A trough cross‐stratified glaucarenite: a Cambrian tidal inlet accumulation

Abstract

The upper part of the Riley Formation, Cambrian of central Texas, is primarily composed of a sequence of thoroughly trough cross‐stratified deposits. The dominant lithologies range from fossiliferous glaucarenite to highly glauconitic bio‐sparrudite. These cross‐stratified deposits accumulated within a tidal inlet and associated lagoonal tributary and distributary channels. Tidal inlet‐fill strata are underlain by shallow, open marine oosparites and biomicrites and are overlain by parallel bedded glaucarenites which accumulated as part of a barrier island complex. The parallel bedded deposits exhibit large scale, gently inclined strata, ripple cross‐stratification, and a minor amount of vertical burrows. Some glaucarenite units within the tidal inlet‐fill have local concentrations of skeletal material, primarily trilobite carapaces. These concentrations are most abundant in the bottoms of troughs. Cementation by bladed to fibrous spar between the carapaces has resulted in the nodular appearance of these skeletal accumulations. Calcite clasts, with relict evaporite textures, occur within the carbonate nodules and surrounding glaucarenite. These clasts were eroded from the shallow subsurface of the barrier island as the tidal inlet migrated. The presence of the former evaporite clasts attest to an arid climate at the time of their formation.

Constraints on the development of Proterozoic basins in central India from 40Ar/39Ar analysis of authigenic glauconitic minerals

“…The glauconitic minerals, irrespective of their depositional settings, occur as syndepositional or penecontemporaneous authigenic phases, replacing other minerals by a dissolution-precipitation process, as direct precipitates on mineral surfaces, or in intergranular pores (Odom, 1976;Odin and Matter, 1981;Ireland et al, 1983;Chafetz, 1978;Dasgupta et al, 1990;Chaudhuri et al, 1994;PatranabisDeb and Fukuoka, 1998;Chafetz and Reid, 2000). The minerals form at or very close to the sediment-water interface, the transition zone between oxidizing conditions above and reducing conditions below.…”

“…Glauconitic minerals in modern environments usually occur in water depths of midshelf to up- Storm-tide-deposited sandstone beds within limestone per slope, where sedimentation rate tends to be effectively null (Odin and Matter, 1981;Ireland et al, 1983), whereas in Purana formations and in the Cambrian-Ordovician strata of southwestern United States, the minerals occur abundantly in sandstones deposited in high-energy tidal fl atand tide-dominated inner-shelf environments (Chafetz, 1978;Dasgupta et al, 1990;Chaudhuri et al, 1994;Patranabis-Deb and Fukuoka, 1998;Chafetz and Reid, 2000). The glauconitic minerals, irrespective of their depositional settings, occur as syndepositional or penecontemporaneous authigenic phases, replacing other minerals by a dissolution-precipitation process, as direct precipitates on mineral surfaces, or in intergranular pores (Odom, 1976;Odin and Matter, 1981;Ireland et al, 1983;Chafetz, 1978;Dasgupta et al, 1990;Chaudhuri et al, 1994;PatranabisDeb and Fukuoka, 1998;Chafetz and Reid, 2000).…”

Glauconitic-rich strata from Oligo-Miocene shallow-marine siliciclastic deposits of the northern margin of Africa (Tunisia): geochemical approach for basin analysis

“…Detailed analysis of literature on glaucony has shown the importance of a thorough investigation of glaucony characteristics as a reliable tool for basin analysis. Specifically, the glauconitic minerals have been extensively studied in terms of genetical models and depositional environments (Chafetz 1970(Chafetz , 1973(Chafetz , 1978Siavochani et al 1978;Odin and Matter 1981;Logvinenko 1982;King and Chafetz 1983;Odin 1985;Chafetz et al 1986;Odin and Fullagar 1988;Odin and Morton 1988; Kelly and Webb 1999;Chafetz and Reid 2000;Pasquini et al 2004;Ozgüner and Varol 2009;Hossain et al 2011a, b;Banerjee et al 2012a, b;Baioumy and Boulis 2012;Li et al 2012), chronostratigraphy (Odin 1988;Morton and Long 1980;Keppens and Pasteels 1982;Odin 1982a, b, c;Grant et al 1984;Craig et al 1989;Clauer et al 1992;Amorosi 1993;Smith et al 1993;Stille and Clauer 1994;;Smith et al 1998;Gopalan 2008;Conrad et al 2011), sequence stratigraphy (Loutit et al 1988;Shanmugam 1988;Van Wagoner et al 1990;Vail et al 1991;Amorosi 1995;Centineo 1997, 2000;Banerjee et al 2008;…”