La, Ce, Nd, and Sr behavior in minette magmas during crystallization of apatite-clinopyroxene-mica paragenesis at upper-mantle conditions

Cid, Jorge Plá; Nardi, Lauro Valentim Stoll; Campos, Cristiani S.; Gisbert, Pere Enrique; Merlet, Claude; Conceição, Herbet; Boyer, Bernard

doi:10.1127/0935-1221/2007/0019-0039

Cited by 3 publications

(1 citation statement)

References 34 publications

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“…Apatite commonly occurs in mantle and crustal environments and possesses high partition coefficients for both Sr and LREE (Chazot et al 1996;Bea and Montero 1999). For example, apatite may concentrate LREE up to 200 times compared to clinopyroxene and, although slightly lower than that of plagioclase (up to 15.8) (Ren et al 2003), its partition coefficient for Sr (D Sr = 5.1-8.2) is still high enough to affect magma composition (Plá Cid et al 2007;Prowatke and Klemme 2006). Petrographic observation of the tonalite porphyry reveals that apatite is mainly enclosed in the garnet phenocrysts which, along with the depletion in P in the spider diagram (Fig.…”

Section: Implications For Genesis Of Adakitic Rocksmentioning

confidence: 99%

Garnet-bearing tonalitic porphyry from East Kunlun, Northeast Tibetan Plateau: implications for adakite and magmas from the MASH Zone

Yuan

Sun

Xiao

et al. 2008

Int J Earth Sci (Geol Rundsch)

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A garnet-bearing tonalitic porphyry from the Achiq Kol area, northeast Tibetan Plateau has been dated by SHRIMP U-Pb zircon techniques and gives a Late Triassic age of 213 ± 3 Ma. The porphyry contains phenocrysts of Ca-rich, Mn-poor garnet (CaO [ 5 wt%; MnO \ 3 wt%), Al-rich hornblende (Al 2 O 3 * 15.9 wt%), plagioclase and quartz, and pressure estimates for hornblende enclosing the garnet phenocrysts yield values of 8-10 kbar, indicating a minimum pressure for the garnet. The rock has SiO 2 of 60-63 wt%, low MgO (\2.0 wt%), K 2 O (\1.3 wt%), but high Al 2 O 3 ([17 wt%) contents, and is metaluminous to slightly peraluminous (ACNK = 0.89-1.05). The rock samples are enriched in LILE and LREE but depleted in Nb and Ti, showing typical features of subduction-related magmas. The relatively high Sr/Y (*38) ratios and low HREE (Yb \ 0.8 ppm) contents suggest that garnet is a residual phase, while suppressed crystallization of plagioclase and lack of negative Eu anomalies indicate a high water fugacity in the magma.Nd-Sr isotope compositions of the rock (eNd T = -1.38 to -2.33; 87 Sr/ 86 Sr i = 0.7065-0.7067) suggest that both mantle-and crust-derived materials were involved in the petrogenesis, which is consistent with the reverse compositional zoning of plagioclase, interpreted to indicate magma mixing. Both garnet phenocrysts and their ilmenite inclusions contain low MgO contents which, in combination with the oxygen isotope composition of garnet separates (+6.23%), suggests that these minerals formed in a lower crust-derived felsic melt probably in the MASH zone. Although the rock samples are similar to adakitic rocks in many aspects, their moderate Sr contents (\260 ppm) and La/Yb ratios (mostly 16-21) are significantly lower than those of adakitic rocks. Because of high partition coefficients for Sr and LREE, fractionation of apatite at an early stage in the evolution of the magma may have effectively decreased both Sr and LREE in the residual melt. It is suggested that extensive crystallization of apatite as an early phase may prevent some arc magmas from evolving into adakitic rocks even under high water fugacity.

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Section: Implications For Genesis Of Adakitic Rocksmentioning

confidence: 99%

Garnet-bearing tonalitic porphyry from East Kunlun, Northeast Tibetan Plateau: implications for adakite and magmas from the MASH Zone

Yuan

Sun

Xiao

et al. 2008

Int J Earth Sci (Geol Rundsch)

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Mineralogical and geochemical evidence for multi-stage origin of mineral veins hosted by teschenites at Tichá, Outer Western Carpathians, Czech Republic

et al. 2010

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Criteria for the recognition of Archean calc-alkaline lamprophyres: examples from the Abitibi Subprovince

et al. 2018

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19Lamprophyres are minor intrusions with atypical sources and crystallisation sequences. 20 Among lamprophyres, the calc-alkaline type (CAL) on which this study focuses has the 21 least distinctive chemistry and petrology. CAL correspond to small-volume mafic 22 intrusions characterised by the early fractionation of amphibole and/or biotite. In the 23 Archean Superior Province (Canada), CAL are temporally and spatially related to several 24 gold deposits and may thus be relevant to mineral exploration. This study focuses on 25 several altered and metamorphosed intrusions of the Abitibi and La Grande 26 Subprovinces, which were designated lamprophyres based on field observations. Several 27 criteria established from thin sections, whole-rock chemical analyses and SEM data are 28 applied to the studied rocks in order to distinguish CAL from other types of magma. As a 29 result, only one of the studied dykes has the morphology, chemistry, and petrology 30 typical of CAL, while the other intrusions are either too altered to be classified or may 31 correspond to metamorphosed and metasomatized gabbro and diorite. This study shows 32 that thin sections and whole-rock chemical analyses are not always sufficient to 33 unequivocally classify an altered and metamorphosed intrusion as a CAL. Also, 34 intrusions as challenging to recognise as CAL should not be used by exploration 35

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La, Ce, Nd, and Sr behavior in minette magmas during crystallization of apatite-clinopyroxene-mica paragenesis at upper-mantle conditions

Cited by 3 publications

References 34 publications

Garnet-bearing tonalitic porphyry from East Kunlun, Northeast Tibetan Plateau: implications for adakite and magmas from the MASH Zone

Garnet-bearing tonalitic porphyry from East Kunlun, Northeast Tibetan Plateau: implications for adakite and magmas from the MASH Zone

Mineralogical and geochemical evidence for multi-stage origin of mineral veins hosted by teschenites at Tichá, Outer Western Carpathians, Czech Republic

Criteria for the recognition of Archean calc-alkaline lamprophyres: examples from the Abitibi Subprovince

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