Crustal-contaminated komatiitic basalts in Southern China: products of a Proterozoic mantle plume beneath the Yangtze Block

doi:10.1016/S0301-9268(00)00077-2

Precambrian Research

Volume 103, Issues 3–4, October 2000, Pages 175-189

https://doi.org/10.1016/S0301-9268(00)00077-2 Get rights and content

Abstract

Abundant mafic and ultramafic rocks including basalts, komatiitic basalts, and peridotites occur in the Proterozoic Sibao Group, northern Guangxi Province, China. Whereas the basalts are generally pillow lavas, the komatiitic basalts are typically spinifex-textured and, in a few cases, show pyroxene accumulation associated with NiCu(PGE) sulfide deposits. The peridotites occur in the lower portions of differentiated sills, which contain gabbro and diorite in their upper parts. The sills are believed to be co-magmatic with the komatiitic basalts. The spinifex rocks of the Jiepai and Hejia Flows have MgO ranging from 8.9 to 14.3 wt%. The Zhongkui Flow is highly fractionated to form a spinifex zone with lower MgO (5.3–5.9 wt%) and a cumulate zone with higher MgO (17.3–17.9 wt%). Overall the rocks have TiO₂=0.44–0.74 wt%. Relative to primitive mantle, they are enriched in Th and LREE, but exhibit negative Ti-, Nb-, and P-anomalies. These features are consistent with their formation from a crustally-contaminated komatiitic magma. During this process of crustal contamination, the magmas assimilated sulfur from sediments, which caused sulfide-segregation resulting in the formation of NiCu(PGE) sulfide deposits. The occurrence of the komatiitic basalts in the Sibao Group can be explained by the ascent of a mantle plume beneath a continental rift environment, and implies that the Yangtze Block may have had an Archean basement through which the Sibao komatiitic basalts erupted.

Introduction

Many Proterozoic terrains, including the Cape Smith Belt, Canada (Hynes and Francis, 1982) and the Baltic Shield (Park et al., 1984, Puchtel et al., 1997) contain komatiitic rocks that are interpreted to represent products of high-Mg magmas derived by partial melting of the upper mantle. These rocks are of considerable importance in studies of the composition of the Proterozoic upper mantle (Jahn et al., 1980, Nisbet, 1982, Sun, 1987, Nisbet et al., 1993, Bickle et al., 1994) and aid in discerning the tectonic regimes of the host terrains.

Although the tectonics of southern China have been widely discussed since Hsu et al., 1988, Hsu et al., 1990 proposed a model involving complex overthrusting to explain the Mesozoic collision between the Yangtze and Cathaysian Blocks, the presence of komatiitic basalts in northern Guangxi Province has not been discussed. Local geologists described spinifex-textured rocks in the Middle Proterozoic Sibao Group as komatiites (Mao et al., 1988, Yang, 1988), but this discovery has remained obscure. Chen and Mao (1995) described some ultramafic rocks as extrusive komatiites, but these appear to be olivine cumulate rocks which have resultant high Mg contents. Because their geochemistry is different from that of typical Archean komatiites, Li (1996) suggested that the spinifex rocks are not komatiite, but normal basalt. It is clear that the geochemical signature of these rocks needs to be re-examined and their significance interpreted.

This study provides a description of the distribution of the ultramafic and related rocks based on a mapping programme carried out by Dong, 1988, Dong, 1990 and during our own field work in the past few years. This mapping has shown that many of the ultramafic and mafic rocks are, in fact, high-level sills that are interpreted to be co-magmatic with lavas. Representative samples have been analyzed for major oxides and trace elements and an attempt has been made to identify the composition of the parental magma. Consequently, some constraints can now be placed on the tectonic setting of the magmatism and the Proterozoic geological evolution of the region.

Section snippets

Regional geology

The area of northern Guangxi Province forms the southern end of the Jiangnan Oldland, north of the Cathaysian continent (Huang, 1945, Chang, 1996) (Fig. 1). The Jiangnan Oldland contains Precambrian rocks interpreted to represent basement to the Yangtze Block, and a cover sequence of Sinian and Devonian sedimentary strata of neritic and terrestrial facies, which appear to deposit in a stable tectonic setting.

In northern Guangxi Province, the Sibao Group forms the basal Proterozoic sequence and

Mafic and ultramafic rocks in the Sibao Group

Basalts and komatiitic basalts in the Wentong Formation of the Sibao Group, occur as lava flows, and peridotites and gabbros as layered, subvolcanic sills (Fig. 2). The basaltic lavas exhibit pillowed, spherulitic, and amygdaloidal structures, and thick flows display columnar jointing (e.g. near Jiepai). These volcanic rocks have compositions similar to andesitic basalts (Mao et al., 1988).

The komatiitic basalts are interbedded with sedimentary rocks of the Wentong Formation and occur as

Geochemistry of the komatiitic basalts

A number of komatiitic basalts from the Jiepai, Hejia, and Zhongkui Flows which display well-developed spinifex or cumulate textures have been selected for geochemical analysis. Major element abundances were determined by X-ray fluorescence spectrometry (XRF) on fused glass pellets. Trace elements Sc, V, Cr, Ni, Cu, and Zn were determined by XRF on pressed powder pellets. Other trace elements, including REE, were analyzed on a VG Elemental PlasmaQuad 3 inductively coupled plasma-mass

Crustal contamination in the komatiitic basalts

The elements Al, Ti, REE, HFSE (Th, Nb, Ta, Zr, Hf), Y, Sc and V are considered the least mobile during hydrothermal alteration and greenschist facies metamorphism of mafic volcanic rocks (e.g. Ludden et al., 1982, Kerrich et al., 1998). Therefore, although the mineralogy of the komatiitic basalts indicates that they have been metamorphosed to sub-greenschist facies, REE, Zr, Y, Nb and Hf have coherent trends, likely reflecting characteristics of the primitive magma and processes of magmatic

Tectonic setting and implications for the geology of southern China

Archean komatiitic magmas are interpreted to have formed as part of ancient oceanic lithosphere (Desrochers et al., 1993) or primitive ocean islands (Hoffman, 1990). However, the Belingwe greenstone belt of Zimbabwe provides a well-argued case that certain komatiites formed in a continental extensional setting (Nisbet et al., 1977, Bickle et al., 1994, Hunter et al., 1998). Old detrital zircons in some Archean komatiites confirm crustal contamination (Compston et al., 1986).

The Early

Conclusions

The komatiitic basalts of the Sibao Group exhibit clinopyroxene spinifex texture and REE patterns enriched in LREE. They are depleted in Ti, Nb, and P and enriched in Th and Si. These features suggest that they represent the quench crystallization of a high-Mg magma contaminated by assimilation of crustal sediments, which erupted in a continental rifting environment. The study further indicates that there was an old continental crust beneath the Sibao Group at the time of its formation and that

Acknowledgements

This study was fully supported by a grant from the Research Grant Council of the Hong Kong Special Administrative Region, China (HKU7120/97P). Three field seasons investigating the Sibao Group were assisted by senior geologists Dong Baolin, Li Guotao, and Liang Guobao, all at the Geological Survey of Guangxi Province, China. We thank Yang Lizhen for informative discussion and Dr Li Jianwei for assistance with the preparation of this manuscript. We appreciate constructive comments made by

References (57)

N.T Arndt et al.
Crustally-contaminated komatiites and basalts from Kambalda, Western Australia
Chem. Geol.
(1986)
E.Z Chang
Collisional orogen between North and South China and its eastern extension in the Korean Penisula
J. SE Asian Earth Sci.
(1996)
W Compston et al.
Zircon xenocrystals from the Kambalda volcanics: age constraints and direct evidence for older continental crust below the Kambalda-Norseman Greenstones
Earth Planet. Sci. lett.
(1986)
R.L Hickey et al.
Geochemical characteristics of boninite series volcanics: implications for their sources
Geochim. Cosmochim. Acta
(1982)
K.J Hsu et al.
Tectonics of south China: key to understanding west Pacific geology
Tectonics
(1990)
G.A Jenner et al.
ICP-MS—a powerful tool for high precision trace element analysis in earth sciences: evidence from analysis of selected USGS reference samples
Chem. Geol.
(1990)
K.P Jochum et al.
NbThLa in komatiites and basalts: constraints on komatiite petrogenesis and mantle evolution
Earth Planet. Sci. Lett.
(1991)
R.R Keays
The role of komatiitic and picritic magmatism and S-saturation in the formation of the ore deposits
Lithos
(1995)
R.W Kerrich et al.
Boninite series: low-Ti tholeiite associations from the 2.7 Ga Abitibi greenstone belt
Earth Planet. Sci. Lett.
(1998)
W.F McDonough
Constraints on the composition of the continental lithospheric mantle
Earth Planet. Sci. Lett.
(1990)

E.G Nisbet et al.

Constraining the potential temperature of the Archean mantle: a review of the evidence from komatiites

Lithos

(1993)

A.F Park et al.

Tectonic evolution at an Early Proterzoic continental margin: the Svecokarelides of eastern Finland

J. Geodyn.

(1984)

J.-L Poidevin

Boninite-like rocks from the Palaeoproterozoic greenstone belt of Bogoin, Central African Republic: geochemistry and petrogenesis

Precam. Res.

(1994)

I.S Puchtel et al.

Petrology and geochemistry of crustally contaminated komatiitic basalts from the Vetreny Belt, Southeatern Baltic Shield: evidence for an early Proterozoic mantle plume beneath rifting Archean continental lithosphere

Geochim. Cosmochim. Acta

(1997)

S.-S Sun

Chemical composition of Archaean komatiites: implications for early history of the earth and mantle evolution

J. Volcan. Geotherm. Res.

(1987)

B Wolde et al.

Neoproterozoic zirconium-depleted boninite and tholeiitic series rocks from Adola, Southern Ethiopia

Precam. Res.

(1996)

N.T Arndt et al.

Geochemistry of the Munro Township basalts

N.T Arndt et al.

Komatiitic and iron-rich tholeiitic lavas of Munro Township, Northeast Ontario

J. Petrol.

(1977)

M.J Bickle et al.

Archean greenstone belts are not oceanic crust

J. Geol.

(1994)

T Chen et al.

J.F Chen et al.

Magmatism along the southeast margin of the Yangtze block: Precambrian collision of the Yangtze and Cathaysian Blocks of China

Geology

(1991)

A.J Crawford et al.

Classification, petrogenesis and tectonic setting of boninites

J.P Desrochers et al.

Accretion of Archean oceanic plateau fragment in the Abitibi greenstone belt

Can. Geol.

(1993)

B.-L Dong

A discussion on the several problems of the Precambrian tectonics in Northern Guangxi (in Chinese)

Geol. Jiangxi

(1988)

B.-L Dong

The Sibao Group of Guangxi Province and its metallogeny (in Chinese)

Guangxi Reg. Geol.

(1990)

S.A Gibson et al.

Late cretaceous rifting-related up-welling and melting of the Trindade Starting mantle plume head beneath Western Brazil

Contrib. Miner. Petrol.

(1997)

L.Z Guo et al.

Plate movement and crustal evolution of the Jiangnan Proterozoic mobile belt, SE China

Earth Sci. J. Geol. Soc. Jpn.

(1985)

Hoffman P.F., 1990. On accretion of granite–greenstone terranes. In: Robert, F. (Ed.), Greenstone Gold and Crustal...

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¹: Present address: Henan Institute of Geology, Zhengzhou, Henan, PR China.

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Crustal-contaminated komatiitic basalts in Southern China: products of a Proterozoic mantle plume beneath the Yangtze Block

Abstract

Introduction

Section snippets

Regional geology

Mafic and ultramafic rocks in the Sibao Group

Geochemistry of the komatiitic basalts

Crustal contamination in the komatiitic basalts

Tectonic setting and implications for the geology of southern China

Conclusions

Acknowledgements

Chem. Geol.

J. SE Asian Earth Sci.

Earth Planet. Sci. lett.

Geochim. Cosmochim. Acta

Tectonics

Chem. Geol.

Earth Planet. Sci. Lett.

Lithos

Earth Planet. Sci. Lett.

Earth Planet. Sci. Lett.

Lithos

J. Geodyn.

Precam. Res.

Geochim. Cosmochim. Acta

J. Volcan. Geotherm. Res.

Precam. Res.

Geochemistry of the Munro Township basalts

Komatiitic and iron-rich tholeiitic lavas of Munro Township, Northeast Ontario

J. Petrol.

Archean greenstone belts are not oceanic crust

J. Geol.

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Geology

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Accretion of Archean oceanic plateau fragment in the Abitibi greenstone belt

Can. Geol.

A discussion on the several problems of the Precambrian tectonics in Northern Guangxi (in Chinese)

Geol. Jiangxi

The Sibao Group of Guangxi Province and its metallogeny (in Chinese)

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Contrib. Miner. Petrol.

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Earth Sci. J. Geol. Soc. Jpn.