Post-Collisional Potassic and Ultrapotassic Magmatism in SW Tibet: Geochemical and Sr-Nd-Pb-O Isotopic Constraints for Mantle Source Characteristics and Petrogenesis

Miller, Christine; Schuster, Ralf; Klötzli, Urs; Frank, Wolfgang; Purtscheller, F.

doi:10.1093/petroj/40.9.1399

Cited by 574 publications

(190 citation statements)

References 75 publications

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“…In contrast, the differing ages of magmatic belts, coupled with other tectonic characteristics, led Tapponnier et al (2001) to suggest that uplift of the plateau was stepwise, initiating in the central Tibet (Qiangtang terrane) during the Eocene before progressing northward and southward in response to the subduction of Asian or Indian continental lithosphere. Thus, the Cenozoic volcanism and uplift of the central plateau (Qiangtang terrane) have been explained by two distinct mechanisms: convective thinning (e.g., Turner et al, 1993Turner et al, , 1996Chung et al, 1998;Miller et al, 1999;Williams et al, 2001) and intracontinental subduction (e.g., Roger et al, 2000;Tapponnier et al, 2001;Ding et al, 2003Ding et al, , 2007Guo et al, 2006;Q. Wang et al, , 2010.…”

Section: Introductionmentioning

confidence: 99%

Geochemistry of Eocene high-Mg# adakitic rocks in the northern Qiangtang terrane, central Tibet: Implications for early uplift of the plateau

Chen

et al. 2013

Geological Society of America Bulletin

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Section: Introductionmentioning

confidence: 99%

Geochemistry of Eocene high-Mg# adakitic rocks in the northern Qiangtang terrane, central Tibet: Implications for early uplift of the plateau

Chen

et al. 2013

Geological Society of America Bulletin

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“…Miocene UPVs erupted along N-S striking grabens or normal faults in southern Tibet ( Fig. 1), under E-W extensional in response to plateau collapse, lithospheric mantle delamination, or Indian plate stalling or breakoff (Miller et al 1999;Williams 2000;Ding et al 2003;Williams et al 2004;Gao et al 2007;Zhao et al 2009;Liu et al 2011Liu et al , 2014Wang et al 2015a). Broadly coeval with these UPV eruptions, a large number of smallvolume, calc-alkaline to high-K alkaline, adakite-like granitoids intruded in the Gangdese belt between ~30 and 10 Ma.…”

Section: Geological Settingmentioning

confidence: 99%

“…UPV rocks in southern Tibet are basaltic trachyandesite, trachyandesite, and trachydacite, characterized by mantlelike ( 187 Os/ 188 Os) i ratios (0.154-0.210; Wang et al 2015a), but with extremely low εNd i values (−17.4 to −7.1) and high ( 87 Sr/ 86 Sr) i and zircon δ 18 O VSMOW values (0.7068-0.7399 and +6.2 to +8.8 ‰, respectively) (e.g., Miller et al 1999;Williams 2000;Ding et al 2003;Williams et al 2004;Gao et al 2007;Zhao et al 2009;Wang et al 2015a) suggesting derivation from an old, metasomatized subcontinental lithospheric mantle (SCLM). In contrast, the coeval calc-alkaline granitoids are commonly quartz monzonite, granodiorite, and granite porphyries, which have relatively low ( 87 Sr/ 86 Sr) i ratios (0.7047-0.7076), high εNd i values (−6.1 to +5.5), moderate ( 187 Os/ 188 Os) i ratios (0.224-0.835), and low zircon δ 18 O VSMOW values (+5.5 to +6.6 ‰), suggestive of a juvenile magma source similar to the Paleocene-Eocene Gangdese arc.…”

Section: Geological Settingmentioning

confidence: 99%

Xenoliths in ultrapotassic volcanic rocks in the Lhasa block: direct evidence for crust–mantle mixing and metamorphism in the deep crust

Wang

Collins²,

Weinberg

et al. 2016

Contrib Mineral Petrol

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juvenile character (εHf i +0.5 to +6.5) of Eocene Gangdese arc magmas. Together these two age groups indicate that a component of the xenolith was sourced from Gangdese arc rocks. The 35-20 Ma Miocene ages are derived from zircons with similar Hf-O isotopic composition as the Eocene Gangdese magmatic zircons. They also have similar steep REE curves, suggesting they grew in the absence of garnet. These zircons mark a period of early Miocene remelting of the Eocene Gangdese arc. By contrast, the youngest zircons (13.0 ± 4.9 Ma, MSWD = 1.3) are not zoned, have much lower HREE contents than the previous group, and flat HREE patterns. They also have distinctive high Th/U ratios, high zircon δ 18 O (+8.73-8.97 ‰) values, and extremely low εHf i (−12.7 to −9.4) values. Such evolved Hf-O isotopic compositions are similar to values of zircons from the UPV lavas that host the xenolith, and the flat REE pattern suggests that the 13 Ma zircons formed in equilibrium with garnet. Garnets from a strongly peraluminous metatonalite xenolith are weakly zoned or unzoned and fall into four groups, three of which are almandine-pyrope solid Abstract Felsic granulite xenoliths entrained in Miocene (~13 Ma) isotopically evolved, mantle-derived ultrapotassic volcanic (UPV) dykes in southern Tibet are refractory meta-granitoids with garnet and rutile in a near-anhydrous quartzo-feldspathic assemblage. High F-Ti (~4 wt.% TiO 2 and ~3 wt.% F) phlogopite occurs as small inclusions in garnet, except for one sample where it occurs as flakes in a quartz-plagioclase-rich rock. High Si (~3.45) phengite is found as flakes in another xenolith sample. The refractory mineralogy suggests that the xenoliths underwent high-T and high-P metamorphism (800-850 °C, >15 kbar). Zircons show four main age groupings: 1.0-0.5 Ga, 50-45, 35-20, and 16-13 Ma. The oldest group is similar to common inherited zircons in the Gangdese belt, whereas the 50-45 Ma zircons match the crystallization age and Communicated by Hans Keppler. Contrib Mineral Petrol (2016) 171:62 1 3 62 Page 2 of 19 solutions and have low δ 18 O (+6 to 7.5 ‰), intermediate (δ 18 O +8.5 to 9.0 ‰), and high δ 18 O (+11.0 to 12.0 ‰). The fourth is almost pure andradite with δ 18 O 10-12 ‰. Both the low and intermediate δ 18 O groups show significant variation in Fe content, whereas the two high δ 18 O groups are compositionally homogeneous. We interpret these features to indicate that the low and intermediate δ 18 O group garnets grew in separate fractionating magmas that were brought together through magma mixing, whereas the high δ 18 O groups formed under high-grade metamorphic conditions accompanied by metasomatic exchange. The garnets record complex, open-system magmatic and metamorphic processes in a single rock. Based on these features, we consider that ultrapotassic magmas interacted with juvenile 35-20 Ma crust after they intruded in the deep crust (>50 km) at ~13 Ma to form hybridized Miocene granitoid magmas, leaving a refractory residue. The ~13 Electronic supplementary material The onli...

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“…As the rocks from the different regional zones broadly follow the same evolution trends in Harker diagrams, the trace element diagrams are not displayed according to geographic areas, but instead using the petrographicalchemical classification, which is in fact the SiO 2 content. The Motru rocks are compared to the classical low-K to shoshonitic calc-alkaline lava suites worldwide: the lowto medium-K calc-alkaline suite is illustrated by the Montserrat volcanic series (data from Zellmer et al 2003), the medium-to high-K suite by the Cainozoic Central Andes (data from Richards and Villeneuve 2002) and the high-K to shoshonitic suite by the Tibet volcanic series (data from Miller et al 1999). All samples, whatever their degree of evolution, are enriched in LILE, Pb and LREE and relatively depleted in Nb, Ta, P and Ti, which is a typical feature of arc-related magmas worldwide (e.g.…”

Section: Whole-rock Trace Elementsmentioning

confidence: 99%

Nature and significance of a Cambro-Ordovician high-K, calc-alkaline sub-volcanic suite: the late- to post-orogenic Motru Dyke Swarm (Southern Carpathians, Romania)

Féménias¹,

Berza²,

Tatu³

et al. 2007

Int J Earth Sci (Geol Rundsch)

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The Motru Dyke Swarm intrudes the Precambrian Danubian basement of the Southern Carpathians (Romania). It is a marker of a sub-volcanic event that occurred during the early Palaeozoic (Cambrian to Ordovician). The geographical distribution of dykes on ã 2,000 km 2 area is heterogeneous; several areas of high dyke density have been the subject of a detailed petrological and geochemical study. Taken altogether, the 150 samples define a single complete magmatic series, from basaltic andesite to rhyolite. Whole-rock major element variations show a medium-to high-K, calc-alkaline magmatic suite. The compositional variations and the general decrease of trace element contents (both compatible and incompatible, including REEs) from basaltic andesite to rhyolite are consistent with 1) the fractionation of the observed phenocryst assemblages, Ca-amphibole (Tipargasite to magnesiohornblende) followed by intermediate plagioclase, clinopyroxene and accessory biotite and quartz and 2) the absence of lower and/or upper crustal contamination. Trace elements diagrams display typical arc patterns (LILE, Pb and LREE enrichment and relative depletion in Nb-Ta, Zr-Hf and Ti). The Th/U, Nb/Ta and Zr/Hf ratios are constant and close to the mantle values throughout the whole series, which argues that the parental magma was generated from a single and homogeneous enriched lithospheric mantle source. The field regional evidence implies that melting occurred during a late-to post-orogenic period of lithospheric extension, and thus took place quite lately after the cessation of Pan-African subduction.

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Post-Collisional Potassic and Ultrapotassic Magmatism in SW Tibet: Geochemical and Sr-Nd-Pb-O Isotopic Constraints for Mantle Source Characteristics and Petrogenesis

Cited by 574 publications

References 75 publications

Geochemistry of Eocene high-Mg# adakitic rocks in the northern Qiangtang terrane, central Tibet: Implications for early uplift of the plateau

Geochemistry of Eocene high-Mg# adakitic rocks in the northern Qiangtang terrane, central Tibet: Implications for early uplift of the plateau

Xenoliths in ultrapotassic volcanic rocks in the Lhasa block: direct evidence for crust–mantle mixing and metamorphism in the deep crust

Nature and significance of a Cambro-Ordovician high-K, calc-alkaline sub-volcanic suite: the late- to post-orogenic Motru Dyke Swarm (Southern Carpathians, Romania)

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