Anhydrous Partial Melting of a Fertile and Depleted Peridotite from 2 to 30 kb and Application to Basalt Petrogenesis

Falloon, Trevor J.; Green, David H.; Hatton, C. J.; Harris, K.L.

doi:10.1093/petrology/29.6.1257

Cited by 336 publications

(125 citation statements)

References 41 publications

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“…They also have relatively high total Fe 2 O 3 (N11.4 wt.%) and TiO 2 (N2.33 wt.%) concentrations (Table A2), indicating that their parental magmas were enriched in Fe and Ti. These geochemical features are similar to those of experimental melts from the fertile peridotite (Falloon et al, 1988;Hirose and Kushiro, 1993). Their Sr-Nd isotopic compositions are slightly enriched relative to OIB and MORB-like magmas, but distinct depleted relative to the Mesozoic mafic igneous rocks from the NCC that were derived from partial melting of an enriched lithospheric mantle .…”

Section: Crustal Contaminationsupporting

confidence: 71%

Petrogenesis of the early Cretaceous intermediate and felsic intrusions at the southern margin of the North China Craton: Implications for crust–mantle interaction

Gao¹,

Zhao²,

Bao³

et al. 2014

Lithos

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Section: Crustal Contaminationsupporting

confidence: 71%

Petrogenesis of the early Cretaceous intermediate and felsic intrusions at the southern margin of the North China Craton: Implications for crust–mantle interaction

Gao¹,

Zhao²,

Bao³

et al. 2014

Lithos

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“…Liquidus olivine of the most primitive LPL melts (Fo 92 ) is refractory enough to suggest their equilibrium with the mantle (e.g., Green 1970). However, high normative diopside contents of these melts ($38% in the olivine-clinopyroxene-quartz projection of Falloon et al 1988), a result of their high CaO contents, makes them unlike any experimentally established depleted peridotite-source magmas (e.g., Falloon et al 1988).…”

Section: Discussionmentioning

confidence: 99%

“…In this case, primary melts should have had temperatures of $1300°C, MgO $14.5 wt%, and Fo 94 liquidus olivine. They will be in equilibrium with the mantle at $10 kbar (Falloon et al 1988).…”

Section: Discussionmentioning

confidence: 99%

Coexistence of two distinct mantle sources during formation of ophiolites: a case study of primitive pillow-lavas from the lowest part of the volcanic section of the Troodos Ophiolite, Cyprus

Portnyagin

Danyushevsky²,

Kamenetsky³

1997

Contributions to Mineralogy and Petrology

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We present a detailed mineralogical, petrological and melt inclusion study of unusually fresh, primitive olivine + clinopyroxene phyric Lower Pillow Lavas (LPL) found near Analiondas village in the northeastern part of the Troodos ophiolite (Cyprus). Olivine phenocrysts in these primitive LPL show a wide compositional range (Fo 82±92 ) and have higher CaO contents than those from the Upper Pillow Lavas (UPL). Cr-spinel inclusions in olivine are signi®cantly less Cr-rich (Cr/Cr + Al = 28±67 mol%) compared to those from the UPL (Cr# = 70±80). These features reect di erences in melt compositions between primitive LPL and the UPL, namely higher CaO and Al 2 O 3 and lower FeO* compared to the UPL at a given MgO. LPL parental melts (in equilibrium with Fo 92 ) had $10.5 wt% MgO and crystallization temperatures $1210°C, which are signi®cantly lower than those previously published for the UPL (14±15 wt% MgO and $1300°C for Fo 92 ). The fractionation path of LPL parental melts is also di erent from that of the UPL. It is characterized initially by olivine + clinopyroxene cotectic crystallization joined by plagioclase at $9 wt% MgO, whereas UPL parental melts experienced a substantial interval of olivine-only crystallization. Primitive LPL melts were formed from a mantle source which was more fertile than that of tholeiites from well-developed intra-oceanic arcs, but broadly similar in its fertility to that of MidOcean Ridge Basalt (MORB) and Back Arc Basin Basalts (BABB). The higher degrees of melting during formation of the LPL primary melts compared to average MORB were caused by the presence of subduction-related components (H 2 O). Our new data on the LPL coupled with existing data for the UPL support the existing idea that the LPL and UPL primary melts originated from distinct mantle sources, which cannot be related by progressive source depletion. Temperature di erences between these sources ($150°C), their position in the mantle ($10 kbar for the colder LPL source vs 15±18 kbar for the UPL source), and temporal succession of Troodos volcanism, all cannot be reconciled in the framework of existing models of mantle wedge processes, thermal structure and evolution, if a single mantle source is invoked. Possible tectonic settings for the origin of the Troodos ophiolite (forearc regions of intra-oceanic island arc, propagation of backarc spreading into arc lithosphere) are discussed.

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“…The low SiO 2 samples have MgO content of more than 10 wt%, indicative of the source being characterized by low CaO (<7.0 wt%) and Al 2 O 3 (>17.0 wt%). These characteristics suggest a refractory source, with a high-proportion of orthopyroxene, which had previously experienced melt extraction (e.g., Hirose, 1997;Falloon et al, 1988;Wang et al, 2007c).…”

Section: Group 4 Showing the Geochemical Affinity To Arc Volcanicsmentioning

confidence: 99%

Geochronological, geochemical and Nd–Hf–Os isotopic fingerprinting of an early Neoproterozoic arc–back-arc system in South China and its accretionary assembly along the margin of Rodinia

Wang

Zhang

Cawood

et al. 2013

Precambrian Research

231

121

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Keywords:Metabasic rocks MORB-and/or arc-like geochemical signatures Earliest Neoproterozoic Arc and back-arc system Eastern South China Block Periphery of Rodinia a b s t r a c t U-Pb geochronology along with elemental and Nd-Hf-Os isotopic data from the earliest Neoproterozoic metabasic rocks within the Cathaysia Block of the South China Block (SCB) constrain the tectonic setting and paleogeography of the block within the Rodinia supercontinent. The metabasic rocks give zircon U-Pb ages of 969-984 Ma, ε Hf (t) values of +1.8 to +15.3 and Hf model ages of 0.92-1.44 Ga. They are subalkaline basalts that can be geochemically classified into four groups. Group 1 has low Nb contents (1.24-4.33 ppm), highly positive ε Nd (t) values (+4.3 to +5.2), and REE and multi-elemental patterns similar to fore-arc MORB-type basalt. Group 2 has Nb contents ranging from 3.13 ppm to 6.48 ppm, ε Nd (t) of +3.1 to +6.2, low Re and Os contents and high initial Os isotopic ratios, and displays an E-MORB geochemical signature. Group 3 has Nb = 7.18-29.87 ppm, Nb/La = 0.60-1.40, Nb/U = 5.0-37, Ce/Pb = 1.1-6.6, ε Nd (t) = +2.9 to +7.0, 187 Re/ 188 Os = 5.87-8.87 and ␥Os (t) = 178-772, geochemically resembling to the Pickle Nb-enriched basalt. Group 4 has strong LREE/HREE and HREE fractionation and high ε Nd (t) values (+2.3 to +5.6), and is characterized by similar element patterns to arc volcanic rocks. Serpentinites coeval to Group 4 show 187 Os/ 188 Os of 0.1143-0.1442 and ␥Os (t) of −7.8 to +0.1. Groups 1 and 2 are interpreted to originate from the N-MORB and E-MORB-like sources with the addition of an arc-like component, genetically linked to fore-and back-arc settings, respectively. Groups 3 and 4 show inputs of newly subduction-derived melt and fluid in the wedge source. These geochronological and geochemical signatures fingerprint the development of an earliest Neoproterozoic (∼970 Ma) arc-back-arc system along the Wuyi-Yunkai domain of the Cathaysia Block. Regional relationships indicate that the Wuyi-Yunkai arc-back-arc system was one of a series of separate convergent margin settings, which included the Shuangxiwu (∼970-880 Ma) and Jiangnan (∼870-820 Ma) systems that developed in the SCB. The formation and closure of these arc-back-arc systems resulted in the northwestwardly episodic amalgamation of various pieces of the Yangtze and Cathaysia to finally form the SCB. These signatures require the SCB to occupy an exterior accretionary orogen along the periphery of Rodinia during 990-820 Ma, rather than to have formed through Mesoproterozoic Sibao orogenesis within the interior of Rodinia.

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Anhydrous Partial Melting of a Fertile and Depleted Peridotite from 2 to 30 kb and Application to Basalt Petrogenesis

Cited by 336 publications

References 41 publications

Petrogenesis of the early Cretaceous intermediate and felsic intrusions at the southern margin of the North China Craton: Implications for crust–mantle interaction

Petrogenesis of the early Cretaceous intermediate and felsic intrusions at the southern margin of the North China Craton: Implications for crust–mantle interaction

Coexistence of two distinct mantle sources during formation of ophiolites: a case study of primitive pillow-lavas from the lowest part of the volcanic section of the Troodos Ophiolite, Cyprus

Geochronological, geochemical and Nd–Hf–Os isotopic fingerprinting of an early Neoproterozoic arc–back-arc system in South China and its accretionary assembly along the margin of Rodinia

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