Constraints on the origin of historic potassic basalts from northeast China by U-Th disequilibrium data

Haibo Zou; Mary R. Reid; Yongshun Liu; Yupeng Yao; Xisheng Xu; Qicheng Fan

doi:10.1016/S0009-2541(03)00188-8

Constraints on the origin of historic potassic basalts from northeast China by U-Th disequilibrium data

Haibo Zou, Mary R. Reid, Yongshun Liu, Yupeng Yao, Xisheng Xu, Qicheng Fan

Earth and Sustainability

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Abstract

The only historic eruptions of potassic basalts on the Earth reported so far took place in 1719-1721 AD in the Wudalianchi area of northeast China. These historic potassic basalts are characterized by significant ²³⁰Th excesses [(²³⁰ Th/²³⁸U)=1.24-1.33], and low ¹⁴³Nd/¹⁴⁴Nd (ε _Nd=-5.0 to -3.7) and ²⁰⁶Pb/ ²⁰⁴Pb(16.8-17.1). Strong ²³⁰Th excesses, low CaO+ Al₂O₃, and large bulk partition coefficients (D) in Rb, K, and Zr(D_Rb ≅ D_K>D_Zr >D_Yb>D_Sm) inferred from a melt-normalized spider diagram suggest phlogopite-bearing garnet peridotites as dominant source rocks. The presence of garnet peridotites as mantle source, combined with negative ε _Nd in basalts and the geophysically determined lithosphere thickness in the study region (120 km), indicates the generation of these basalts at the depth of 80-120 km in the subcontinental lithospheric mantle. Dynamic melting inversion (DMI) of between-magma trace element concentration ratios and U-Th disequilibrium data suggests low-degree partial melting (5-7%) of a slow upwelling (<1.6 cm/year) mantle source, although extremely low- degree batch partial melting (0.3-0.5%) of a static source is also possible. Source Nd model ages suggest that the source rocks for the Wudalianchi basalts were metasomatized at 1.0 Ga, provided that it has not experienced multistage enrichment history. Lithospheric extension since late Tertiary in the study region was responsible for slow decompression melting of phlogopite-bearing garnet peridotites in deep subcontinental lithospheric mantle. Recent (<350 ka) subduction of the Pacific Plate may have produced lithospheric extension in the study region, but did not directly contribute subduction-related fluids to the source rocks for these potassic basalts because ²³⁰Th enrichments are uncharacteristic of melts generated by subduction. The subducted slab may have lost fluids released from subducted sediments before the slab can reach the mantle beneath NE China.

Original language	English (US)
Pages (from-to)	189-201
Number of pages	13
Journal	Chemical Geology
Volume	200
Issue number	1-2
DOIs	https://doi.org/10.1016/S0009-2541(03)00188-8
State	Published - Oct 16 2003

Keywords

Basalt isotopes
Basalt trace elements
China basalts
Historic basalts
Mantle melting
Mantle metasomatism

ASJC Scopus subject areas

Geology
Geochemistry and Petrology

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10.1016/S0009-2541(03)00188-8

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@article{84328576d32047e6afd2987977253bac,

title = "Constraints on the origin of historic potassic basalts from northeast China by U-Th disequilibrium data",

abstract = "The only historic eruptions of potassic basalts on the Earth reported so far took place in 1719-1721 AD in the Wudalianchi area of northeast China. These historic potassic basalts are characterized by significant 230Th excesses [(230 Th/238U)=1.24-1.33], and low 143Nd/144Nd (ε Nd=-5.0 to -3.7) and 206Pb/ 204Pb(16.8-17.1). Strong 230Th excesses, low CaO+ Al2O3, and large bulk partition coefficients (D) in Rb, K, and Zr(DRb ≅ DK>DZr >DYb>DSm) inferred from a melt-normalized spider diagram suggest phlogopite-bearing garnet peridotites as dominant source rocks. The presence of garnet peridotites as mantle source, combined with negative ε Nd in basalts and the geophysically determined lithosphere thickness in the study region (120 km), indicates the generation of these basalts at the depth of 80-120 km in the subcontinental lithospheric mantle. Dynamic melting inversion (DMI) of between-magma trace element concentration ratios and U-Th disequilibrium data suggests low-degree partial melting (5-7%) of a slow upwelling (<1.6 cm/year) mantle source, although extremely low- degree batch partial melting (0.3-0.5%) of a static source is also possible. Source Nd model ages suggest that the source rocks for the Wudalianchi basalts were metasomatized at 1.0 Ga, provided that it has not experienced multistage enrichment history. Lithospheric extension since late Tertiary in the study region was responsible for slow decompression melting of phlogopite-bearing garnet peridotites in deep subcontinental lithospheric mantle. Recent (<350 ka) subduction of the Pacific Plate may have produced lithospheric extension in the study region, but did not directly contribute subduction-related fluids to the source rocks for these potassic basalts because 230Th enrichments are uncharacteristic of melts generated by subduction. The subducted slab may have lost fluids released from subducted sediments before the slab can reach the mantle beneath NE China.",

keywords = "Basalt isotopes, Basalt trace elements, China basalts, Historic basalts, Mantle melting, Mantle metasomatism",

author = "Haibo Zou and Reid, {Mary R.} and Yongshun Liu and Yupeng Yao and Xisheng Xu and Qicheng Fan",

note = "Funding Information: We are grateful to Simon Turner, Yemane Asmerom, and Editor Steve Goldstein for their constructive reviews that significantly improved the quality of this paper. We are also indebted to An Yin, James Gill, Ken Sims, and Jorge Vazquez for fruitful discussion and help. This work was supported by the National Science Foundation [EAR 9805687 (an NSF postdoctoral research fellowship) to Zou and EAR 9980646 to Reid], by the Natural Science Foundation of China (49802006 to Liu), and by the Geological Society of America (6744-00 to Zou). [SG] Copyright: Copyright 2017 Elsevier B.V., All rights reserved.",

year = "2003",

month = oct,

day = "16",

doi = "10.1016/S0009-2541(03)00188-8",

language = "English (US)",

volume = "200",

pages = "189--201",

journal = "Chemical Geology",

issn = "0009-2541",

publisher = "Elsevier",

number = "1-2",

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TY - JOUR

T1 - Constraints on the origin of historic potassic basalts from northeast China by U-Th disequilibrium data

AU - Zou, Haibo

AU - Reid, Mary R.

AU - Liu, Yongshun

AU - Yao, Yupeng

AU - Xu, Xisheng

AU - Fan, Qicheng

N1 - Funding Information: We are grateful to Simon Turner, Yemane Asmerom, and Editor Steve Goldstein for their constructive reviews that significantly improved the quality of this paper. We are also indebted to An Yin, James Gill, Ken Sims, and Jorge Vazquez for fruitful discussion and help. This work was supported by the National Science Foundation [EAR 9805687 (an NSF postdoctoral research fellowship) to Zou and EAR 9980646 to Reid], by the Natural Science Foundation of China (49802006 to Liu), and by the Geological Society of America (6744-00 to Zou). [SG] Copyright: Copyright 2017 Elsevier B.V., All rights reserved.

PY - 2003/10/16

Y1 - 2003/10/16

N2 - The only historic eruptions of potassic basalts on the Earth reported so far took place in 1719-1721 AD in the Wudalianchi area of northeast China. These historic potassic basalts are characterized by significant 230Th excesses [(230 Th/238U)=1.24-1.33], and low 143Nd/144Nd (ε Nd=-5.0 to -3.7) and 206Pb/ 204Pb(16.8-17.1). Strong 230Th excesses, low CaO+ Al2O3, and large bulk partition coefficients (D) in Rb, K, and Zr(DRb ≅ DK>DZr >DYb>DSm) inferred from a melt-normalized spider diagram suggest phlogopite-bearing garnet peridotites as dominant source rocks. The presence of garnet peridotites as mantle source, combined with negative ε Nd in basalts and the geophysically determined lithosphere thickness in the study region (120 km), indicates the generation of these basalts at the depth of 80-120 km in the subcontinental lithospheric mantle. Dynamic melting inversion (DMI) of between-magma trace element concentration ratios and U-Th disequilibrium data suggests low-degree partial melting (5-7%) of a slow upwelling (<1.6 cm/year) mantle source, although extremely low- degree batch partial melting (0.3-0.5%) of a static source is also possible. Source Nd model ages suggest that the source rocks for the Wudalianchi basalts were metasomatized at 1.0 Ga, provided that it has not experienced multistage enrichment history. Lithospheric extension since late Tertiary in the study region was responsible for slow decompression melting of phlogopite-bearing garnet peridotites in deep subcontinental lithospheric mantle. Recent (<350 ka) subduction of the Pacific Plate may have produced lithospheric extension in the study region, but did not directly contribute subduction-related fluids to the source rocks for these potassic basalts because 230Th enrichments are uncharacteristic of melts generated by subduction. The subducted slab may have lost fluids released from subducted sediments before the slab can reach the mantle beneath NE China.

AB - The only historic eruptions of potassic basalts on the Earth reported so far took place in 1719-1721 AD in the Wudalianchi area of northeast China. These historic potassic basalts are characterized by significant 230Th excesses [(230 Th/238U)=1.24-1.33], and low 143Nd/144Nd (ε Nd=-5.0 to -3.7) and 206Pb/ 204Pb(16.8-17.1). Strong 230Th excesses, low CaO+ Al2O3, and large bulk partition coefficients (D) in Rb, K, and Zr(DRb ≅ DK>DZr >DYb>DSm) inferred from a melt-normalized spider diagram suggest phlogopite-bearing garnet peridotites as dominant source rocks. The presence of garnet peridotites as mantle source, combined with negative ε Nd in basalts and the geophysically determined lithosphere thickness in the study region (120 km), indicates the generation of these basalts at the depth of 80-120 km in the subcontinental lithospheric mantle. Dynamic melting inversion (DMI) of between-magma trace element concentration ratios and U-Th disequilibrium data suggests low-degree partial melting (5-7%) of a slow upwelling (<1.6 cm/year) mantle source, although extremely low- degree batch partial melting (0.3-0.5%) of a static source is also possible. Source Nd model ages suggest that the source rocks for the Wudalianchi basalts were metasomatized at 1.0 Ga, provided that it has not experienced multistage enrichment history. Lithospheric extension since late Tertiary in the study region was responsible for slow decompression melting of phlogopite-bearing garnet peridotites in deep subcontinental lithospheric mantle. Recent (<350 ka) subduction of the Pacific Plate may have produced lithospheric extension in the study region, but did not directly contribute subduction-related fluids to the source rocks for these potassic basalts because 230Th enrichments are uncharacteristic of melts generated by subduction. The subducted slab may have lost fluids released from subducted sediments before the slab can reach the mantle beneath NE China.

KW - Basalt isotopes

KW - Basalt trace elements

KW - China basalts

KW - Historic basalts

KW - Mantle melting

KW - Mantle metasomatism

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U2 - 10.1016/S0009-2541(03)00188-8

DO - 10.1016/S0009-2541(03)00188-8

M3 - Article

AN - SCOPUS:0041620208

SN - 0009-2541

VL - 200

SP - 189

EP - 201

JO - Chemical Geology

JF - Chemical Geology

IS - 1-2

ER -

Constraints on the origin of historic potassic basalts from northeast China by U-Th disequilibrium data

Abstract

Keywords

ASJC Scopus subject areas

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