Kimban orogeny

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The Kimban orogenesis is a plate tectonic and orogenic event that occurred from 1730 to 1690 mya between the still connected South Australian Gawler Craton and Terre Adélie Craton on the one hand and the Curnamona Craton on the other. Together with the recent but somewhat older Nimrod orogeny , which occurred on the eastern edge of East Antarctica at the time , they define the existence of the Mawson craton . These orogenic processes are collectively referred to as Nimrod-Kimban orogenesis. In terms of time, they coincide with the formation range of the hypothetical supercontinent Columbia , which developed from around 2000 mya.

Name reference

The name of the Kimban orogeny is based on the South Australian town of Kimba . This is located in the northwest of the Eyre Peninsula in South Australia on the Eyre Highway . Kimba is an Aboriginal word for bush fire .

Geological framework

The Kimban orogeny can be traced on the eastern edge of the Gawler craton and the Terre Adélie craton. These continental crustal units, which are now separate, were tectonically connected up to rift fractures from around 160 mya. The hypothetical Curnamona kraton collided with these. Little is known of its shape, size and structure. The multiple rift breaks with their volcanic and sedimentary deposits in the neoproterozoic to central Cambrian Adelaide Geosyncline (Adelaide Rift Complex) form a large subsidence zone between the Curnamona craton and the Gawler craton. This extends from the Flinders Ranges (Flinders Ranges) in the north to Kangaroo Island (Kangaroo Iceland) in the south of South Australia.

From comparable overburden sequences in the Mount Isa Basin in northwest Queensland and in the Willyama Supergroup in the Curnamona Province, it was concluded that they were deposited on the basement of the Curnamona craton. This paleo- to early Mesoproterozoic basement was highly metamorphic overprinted and complexly deformed. It is open in the Willyama Inlier ( Zeugenberg ) in the southern zone of the Curnamona Province and in the Mount Painter Inlier and Mount Babbage Inlier on the northern edge of the Curnamona Province. The Curnamona Province extends to the east of South Australia and western New South Wales .

Geodynamic processes

The Kimban orogeny is understood as a profound tectono-volcano-metamorphic process in a transpressional tectonic regime. This is characterized by sheet displacements (strike-slip fault), combined with shortening and often exhumation of crustal units. It is particularly well documented on the South Australian Eyre Peninsula . This is the southern part of the Gawler craton. On it, two significant, geologically completely different crustal units can be distinguished, in which subhorizontal elongation linear , extrusions of magmatites , formation of large-scale shear zone systems and drastic changes in metamorphic degrees occurred. These crustal units form the Cleve Domain and the Spencer Domain.

The Cleve Domain developed in the western area of ​​the Eyre Peninsula. Their geology is dominated by paleoproterozoic metasedimentary rocks of the Hutchison group and by Felsic gneisses . The western part of the Cleve Domain was penetrated by granites of the Mesoproterozoic Hiltaba Suite. The Spencer Domain is located in the easternmost areas of the Eyre Peninsula and is characterized in the south by the granites of the Donington Suite. The northwestern part of the Spencer Domain contains mesoarchic granites and gneisses and paleoproterozoic metasedimentary rocks in the northeast. While the Cleve domain has an evenly low magnetic signature , the Spencer domain has a high magnetic signature. Their differences result from the different magnetic components in the rocks . The Spencer domain is rich in iron ore , including at bands ores (banded iron formation) and other metal ores .

The Kalinjala Shear Zone separates the different lithostratigraphic zones of the Cleve Domain from the Spencer Domain. This is a 4 to 6 kilometer wide, dextral (right-facing) transpressive, sub-vertical, highly stressed shear zone . It also corresponds to a large magnetic discontinuity . Along this shear zone, rocks were severely deformed, sometimes extremely folded and metamorphically overprinted. The degree of metamorphosis ranges from green slate facies to granulite facies . The Kalinjala Shear Zone can be followed up to the Mertz shear zone, named after the neighboring Antarctic Mertz Glacier , in the Terre Adélie craton. Both represent a geosuture on the eastern edge of the craton that separates the western archaic from the younger eastern crustal units.

During the Kimban orogeny from 1715 mya sedimentation and volcanism formed in the central Gawler craton in isolated basins with conglomerates , quartzites and schists as well as rockic and mafic volcanic rocks .

The Magmatismus during Kimban-Orogenese comprises granite assemblages mainly I-type (from magmatic rocks coming) and (derived from molten sediment) from the S-type. This magmatism extends over most of the Gawler Craton. It dates between 1735 and 1690 mya.

Web links

  • Justin L. Payne, Martin Hand, Karin M. Barovich, Anthony Reid, and David AD Evans: Correlations and reconstruction models for the 2500-1500 Ma evolution of the Mawson Continent. In: Palaeoproterozoic Supercontinents and Global Evolution. Geological Society, London, Special Publications, 323, 319-355. doi: 10.1144 / SP323.16 , PDF
  • Anthony Reid: Geological overview Western Gawler Craton. In: Department for Energy and Mining, online article. PDF
  • BR Bendall: Metamorphic and geochronological constraints on the Kimban Orogeny, southern Eyre Peninsula. In: School of Physical Sciences, The University of Adelaide, South Australia. Thesis
  • JD Hoek & BF Schaefer: Palaeoproterozoic Kimban mobile belt, Eyre Peninsula: Timing and significance of felsic and mafic magmatism and deformation. In: Australian Journal of Earth Sciences, Volume 55, 2008 - Issue 5, 2008. doi: 10.1080 / 08120099808728389 , alternative
  • Geology & crustal architecture of Eyre Peninsula. In: Government of South Australia's online article, Primary Industries an Resources SA. PDF

Individual evidence

  1. ^ Anthony J. Reid, Stacey O. McAvaney, and Geoff L. Fraser: Nature of the Kimban Orogeny across northern Eyre Peninsula. In: MESA Journal 51 December 2008. PDF
  2. ↑ a b N. Kositcin: Geodynamic Synthesis of the Gawler Craton and Curnamona Province. In: Geoscience Australia, Record, 2010/27, 113p. PDF
  3. ^ Nick MW Roberts: The boring billion? - Lid tectonics, continental growth and environmental change associated with the Columbia supercontinent. In: Geoscience Frontiers, Volume 4, Issue 6, November 2013, Pages 681-691. doi: 10.1016 / j.gsf.2013.05.004 , alternatively
  4. ^ MH Monroe: Antarctica - Before and After Gondwana. In: Gondwana Research, Volume 19, Issue 2, March 2011, Pages 335-371. doi: 10.1016 / j.gr.2010.09.003 , alternatively
  5. ↑ W .V. Prize: The Adelaide Geosyncline of South Australia and its significance in Neoproterozoic continental reconstruction. In: Precambrian Research, Volume 100, Issues 1-3, March 2000, Pages 21-63. doi: 10.1016 / S0301-9268 (99) 00068-6 , alternatively
  6. ^ Paul A. Polito, T. Kurtis Kyser, Peter N. Southgate, and M. Jim Jackson: Sandstone Diagenesis in the Mount Isa Basin: An Isotopic and Fluid Inclusion Perspective in Relationship to District-Wide Zn, Pb, and Cu Mineralization. In: Economic Geology (2006) 101 (6): 1159-1188. doi: 10.2113 / gsecongeo.101.6.1159 , alternatively
  7. ^ Colin HH Conor and Wolfgang V. Preiss: Understanding the 1720-1640 Ma Palaeoproterozoic Willyama Supergroup, Curnamona Province, Southeastern Australia: Implications for tectonics, basin evolution and ore genesis. In: Precambrian Research, Volume 166, Issues 1-4, October 30, 2008, Pages 297-317. doi: 10.1016 / j.precamres.2007.08.020 , alternatively
  8. ^ Wolfgang Preiss: Curnamona Province. In: Geology of South Australia. Online article
  9. ↑ Luisa Ruperto and Patrice de Caritat: Geological Rewiev of the southern Curnamona Region. In: CRC LEME Open File Report 183, January 2006. PDF
  10. ↑ Katherine E Howard, Anthony J Reid, Martin P Hand, Karin M Barovich and Elena A Belousova: Does the Kalinjala Shear Zone represent a palaeosuture zone? Implications for distribution of styles of Mesoproterozoic mineralization in the Gawler Craton. In: MESA Journal 43 December 2006. PDF
  11. ↑ Gaëlle Lamarque, Jérôme Bascou, Claire Maurice, Jean-Yves Cottin, Nicolas Riel and René-Pierre Ménot: Microstructures, deformation mechanisms and seismic properties of a Palaeoproterozoic shear zone: The Mertz shear zone, East-Antarctica. In: Tectonophysics, Volume 680, 12 June 2016, Pages 174-191. doi: 10.1016 / j.tecto.2016.05.011 , alternatively