Petrogenesis and tectonic significance of the Early Devonian lamprophyres and diorites in the Alxa Block, NW China

Zeng, Renyu; Lai, Jin; Mao, Xiaoming; Xiao, Wenzhou; Yan, Jie; Zhang, Chenguang; Hu, Jianxiong; Ai, Qixing

doi:10.1016/j.chemer.2020.125685

Cited by 5 publications

(4 citation statements)

References 87 publications

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“…Since the multielement spidergrams present strong positive anomalies in LILE (K and Rb) and Pb, as well as negative anomalies in HFSE (Nb, Ta, Zr, Hf, Ti), subduction-related materials are likely to be responsible for the mantle source enrichment. The influence of a previous subduction event is reflected in several trace element ratios such as Ta/Yb (0.6-0.7), the (Štemprok et al, 2014) low Lu/Hf (≈ 0.03), Sm/Nd (≈ 0.16), and Sm/La (≈ 0.14), the high Th/La (0.17-0.21), La/Nb (4.0-5.1), and Th/Ta (18.0-19.2), as well as the Th/Yb ratio (11.7-13.6) whose values are higher than those of N-MORB (Zeng et al, 2020). European lamprophyres of late-Variscan age typically present high contents in Rb, Ba, Pb, Sr, U, and Th, high values for the Th/La ratio, and low values for the Sm/La ratio (Štemprok et al, 2014 and references therein).…”

Section: Lamprophyre Petrogenesis and Source Compositionmentioning

confidence: 91%

“…12). The Th/U ratio ranges between 0.04-2.10 (mean Th/U = 0.63), which is characteristic of primary zircon crystals in mafic or intermediate lithologies (Rubatto & Gebauer, 2000;Zeng et al, 2020). Weighted means (errors reported at one σ level) of the 204-corrected 206 Pb/ 238 U age yield a value of 295 ± 2 Ma (MSWD = 2.1), and presumably represent the lamprophyre crystallization age.…”

Section: Geochronology and Isotope Geochemistrymentioning

confidence: 99%

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Permo-Carboniferous hypabyssal magmatism in northern Portugal: the case of the Lamas de Olo microgranite and lamprophyre dykes

2021

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During the final stages of the Variscan orogeny, several subvolcanic dykes intruded throughout NW and SW Europe. In northern Portugal, the microgranite and lamprophyre of the Lamas de Olo region constitute a local manifestation of this magmatic event. To understand their petrogenesis, field, petrographic, and bulk-rock geochemical studies were undertaken. The lamprophyre was also analyzed for the Rb-Sr, Sm-Nd, and zircon U-Pb systematics. Mineralogically, the microgranite resembles alkali-feldspar granites, while the lamprophyre is a minette. Geochemically, the felsic dyke was probably derived from an evolved crustal source, possibly uncontaminated by mantellic or young crustal influences. The results suggest that the source is similar to that of the most evolved facies of the Lamas de Olo pluton. Structurally, the emplacement of the microgranite was presumably controlled by the regional WSW-ENE fracture system. On the other hand, lamprophyre emplacement is related to the regional NNE-SSW system. Fractional crystallization is likely to have conditioned the petrogenesis of the mafic dyke while crustal contamination probably played only a minor role. Several trace element ratios suggest that the lamprophyre resulted from low-degree melting of an enriched mantle source located in the lithospheric mantle. Source enrichment was presumably caused by subduction-related materials and metasomatism triggered by carbonate-rich fluids. When compared to other late-Variscan lamprophyres, the Lamas de Olo mafic dyke shares more similarities with the calcalkaline specimens of Western Europe. The present work corroborates previous studies concerning the hypothesis that late to post-Variscan lamprophyres may constitute a geodynamic pointer for a change in the tectonic regime.

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Section: Lamprophyre Petrogenesis and Source Compositionmentioning

confidence: 91%

Section: Geochronology and Isotope Geochemistrymentioning

confidence: 99%

Permo-Carboniferous hypabyssal magmatism in northern Portugal: the case of the Lamas de Olo microgranite and lamprophyre dykes

2021

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“…It is generally considered that mantle-sourced primitive melts may have had relatively high Ni (> 400 ppm), Cr (> 1,000 ppm) and Mg# (73-81) contents (Mahoney, 1997;Wilson, 1989), which are not found in the Longlin basalts . This shows that fractionation of mafic minerals (e.g., olivine and pyroxene) has likely occurred (Frey and Prinz, 1978;Wang et al, 2016;Zeng et al, 2021b). Due to the insufficient element geochemical data, it is hard to determine the fractionated minerals from the Harker-type diagrams.…”

Section: Fractional Crystallizationmentioning

confidence: 99%

“…FIGURE 8 | (A) ( 87 Sr/ 86 Sr) i -εNd(t) and (B) εHf(t)-εNd(t) (base map afterZeng et al, 2021a;Zeng et al, 2021b) diagrams for the Longlin basalt samples. MORB, mid-ocean-ridge basalt; EM I and EM II, enriched mantle; HIMU, LCC/MCC, middle to lower continental crust; UC, upper continental crust; IMM, Indian MORB; PMM, Pacific MORB.…”

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confidence: 99%

Late Permian High-Ti Basalt in Western Guangxi, SW China and Its Link With the Emeishan Large Igneous Province: Geochronological and Geochemical Perspectives

et al. 2021

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High-Ti (Ti/Y) flood basalts are widely distributed in the Late Permian Emeishan large igneous province (LIP), SW China, and their spatial distribution and genetic mechanism are important to reveal the role of plume-lithosphere interactions in the LIP origin. Western Guangxi is located on the eastern edge of Emeishan LIP. To explore the genesis of the high-Ti basalt in western Guangxi and any genetic link with the Emeishan LIP, we performed whole-rock geochemical and Sr-Nd isotope and zircon U-Pb-Hf isotope analyses on the Longlin basalts from western Guangxi. The results indicate that the Longlin basalt from Tongdeng area has relatively high SiO2 but low MgO and TFe2O3 contents. The rocks have zircon εHf(t) = −0.42 to 6.41, whole-rock (87Sr/86Sr)i = 0.707167–0.707345, and εNd(t) = −2.5 to −2.14. In contrast, the Longlin basalt from Zhoudong area has relatively low SiO2 but high MgO and TFe2O3 contents. The rocks have whole-rock (87Sr/86Sr)i = 0.706181–0.706191 and εNd(t) = −0.57 to 0.69. Four Longlin basalt samples display LREE enrichments and HREE depletions, and with indistinct δEu and δCe anomalies. LA-ICP-MS zircon U-Pb dating on three Longlin basalt samples (from different localities) yielded consistent weighted average age of 257.9 ± 2.6 Ma (MSWD = 0.55), 259.5 ± 0.75 Ma (MSWD = 3.0), and 256.7 ± 2.0 Ma (MSWD = 0.68), indicating a Late Permian emplacement. Considering the similar age and geochemical features between the Longlin basalt and Emeishan flood basalts, we interpret that the former is spatially, and temporally associated with the Emeishan LIP. Geochemical features show that the high-Ti basalts in western Guangxi resemble Deccan-type continental flood basalts (CFBs), which were derived by decompression melting of the mantle plume. Combined with previous geochemical studies, we suggest that the difference in Ti content and Ti/Y ratio in CFBs are related to the depth and melting degree of mantle source, in which high-Ti features may have been linked to low degree of partial melting in the deep mantle.

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Mafic dikes of the Mariinsky Taiga Alkaline Province, Kuznetsk Alatau terrane, southwestern Siberia: Intraplate alkaline magmatism in the Central Asian Orogenic Belt

Mustafaev

Ernst²,

Гертнер³

et al. 2022

Lithos

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Petrogenesis and tectonic significance of the Early Devonian lamprophyres and diorites in the Alxa Block, NW China

Cited by 5 publications

References 87 publications

Permo-Carboniferous hypabyssal magmatism in northern Portugal: the case of the Lamas de Olo microgranite and lamprophyre dykes

Permo-Carboniferous hypabyssal magmatism in northern Portugal: the case of the Lamas de Olo microgranite and lamprophyre dykes

Late Permian High-Ti Basalt in Western Guangxi, SW China and Its Link With the Emeishan Large Igneous Province: Geochronological and Geochemical Perspectives

Mafic dikes of the Mariinsky Taiga Alkaline Province, Kuznetsk Alatau terrane, southwestern Siberia: Intraplate alkaline magmatism in the Central Asian Orogenic Belt

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