Geochemical Sr–Nd–Pb isotopic compositions of mafic dikes from the Jiaodong Peninsula, China: evidence for vein-plus-peridotite melting in the lithospheric mantle
Resource
Lithos 73,145-160
Journal
Lithos 73
Pages
145-160
Date Issued
2004
Date
2004
Author(s)
DOI
246246/2006111501254511
Abstract
Major and trace elements and Sr –Nd–Pb isotope data are reported for Cretaceous mafic dikes from the Jiaodong Peninsula,
eastern China. These dikes range from medium-K and high-K calc-alkaline to shoshonitic or ultrapotassic rocks, which are
characterized by high MgO (Mg
#
= 71–53) and Cr (177–1012 ppm) and low TiO2 (0.55 –0.90 wt.%), total Fe2 O3 (5.12 –9.48
wt.%) and CaO (4.99 –9.94 wt.%). Overall, they are enriched in the large ion lithophile elements (LILE, e.g., Rb, Ba, Sr) and
light rare earth elements (LREE), depleted in the high field strength elements (HFSE, e.g., Nb, Ti, P), and possess uniform
initial
87
Sr/
86
Sr (0.7094 –0.7114) but relatively wide ranges of Nd [eNd (T) =
10.1 –
17.0] and Pb (
206
Pb/
204
Pb = 16.75 –
18.03) isotopic ratios, implying a magma origin from enriched but heterogeneous mantle sources. These geochemical and
isotopic characteristics can be explained by the vein-plus-peridotite melting model, with amphibole- or phlogopite-bearing
pyroxenite veins that reside in refractory lithospheric mantle beneath the North China Block. Such a vein-enriched mantle
source formed by multiple metasomatic events, which we infer to have resulted from subduction-related processes that may
have occurred in the Late Archean and Mesoproterozoic. The mafic dikes constitute a member of the widespread Mesozoic
magmas emplaced in the North China Block as a result of regional lithospheric extension.
Subjects
Mafic dike
Vein-plus-peridotite
Geochemistry
Lithospheric mantle
Jiaodong Peninsula
China
Type
journal article
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