Metasomatic Processes in the Lithospheric Mantle Beneath the No. 30 Kimberlite (Wafangdian Region, North China Craton)

2019 ◽  
Vol 57 (4) ◽  
pp. 499-517 ◽  
Author(s):  
Ren Z. Zhu ◽  
Pei Ni ◽  
Jun Y. Ding ◽  
Guo G. Wang ◽  
Ming S. Fan ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Trace Element ◽  
North China Craton ◽  
Lithospheric Mantle ◽  
North China ◽  
Compositional Data ◽  
Early Stage ◽  
Mantle Metasomatism ◽  
Element Data

AbstractThis paper presents the first major and trace element compositions of mantle-derived garnet xenocrysts from the diamondiferous No. 30 kimberlite pipe in the Wafangdian region, and these are used to constrain the nature and evolution of mantle metasomatism beneath the North China Craton (NCC). The major element data were acquired using an electron probe micro-analyzer and the trace element data were obtained using laser ablation inductively coupled plasma-mass spectrometry. Based on Ni-in-garnet thermometry, equilibrium temperatures of 1107–1365 °C were estimated for peridotitic garnets xenocrysts from the No. 30 kimberlite, with an average temperature of 1258 °C, and pressures calculated to be between 5.0 and 7.4 GPa. In a CaO versus Cr2O3 diagram, 52% of the garnets fall in the lherzolite field and 28% in the harzburgite field; a few of the garnets are eclogitic. Based on rare earth element patterns, the lherzolitic garnets are further divided into three groups. The compositional variations in garnet xenocrysts reflect two stages of metasomatism: early carbonatite melt/fluid metasomatism and late kimberlite metasomatism. The carbonatite melt/fluids are effective at introducing Sr and the light rare earth elements, but ineffective at transporting much Zr, Ti, Y, or heavy rare earth elements. The kimberlite metasomatic agent is highly effective at element transport, introducing, e.g., Ti, Zr, Y, and the rare earth elements. Combined with compositional data for garnet inclusions in diamonds and megacrysts from the Mengyin and Wafangdian kimberlites, we suggest that these signatures reflect a two-stage evolution of the sub-continental lithospheric mantle (SCLM) beneath the NCC: (1) early-stage carbonatite melt/fluid metasomatism resulting in metasomatic modification of the SCLM and likely associated with diamond crystallization; (2) late-stage kimberlite metasomatism related to the eruption of the 465 Ma kimberlite.

Heterogeneous lithospheric mantle metasomatism in the eastern North China Craton: He–Ar isotopes in peridotite xenoliths from Cenozoic basalts

2014 ◽  
Vol 80 ◽  
pp. 185-196 ◽  
Author(s):  
Huayun Tang ◽  
Takuya Matsumoto ◽  
Jianping Zheng ◽  
György Czuppon ◽  
Chunmei Yu ◽  
...  
Keyword(s):  
North China Craton ◽  
Lithospheric Mantle ◽  
North China ◽  
Mantle Metasomatism ◽  
Peridotite Xenoliths

Significance of the metasomatized lithospheric mantle in the formation of early basalts and Cu – platinum group element sulfide mineralization in the Coldwell Complex, Midcontinent Rift, Canada

2019 ◽  
Vol 56 (7) ◽  
pp. 693-714 ◽  
Author(s):  
David J. Good ◽  
Peter C. Lightfoot
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Trace Element ◽  
Lithospheric Mantle ◽  
Group Element ◽  
Light Rare Earth ◽  
Midcontinent Rift ◽  
Northern Margin ◽  
Lithospheric Mantle Source ◽  
Light Rare Earth Elements

A diverse suite of tholeiitic to alkaline basalt and gabbroic intrusions located in the Coldwell Complex on the northern margin of the Midcontinent Rift exhibit unusual trace element signatures that show enriched large ion lithophile elements and light rare earth elements with negative Nb and Zr anomalies. These features are not typical of magmas derived by partial melting within or above a rising mantle plume, as might be expected in an early Midcontinent Rift magmatic event. In this paper, we provide a detailed geochemical study of a 500 m thick sequence of metabasalt that represents the earliest stage of magmatism in the Coldwell Complex. We show that contamination or crystallization processes or subsequent metasomatism cannot explain the trace element variations. Instead, we propose partial melting in a metasomatized Subcontinental Lithospheric Mantle source to explain the decoupled behavior of large ion lithophile elements from light rare earth elements and heavy rare earth elements and rare earth elements from high field strength elements and the enriched Nd isotope signature of metabasalt. Similar features occur in unit 5b of the Mamainse Point Volcanic Group located at the northern margin of the Rift. An objective of this paper is to relate Two Duck Lake gabbro, host rock for low-sulfur, high precious metal sulfide mineralization at the Marathon deposit, to the metabasalt sequence. The excellent match of trace element abundances in Two Duck Lake gabbro to metabasalt unit 3 confirms an early Coldwell Complex age for metabasalt and a Subcontinental Lithospheric Mantle source for Cu – platinum group element mineralized gabbros.

scholarly journals Identification and Geological Significance of Early Jurassic Adakitic Volcanic Rocks in Xintaimen Area, Western Liaoning

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 331
Author(s):  
Zhi-Wei Song ◽  
Chang-Qing Zheng ◽  
Chen-Yue Liang ◽  
Bo Lin ◽  
Xue-Chun Xu ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
North China Craton ◽  
Lower Crust ◽  
North China ◽  
Basaltic Magma ◽  
Volcanic Rocks ◽  
Early Jurassic ◽  
Magma Source ◽  
Western Liaoning

The Western Liaoning area, where a large number of Jurassic-Cretaceous volcanic rocks are exposed, is one of the typical areas for studying the Mesozoic Paleo-Pacific and Mongolia-Okhotsk subduction process, and lithospheric destruction of North China Craton. The identification and investigation of Early Jurassic adakitic volcanic rocks in the Xintaimen area of Western Liaoning is of particular significance for exploring the volcanic magma source and its composition evolution, tracking the crust-mantle interaction, and revealing the craton destruction and the subduction of oceanic plates. Detailed petrography, zircon U–Pb dating, geochemistry, and zircon Hf isotope studies indicate that the Early Jurassic intermediate-acidic volcanic rocks are mainly composed of trachydacites and a few rhyolites with the formation ages of 178.6–181.9 Ma. Geochemical characteristics show that they have a high content of SiO2, MgO, Al2O3, and total-alkali, typical of the high-K calc-alkaline series. They also show enrichment of light rare earth elements (LREEs) and large ion lithophile elements (LILEs), depletion of heavy rare earth elements (HREEs) and high field strength elements (HFSEs), and have a high content of Sr and low content of Y and Yb, suggesting that they were derived from the partial melting of the lower crust. The εHf(t) values of dated zircons and two-stage model ages (TDM2) vary from −11.6 to −7.4 and from 1692 to 1958 Ma, respectively. During the Early Jurassic, the study area was under long-range tectonic effects with the closure of the Mongolia-Okhotsk Ocean and the subduction of the Paleo-Pacific plate, which caused the basaltic magma to invade the lower crust of the North China Craton. The mantle-derived magma was separated and crystallized while heating the Proterozoic lower crust, and part of the thickened crust melted to form these intermediate-acidic adakitic volcanic rocks.

scholarly journals Metasomatized lithospheric mantle for Mesozoic giant gold deposits in the North China craton

Geology ◽  
2019 ◽  
Vol 48 (2) ◽  
pp. 169-173 ◽  
Author(s):  
Zaicong Wang ◽  
Huai Cheng ◽  
Keqing Zong ◽  
Xianlei Geng ◽  
Yongsheng Liu ◽  
...  
Keyword(s):  
North China Craton ◽  
Lithospheric Mantle ◽  
North China ◽  
Mantle Metasomatism ◽  
Gold Deposits ◽  
Mantle Xenoliths ◽  
Lode Gold ◽  
The North ◽  
Craton Destruction ◽  
Lode Gold Deposits

Abstract The origin of giant lode gold deposits of Mesozoic age in the North China craton (NCC) is enigmatic because high-grade metamorphic ancient crust would be highly depleted in gold. Instead, lithospheric mantle beneath the crust is the likely source of the gold, which may have been anomalously enriched by metasomatic processes. However, the role of gold enrichment and metasomatism in the lithospheric mantle remains unclear. Here, we present comprehensive data on gold and platinum group element contents of mantle xenoliths (n = 28) and basalts (n = 47) representing the temporal evolution of the eastern NCC. The results indicate that extensive mantle metasomatism and hydration introduced some gold (<1–2 ppb) but did not lead to a gold-enriched mantle. However, volatile-rich basalts formed mainly from the metasomatized lithospheric mantle display noticeably elevated gold contents as compared to those from the asthenosphere. Combined with the significant inheritance of mantle-derived volatiles in auriferous fluids of ore bodies, the new data reveal that the mechanism for the formation of the lode gold deposits was related to the volatile-rich components that accumulated during metasomatism and facilitated the release of gold during extensional craton destruction and mantle melting. Gold-bearing, hydrous magmas ascended rapidly along translithospheric fault zones and evolved auriferous fluids to form the giant deposits in the crust.

Rare earth and other trace element mobility accompanying albitization in a Proterozoic granite, W. Bergslagen, Sweden

1985 ◽  
Vol 49 (350) ◽  
pp. 107-115 ◽  
Author(s):  
J. H. Baker
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Trace Element ◽  
Atomic Number ◽  
Hydrothermal Fluid ◽  
Trace Element Data ◽  
Element Mobility ◽  
Element Data ◽  
Trace Element Mobility ◽  
Important Constituent

AbstractZones of albitization 20 m wide are developed in the peraluminous, undeformed Proterozoic Bastfallshöjden granite, W. Bergslagen, central Sweden. During albitization Na, Si, Mg, Ni, Zn, and Ga are added, while Fe2+, Fe3+, Mn, K, Sc, Rb, Cs, Ba, Pb, U, and F are lost, together with the rare earth elements (REE) in decreasing amounts with increasing atomic number. Ti, Al, P, and Y were immobile. Trace element data for chlorites separated from hydrothermally altered country rocks and from a quartz-chlorite vein in the albitized granite show similar REE patterns indicating a common origin: the most altered granite has a similar REE pattern, probably resulting from interaction with the same hydrothermal fluid which produced the chlorites, in which seawater is thought to have been an important constituent.

Early Devonian ultrapotassic magmatism in the North China Craton: geochemical and isotopic evidence for subcontinental lithospheric mantle metasomatism by subducted sediment-derived fluids

2019 ◽  
Vol 158 (1) ◽  
pp. 158-174 ◽  
Author(s):  
Xiaolu Niu ◽  
Yildirim Dilek ◽  
Fei Liu ◽  
Guangying Feng ◽  
Jingsui Yang
Keyword(s):  
North China Craton ◽  
Lithospheric Mantle ◽  
North China ◽  
Mantle Metasomatism ◽  
Alkaline Magmatism ◽  
Subcontinental Lithospheric Mantle ◽  
Early Devonian ◽  
Isotopic Compositions ◽  
The North

AbstractWe report new U–Pb zircon age data, zircon in situ oxygen isotope, mineral chemistry, whole-rock geochemistry and Sr–Nd isotopic compositions from the Early Devonian ultrapotassic Gucheng pluton in the North China Craton, and discuss its petrogenesis. The Gucheng pluton is exposed in the northern part of the North China Craton and forms a composite intrusion, consisting of K-feldspar-bearing clinopyroxenite, clinopyroxene-bearing syenite and alkali-feldspar syenite. Mineral phases in these lithologies include clinopyroxene (Wo43–48En19–35Fs18–38), sanidine (An0Ab3–11Or89–97), and subordinate titanite, andradite and Na-feldspar. These rocks show homogeneous Sr but variable Nd isotopic compositions, and have relatively high zircon in situ oxygen isotopes (δ18O = 5.2–6.7). The Gucheng plutonic rocks formed through fractional crystallization and accumulation from ultrapotassic magmas, which were originated from partial melting of metasomatic vein systems in the subcontinental lithospheric mantle of the North China Craton. These vein networks developed as a result of the reactions of fluids derived from subducted pelitic sediments on the downgoing Palaeo-Asian ocean floor with the enriched, subcontinental lithospheric mantle peridotites. Sensitive high-resolution ion microprobe (SHRIMP) U–Pb zircon dating has revealed a crystallization age of 415 Ma for the timing of the emplacement of the Gucheng pluton that marks the early stages of alkaline magmatism associated with the Andean-type continental margin evolution along the northern edge of the North China Craton facing the Palaeo-Asian Ocean.

In-situ reaction-replacement origin of hornblendites in the Early Cretaceous Laiyuan complex, North China Craton, and implications for its tectono-magmatic evolution

2021 ◽  
Author(s):  
Jia Chang ◽  
Andreas Audétat ◽  
Jian-Wei Li
Keyword(s):  
Partial Melting ◽  
North China Craton ◽  
Lithospheric Mantle ◽  
Lower Crust ◽  
North China ◽  
Ultramafic Rocks ◽  
Magmatic Evolution ◽  
Mafic Magmas ◽  
Felsic Rocks

Abstract Two suites of amphibole-rich mafic‒ultramafic rocks associated with the voluminous intermediate to felsic rocks in the Early Cretaceous Laiyuan intrusive-volcanic complex (North China Craton) are studied here by detailed petrography, mineral- and melt inclusion chemistry, and thermobarometry to demonstrate an in-situ reaction-replacement origin of the hornblendites. Moreover, a large set of compiled and newly obtained geochronological and whole-rock elemental and Sr-Nd isotopic data are used to constrain the tectono-magmatic evolution of the Laiyuan complex. Early mafic‒ultramafic rocks occur mainly as amphibole-rich mafic‒ultramafic intrusions situated at the edge of the Laiyuan complex. These intrusions comprise complex lithologies of olivine-, pyroxene- and phlogopite-bearing hornblendites and various types of gabbroic rocks, which largely formed by in-situ crystallization of hydrous mafic magmas that experienced gravitational settling of early-crystallized olivine and clinopyroxene at low pressures of 0.10‒0.20 GPa (∼4‒8 km crustal depth); the hornblendites formed in cumulate zones by cooling-driven crystallization of 55‒75 vol% hornblende, 10‒20 vol% orthopyroxene and 3‒10 vol% phlogopite at the expense of olivine and clinopyroxene. A later suite of mafic rocks occurs as mafic lamprophyre dikes throughout the Laiyuan complex. These dikes occasionally contain some pure hornblendite xenoliths, which formed by reaction-replacement of clinopyroxene at high pressures of up to 0.97‒1.25 GPa (∼37‒47 km crustal depth). Mass balance calculations suggest that the olivine-, pyroxene- and phlogopite-bearing hornblendites in the early mafic‒ultramafic intrusions formed almost without melt extraction, whereas the pure hornblendites brought up by lamprophyre dikes required extraction of ≥ 20‒30 wt% residual andesitic to dacitic melts. The latter suggests that fractionation of amphibole in the middle to lower crust through the formation of reaction-replacement hornblendites is a viable way to produce adakite-like magmas. New age constraints suggest that the early mafic-ultramafic intrusions formed during ∼132‒138 Ma, which overlaps with the timespan of ∼126‒145 Ma recorded by the much more voluminous intermediate to felsic rocks of the Laiyuan complex. By contrast, the late mafic and intermediate lamprophyre dikes were emplaced during ∼110‒125 Ma. Therefore, the voluminous early magmatism in the Laiyuan complex was likely triggered by the retreat of the flat-subducting Paleo-Pacific slab, whereas the minor later, mafic to intermediate magmas may have formed in response to further slab sinking-induced mantle thermal perturbations. Whole-rock geochemical data suggest that the early mafic magmas formed by partial melting of subduction-related metasomatized lithospheric mantle, and that the early intermediate to felsic magmas with adakite-like signatures formed from mafic magmas through strong amphibole fractionation without plagioclase in the lower crust. The late mafic magmas seem to be derived from a slightly different metasomatized lithospheric mantle by lower degrees of partial melting.

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