TY - JOUR
T1 - Stratigraphic record of an Atlantic-type global tectonic cycle in the Palaeoproterozoic Ashburton Province of Western Australia
AU - Krapez, B.
PY - 1999
Y1 - 1999
N2 - New descriptive and interpretive stratigraphic frameworks for the Ashburton (and Gascoyne) Province of the Capricorn Orogen are based on sequence stratigraphy. Two megasequences are recognised. A lower megasequence (Megasequence VIIIL) is interpreted to record the opening, to the northwest, of an Atlantic-type ocean. Four supersequences record rift and thermal-subsidence stages of a divergent continental margin, with north- or northeast-trending ocean-margin and northwest-trending failed-rift geometries. There is no evidence for a southern oceanic regime. Rather, the Gawler Craton of South Australia is interpreted to have lain to the southwest of the Pilbara Craton, such that the cratons were a contiguous divergent continental margin. An upper megasequence (Megasequence VIIIU) is interpreted to record the conversion of the divergent margin to a convergent (hinterland) margin during southeast-dipping subduction. Eight supersequences are recognised. These record backarc, remnant-ocean, retroarc-satellite and indent-linked hinterland basins. All the basins preserve the failed-rift geometry. To the southwest, collision-indentation of the hinterland (Pilbara-Gawler) continent by an indenter (Yilgarn Craton) is interpreted to have begun during the remnant-ocean stage. An east- to east-southeast-trending megashear between the Pilbara and Yilgarn Cratons is interpreted to have been the boundary transform fault on the northern margin of that indenter.
AB - New descriptive and interpretive stratigraphic frameworks for the Ashburton (and Gascoyne) Province of the Capricorn Orogen are based on sequence stratigraphy. Two megasequences are recognised. A lower megasequence (Megasequence VIIIL) is interpreted to record the opening, to the northwest, of an Atlantic-type ocean. Four supersequences record rift and thermal-subsidence stages of a divergent continental margin, with north- or northeast-trending ocean-margin and northwest-trending failed-rift geometries. There is no evidence for a southern oceanic regime. Rather, the Gawler Craton of South Australia is interpreted to have lain to the southwest of the Pilbara Craton, such that the cratons were a contiguous divergent continental margin. An upper megasequence (Megasequence VIIIU) is interpreted to record the conversion of the divergent margin to a convergent (hinterland) margin during southeast-dipping subduction. Eight supersequences are recognised. These record backarc, remnant-ocean, retroarc-satellite and indent-linked hinterland basins. All the basins preserve the failed-rift geometry. To the southwest, collision-indentation of the hinterland (Pilbara-Gawler) continent by an indenter (Yilgarn Craton) is interpreted to have begun during the remnant-ocean stage. An east- to east-southeast-trending megashear between the Pilbara and Yilgarn Cratons is interpreted to have been the boundary transform fault on the northern margin of that indenter.
U2 - 10.1046/j.1440-0952.1999.00688.x
DO - 10.1046/j.1440-0952.1999.00688.x
M3 - Article
SN - 0812-0099
VL - 46
SP - 71
EP - 87
JO - Australian Journal of Earth Sciences
JF - Australian Journal of Earth Sciences
ER -