Upper Permian-Lower Cretaceous clay mineralogy of East Greenland: provenance, palaeoclimate and volcanicity
Abstract:The clay mineralogy of Upper Permian-Lower Cretaceous mudstones from East Greenland has been investigated by X-ray diffraction (XRD), atomic force microscopy (AFM) and thermal analysis in order to evaluate long-term trends in provenance and palaeoclimate and to detect possible volcanic events. The Upper Permian-Lower Triassic mudstones contain illite, chlorite, vermiculite, kaolinite and illite-smectite (I-S), whereas the Rhaetian-Sinemurian mudstones are dominated by kaolinite. Aalenian-Albian mudstones contain kaolinite and large amounts of I-S with ˜80% illite layers. Exceptions are three Kimmeridgian samples, which contain mainly I-S with 30% illite layers, and three Upper Barremian-Lower Aptian samples with large amounts of smectite layers. Discrete clay minerals in the Upper Permian-Jurassic mudstones are largely detrital. The smectite-rich I-S probably reflects episodes of volcanic activity in late Jurassic and late Barremian- early Aptian times. This is the first indication of Mesozoic volcanism from the Mesozoic rift basin of East Greenland. The main sediment source during late Permian-early Cretaceous times was weathered Precambrian and Caledonian crystalline basement. The only possibly climate-induced change is a change from chlorite, illite, vermiculite and kaolinite in Upper Permian-Lower Triassic mudstones to kaolinite and I-S in the Jurassic mudstones and is probably due to an increase in precipitation.
Document Type: Research Article
Publication date: 2000-12-01