The post-Mesoproterozoic tectonometamorphic history of the Musgrave Province, central Australia, has previously been solely attributed to intracontinental compressional deformation during the 580 -520 Ma Petermann Oro...The post-Mesoproterozoic tectonometamorphic history of the Musgrave Province, central Australia, has previously been solely attributed to intracontinental compressional deformation during the 580 -520 Ma Petermann Orogeny. However, our new structurally controlled multi-mineral geochronology results,from two north-trending transects, indicate protracted reactivation of the Australian continental interior over ca. 715 million years. The earliest events are identified in the hinterland of the orogen along the western transect. The first tectonothermal event, at ca. 715 Ma, is indicated by40 Ar/39 Ar muscovite and U e Pb titanite ages. Another previously unrecognised tectonometamorphic event is dated at ca. 630 Ma by Ue Pb analyses of metamorphic zircon rims. This event was followed by continuous cooling and exhumation of the hinterland and core of the orogen along numerous faults, including the Woodroffe Thrust,from ca. 625 Ma to 565 Ma as indicated by muscovite, biotite, and hornblende40 Ar/39 Ar cooling ages. We therefore propose that the Petermann Orogeny commenced as early as ca. 630 Ma. Along the eastern transect,40 Ar/39 Ar muscovite and zircon(Ue Th)/He data indicate exhumation of the foreland fold and thrust system to shallow crustal levels between ca. 550 Ma and 520 Ma, while the core of the orogen was undergoing exhumation to mid-crustal levels and cooling below 600-660℃. Subsequent cooling to 150 -220℃ of the core of the orogen occurred between ca. 480 Ma and 400 Ma(zircon [Ue Th]/He data)during reactivation of the Woodroffe Thrust, coincident with the 450 -300 Ma Alice Springs Orogeny.Exhumation of the footwall of the Woodroffe Thrust to shallow depths occurred at ca. 200 Ma. More recent tectonic activity is also evident as on the 21 May, 2016(Sydney date), a magnitude 6.1 earthquake occurred, and the resolved focal mechanism indicates that compressive stress and exhumation along the Woodroffe Thrust is continuing to the present day. Overall, these results demonstrate repeated amagmatic reactivation of the continental interior of Australia for ca. 715 million years, including at least 600 million years of reactivation along the Woodroffe Thrust alone. Estimated cooling rates agree with previously reported rates and suggest slow cooling of 0.9 -7.0℃/Ma in the core of the Petermann Orogen between ca. 570 Ma and 400 Ma. The long-lived, amagmatic, intracontinental reactivation of central Australia is a remarkable example of stress transmission, strain localization and cratonization-hindering processes that highlights the complexity of Continental Tectonics with regards to the rigid-plate paradigm of Plate Tectonics.展开更多
The Amadeus Basin of central Australia has a depositional history spanning the Neoproterozoic to the Devonian/Carboniferous.It was initiated as part of the Neoproterozoic Centralian Superbasin,which formed in an intra...The Amadeus Basin of central Australia has a depositional history spanning the Neoproterozoic to the Devonian/Carboniferous.It was initiated as part of the Neoproterozoic Centralian Superbasin,which formed in an intracratonic setting related to the break up of Rodinia.Sedimentation continued until the 580–540 Ma Petermann Orogeny,coinciding with the assembly of Gondwana,which resulted in the fragmentation of the superbasin into separate intracratonic basins.The Petermann Orogeny was focused in the Musgrave Province and the southern part of the Amadeus Basin,and involved significant N-directed shortening on largescale structures that involved both the basement and the overlying Neoproterozoic sedimentary rocks.It significantly transformed the basin architecture,with the development of major basin features that controlled subsequent sedimentation.Deposition of Paleozoic successions was largely concentrated in sub-basins and troughs in the N of the basin,where up to 14 km is preserved.Minor events or uplifts punctuated this depositional history and account for local disconformities and absent sections.The 450–300 Ma Alice Springs Orogeny was a multi-phase,intracratonic event concentrated in the Arunta Region and the northern part of the Amadeus Basin.Like the earlier Petermann Orogeny,the Alice Springs Orogeny involved both basement and basin sedimentary rocks,but with overall S-directed movement.Synorogenic sedimentation accompanied Mid–Late Devonian uplift,with Late Devonian–Carboniferous basin inversion terminating sedimentation,and folding the youngest successions.The Amadeus Basin has known reserves of U,minor historic and recent Au production,and is prospective for base metals,especially Cu,and phosphate.The Ordovician succession supports commercial gas production,and the Neoproterozoic succession is considered prospective for oil and gas.展开更多
基金M.D. was supported by the AuScope NCRIS2 program,Australian Scientific Instruments Pty Ltd., Australian ResearchCouncil (ARC) Discovery funding scheme (DP160102427)Cur-tin Research Fellowship
文摘The post-Mesoproterozoic tectonometamorphic history of the Musgrave Province, central Australia, has previously been solely attributed to intracontinental compressional deformation during the 580 -520 Ma Petermann Orogeny. However, our new structurally controlled multi-mineral geochronology results,from two north-trending transects, indicate protracted reactivation of the Australian continental interior over ca. 715 million years. The earliest events are identified in the hinterland of the orogen along the western transect. The first tectonothermal event, at ca. 715 Ma, is indicated by40 Ar/39 Ar muscovite and U e Pb titanite ages. Another previously unrecognised tectonometamorphic event is dated at ca. 630 Ma by Ue Pb analyses of metamorphic zircon rims. This event was followed by continuous cooling and exhumation of the hinterland and core of the orogen along numerous faults, including the Woodroffe Thrust,from ca. 625 Ma to 565 Ma as indicated by muscovite, biotite, and hornblende40 Ar/39 Ar cooling ages. We therefore propose that the Petermann Orogeny commenced as early as ca. 630 Ma. Along the eastern transect,40 Ar/39 Ar muscovite and zircon(Ue Th)/He data indicate exhumation of the foreland fold and thrust system to shallow crustal levels between ca. 550 Ma and 520 Ma, while the core of the orogen was undergoing exhumation to mid-crustal levels and cooling below 600-660℃. Subsequent cooling to 150 -220℃ of the core of the orogen occurred between ca. 480 Ma and 400 Ma(zircon [Ue Th]/He data)during reactivation of the Woodroffe Thrust, coincident with the 450 -300 Ma Alice Springs Orogeny.Exhumation of the footwall of the Woodroffe Thrust to shallow depths occurred at ca. 200 Ma. More recent tectonic activity is also evident as on the 21 May, 2016(Sydney date), a magnitude 6.1 earthquake occurred, and the resolved focal mechanism indicates that compressive stress and exhumation along the Woodroffe Thrust is continuing to the present day. Overall, these results demonstrate repeated amagmatic reactivation of the continental interior of Australia for ca. 715 million years, including at least 600 million years of reactivation along the Woodroffe Thrust alone. Estimated cooling rates agree with previously reported rates and suggest slow cooling of 0.9 -7.0℃/Ma in the core of the Petermann Orogen between ca. 570 Ma and 400 Ma. The long-lived, amagmatic, intracontinental reactivation of central Australia is a remarkable example of stress transmission, strain localization and cratonization-hindering processes that highlights the complexity of Continental Tectonics with regards to the rigid-plate paradigm of Plate Tectonics.
文摘The Amadeus Basin of central Australia has a depositional history spanning the Neoproterozoic to the Devonian/Carboniferous.It was initiated as part of the Neoproterozoic Centralian Superbasin,which formed in an intracratonic setting related to the break up of Rodinia.Sedimentation continued until the 580–540 Ma Petermann Orogeny,coinciding with the assembly of Gondwana,which resulted in the fragmentation of the superbasin into separate intracratonic basins.The Petermann Orogeny was focused in the Musgrave Province and the southern part of the Amadeus Basin,and involved significant N-directed shortening on largescale structures that involved both the basement and the overlying Neoproterozoic sedimentary rocks.It significantly transformed the basin architecture,with the development of major basin features that controlled subsequent sedimentation.Deposition of Paleozoic successions was largely concentrated in sub-basins and troughs in the N of the basin,where up to 14 km is preserved.Minor events or uplifts punctuated this depositional history and account for local disconformities and absent sections.The 450–300 Ma Alice Springs Orogeny was a multi-phase,intracratonic event concentrated in the Arunta Region and the northern part of the Amadeus Basin.Like the earlier Petermann Orogeny,the Alice Springs Orogeny involved both basement and basin sedimentary rocks,but with overall S-directed movement.Synorogenic sedimentation accompanied Mid–Late Devonian uplift,with Late Devonian–Carboniferous basin inversion terminating sedimentation,and folding the youngest successions.The Amadeus Basin has known reserves of U,minor historic and recent Au production,and is prospective for base metals,especially Cu,and phosphate.The Ordovician succession supports commercial gas production,and the Neoproterozoic succession is considered prospective for oil and gas.
