Chemistry and mineralogy of podiform chromitite deposits, southern NSW, Australia: a guide to their origin and evolution

Graham, Ian T.; Franklin, B. J.; Marshall, Brian D.

doi:10.1007/bf01162355

Cited by 60 publications

(13 citation statements)

References 20 publications

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“…The Coolac serpentinite belt, Wambidgee serpentinite belt, Tumut Ponds serpentinite belt, and smaller bodies form the ~250-km-long Tumut ophiolitic complex in the Lachlan fold belt of southeastern Australia ( Fig. 1; Graham et al, 1996aGraham et al, , 1996bSpaggiari et al, 2003). The Coolac serpentinite belt is ≥63 km long, up to 3.5 km wide, and ≥5 km thick.…”

Section: Geological Setting and Sample Backgroundmentioning

confidence: 99%

The enigma of crustal zircons in upper-mantle rocks: Clues from the Tumut ophiolite, southeast Australia

Белоусова¹,

Gonzáléz-Jiménez²,

Graham³

et al. 2015

Geology

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Artículo de publicación ISIWe suggest a new explanation for the presence of crustally derived zircons in the upper-mantle rocks of ophiolitic complexes, as an alternative to subduction-related models. Integrated isotopic (U-Pb, Hf, and O isotopes) and trace-element data for zircons from the Tumut ophiolitic complex (southeast Australia) indicate that these grains are related to granitic magmatism and were introduced into the mantle rocks after their emplacement into the crust. These observations emphasize that a clear understanding of the origin of individual zircon populations and their relationship to the host rock is essential to interpretations of the tectonic history of upper-mantle rocks and the dynamics of crust-mantle interactions

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Section: Geological Setting and Sample Backgroundmentioning

confidence: 99%

The enigma of crustal zircons in upper-mantle rocks: Clues from the Tumut ophiolite, southeast Australia

Белоусова¹,

Gonzáléz-Jiménez²,

Graham³

et al. 2015

Geology

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“…The genetic model of common occurrence of Cr-and Al-spinels in one ophiolite complex is widely discussed in the literature [44][45][46][47][48]. Composition of chromian spinels can explain how magma processes happened in different geodynamic environments.…”

Section: Discussionmentioning

confidence: 99%

The Cyclops Ophiolite as a Source of High-Cr Spinels from Marine Sediments on the Jayapura Regency Coast (New Guinea, Indonesia)

2020

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The first detailed mineralogy, geochemistry and origin of heavy minerals in marine sediments along the Jayapura Regency coast on the Indonesian part of New Guinea Island are reported as part of a larger set of investigations conducted since 2009. In these sediments, the following heavy minerals were identified: high-Al and high-Cr spinels, chromian andradite, Mg-olivine, magnetite, mixture of iron (III) oxyhydroxides (limonite) and minerals from serpentine-group minerals (lizardite, antigorite). The heavy mineral fraction of marine sediments contains increased concentrations of metals, including W (up to 257.72 ppm) and Ag (up to 1330.29 ppb) as well as minor amounts of Ni (7.1–3560.9 ppm) and Cr (68.0–5816.0 ppm). The present state of geological knowledge suggests that there are no known prospects for rich Ti, Ni, Co, Cr, Au deposits along the examined part of the Jayapura coast. However, the average content of Ag and W is high enough to provide an impulse for suggested further deposit research. The source of marine sediments is Cyclops ophiolite, which contains a typical ophiolite sequence. Cyclops Mountain rocks have undergone intense chemical weathering processes and the resulting eroded material has been deposited on the narrow continental shelf. The chemical composition of chromian spinels indicates that their source is depleted peridotites from the SSZ (supra-subduction zone) environment of the Cyclops ophiolite. A detailed geochemical examination indicates that the evolution of parental melt of these rocks evolved towards magma with geochemical parameters similar to mid-ocean ridge basalt (MORB).

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“…The coexistence of both high-Cr and high-Al chromitites in the same ophiolitic block has been commonly interpreted as reflecting different melt activities that originated from different mantle sources in different tectonic environments (Zhou et al, 1994(Zhou et al, , 1996(Zhou et al, , 1998Economou-Eliopoulos, 1996;Proenza et al, 1999;Ahmed and Arai, 2002;Rollinson, 2008;Tsoupas and Economou-Eliopoulos, 2008). Although, the progressive evolution of parental melts during melt-rock reaction or via melt-migration in supra-subduction zone (SSZ) environment can also provide interpretation for the coexistence of both high-Cr and high-Al chromitites in a single ophiolitic belt (Leblanc, 1995;Graham et al, 1996;Melcher et al, 1997;Ahmed and Arai, 2002;Rollinson, 2005;Uysal et al, 2009a).…”

Section: Tectonic Setting Of Chromitites and Peridotites Of Dargai Comentioning

confidence: 99%

Petrochemistry of High-Cr and High-Al chromitites occurrences of Dargai Complex along Indus Suture Zone, Northern Pakistan

et al. 2020

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The present study has been carried out to determine the chromian spinel and platinum group elements (PGEs) geochemistry of podiform chromitites of Dargai Complex which provides significant information regarding the mantlecrust transition zone (MTZ) to mantle section during the emplacement and genesis of ophiolitic complexes. The mineral chemistry and platinum group elements (PGEs) were analysed using the Electron Probe Micro Analyzer (EPMA) and inductively-coupled plasma mass spectrometer (ICP-MS). Chromian spinels in the high-Cr chromitites (Cr# >60), harzburgite and mantle dunites have much higher Cr# values in the range of 78.4 to 81.9, 72.2 to 77.5 and 79.8 to 82.6, respectively. However, the chromian spinels in the high-Al chromitites (Cr# <60) and MTZ dunites have much lower Cr# values in the range of 47.5 to 52.9 and 46.7 to 49.4, respectively. Based on behaviours of PGEs, the chemical differences are reflected in these two types of chromitites. The Ir-group (IPGE) concentration is relatively higher than the Pt-group (PPGE) in the high-Cr chromitites, while high-Al chromitites have relatively greater PPGE/IPGE ratios. The melts responsible for the formation of High-Cr chromitites exhibit boninitic affinities, while that of the high-Al chromitites show mid ocean ridges basalt (MORB) signature with hydrous, oxidized and TiO 2 poor characteristics. Chromian spinel mineral chemistry and PGE geochemistry data confirm that the coexistence of both types of chromitites in the Dargai Complex may indicate a change in the composition of the parent magma from MORB to boninitic type in a proto fore-arc environment during subduction initiations. This coexistence of compositionally different mantle suites with episodic melting histories in a single ophiolitic complex can be attributed to the mechanically juxtaposition of mantle convection during recycling process within the mantle.

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Chemistry and mineralogy of podiform chromitite deposits, southern NSW, Australia: a guide to their origin and evolution

Cited by 60 publications

References 20 publications

The enigma of crustal zircons in upper-mantle rocks: Clues from the Tumut ophiolite, southeast Australia

The enigma of crustal zircons in upper-mantle rocks: Clues from the Tumut ophiolite, southeast Australia

The Cyclops Ophiolite as a Source of High-Cr Spinels from Marine Sediments on the Jayapura Regency Coast (New Guinea, Indonesia)

Petrochemistry of High-Cr and High-Al chromitites occurrences of Dargai Complex along Indus Suture Zone, Northern Pakistan

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