Source of the Lachlan fold belt flysch linked to convective removal of the lithospheric mantle and rapid exhumation of the Delamerian-Ross fold belt

Abstract

Research Article| October 01, 1996 Source of the Lachlan fold belt flysch linked to convective removal of the lithospheric mantle and rapid exhumation of the Delamerian-Ross fold belt S. P. Turner; S. P. Turner 1Department of Earth Sciences, Open University, Milton Keynes MK7 6AA, United Kingdom Search for other works by this author on: GSW Google Scholar S. P. Kelley; S. P. Kelley 1Department of Earth Sciences, Open University, Milton Keynes MK7 6AA, United Kingdom Search for other works by this author on: GSW Google Scholar A. H. M. VandenBerg; A. H. M. VandenBerg 2Department of Energy and Minerals, Victoria 3065, Australia Search for other works by this author on: GSW Google Scholar J. D. Foden; J. D. Foden 3Department of Geology and Geophysics, University of Adelaide, South Australia 5005, Australia Search for other works by this author on: GSW Google Scholar M. Sandiford; M. Sandiford 3Department of Geology and Geophysics, University of Adelaide, South Australia 5005, Australia Search for other works by this author on: GSW Google Scholar T. Flöttmann T. Flöttmann 3Department of Geology and Geophysics, University of Adelaide, South Australia 5005, Australia Search for other works by this author on: GSW Google Scholar Author and Article Information S. P. Turner 1Department of Earth Sciences, Open University, Milton Keynes MK7 6AA, United Kingdom S. P. Kelley 1Department of Earth Sciences, Open University, Milton Keynes MK7 6AA, United Kingdom A. H. M. VandenBerg 2Department of Energy and Minerals, Victoria 3065, Australia J. D. Foden 3Department of Geology and Geophysics, University of Adelaide, South Australia 5005, Australia M. Sandiford 3Department of Geology and Geophysics, University of Adelaide, South Australia 5005, Australia T. Flöttmann 3Department of Geology and Geophysics, University of Adelaide, South Australia 5005, Australia Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1996) 24 (10): 941–944. https://doi.org/10.1130/0091-7613(1996)024<0941:SOTLFB>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation S. P. Turner, S. P. Kelley, A. H. M. VandenBerg, J. D. Foden, M. Sandiford, T. Flöttmann; Source of the Lachlan fold belt flysch linked to convective removal of the lithospheric mantle and rapid exhumation of the Delamerian-Ross fold belt. Geology 1996;; 24 (10): 941–944. doi: https://doi.org/10.1130/0091-7613(1996)024<0941:SOTLFB>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract During the Cambrian-Ordovician the paleo–Pacific margin of Gondwana underwent a rapid transition from a site of convergent deformation (Delamerian-Ross orogeny) to one of sedimentation during which the thick turbiditic sequences of the adjacent basal Lachlan fold belt were deposited. Laser-probe 40Ar-39Ar data show that the synkinematic (523–486 Ma), mid-crustal I- and S-type granites and metamorphic country rocks of the Delamerian fold belt were rapidly cooled at 490–485 Ma, coincident with the intrusion of a suite of high-level, postkinematic A-type granites and gabbros (ca. 497–481 Ma). 40Ar-39Ar data on detrital muscovites from the basal sections of the Lachlan fold belt provide information on exhumation rather than cooling but yield an age pattern (507–480 Ma) identical to that of the Delamerian fold belt, demonstrating that this was the source of the sediments. The combined data require that some 15 km of exhumation occurred very rapidly (∼ 5–15 mm ·yr−1), coincident (as implied by overlapping ages) with the cessation of convergent deformation and partial melting to form the postkinematic magmas. This scenario implies a causative link, which we infer to have been convective removal of lithospheric mantle following orogenic thickening. The model is analogous to the Tertiary uplift of the India-Asia orogen, which provided the sediment source for the Bengal fan. Our results suggest that similar processes were important in the evolution of mountain belts at least as far back as the early Phanerozoic. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.