Depositional and tectonic history of the southern New England Orogen

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Abstract
The southern part of the New England Orogen in the Hunter‐Myall region of NSW consists of the southeasterly extremity of the Tamworth Belt, a region of Devonian‐Carboniferous shelfal deposition between a volcanic arc in the west and a deep water accretionary wedge in the east. These depositional elements, which may have been separated from the Australian continent during the Devonian‐Middle Carboniferous, were deformed during the Permian and Triassic by up to four folding events separated by episodes of granitoid emplacement. Depositional patterns were influenced by five major cycles of sea level changes between the Late Devonian and Permian, an influx of volcanic detritus from an arc which changed in composition from andesitic in the Devonian, through dacitic in the Early Carboniferous to mainly rhyolitic in the Late Carboniferous, and in the Early Carboniferous by penecontemporaneous faulting within the shelf. The overall Carboniferous pattern of deposition was regressive. Rapid southerly movement of the Yarrol‐New England Orogen and possible accretion with the Australian continent in the mid‐Carboniferous coincided with the culmination of volcanic activity, a widespread disconformity, and a rapid change of climate that led to the extinction of the cosmopolitan marine invertebrate fauna, its replacement by the cold water Gondwanan fauna, and establishment of a widespread ice cap. The first orogenic event late in the Carboniferous was followed by rifting and subsidence of the Sydney Basin on the south and west flanks of New England. Folding of the southern Tamworth Belt and injection of serpentinite into the Peel and Manning Fault Systems took place in the Early Permian and was followed by emplacement of the Barrington Tops Granodiorite, and further folding in the Late Permian was similarly followed by intrusion of the New England Batholith. The initial folding generated active basins of deposition (Stroud‐Gloucester Syncline) in which Permian marine and coal measure sediments were deposited. Uplift associated with Late Permian or Triassic granitoid intrusion caused the detachment of Carboniferous blocks which slid south and southwest, generating a low angle thrust along southern parts of the Hunter Fault System. Final folding in the Late Triassic may have been related to dextral movement along the Demon Fault in the northern New England Orogen.