Preferential retrogression of high-P metasediments and the preservation of blueschist to eclogite facies metabasite during exhumation, Diahot terrane, NE New Caledonia

Fitzherbert, J. A.; Clarke, Graeme; Powell, Roger

doi:10.1016/j.lithos.2005.01.005

Cited by 48 publications

(33 citation statements)

References 41 publications

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“…This new result has several implications regarding the New Caledonia Basin in terms of age, tectonic and sedimentary evolution and links with its neighboring structural elements. Taking a close look at the New Caledonia onshore geology [ Avias , 1967; Brothers and Blake , 1973; Prinzhofer et al , 1980; Paris , 1981; Collot et al , 1987; Aitchison and Meffre , 1992; Aitchison , 1995; Cluzel et al , 1997; Aitchison et al , 1998; Cluzel , 1998; Cluzel et al , 1998; Ali and Aitchison , 2000; Cluzel et al , 2001; Ali and Aitchison , 2002; Spandler et al , 2004; Fitzherbert et al , 2005; Spandler et al , 2005; Cluzel et al , 2006], we here propose to establish links between the marine tectonic event observed in the seismic data and the tectonic events observed onshore.…”

Section: Discussionmentioning

confidence: 76%

Tectonic history of northern New Caledonia Basin from deep offshore seismic reflection: Relation to late Eocene obduction in New Caledonia, southwest Pacific

et al. 2008

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International audienceNew, high-quality multichannel seismic reflection data from the western New Caledonia offshore domain allow for the first time the direct, continuous connection of seismic reflectors between the Deep Sea Drilling Project 208 drill hole on the Lord Howe Rise and the New Caledonia Basin. A novel seismic interpretation is hence proposed for the northern New Caledonia Basin stratigraphy, which places the Eocene/Oligocene unconformity deeper than previously thought and revisits the actual thickness of the pre-Oligocene sequences. A causal link is proposed between the obduction of the South Loyalty Basin over New Caledonia (NC) and the tectonic history of the northern New Caledonia Basin. Here it is suggested that as the South Loyalty Basin was being obducted during early Oligocene times, the NC Basin subsided under the effect of the overloading and underthrusted to accommodate the compressional deformation, which resulted in (1) the uplift of the northern Fairway Ridge and (2) the sinking of the western flank of New Caledonia. This event also had repercussions farther west with the incipient subsidence of the Lord Howe Rise

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Section: Discussionmentioning

confidence: 76%

Tectonic history of northern New Caledonia Basin from deep offshore seismic reflection: Relation to late Eocene obduction in New Caledonia, southwest Pacific

et al. 2008

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“…consists of a melange of eclogite-facies magmatic rocks genetically related to the Poya terrane which were metamorphosed in the northeast dipping subduction ( [Cluzel et al, 1994], [Cluzel et al, 2001], [Rawling and Lister, 2002], [Fitzherbert et al, 2004], [Spandler et al, 2004], [Spandler et al, 2005] and [Fitzherbert et al, 2005]). Fig.…”

Section: Discussionmentioning

confidence: 99%

Multiple melting stages and refertilization as indicators for ridge to subduction formation: The New Caledonia ophiolite

Ulrich

Picard

Guillot

et al. 2010

Lithos

123

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The origin of the New Caledonia ophiolite (South West Pacific), one of the largest in the world, is controversial. This nappe of ultramafic rocks (300 km long, 50 km wide and 2 km thick) is thrust upon a smaller nappe (Poya terrane) composed of basalts from mid-ocean ridges (MORB), back arc basins (BABB) and ocean islands (OIB). This nappe was tectonically accreted from the subducting plate prior and during the obduction of the ultramafic nappe.The bulk of the ophiolite is composed of highly depleted harzburgites (± dunites) with characteristic U-shaped bulk-rock rare-earth element (REE) patterns that are attributed to their formation in a forearc environment. In contrast, the origin of spoon-shaped REE patterns of lherzolites in the northernmost klippes was unclear. Our new major element and REE data on whole rocks, spinel and clinopyroxene establish the abyssal affinity of these lherzolites. Significant LREE enrichment in the lherzolites is best explained by partial melting in a spreading ridge, followed by near in-situ refertilization from deeper mantle melts. Using equilibrium melting equations, we show that melts extracted from these lherzolites are compositionally similar to the MORB of the Poya terrane. This is used to infer that the ultramafic nappe and the mafic Poya terrane represent oceanic lithosphere of a single marginal basin that formed during the late Cretaceous. In contrast, our spinel data highlights the strong forearc affinities of the most depleted harzburgites whose compositions are best modeled by hydrous melting of a source that had previously experienced depletion in a spreading ridge. The New Caledonian boninites probably formed during this second stage of partial melting.The two melting events in the New Caledonia ophiolite record the rapid transition from oceanic accretion to convergence in the South Loyalty Basin during the Late Paleocene, with initiation of a new subduction zone at or near the ridge axis.

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“…Abundant pelitic schists within the Besshi eclogite unit would reduce the bulk rock density and strength and thus promote buoyancy-driven exhumation (Endo et al, 2012). The buoyancy-driven exhumation of HP rocks proceeds quickly (>cm/year: Ernst, 2001;Rubatto & Hermann, 2001). Wallis et al (2009) suggested that the Sanbagawa eclogite units were emplaced into the non-eclogite unit during rapid exhumation with rates of >2.5 cm/year.…”

Section: Areal Distribution Of the Eclogite Unit And Its Tectonic Imentioning

confidence: 99%

“…Quantifying the metamorphic character of an eclogite facies region and its areal distribution has received extensive attention because of clear documentation of subduction‐ or collision‐related metamorphism, and a subsequent exhumation process at plate convergent margins (e.g., Hacker, ; Katayama, Zayachkovsky, & Maruyama, ; Medaris, Fournelle, Ghent, Jelínek, & Mísař, ; Sobolev, Shatsky, Vavilov, & Goryaynov, ). Eclogites and eclogite facies rocks in many HP metamorphic belts occur as lenses, boudins, bodies, layers, or nappes in various scales within surrounding country rocks, and show definite differences between their metamorphic conditions and those of country rocks (e.g., Clarke, Aitchison, & Cluzel, ; Fitzherbert, Clarke, & Powell, ; Krogh, Andresen, Bryhni, Broks, & Kristensen, ; Tsujimori, Matsumoto, Wakabayashi, & Liou, ; Vitale Brovarone & Agard, ; Wallis & Aoya, ). Determining whether or not country rock once experienced eclogite facies metamorphism along with the enclosed HP rock depends on the presence of index HP minerals (e.g., omphacite, jadeite).…”

Section: Introductionmentioning

confidence: 99%

Metamorphic record of the Asemi‐gawa eclogite unit in the Sanbagawa belt, southwest Japan: Constraints from inclusions study in garnet porphyroblasts

Taguchi

Enami

Kouketsu

2018

Journal Metamorphic Geology

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The Sanbagawa belt is one of the famous subduction‐related high‐pressure (HP) metamorphic belts in the world. However, spatial distributions of eclogite units in the belt have not yet satisfactorily established, except within the Besshi region, central Shikoku, southwest Japan because most eclogitic rocks were affected by lower pressure overprinting during exhumation. In order to better determine the areal distribution of the eclogite units and their metamorphic features, inclusion petrography of garnet porphyroblasts using a combination of electron probe microanalyser and Raman spectroscopy was applied to pelitic and mafic schists from the Asemi‐gawa region, central Shikoku. All pelitic schist samples are highly retrogressed, and include no index HP minerals such as jadeite, omphacite, paragonite, or glaucophane in the matrix. Garnet porphyroblasts in pelitic schists occur as subhedral or anhedral crystals, and show compositional zoning with irregular‐shaped inner segments and overgrown outer segments, the boundary of which is marked by discontinuous changes in spessartine. This feature suggests that a resorption process of the inner segment occurred prior to the formation of the outer segment, indicating discontinuous crystallization between the two segments. The inner segment of some composite‐zoned garnet grains displays Mn oscillations, implying infiltration of metamorphic fluid during the initial exhumation stage. Evidence for an early eclogite facies event was determined from mineral inclusions (e.g., jadeite, paragonite, glaucophane) in the garnet inner segments. Mafic schists include no index HP minerals in the matrix as with pelitic schists. Garnet grains in mafic schists show simple normal zoning, recording no discontinuous growth during crystal formation. There are no index HP mineral inclusions in the garnet, and thus no evidence suggesting eclogite facies conditions. Quartz inclusions in garnet of the pelitic and mafic schists show residual pressure values (∆ω1) of >8.5 cm−1 and <8.5 cm−1 respectively. The combination of Raman geobarometry and conventional thermodynamic calculations gives peak P–T conditions of 1.6–2.1 GPa at 460–520°C for the pelitic schists. The ∆ω1 values of quartz inclusions in mafic schists are converted to a metamorphic pressure of 1.2–1.4 GPa at 466–549°C based on Raman geothermometry results. These results indicate that a pressure gap definitely exists between the mafic schists and the almost adjacent pelitic schists, which have experienced a different metamorphic history. Furthermore, the peak P–T values of the Asemi‐gawa eclogite unit are compatible with those of Sanbagawa eclogite unit in the Besshi region of central Shikoku, suggesting that these eclogite units share a similar P–T trajectory. The Asemi‐gawa eclogite unit exists in a limited area and is composed of mostly pelitic schists. We infer that these abundant pelitic schists played a key role in buoyancy‐driven exhumation by reducing bulk rock density and strength.

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Preferential retrogression of high-P metasediments and the preservation of blueschist to eclogite facies metabasite during exhumation, Diahot terrane, NE New Caledonia

Cited by 48 publications

References 41 publications

Tectonic history of northern New Caledonia Basin from deep offshore seismic reflection: Relation to late Eocene obduction in New Caledonia, southwest Pacific

Tectonic history of northern New Caledonia Basin from deep offshore seismic reflection: Relation to late Eocene obduction in New Caledonia, southwest Pacific

Multiple melting stages and refertilization as indicators for ridge to subduction formation: The New Caledonia ophiolite

Metamorphic record of the Asemi‐gawa eclogite unit in the Sanbagawa belt, southwest Japan: Constraints from inclusions study in garnet porphyroblasts

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