On thrusting, regional unconformities and exhumation of high-grade greenstones in Neoarchean orogens. The case of the Waroonga Shear Zone, Yilgarn Craton

Zibra, I.; Korhonen, Fawna J.; Peternell, Mark; Weinberg, Roberto F.; Romano, Sandra S.; Braga, Roberto; Paoli, M. C. De; Roberts, Malcolm P.

doi:10.1016/j.tecto.2017.05.017

Cited by 24 publications

(35 citation statements)

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“…Crustal thickening at the onset of the Yilgarn Orogeny is likely an expression of the progressive Neoarchean strengthening of the continental lithosphere, which produced a secular change in tectonic style and a transition from Archean‐type to modern‐type orogens [ Rey and Coltice , ; Condie and O'Neill , ]. A genetic link between thrusting, large‐scale rock uplift, and erosion has been recently documented for the mature tectonic stages of the Yilgarn Orogen [ Zibra et al ., ] and applies to the tectonomagmatic and stratigraphic evolution described here.…”

Section: Discussionmentioning

confidence: 99%

“…The bulk E‐W horizontal shortening recorded during most of the tectonic evolution of the Yilgarn Orogen is commonly ascribed to a series of accretion episodes that led to amalgamation of the EGST, the Narryer and Southwest Terranes onto an older foreland represented by the Youanmi Terrane (Figures a–c) [ Myers , ; Wilde et al ., ; Barley et al ., ]. The Ida Fault is regarded as the suture between the EGST and the Youanmi Terrane [ Myers , ], i.e., a scenario that is consistent with the existence of an ~2736–2724 Ma volcanic arc setting now preserved in the hangingwall of the Ida Fault (Figures b and c) [ de Joux et al ., ], together with the occurrence of high‐grade greenstones along this major structure (Figures b and c) [ Zibra et al ., ]. Alternatively, the various terranes could have once been part of a Mesoarchean “proto‐Yilgarn” continent, subsequently rifted into a series of ribbon continents during possible extensional events within the ~2960–2750 Ma time slice, and in turn amalgamated again by inversion tectonics, during the Neoarchean Yilgarn Orogeny (autochthonous models [ Czarnota et al ., ; Pawley et al ., ; Van Kranendonk et al ., ]).…”

Section: Discussionmentioning

confidence: 99%

“…Locations of HP‐HT greenstone slivers and the ~2736–2724 Ma arc sequence are from Zibra et al . [] and de Joux et al . [], respectively.…”

Section: Regional Geological Settingmentioning

confidence: 99%

“…They are juxtaposed by the “Ida Fault,” a crustal‐scale, E dipping shear zone that depending on the tectonic model has been interpreted as an intracratonic structure [ Van Kranendonk et al ., ] or a major suture between allochthonous terranes [ Myers , ]. This large‐scale structure is truncated by the late‐orogenic, W dipping Waroonga Shear Zone (WSZ, ~2660 Ma; Figures a–c), which contains slivers of high‐grade, Youanmi‐type greenstones that were previously buried to lower crustal depths (Figures b and c) [ Zibra et al ., ]. East of the Ida Fault, the main ~2730–2660 Ma EGST greenstone sequence [ Hayman et al ., ], including an ~2736–2724 Ma arc sequence (Figures b and c) [ de Joux et al ., ], is overlain by clastic sequences deposited above an ~2665–2655 Ma regional unconformity [ Squire et al ., ].…”

Section: Regional Geological Settingmentioning

confidence: 99%

“…• Table S1 • Table S2 • Table S3 Correspondence to: I. Zibra, ivan.zibra@dmp.wa.gov.au Citation: Zibra, I., F. Clos, R. F. Weinberg, and M. Peternell (2017), The~2730 Ma onset of the Neoarchean Yilgarn Orogeny, Tectonics, 36, 1787-1813, doi:10.1002/ 2017TC004562.…”

Section: Introductionmentioning

confidence: 99%

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The ~2730 Ma onset of the Neoarchean Yilgarn Orogeny

et al. 2017

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The timing of the onset of an orogeny is commonly constrained indirectly, because early orogenic structures are rarely exposed or are overprinted. Establishing the onset of an Archean orogeny is considerably more challenging, because of the more fragmented geological record and the general lack of consensus about Archean geodynamics. We combine existing tectonostratigraphic data with new structural and geophysical data sets to establish the onset of the Neoarchean Yilgarn Orogeny (Yilgarn Craton, Western Australia). We show that the surface of the ~2960–2750 Ma deep‐marine Yilgarn greenstone sequence was uplifted, eroded, and unconformably overlain by an ~2730 Ma, syntectonic clastic sequence, deposited in shallow marine to subaerial conditions, and derived from the erosion of the underlying greenstones. This ~2730 Ma regional unconformity predates the oldest known Yilgarn structures; therefore, its tectonic significance is so far unknown. At around the same time, at deeper crustal levels, the ~2728 Ma Yarraquin pluton was being emplaced along an active, large‐scale shear zone network. Our mesostructural and microstructural analysis shows that the bulk of the fabric in the granite and its country rocks developed during pluton emplacement and was largely assisted by magma‐present shearing. Overall, these structures reflect an important event of synemplacement crustal shortening. The regional unconformity and the syndeformational emplacement of the Yarraquin pluton are both expressions of an ~2730 Ma regional deformation event associated with significant crustal thickening, marking the onset of the Neoarchean Yilgarn Orogeny.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

“…Locations of HP‐HT greenstone slivers and the ~2736–2724 Ma arc sequence are from Zibra et al . [] and de Joux et al . [], respectively.…”

Section: Regional Geological Settingmentioning

confidence: 99%

Section: Regional Geological Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The ~2730 Ma onset of the Neoarchean Yilgarn Orogeny

et al. 2017

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A newly recognised mafic sill-hosted Ni-sulfide deposit emplaced during the 2.4 Ga Widgiemooltha dike swarm event, Eastern Goldfields, Western Australia

Siégel,

Schoneveld,

Spaggiari

et al. 2024

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The Cathedrals Ni-Cu prospect, located at the western margin of the Eastern Goldfields of the Yilgarn Craton, is hosted within a mafic intrusion interpreted as a sill complex. U-Pb dating of apatite from the sill yielded a crystallisation age of 2336 ± 64 Ma, inferring an association of sill emplacement and Ni mineralisation related to emplacement of the c. 2400 Ma Widgiemooltha dike swarm. The sill is typically differentiated into a lower olivine orthocumulate layer overlain by a dolerite unit containing xenoliths of partially assimilated granitoids in its upper portion. The latter is interpreted to be the result of stoping and melting of the granitic hanging wall, thereby creating a gravitationally stable buoyant melt layer beneath the top contact. Ni-Cu-Fe sulfides are increasingly abundant towards the base of the sill, ranging from globular disseminated sulfides to net-textured and massive sulfides at the basal contact. The presence and orientation of sulfide globule-bubble pairs indicates a primary near-horizontal orientation. Massive sulfides commonly exhibit a loop texture with pyrrhotite grains surrounded by pentlandite and chalcopyrite. Despite the variety of sulfide textures, sulfur isotopes have a homogeneous mantle-like signature without significant mass independent fractionation. Mineral chemistries that indicate sulfide prospectivity in larger intrusions do not work as effectively in this small sill, therefore new indicators may need to be developed to explore for similar deposits. To date, there are no other known magmatic deposits of this age in Australia. Sills of this age may be more prospective than previously recognised.

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Geological Evidence for the Operation of Plate Tectonics throughout the Archean: Records from Archean Paleo-Plate Boundaries

2018

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Plate tectonics describes the horizontal motion of rigid lithospheric plates away from midoceanic ridges and parallel to transforms, towards deep-sea trenches, where the oceanic lithosphere is subducted into the mantle. This process is the surface expression of modern-day heat loss from Earth. One of the biggest questions in Geosciences today is "when did plate tectonics begin on Earth" with a wide range of theories based on an equally diverse set of constraints from geology, geochemistry, numerical modeling, or pure speculation. In this contribution, we turn the coin over and ask "when was the last appearance in the geological record for which there is proof that plate tectonics did not operate on the planet as it does today". We apply the laws of uniformitarianism to the rock record to ask how far back in time is the geologic record consistent with presently-operating kinematics of plate motion, before which some other mechanisms of planetary heat loss may have been in operation. Some have suggested that evidence shows that there was no plate tectonics before 800 Ma ago, others sometime before 1.8-2.7 Ga, or before 2.7 Ga. Still others recognize evidence for plate tectonics as early as 3.0 Ga, 3.3-3.5 Ga, the age of the oldest rocks, or in the Hadean before 4.3 Ga. A key undiscussed question is: why is there such a diversity of opinion about the age at which plate tectonics can be shown to not have operated, and what criteria are the different research groups using to define plate tectonics, and to recognize evidence of plate tectonics in very old rocks? Here, we present and evaluate data from the rock record, constrained by relevant geochemical-isotopic data, and conclude that the evidence shows indubitably that plate tectonics has been operating at least since the formation of the oldest rocks, albeit with some differences in processes, compositions, and products in earlier times of higher heat generation and mantle temperature, weaker oceanic lithosphere, hotter subduction zones caused by more slab-melt generation, and under different biological and atmospheric conditions.

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On thrusting, regional unconformities and exhumation of high-grade greenstones in Neoarchean orogens. The case of the Waroonga Shear Zone, Yilgarn Craton

Cited by 24 publications

References 83 publications

The ~2730 Ma onset of the Neoarchean Yilgarn Orogeny

The ~2730 Ma onset of the Neoarchean Yilgarn Orogeny

A newly recognised mafic sill-hosted Ni-sulfide deposit emplaced during the 2.4 Ga Widgiemooltha dike swarm event, Eastern Goldfields, Western Australia

Geological Evidence for the Operation of Plate Tectonics throughout the Archean: Records from Archean Paleo-Plate Boundaries

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