain). The studied rocks are arranged in Wve high-frequency sequences A-E (5-26 m thick) bounded by discontinuities traceable across the entire study area (20 £ 25 km). Facies analysis across these sequences resulted in the reconstruction of three sedimentary models showing the transition from interior ramp environments (i.e., lagoon, backshoal, and shoal) to the progressively deeper foreshoal and oVshore areas. Coral-microbial reefs (meter-sized patch and pinnacle reefs) have a variable development throughout the sequences, mostly in the foreshoal and oVshore-proximal environments. The preferential occurrence and down-dip gradation of non-skeletal carbonate grains has been evaluated across the three models: low-energy peloidal-dominated, intermittent high-energy oolitic-dominated and highenergy oolitic-oncolitic dominated. The predominance of these non-skeletal grains in the shoal facies was mainly controlled by the hydrodynamic conditions and spatial heterogeneity of terrigenous input. The models illustrate particular cases of down-dip size-decrease of the resedimented grains (ooids, peloids, oncoids) due to storm-induced density Xows. OVshore coarsening of certain particles (intraclasts, oncoids) is locally observed in the mid-ramp areas favorable for microbial activity, involving coral-microbial reef and oncoid development. The observed facies variations can be applicable to carbonate platforms including similar non-skeletal components, where outcrop conditions make the recognition of their three-dimensional distribution diYcult.

Revisiting the Late Jurassic-Early Cretaceous of the NW South Iberian Basin: new ages and sedimentary environments

“…After deposition in the carbonate platform, siliciclastic deposits would have been colonized by burrowers and/or reworked by marine currents. This is supported by paleocurrent data pointing to predominant transport directions oncolitic deposits of the Higueruelas Fm (Aurell, 1990;Aurell et al, 1994) and the Torrecilla Fm (Bádenas and Aurell, 2010) in other sectors of the Iberian Basin, which have been interpreted as oncolitic shoals developed in highly agitated open-marine areas around or above the fair-weather wave base in the inner-ramp of a carbonate platform.…”

Late Jurassic facies architecture of the Złoczew Graben: implications for evolution of the tectonic-controlled northern peri-Tethyan shelf (Upper Oxfordian–Lower Kimmeridgian, Poland)

“…2) to form a succession from mid-ramp microbial-Crescentiella reefs to shallow-water, inner-ramp oolitic fore-shoal, shoal, and back-shoal facies (cf. Bádenas and Aurell 2010). These sediments occur exclusively in the western and northwestern blocks of the graben (Fig.…”

“…Facies interpretation The FT 3 microfacies represents the succession from fore shoal through shoal to back shoal of an oolitic-dominated inner-ramp setting, in which nonskeletal components prevailed (e.g., Bádenas and Aurell 2010). The oolitic grainstone is interpreted as normalmarine shallow water within the range of normal wave base (e.g., Flügel 2004).…”

“…The presence of Bacinella irregularis Radoičić, 1959 suggests a shallow, subtidal, back-shoal environment. The Bacinella oncoids are genetically linked to low-energy, oligotrophic interior lagoons (e.g., Dupraz and Strasser 1999;Védrine et al 2007;Bádenas and Aurell 2010), although, in the Złoczew area, these occur in a higher-energy back shoal with ooid-dominated grainstone.…”

A Review on Microbialites: a Korean Perspective

“…이 시 기의 미생물암은 주로 저위도 지역의 다양한 퇴적 환 경에 분포하였으며 (Kershaw et al, 2012), 트라이아 스기 중기 이후 후생동물 생태계가 대멸종의 타격에 서 점차 회복되면서 크게 감소하였다 (Xie et al, 2010;Brayard et al, 2011). 이후 쥐라기 중후기 및 백악기 초기에 주로 쓰롬볼 라이트와 스트로마톨라이트로 구성된 미생물암이 상 대적으로 흔하게 나타나며, 이들은 얕은 바다에서는 산호와, 깊은 바다에서는 해면동물과 함께 생물초를 형성하였다 (Leinfelder et al, 1993(Leinfelder et al, , 1994Dupraz and Strasser, 1999;Parcell, 2002;Olivier et al, 2003Olivier et al, , 2006Bádenas and Aurell, 2010). 이 시기의 미생물암은 주로 미생물 피각(microbial crust) 형태로 나타나며, 이들은 생물초의 뼈대를 구성하는 산호 등 여러 생물의 표면에 붙어 생장하여 생물초가 물리적 및 생물학적 침식 작용을 버틸 수 있도록 도와준다 (Leinfelder et al, 1993(Leinfelder et al, , 1994Olivier et al, 2003).…”