Multiple fracture sets in the southeastern Permian-Triassic Sydney Basin, New South Wales
Titel:
Multiple fracture sets in the southeastern Permian-Triassic Sydney Basin, New South Wales
Auteur:
Memarian, H. Fergusson, C. L.
Verschenen in:
Australian journal of earth sciences
Paginering:
Jaargang 50 (2003) nr. 1 pagina's 49-61
Jaar:
2003-02
Inhoud:
Fractures in the Upper Permian to Lower Triassic sedimentary succession of the Sydney Basin, along the coast between Wollongong and Coalcliff, include early east-southeast-trending normal faults and abundant joints, faulted joints and secondary cracks that are divided into two main groups. Group I has three main sets trending 010°, 043° and 128°. The 128° set is related to the same stress field that formed the early normal faults. The 010° set is considered related to the north-trending Camden Syncline that forms the major structural feature of the southern Sydney Basin. The 043° set has been related to contractional structures in the Hunter Valley such as the Hunter Thrust. These fractures are considered to have developed interchangeably throughout the Late Permian to Early Triassic in response to a complex stress field. Group I fractures have been reactivated in a number of late-stage events that resulted in the formation of faulted joints, recracked joints and secondary joints which developed adjacent to Group I fractures. Group II includes secondary joints (fringe cracks, en echelon cracks, horsetail cracks, joints <1 m in length) with mean orientations of 024°, 097° and 167°, and a relationship is inferred between the orientation of two of these late events and modern in situ stresses developed in eastern Australia.
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