scholarly journals Petrogenesis and Geodynamic Implications of a Newly Discovered Basanite Dike in Zaolin, Jingdezhen City, South China

Lithosphere ◽  
2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Xiaofei Pan ◽  
Yufeng Ren ◽  
Zengqian Hou ◽  
Yongpeng Ouyang ◽  
Xuejing Gong ◽  
...  
Keyword(s):  
South China ◽  
Lithospheric Mantle ◽  
Eastern China ◽  
Crustal Contamination ◽  
Alkaline Basalt ◽  
Southeastern China ◽  
Ocean Island Basalts ◽  
Asthenospheric Mantle ◽  
The Matrix ◽  
Geochemical Analyses

Abstract A recently discovered basanite dike in the Zaolin area of Jingdezhen, South China, contains mantle xenocrysts such as kink-banded olivines, olivines + orthopyroxenes assemblage, and chromites. In addition, polymorphic carbonates of the MgCO3–FeCO3 series occur as augens, either independently or interspersed with diopside and spinel in the matrix. The rock is characterized by high Cr and Ni contents, high whole-rock Mg# values (0.66–0.72), and high Ca/Al (0.72–1.03) and TFeO/MgO (1.1–1.3) ratios and is alkali-rich with Na2O > K2O. The trace-element partition patterns are similar to those of other basanites in eastern China as well as ocean island basalts. Whole-rock geochemical analyses show depleted Sr and Nd isotopic compositions (86Sr/87Sr=0.70358–0.703853, εNd=2.52–6.73). These data indicate that the rock has experienced negligible crustal contamination, should be derived from asthenospheric mantle, or mixed by the MORB with EMI/EMII mantle and have been carbonated. The calculated T–P conditions of the melt in equilibrium with xeno-olivine are 1160–1320°C at the mantle depth. The high Cr# values of the spinel xenocrysts indicate that the lithospheric mantle under the Jingdezhen area was probably relict Proterozoic mantle. The Ar–Ar plateau age and the isochron and inverse isochron ages for the matrix of the basanite are all 44 Ma. The basanite, as well as other alkaline basalt or lamprophyre dikes in southeastern China, formed in a rifting regime during the Eocene.

Generation of Late Cretaceous Ji’an basalts through asthenosphere-slab interaction in South China

2020 ◽  
Vol 132 (5-6) ◽  
pp. 1316-1332 ◽  
Author(s):  
Yangming Wu ◽  
Feng Guo ◽  
Xuan-Ce Wang ◽  
Bo Zhang ◽  
Xiaobing Zhang ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Oceanic Crust ◽  
Late Cretaceous ◽  
South China ◽  
Melt Inclusions ◽  
Melt Inclusion ◽  
Geochemical Data ◽  
Oceanic Plate ◽  
Asthenospheric Mantle ◽  
Geochemical Analyses

Abstract Recycled crustal components have been widely identified in the source of continental basalts with geochemical features similar to oceanic island basalts (OIBs). However, the mechanism of how these recycled materials are involved remains highly debatable. Here we conduct comprehensive geochemical analyses (including whole-rock, olivine, and melt inclusion) and numerical modeling on Late Cretaceous Ji’an basalts from South China interior, aiming to investigate the possible role of recycled crustal components in basalt petrogenesis driven by the subducted paleo-Pacific oceanic plate. The Ji’an basalts show geochemical characteristics akin to OIBs and have depleted asthenospheric mantle-like Sr-Nd-Pb-Hf isotopic compositions with moderately radiogenic Os. Their olivine-hosted melt inclusions have low H2O and highly negative δD values and olivine phenocrysts are mainly characterized by depletion of 18O with δ18O values lowering to 3.9‰. These features are consistent with positive Sr and Eu anomalies in some whole-rock samples. The combined geochemical data suggest that the primary magmas were derived from an asthenospheric mantle enriched by melts from an altered gabbroic oceanic crust, which had experienced intensive dehydration. Further numerical modeling shows that melting of the dehydrated oceanic crust can occur along the torn flank of the subducting lithosphere, in the case that the slab is strongly thinned and fractured. The low δ18O preserved in olivine and the estimated slab age (<300 Ma) from the radiogenic whole-rock Os and Pb compositions also require the involvement of a recently recycled slab, probably represented by the subducted paleo-Pacific oceanic plate. Rollback of the subducting paleo-Pacific slab might create a slab window, in which melt from the torn/fractured slab reacted with the upwelling asthenosphere to form an enriched mantle source for the Ji’an basalts and similar counterparts.

scholarly journals Petrology of lamprophyric in northern Jirandeh, Iran

2021 ◽  
Vol 34 (04) ◽  
pp. 1200-1214
Author(s):  
Abdolreza Soleimani ◽  
Shahrooz Haghnazar ◽  
Mansour Vosoughi Abedini ◽  
Saeed Hakimi Asiaber
Keyword(s):  
Middle Eocene ◽  
Crustal Contamination ◽  
Primitive Mantle ◽  
The North ◽  
Rare Elements ◽  
Intraplate Magmatism ◽  
The Matrix ◽  
Green Core ◽  
North Of Iran ◽  
Geochemical Analyses

This study was performed on the outcrops of lamprophyric lavas found in the north of Jirandeh and east of Lushan in the mountain of Alborz (north of Iran). These lavas has been placed discordantly on the middle Eocene lime..Petrographic observation indicates olivine phenocrysts, green-core alkaline clinopyroxenes, nepheline, abundant biotite, and apatites with flakes. and in the matrix it also contains biotite, olivine, clinopyroxene and plagioclase.The presence of carbonates, plagioclase and xenocrystals with rounded margins asserts the contamination with continental crust Petrologically, these rocks classify as alkaline lamprophyres of comptonite variety.These rocks can be subsumed under alkaline sodic categories at K2O/Na2O<1 ratio. The rare elements patterns in the rocks, normalized with the primitive mantle, causing partial negative Nb anomalies and showing no blades at the surface. It, therefore, can be indicative of the evidence for an intraplate magmatism with the different degree in the crustal contamination. Geochemistry states the first cause of asthenospheric flow can be occurred at La/Nb<1 and La/Ta 13 ratios, and the presence of garnet can be assumed at 1/8< (Tb/Yb) N ratio in the rocks origin area. In tectonic discrimination diagrams, these rocks fall in the range of intra-continental rift zones. Geochemical analyses indicate that these lamprophyres originate from partial (1%) melting of an OIB-like asthenospheric mantle source of lherzolite garnet nature.

Carbonatites and lamprophyres of the Gardar Province – a ‘window’ to the sub-Gardar mantle?

2003 ◽  
Vol 67 (5) ◽  
pp. 855-872 ◽  
Author(s):  
I. M. Coulson ◽  
K. M. Goodenough ◽  
N. J. G. Pearce ◽  
M. J. Leng
Keyword(s):  
Lithospheric Mantle ◽  
Nepheline Syenite ◽  
Crustal Contamination ◽  
Small Degree ◽  
Isotopic Signatures ◽  
Asthenospheric Mantle ◽  
Isotope Data ◽  
Mantle Sources ◽  
O Isotope ◽  
Parental Melts

AbstractCarbonatite magmas are considered to be ultimately derived from mantle sources, which may include lithospheric and asthenospheric reservoirs. Isotopic studies of carbonatite magmatism around the globe have typically suggested that more than one source needs to be invoked for generation of the parental melts to carbonatites, often involving the interaction of asthenosphere and lithosphere.In the rift-related, Proterozoic Gardar Igneous Province of SW Greenland, carbonatite occurs as dykes within the Igaliko Nepheline Syenite Complex, as eruptive rocks and diatremes at Qassiarsuk, as a late plug associated with nepheline syenite at Grønnedal-Íka, and as small bodies associated with ultramafic lamprophyre dykes. The well-known cryolite deposit at Ivittuut was also rich in magmatic carbonate. The carbonatites are derived from the mantle with relatively little crustal contamination, and therefore should provide important information about the mantle sources of Gardar magmas. In particular, they are found intruded both into Archaean and Proterozoic crust, and hence provide a test for the involvement of lithospheric mantle.A synthesis of new and previously published major and trace element, Sr, Nd, C and O isotope data for carbonatites and associated lamprophyres from the Gardar Province is presented. The majority of Gardar carbonatites and lamprophyres have consistent geochemical and isotopic signatures that are similar to those typically found in ocean island basalts. The geochemical characteristics of the two suites of magmas are similar enough to suggest that they were derived from the same mantle source. C and O isotope data are also consistent with a mantle derivation for the carbonatite magmas, and support the theory of a cogenetic origin for the carbonatites and the lamprophyres. The differences between the carbonatites and lamprophyres are considered to represent differing degrees of partial melting of a similar source.We suggest that the ultimate source of these magmas is the asthenospheric mantle, since there is no geochemical or isotopic evidence for their having been derived directly from ancient, enriched sub-continental lithospheric mantle. However, it is likely that the magmas actually formed through a two-stage process, with small-degree volatile-rich partial melts rising from the asthenospheric mantle and being ‘frozen in’ as metasomites, which were then rapidly remobilized during Gardar rifting.

Geochemical and isotopic (Nd–Sr–Hf–Pb) evidence for a lithospheric mantle source in the formation of the alkaline Monteregian Province (Quebec)

2013 ◽  
Vol 50 (6) ◽  
pp. 650-666 ◽  
Author(s):  
Emilie Roulleau ◽  
Ross Stevenson
Keyword(s):  
Mantle Source ◽  
Lithospheric Mantle ◽  
North Atlantic Ocean ◽  
Crustal Contamination ◽  
Ocean Island Basalts ◽  
The North ◽  
Enriched Mantle ◽  
Lithospheric Extension ◽  
Depleted Mantle ◽  
Lithospheric Mantle Source

We present new major element and isotopic (Nd–Sr–Hf–Pb) data and modelling from alkaline rocks of the Monteregian Igneous Province of southern Quebec (Canada) that constrain the mantle source and the magmatic origin of these rocks. The whole-rock chemical composition of the intrusions is consistent with fractional crystallization of an assemblage of olivine ± clinopyroxene (± plagioclase) derived from ocean island basalts (OIB)-like magmas, and variations in the Sr and Nd isotope compositions suggest as much as 20% crustal contamination. The bulk of the Nd–Sr–Hf and Pb isotopic data form a tight cluster between a depleted mantle end-member (HIMU, high-U/Pb mantle) and an enriched mantle (EMI) end-member and are thought to reflect a sub-continental lithospheric mantle that was metasomatized by a convecting asthenospheric plume. Variations in these isotopic compositions along the west–east axis of the Monteregian Province (from the Oka carbonatite to the Mount Shefford intrusion) may reflect various degrees of mixing between HIMU and EMI enriched mantle reservoirs. Anomalously low 207Pb/204Pb and 208Pb/204Pb isotopic ratios from some of the intrusions likely indicate incorporation of an Archean component within the lithospheric mantle. We propose a model in which Monteregian magmatism formed from melting of a predominantly Proterozoic metasomatized lithospheric mantle in response to lithospheric extension during the opening of the North Atlantic Ocean at ca. 124 Ma.

scholarly journals Constraints on the Petrogenesis and Metallogenic Setting of Lamprophyres in the World-Class Zhuxi W–Cu Skarn Deposit, South China

Minerals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 642 ◽  
Author(s):  
Wei Zhang ◽  
Shao-Yong Jiang ◽  
Tianshan Gao ◽  
Yongpeng Ouyang ◽  
Di Zhang
Keyword(s):  
South China ◽  
Lithospheric Mantle ◽  
Crustal Extension ◽  
Skarn Deposit ◽  
Mantle Sources ◽  
The World ◽  
World Class ◽  
Granite Magmatism ◽  
Geochemical Analyses ◽  
Light Rare Earth Elements

Whole-rock and apatite geochemical analyses and zircon U–Pb dating were carried out on the lamprophyres in the world-class Zhuxi W–Cu skarn deposit in northern Jiangxi, South China, in order to understand their origin of mantle sources and their relationship with the deposit, as well as metallogenic setting. The results show the lamprophyres were formed at ca. 157 Ma, just before the granite magmatism and mineralization of the Zhuxi deposit. These lamprophyres have from 58.98–60.76 wt% SiO2, 2.52–4.96 wt% K2O, 5.92–6.41 wt% Fe2O3t, 3.75–4.19 wt% MgO, and 3.61–5.06 wt% CaO, and enrichment of light rare earth elements (LREE) and large-ion lithophile elements (LILE), and depletion of high-field-strength elements (HFSE). Apatites in the lamprophyres are enriched in LREE and LILE, Sr, S, and Cl, and have 87Sr/86Sr ratios ranging from 0.7076 to 0.7078. The conclusions demonstrate that the lithospheric mantle under the Zhuxi deposit was metasomatized during Neoproterozoic subduction. Late Jurassic crustal extension caused upwelling of the asthenospheric mantle and consecutively melted the enriched lithospheric mantle and then crustal basement, corresponding to the formation of lamprophyres and mineralization-related granites in the Zhuxi deposit, respectively.

Mineral ages and zircon Hf isotopic composition of the Andong ultramafic complex: implications for the evolution of Mesozoic subduction system and subcontinental lithospheric mantle beneath SE Korea

2013 ◽  
Vol 151 (5) ◽  
pp. 765-776 ◽  
Author(s):  
GI YOUNG JEONG ◽  
CHANG-SIK CHEONG ◽  
KEEWOOK YI ◽  
JEONGMIN KIM ◽  
NAMHOON KIM ◽  
...  
Keyword(s):  
Lithospheric Mantle ◽  
Tectonic Setting ◽  
Eastern China ◽  
Mantle Xenoliths ◽  
Late Triassic ◽  
Magmatic Differentiation ◽  
Suprasubduction Zone ◽  
Ultramafic Complex ◽  
Yeongnam Massif ◽  
Subduction System

AbstractThe Phanerozoic subduction system of the Korean peninsula is considered to have been activated by at least Middle Permian time. The geochemically arc-like Andong ultramafic complex (AUC) occurring along the border between the Precambrian Yeongnam massif and the Cretaceous Gyeongsang back-arc basin provides a rare opportunity for direct study of the pre-Cretaceous mantle wedge lying above the subduction zone. The tightly constrained SHRIMP U–Pb age of zircons extracted from orthopyroxenite specimens (222.1±1.0 Ma) is indistinguishable from the Ar/Ar age of coexisting phlogopite (220±6 Ma). These ages represent the timing of suprasubduction zone magmatism likely in response to the sinking of cold and dense oceanic lithosphere and the resultant extensional strain regime in a nascent arc environment. The nearly coeval occurrence of a syenite-gabbro-monzonite suite in the SW Yeongnam massif also suggests an extensional tectonic setting along the continental margin side during Late Triassic time. The relatively enriched ɛHf range of dated zircons (+6.2 to −0.6 at 222 Ma) is in contrast to previously reported primitive Sr–Nd–Hf isotopic features of Cenozoic mantle xenoliths from Korea and eastern China. This enrichment is not ascribed to contamination by the hypothetical Palaeozoic crust beneath SE Korea, but is instead attributable to metasomatism of the lithospheric mantle during the earlier subduction of the palaeo-Pacific plate. Most AUC zircons show a restricted core-to-rim spread of ɛHf values, but some grains testify to the operation of open-system processes during magmatic differentiation.

Microscale effects of melt infiltration into the lithospheric mantle: Peridotite xenoliths from Xilong, South China

Lithos ◽  
2015 ◽  
Vol 232 ◽  
pp. 111-123 ◽  
Author(s):  
Jianggu Lu ◽  
Jianping Zheng ◽  
William L. Griffin ◽  
Suzanne Y. O'Reilly ◽  
Norman J. Pearson
Keyword(s):  
South China ◽  
Lithospheric Mantle ◽  
Mantle Peridotite ◽  
Peridotite Xenoliths ◽  
Melt Infiltration

scholarly journals Increasing surface ozone concentrations in the background atmosphere of Southern China, 1994–2007

2009 ◽  
Vol 9 (16) ◽  
pp. 6217-6227 ◽  
Author(s):  
T. Wang ◽  
X. L. Wei ◽  
A. J. Ding ◽  
C. N. Poon ◽  
K. S. Lam ◽  
...  
Keyword(s):  
Hong Kong ◽  
South China ◽  
Surface Ozone ◽  
Eastern China ◽  
Rate Of Change ◽  
Urban Site ◽  
Coastal Regions ◽  
Air Masses ◽  
Background Ozone ◽  
Rate Of Increase

Abstract. Tropospheric ozone is of great importance with regard to air quality, atmospheric chemistry, and climate change. In this paper we report the first continuous record of surface ozone in the background atmosphere of South China. The data were obtained from 1994 to 2007 at a coastal site in Hong Kong, which is strongly influenced by the outflow of Asian continental air during the winter and the inflow of maritime air from the subtropics in the summer. Three methods are used to derive the rate of change in ozone. A linear fit to the 14-year record shows that the ozone concentration increased by 0.58 ppbv/yr, whereas comparing means in years 1994–2000 and 2001–2007 gives an increase of 0.87 ppbv/yr for a 7-year period. The ozone changes in air masses from various source regions are also examined. Using local wind and carbon monoxide (CO) data to filter out local influence, we find that ozone increased by 0.94 ppbv/yr from 1994–2000 to 2001–2007 in air masses from Eastern China, with similar changes in the other two continent-influenced air-mass groups, but no statistically significant change in the marine air. An examination of the nitrogen dioxide (NO2) column obtained from GOME and SCIAMACHY reveals an increase in atmospheric NO2 in China's three fastest developing coastal regions, whereas NO2 in other parts of Asia decreased during the same period, and no obvious trend over the main shipping routes in the South China Sea was indicated. Thus the observed increase in background ozone in Hong Kong is most likely due to the increased emissions of NO2 (and possibly volatile organic compounds (VOCs) as well) in the upwind coastal regions of mainland China. The CO data at Hok Tsui showed less definitive changes compared to the satellite NO2 column. The increase in background ozone likely made a strong contribution (81%) to the rate of increase in "total ozone" at an urban site in Hong Kong, suggesting the need to consider distant sources when developing long-term strategies to mitigate local ozone pollution.

Relative roles of source composition, fractional crystallization and crustal contamination in the petrogenesis of Andean volcanic rocks

1984 ◽  
Vol 310 (1514) ◽  
pp. 675-692 ◽  
Keyword(s):  
Subduction Zone ◽  
Continental Crust ◽  
Fractional Crystallization ◽  
Magma Mixing ◽  
Volcanic Rocks ◽  
Crustal Contamination ◽  
Oceanic Lithosphere ◽  
Alkaline Basalt ◽  
Complex Process ◽  
Heterogeneous Mantle

There are well established differences in the chemical and isotopic characteristics of the calc-alkaline basalt—andesite-dacite-rhyolite association of the northern (n.v.z.), central (c.v.z.) and southern volcanic zones (s.v.z.) of the South American Andes. Volcanic rocks of the alkaline basalt-trachyte association occur within and to the east of these active volcanic zones. The chemical and isotopic characteristics of the n.v.z. basaltic andesites and andesites and the s.v.z. basalts, basaltic andesites and andesites are consistent with derivation by fractional crystallization of basaltic parent magmas formed by partial melting of the asthenospheric mantle wedge containing components from subducted oceanic lithosphere. Conversely, the alkaline lavas are derived from basaltic parent magmas formed from mantle of ‘within-plate’ character. Recent basaltic andesites from the Cerro Galan volcanic centre to the SE of the c.v.z. are derived from mantle containing both subduction zone and within-plate components, and have experienced assimilation and fractional crystallization (a.f.c.) during uprise through the continental crust. The c.v.z. basaltic andesites are derived from mantle containing subduction-zone components, probably accompanied by a.f.c. within the continental crust. Some c.v.z. lavas and pyroclastic rocks show petrological and geochemical evidence for magma mixing. The petrogenesis of the c.v.z. lavas is therefore a complex process in which magmas derived from heterogeneous mantle experience assimilation, fractional crystallization, and magma mixing during uprise through the continental crust.

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