Stable Isotope Geochemistry of Kaolinite from the “White Section,” Black Ridge, Clermont, Central Queensland: Implications For The Age And Origin of the “White Section”

Abstract

Abstract--Kaolinite from the Black Ridge, Clermont, has relatively low ~lsO (12.3%0 to 14.8%o) and very low ~D values with a large variation (-120%o0 to -85%0). Comparison of these data with those from the nearby Denison Trough and elsewhere in eastern Australia, together with previous studies of the mineralogy of the sedimentary rocks, suggests that extensive kaolinization of the "White Section" resulted from weathering during the Late Triassic to Early Jurassic periods. The relatively large variation in #D values of kaolinite probably derives from post-formational isotopic exchange with other fluids.The similarity between ~lsO values of kaolinites from Black Ridge and from the Denison Trough suggests that the small Miclere-Black Ridge basin may have been part of the Denison Trough before the Late-Triassic inversion. The preservation of original ~D values in kaolinite at Black Ridge indicates that unlike the Denison Trough, which was reburied at more than 1000 m, the Miclere-Black Ridge basin was not rebuffed at great depth during the Mesozoic period.