Petrogenesis of arc-related serpentinized peridotites (Egypt): Insights into Neoproterozoic mantle evolution beneath the Arabian-Nubian Shield

Khedr, Mohamed Zaki; Takazawa, Eiichi; Hauzenberger, Christoph; Tamura, Akihiro; Arai, Shoji; Stern, Robert J.; Morishita, Tomoaki; El-Awady, Amr

doi:10.1016/j.jseaes.2022.105078

Cited by 22 publications

(10 citation statements)

References 100 publications

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“…Trace-element patterns of Ol from AK and KN metaperidotites, as well as those from KN harzburgites and dunites, correspond to those of the New Caledonia mantlewedge peridotites [30] and are located between Korab Kansi and Abu Dahr forearc highly depleted peridotites (25%-40% of partial melting) [70] and retrograde metaperidotites of Happo O'ne [31,71]. They are characterized by similar contents of relatively fluidimmobile HFSE and some REE (Yb, Y, Zr, and Ce) and variably mobile LILE (Sr, Pb, and Ba) elements; some Ol analyses exhibit contents below the limit of determination (LOD) (Figure 7A,B).…”

Section: In Situ Trace-element Composition Of Mineral Phasesmentioning

confidence: 74%

“…0.04-0.1 PM for AK) contents (Figure 8A,B). Opx in both KN and AK metaperidodites have intermediate contents of the least incompatible HFSE and HREE (Zr-Yb) between Korab Kansi and Abu Dahr forearc highly depleted peridotites [70] and retrograde metaperidotites of Happo O'ne [31,71]. FMEs in Opx KN have values similar to that of Opx in the Korab Kansi and Abu Dahr metaperidodites, whereas, in AK samples, they are much higher (Figure 8A,B).…”

Section: In Situ Trace-element Composition Of Mineral Phasesmentioning

confidence: 91%

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In Situ Geochemical Evaluation of Retrograde Hydration Effects in the Peri-Siberian Forearc Mantle (Khara-Nur and Alag-Khadny Peridotite Complexes)

Karimov,

Gornova,

Belyaev

et al. 2024

Minerals

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In order to assess the geochemical effects of retrograde metamorphic rehydration, fluid metasomatism, and the fluid-mobile elements (FMEs) budget in the case of oceanic and continental subduction, we report the petrography, bulk, and in situ LA-ICP-MS trace-element data for the two poorly studied ophiolites in the northern (Khara-Nur, Eastern Sayan, Russia) and central (Alag-Khadny accretionary wedge, SW Mongolia) parts of the peri-Siberian orogenic framing. Both complexes are relics of the ancient oceanic mantle, which was subjected to processes of partial melting, metasomatism, and retrograde metamorphism. Typical mineral assemblages include olivine + orthopyroxene + chlorite + tremolite ± secondary olivine (640–800 °C), olivine + antigorite ± secondary clinopyroxene (<640 °C), and olivine + chrysotile ± secondary clinopyroxene (<250 °C) and are stable at pressures up to 2 GPa. Hydration and partial serpentinization of mantle peridotites lead to tremolite formation after orthopyroxene, followed by olivine replacement by antigorite. Serpentine-group minerals (antigorite and chrysotile) were distinguished by Raman spectroscopy, and the contents of incompatible elements (mobile and immobile in fluids) in metamorphic minerals (tremolite, antigorite, and chrysotile) were examined in situ by LA-ICP-MS. The behavior of conservative HFSE (Zr, Nb, Ta, and Ti) and—in part—HREE does not distinguish between the two types (oceanic and continental) of subduction environments. Different patterns of FMEs (Cs, Rb, Ba, U, Sb, Pb, Sr, and LREE) enrichment in metaperidotites reflect variations in the slab fluid composition, which was primarily governed by the contrasting nature of subducted lithologies. The affinity of Alag-Khadny to the subduction of a continental margin is recorded by increased FME contents and selective enrichment by some moderately mobile elements, such as U, Th, and LREE, with respect to the oceanic-type subduction environment of Khara-Nur. Distinct patterns of FME enrichment in tremolite and antigorite from two complexes indicate different sequences of fluid-induced replacement, which was controlled by Opx composition. We demonstrate that evaluation of the initial composition of precursor minerals affected by multi-stage melting and melt metasomatism should be considered with care to estimate the differential fluid overprint and associated elemental uptake from subduction fluids.

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Section: In Situ Trace-element Composition Of Mineral Phasesmentioning

confidence: 74%

Section: In Situ Trace-element Composition Of Mineral Phasesmentioning

confidence: 91%

In Situ Geochemical Evaluation of Retrograde Hydration Effects in the Peri-Siberian Forearc Mantle (Khara-Nur and Alag-Khadny Peridotite Complexes)

Karimov,

Gornova,

Belyaev

et al. 2024

Minerals

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“…In many cases where peridotite is highly serpentinized, as in the case of the Atlantis Massif, Cr-spinel commonly represents the only identifiable phase that retains the primary characteristics. Nonetheless, Cr-spinel is also subject to alteration and many studies have focused on and described the effects of hydrothermal alteration during serpentinization and metamorphism of primary Cr-spinel (e.g., Evans and Frost 1975;Kimball 1990;Burkhard 1993;Absalov 1998;Arai et al 2006;Säntii et al 2006;Khalil and El-Makky 2009;Merlini et al 2009;Aswad et al 2011;Gargiulo et al 2013;Saumur and Hattori 2013;Barra et al 2014;Bhat et al 2019;Khedr and Arai 2013;Khedr et al 2022). Of relevance to this study is the modification of Cr-spinel compositions during melt-rock interaction and metamorphism.…”

Section: Evidence Of Sub-greenschist To Lower Amphibolite Metamorphismmentioning

confidence: 95%

Link between melt-impregnation and metamorphism of Atlantis Massif peridotite (IODP Expedition 357)

Whattam

Hoog

Leybourne

et al. 2022

Contrib Mineral Petrol

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IODP Expedition 357 drilled 17 shallow sites scattered over ~ 10 km in the west to east spreading direction across the Atlantis Massif oceanic core complex (OCC, MAR, 30 ºN). Mantle exposed in the footwall of the Atlantic Massif OCC is nearly wholly serpentinized (80–100%) harzburgite and subordinate dunite. A recent whole-rock chemistry study by Whattam et al. (Chemical Geology 594. 10.1016/j.chemgeo.2021.120681, 2022) subdivides Atlantis Massif peridotites into: Type I fluid–rock dominated serpentinite, which exhibits almost nil evidence of melt-impregnation or silica metasomatism; Type II melt–rock dominated, mafic melt-impregnated serpentinite; and Type III melt–rock dominated Si-metasomatized serpentinite. In this study, on the basis of EPMA, three kinds of Cr–spinel are distinguished in Expedition 357 serpentinite: (I) primary, unmetamorphosed mantle array, (II) low-Ti metamorphosed, and (III) high-Ti melt reacted. All Cr–spinel of western site Type I serpentinite is unmetamorphosed (n = 34) and comprises 68% of all unmetamorphosed Cr–spinel. Metamorphosed Cr–spinel (n = 100) are the most abundant and occur in the central and eastern site Type II and Type III serpentinite, whereas melt-reacted Cr–spinel and chromite are restricted to the central sites and occur predominantly in serpentinized dunite. Estimates of the degree of melt extraction of Type I serpentinite using F = 10ln(spinel Cr#) + 24 are ~ 9–17%. Fugacity calculations of primary, unmetamorphosed Cr–spinel yield Δlog(fO2)FMQ of − 1.7 to + 1.0 and calculations using olivine–spinel Mg–Fe exchange thermometry yield a mean closure temperature of 808 ± 39 °C. Mafic melt-impregnation resulted in Cr–spinel with anomalously high TiO2 of 0.27–0.68 wt.% and production of Ti-rich chromite (up to 1.23 wt.% TiO2). Greenschist facies metamorphism (< 500 °C) resulted in Mg–Fe2+ exchange between Cr–spinel and forsterite and anomalously low Cr–spinel Mg#; higher degrees of amphibolite facies metamorphism (~ 500–700 °C) also resulted in anomalously high Cr# due to Al–Cr exchange. As has been previously established, significant Al loss from chromite cores above 550 °C is the result of equilibration with fluids in equilibrium with chlorite, which may be valid for our samples. On the basis of Cr–spinel vs. whole-rock compositions, a clear relationship exists between melt-impregnation and metamorphism of central and eastern serpentinite, which we postulate to be the result of heat associated with magma injection and subsequent localized contact metamorphism. To our knowledge, such a relation between mafic melt-impregnation of peridotite and metamorphism (of peridotite) has not previously been established in general and specifically for the Atlantis Massif peridotite. Closure temperatures of 440–731 °C of metamorphosed Cr–spinel approximate greenschist to amphibolite facies metamorphic conditions.

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“…1) is located in the South Eastern Desert of Egypt, ~70 km NW of Shalatin city on the Red Sea, and covers the largest part of Beitan province. It forms a part of the Arabo-Nubian Shield (890-570 Ma, Stern et al, 2004) and comprises Neoproterozoic Beitan gneisses, dismembered ophiolite, island arc metavolcanicplutonic assemblage, volcaniclastic metasediments (mélange matrix), and syn-to late-tectonic granite intrusions (Ashmawy, 1987;Abdel-Khalek et al, 1992;El Tahlawi et al, 1997;Zoheir et al, 2008;Arai, 2013, 2016;Gahlan et al, 2015;Abdel-Halim et al, 2020;Khedr et al, 2022). According to field relationships, the following sequence was established by El Tahlawi et al (1997) starting with the uppermost rock unit: 1) Abu Dahr Nappe, 2) Arayis ophiolitic mélange, 3) Egat metavolcaniclastics, and 4) Beitan gneisses.…”

Section: Geological Setting and Samplesmentioning

confidence: 99%

“…According to field relationships, the following sequence was established by El Tahlawi et al (1997) starting with the uppermost rock unit: 1) Abu Dahr Nappe, 2) Arayis ophiolitic mélange, 3) Egat metavolcaniclastics, and 4) Beitan gneisses. The Abu Dahr ophiolite consists, from the base upward, of a mantle section (Abu Dahr Peridotite Nappe), ultramaficmafic cumulates, and crustal metagabbros and metabasalts (Gahlan et al, 2015;Abdel-Halim et al, 2020;Khedr et al, 2022). The crustal rocks are associated with the Arais and Balamhindit ophiolite complexes Arai, 2013, 2016).…”

Section: Geological Setting and Samplesmentioning

confidence: 99%

Hydrothermal alteration of Ni-rich sulfides in peridotites of Abu Dahr, Eastern Desert, Egypt: Relationships among minerals in the Fe-Ni-Co-O-S system,fO2 andfS2

Abdel-Halim

2023

American Mineralogist

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The Neoproterozoic peridotites of Abu Dahr, Eastern Desert of Egypt, consist mainly of highly depleted harzburgites that have experienced multiple stages of serpentinization (lizarditization and antigoritization) and carbonation/listvenitization in a forearc environment.The Abu Dahr forearc harzburgites are more oxidized than oceanic mantle, with the oxygen fugacity (fO 2 ) values ranging from FMQ +0.41 to FMQ +1.20 (average = +0.60 FMQ), and were equilibrated at temperatures of 910-1217°C and pressures of 4.1-7.8 kbar. This study has documented for the first time the presence of a variety of Ni-rich Ni-Fe (-Co) sulfide and metal phases along with Fe-oxides/oxyhydroxides in serpentinized-carbonated peridotites of the Abu Dahr forearc. Here I concentrate on the relationship between redox state and Fe-Ni-Co-O-S minerals with emphasis on the role of hydrothermal processes in upgrading magmatic sulfide tenors, desulfurization (sulfur-loss) of magmatic pentlandite and hydrothermal upgrading of the sulfide phases in Abu Dahr forearc environment. The minerals involved are high-Ni pentlandite (Fe 4 Ni 5 S 8 ), cobaltian pentlandite (Fe 3.47 Ni 4.78 Co 0.75 S 8 ), heazlewoodite (Fe 0.07 Ni 2.93 S 2 ), godlevskite (Fe 0.26 Ni 8.73 Co 0.01 S 8 ), millerite (Fe 0.01 Ni 0.98 Cu 0.01 S), awaruite (Ni 75 Fe 21 ) and native Ni (Ni 93 Fe 5 ), and nickeliferous magnetite and goethite. Chalcopyrite is a rare mineral; other Cuphases, Fe-sulfides and Ni-arsenides/phosphides are not present. Texturally, Ni-sulfide and alloy

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Petrogenesis of arc-related serpentinized peridotites (Egypt): Insights into Neoproterozoic mantle evolution beneath the Arabian-Nubian Shield

Cited by 22 publications

References 100 publications

In Situ Geochemical Evaluation of Retrograde Hydration Effects in the Peri-Siberian Forearc Mantle (Khara-Nur and Alag-Khadny Peridotite Complexes)

In Situ Geochemical Evaluation of Retrograde Hydration Effects in the Peri-Siberian Forearc Mantle (Khara-Nur and Alag-Khadny Peridotite Complexes)

Link between melt-impregnation and metamorphism of Atlantis Massif peridotite (IODP Expedition 357)

Hydrothermal alteration of Ni-rich sulfides in peridotites of Abu Dahr, Eastern Desert, Egypt: Relationships among minerals in the Fe-Ni-Co-O-S system,fO2 andfS2

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