Apophyllite ⁴⁰Ar/³⁹Ar and Rb‐Sr geochronology: Potential utility and application to the timing of secondary mineralization of the Kirkpatrick Basalt, Antarctica

Exceptional Multi Stage Mineralization of Secondary Minerals in Cavities of Flood Basalts from the Deccan Volcanic Province, India

“…With respect to the Rb-Sr method, it has to be mentioned that even if the Rb content is low in stilbite, extremely low in calcite, and the Sr content in some of the apopyllite is less than 1 ppm, the results are reliable from an analytical point of view. Two arguments support this assumption: (i) apophyllite and stilbite show characteristic concentrations for Rb and Sr in a limited range, which fits to data from the literature [70,107]; and (ii) repeated analyses of one apophyllite concentrate (JAL-16B) and two separates representing the core and rim of a centimeter-sized apophyllite crystal (JAL-13C) yield consistent analytical results. The 87 Rb/ 86 Sr ratios (40-860) fit to those reported in Fleming [70] and are in the range of muscovite or biotite.…”

“…Two arguments support this assumption: (i) apophyllite and stilbite show characteristic concentrations for Rb and Sr in a limited range, which fits to data from the literature [70,107]; and (ii) repeated analyses of one apophyllite concentrate (JAL-16B) and two separates representing the core and rim of a centimeter-sized apophyllite crystal (JAL-13C) yield consistent analytical results. The 87 Rb/ 86 Sr ratios (40-860) fit to those reported in Fleming [70] and are in the range of muscovite or biotite. The second data points used for age calculation are characterized by low 87 Rb/ 86 Sr ratios (<1), and, therefore, the measured 87 K contents of the apophyllite concentrate used for K-Ar age determination were measured by atomic absorption spectrometry (AAS).…”

“…In XRD analyses, a double peak was present at the beginning of the spectra, indicating a hydroxyl-apophyllite component. The measured molar K/Ca ratios were in the range of 0.238-0.259 and fit to those of ideal fluor-apophyllite (0.244) [70]. Apophyllite represented the youngest mineral generation in the cavities of the Savda quarries and was commonly deposited on the chalcedony crust of the filaments or wall linings and other earlier crystallized minerals.…”

Paleomagnetism of the Jurassic Transantarctic Mountains revisited — Evidence for large dispersion of apparent polar wander within less than 3 Myr

“…K-Ar studies of Ferrar apophyllites (Fleming et al, 1999;Molzahn et al, 1999) dating thermal events postdating the emplacement of the Ferrar volcanics by up to 80 Ma. However, since formation of apophyllite is related to groundwater flow and uplift at rather low temperatures, it is more than unlikely that a link between zeolite (e.g.…”

Permian-Triassic boundary in the central Transantarctic Mountains, Antarctica

“…The occurrence of prehnite in the claystone breccia bed also suggests elevated temperatures, possibly more than 200 °C (Schiffman and Day, 1999). Fullerenes may be extremely resistant, but it is surprising that they, with their encapsulated noble gases and Fe-Ni-Si meteoritic fragments, could have survived such conditions in the Jurassic and also survived younger hydrologic regime changes related to uplift (Fleming et al, 1999). However, such fragments might have been isolated by enclosure within the berthierine nodules reported by Sheldon and Retallack (2002).…”