Mineralogical characteristics and geological significance of Albian (Early Cretaceous) glauconite in Zanda, southwestern Tibet, China

Abstract

<jats:title>Abstract</jats:title><jats:p>Early Cretaceous glauconite from the Xiala section, southwestern Tibet, China, was investigated by petrographic microscopy and scanning electron microscopy (SEM), X-ray diffractometry (XRD), Fourier transform infrared (FTIR) spectroscopy, and electron probe microanalysis (EPMA). The investigations revealed that the glauconite in both sandstones and limestone is highly evolved. The glauconite in sandstone is autochthonous, but in limestone it may be derived from the underlying glauconitic sandstone. Based on analyses of the depositional environments and comparisons of glauconite-bearing strata in Zanda with sequences in adjacent areas, we conclude that the glauconitization at Zanda was probably associated with rising sea levels during the Late Albian, which represent the final separation of the Indian continent from the Australian-Antarctic continent. After the separation of the Indian continent from the Australian-Antarctic continent, cooling of the Indian continent resulted in subsidence and northward subduction of the Indian plate. A gradually rising sea level in Zanda, located along the northern margin of the Indian continent, was the cause of the low sedimentation rate. Continued transgression resulted in the occurrence of the highly evolved glauconite in this area.</jats:p>

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

“…The relationships observed between the glaucony maturity and the geochemical composition of the green grains are consistent with previous works (Kelly and Webb 1999;Giresse et al 2004;Amorosi et al 2007;Banerjee et al 2008Banerjee et al , 2012aLi et al 2012;Baioumy and Boulis 2012;Baldermann et al 2012). Particularly, Fe 2 O 3 and Rb show positive correlations with K 2 O.…”

“…11a). This fact, confirming data from many authors (Odin and Matter 1981;Velde 1985;Odin and Fullagar 1988;Amorosi et al 2007;Banerjee et al 2008Banerjee et al , 2012aLi et al 2012;Baioumy and Boulis 2012;Baldermann et al 2012), suggests that the incorporation of iron mostly predates any potassium uptake into the structure of glauconitic minerals (Odin and Létolle 1980;Odin and Matter 1981;Banerjee et al 2008;Baldermann et al 2012). The direct correlation between K 2 O and Fe 2 O 3 (Fig.…”

“…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;…”

Influence of Zwitterionic CAPB on Flocculation of the Aqueous Cationic Guar Gum/Glauconite Suspensions at Various pH

“…Figure 11 depicts the FTIR spectra of the natural GT clay and the organically modified samples (organoclays). Their comparison shows that the organoclays retain the profile of the starting clay spectrum whose major bands occur in the OH-stretching vibration region (3700-3400 cm −1 ) and in the Si-O/Al-O stretching (1100-900 cm −1 ) and Si-O/Al-O bending vibration areas (600-400 cm −1 ) [45,47]. This observation indicates that the crystalline structure of GT remained unchanged after the modifications made to CGG and CAPB.…”

Variation of minerals and clay minerals recorded in the Neo-Tethys (central Turkey): new evidence of climatic changes during the middle Eocene

“…The presence of the green mineral shows that the carbonates and siliciclastic material composing the Sisters was coming from a shallower platform, in which sedimentation rates were low. Moreover, other studies have related the process of glauconitization during periods of sea-level transgressions(LI et al, 2012). More work is still required in all calcarenite beds throughout the studied section, including detailed work of facies description and thinsections, in order to obtain a conclusive result regarding the origin and forcing mechanisms related to the calcarenite deposition.…”