scholarly journals Coexisting Late Cenozoic Potassic and Sodic Basalts in NE China: Role of Recycled Oceanic Components in Intraplate Magmatism and Mantle Heterogeneity

Lithosphere ◽  
2020 ◽  
Vol 2020 (1) ◽  
pp. 1-28
Author(s):  
Ming Lei ◽  
Zhengfu Guo ◽  
Wenbin Zhao ◽  
Maoliang Zhang ◽  
Lin Ma
Keyword(s):  
Trace Element ◽  
Oceanic Crust ◽  
Geochemical Data ◽  
Late Cenozoic ◽  
Ne China ◽  
Isotopic Compositions ◽  
Intraplate Magmatism ◽  
The Pacific ◽  
High Concentrations ◽  
End Members

Abstract This study presents an integrated geochemical study of the Wudalianchi-Erkeshan potassic basalts and Halaha sodic basalts of NE China, and uses these data to further our understanding of the petrogenetic relationships between the coeval potassic and sodic basalts in this region. The potassic basalts with high concentrations of K2O have arc-like trace-element compositions and enriched Sr-Nd-Hf isotopic compositions with unradiogenic 206Pb/204Pb values (16.77–16.90). In contrast, the sodic basalts with high concentrations of Na2O have OIB-like trace-element compositions and depleted Sr-Nd-Hf isotopic compositions with radiogenic 206Pb/204Pb values (18.27–18.40). These data suggest that the potassic and sodic basalts were derived from mixed depleted mid-ocean-ridge basalt mantle (DMM) and enriched mantle source end-members, where the enriched end-members are ancient sediment for the potassic basalts and Pacific oceanic crust for the sodic basalts. The combined geophysical and geochemical data indicate that these two enriched end-members are located in the mantle transition zone. We propose that partial melting of upwelling asthenospheric mantle comprising ambient DMM and recycled materials shifting from the ancient sediment to the Pacific oceanic crust could have produced the coeval potassic and sodic basalts in NE China. The proposed mantle sources for the potassic and sodic basalts indicate that the upper mantle beneath NE China was highly heterogeneous during late Cenozoic.

Mineralogical composition of and trace-element accumulation in lower Toarcian anoxic sediments: a case study from the Bilong Co. oil shale, eastern Tethys

2015 ◽  
Vol 153 (4) ◽  
pp. 618-634 ◽  
Author(s):  
XIUGEN FU ◽  
JIAN WANG ◽  
XINGLEI FENG ◽  
WENBIN CHEN ◽  
DONG WANG ◽  
...  
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
Oil Shale ◽  
Volcanic Rocks ◽  
Mineralogical Composition ◽  
Geochemical Data ◽  
Anoxic Sediments ◽  
Marine Influence ◽  
High Concentrations ◽  
Element Enrichment

AbstractThe sediments of organic-rich oil shales in the Bilong Co. area can be correlated with those of the early Toarcian anoxic black-shale events in Europe. The Bilong Co. sediments are rich in trace elements Se, Mo, Cd, As and Ni, and, to a lesser extent, Li, F, V, Co, Cu, Cs, Hg and Bi, in comparison to the upper continental crust. Thirty-two oil shale samples were collected from the Bilong Co. oil shale to evaluate the controlling factors of trace-element enrichment in the lower Toarcian anoxic sediments. Minerals identified in the Bilong Co. oil shale include calcite, quartz, illite, feldspar and dolomite, and trace amounts of siderite, magnesite, halite, haematite, zeolite, amphibole, gypsum, anhydrite, apatite, pyrite, sphalerite, barite and mixed-layer illite/smectite. Mineralogical and geochemical data show that seawater and hydrothermal activities are the dominant influences on the mineralogical composition and elevated trace-element concentrations in the oil shale. The clay minerals, quartz and feldspar in the Bilong Co. oil shale were derived from the Nadi Kangri volcanic rocks. Input of sediment from this source may have led to enrichment of trace elements Li, Cr and Cs in the oil shale. Carbonate minerals and nodular- and framboidal-pyrite are authigenic phases formed from seawater. The enrichment of V, Co, Ni, Cu, Mo, As, Se, Bi and U in the oil shale was owing to marine influence. Barite, sphalerite and fracture-filling pyrites were derived from hydrothermal solutions. High concentrations of F, Zn and Cd were probably derived from hydrothermal fluids.

The Chengwatana Volcanics, Wisconsin and Minnesota: petrogenesis of the southernmost volcanic rocks exposed in the Midcontinent rift

1997 ◽  
Vol 34 (4) ◽  
pp. 536-548 ◽  
Author(s):  
Karl R. Wirth ◽  
Zachary J. Naiman ◽  
Jeffrey D. Vervoort
Keyword(s):  
Trace Element ◽  
Volcanic Rocks ◽  
Crustal Contamination ◽  
Geothermal Gradient ◽  
Limited Range ◽  
Geochemical Data ◽  
Rift System ◽  
Midcontinent Rift ◽  
Element Abundances ◽  
Isotopic Compositions

The southernmost exposed rocks of the North American Midcontinent rift system (1100 Ma) consist of 3000 m of mafic volcanic flows and minor interflow sediment exposed along the St. Croix River in Minnesota and Wisconsin. The flows are mostly high-Fe tholeiitic basalt with plagioclase phenocrysts and ophitic to subophitic clinopyroxene. Abundant secondary chlorite, epidote, and actinolite indicate the group was metamorphosed to greenschist facies (~350 °C). Low sodium (M4 site) and tetrahedral aluminum (AlIV) contents of actinolite indicate low-pressure metamorphism (0.25 GPa) and imply a geothermal gradient of 45 – 50 °C/km. Low magnesium (Mg# = 0.37–0.58) and Ni contents (36–185 ppm) indicate the basalts have undergone significant fractionation and are not primary mantle melts. Incompatible element abundances are inversely correlated with Mg#, and most samples plot within either high or low trace element groups (e.g., Ti, P, Zr). The basalts are enriched in the light rare earth elements and Th, and are variably depleted in Ta and Nb relative to La and Th. Initial 143Nd/144Nd compositions of the group range from 0.51099 to 0.51122 (initial εNd = −4.5 to +0.1). Most flows have isotopic compositions within a relatively limited range (initial εNd = −2.5 to −1.6), but exhibit variable trace element abundances. Flows with the highest and lowest initial 143Nd/144Nd ratios have isotopic compositions that are inversely correlated with trace element abundances and ratios (e.g., La/Yb, Th/La, Th/Ta). The combined geochemical data suggest that the Chengwatana basalts originated from plume-derived melts and underwent variable fractional crystallization and crustal contamination. These melts may have interacted with lithospheric mantle enriched during Penokean subduction.

The Late Cenozoic Volcanic Groups in the South Daxing'anling, NE China: Geology, Geochemistry, and Chronology

2020 ◽  
pp. SP510-2020-28
Author(s):  
Ni Li ◽  
Yong-Wei Zhao ◽  
Li-Wen Gong ◽  
Jia-Long Wang
Keyword(s):  
Inner Mongolia ◽  
Large Scale ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Mantle Xenoliths ◽  
Late Cenozoic ◽  
The South ◽  
Ne China ◽  
The Pacific ◽  
Eastern Inner Mongolia

AbstractDuring the late Cenozoic, the extensional tectonic setting in northeastern China caused large-scale block uplifts and depressions, and thus a large amount of magma erupted along structural fractures in the eastern Inner Mongolia, NE China. The Abaga, Beilike, Dalinor and Wulanhada (ABDW) volcanic rocks along the Daxing'anling-Taihangshan Gravity Lineament in the southern section of the Daxing'anling are characterized by their extensive distribution, numerous volcanic cones and various eruption types. Each volcanic group has distinctive volcanic landforms and geochemical characteristics. The geochronological data have revealed that the volcanism spanned Miocene to late Pleistocene. The ABDW volcanic rocks contain primary alkaline basalts and subordinate tholeiites. The trace element curve pattern is similar to that of OIB, but completely different from that of MORB, while the LREE are more enriched than HREE. The geochemical features of the volcanic rocks and the entrained mantle xenoliths reveal the broad heterogeneities of the lithospheric mantle and varieties of the volcanic rock evolution in the south Daxing'anling. The Cenozoic volcanism in eastern Inner Mongolia, and even within the east Asian plate, is attributed to the westward subduction and rolling backward of the Pacific slab as well as the trench retreat.

Early Cretaceous crust–mantle interaction linked to rollback of the Palaeo-Pacific flat-subducting slab: constraints from the intermediate–felsic volcanic rocks of the northern Great Xing’an Range, NE China

2021 ◽  
pp. 1-22
Author(s):  
Jia-Hao Jing ◽  
Hao Yang ◽  
Wen-Chun Ge ◽  
Yu Dong ◽  
Zheng Ji ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Volcanic Rocks ◽  
Geochemical Data ◽  
Calc Alkaline ◽  
Ne China ◽  
Asthenospheric Mantle ◽  
High K ◽  
Wide Range ◽  
Great Xing’An Range ◽  
Subducting Slab

Abstract Late Mesozoic igneous rocks are important for deciphering the Mesozoic tectonic setting of NE China. In this paper, we present whole-rock geochemical data, zircon U–Pb ages and Lu–Hf isotope data for Early Cretaceous volcanic rocks from the Tulihe area of the northern Great Xing’an Range (GXR), with the aim of evaluating the petrogenesis and genetic relationships of these rocks, inferring crust–mantle interactions and better constraining extension-related geodynamic processes in the GXR. Zircon U–Pb ages indicate that the rhyolites and trachytic volcanic rocks formed during late Early Cretaceous time (c. 130–126 Ma). Geochemically, the highly fractionated I-type rhyolites exhibit high-K calc-alkaline, metaluminous to weakly peraluminous characteristics. They are enriched in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs) but depleted in high-field-strength elements (HFSEs), with their magmatic zircons ϵHf(t) values ranging from +4.1 to +9.0. These features suggest that the rhyolites were derived from the partial melting of a dominantly juvenile, K-rich basaltic lower crust. The trachytic volcanic rocks are high-K calc-alkaline series and exhibit metaluminous characteristics. They have a wide range of zircon ϵHf(t) values (−17.8 to +12.9), indicating that these trachytic volcanic rocks originated from a dominantly lithospheric-mantle source with the involvement of asthenospheric mantle materials, and subsequently underwent extensive assimilation and fractional crystallization processes. Combining our results and the spatiotemporal migration of the late Early Cretaceous magmatic events, we propose that intense Early Cretaceous crust–mantle interaction took place within the northern GXR, and possibly the whole of NE China, and that it was related to the upwelling of asthenospheric mantle induced by rollback of the Palaeo-Pacific flat-subducting slab.

Lithospheric roots beneath western Laurentia: the geochemical signal in mantle garnets

2003 ◽  
Vol 40 (8) ◽  
pp. 1027-1051 ◽  
Author(s):  
D Canil ◽  
D J Schulze ◽  
D Hall ◽  
B C Hearn Jr. ◽  
S M Milliken
Keyword(s):  
Rare Earth ◽  
North America ◽  
Trace Element ◽  
Earth Element ◽  
Geochemical Data ◽  
Trace Element Data ◽  
Mantle Lithosphere ◽  
Western North America ◽  
Wyoming Province ◽  
Thick Mantle

This study presents major and trace element data for 243 mantle garnet xenocrysts from six kimberlites in parts of western North America. The geochemical data for the garnet xenocrysts are used to infer the composition, thickness, and tectonothermal affinity of the mantle lithosphere beneath western Laurentia at the time of kimberlite eruption. The garnets record temperatures between 800 and 1450°C using Ni-in-garnet thermometry and represent mainly lherzolitic mantle lithosphere sampled over an interval from about 110–260 km depth. Garnets with sinuous rare-earth element patterns, high Sr, and high Sc/V occur mainly at shallow depths and occur almost exclusively in kimberlites interpreted to have sampled Archean mantle lithosphere beneath the Wyoming Province in Laurentia, and are notably absent in garnets from kimberlites erupting through the Proterozoic Yavapai Mazatzal and Trans-Hudson provinces. The similarities in depths of equilibration, but differing geochemical patterns in garnets from the Cross kimberlite (southeastern British Columbia) compared to kimberlites in the Wyoming Province argue for post-Archean replacement and (or) modification of mantle beneath the Archean Hearne Province. Convective removal of mantle lithosphere beneath the Archean Hearne Province in a "tectonic vise" during the Proterozoic terminal collisions that formed Laurentia either did not occur, or was followed by replacement of thick mantle lithosphere that was sampled by kimberlite in the Triassic, and is still observed there seismically today.

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