In order to distinguish the primary microstructures developed under mantle conditions from the secondary phenomena after xenolith entrainment in the host magma, this study intends to discuss the genesis of spongy, sie...In order to distinguish the primary microstructures developed under mantle conditions from the secondary phenomena after xenolith entrainment in the host magma, this study intends to discuss the genesis of spongy, sieve-textured, and reaction rims on mineral grains of mantle xenoliths in the Cenozoic basalts from the western North China craton. The spongy rims on primary clinopyroxene show neither obvious compositional zoning nor preferential development towards the host basalt and probably suggest an origin via partial melting within the lithospheric mantle or pressure release as the xenoliths were carried upwards. The sieve-textured rims on primary spinel show clear chemical zoning with increasing Cr# and decreasing AI towards the host basalt. They are interpreted as the result of partial melting due to heating of the host basaltic magma and decreasing pressure during ascent proc- ess. Post-entrainment reaction mainly generated secondary minerals at contacts between the host ba- saltic melt and xenoliths. The secondary clinopyroxene in reaction rims develops on primary clinopy- roxene and has higher Ti, Ca, and Fe contents and lower Mg# and Si contents than primary one, while the secondary spinel on primary Cr-AI spinel is titanomagnetite. The secondary olivine and clinopy- roxene in the reaction rims on primary orthopyroxene are enriched in Fe, Al, and Ti. The occurrence of reaction rims in mantle xenoliths reflects disequilibrium processes after xenolith entrainment in the basaltic melt. The spongy rims on primary clinopyroxene may not be related to the interaction with thehost basaltic melt, while the sieve-textured rims on primary spinel and reactions rims on primary clinopyroxene, spinel, and orthopyroxene may result from post-entrainment reaction between the host basaltic melt and xenolith minerals.展开更多
This paper focuses on the status quo of heavy metal cadmium pollution sites, analyzes and summarizes the physical, chemical and bioremediation technologies of cadmium contaminated soil, and carefully analyzes the adva...This paper focuses on the status quo of heavy metal cadmium pollution sites, analyzes and summarizes the physical, chemical and bioremediation technologies of cadmium contaminated soil, and carefully analyzes the advantages and disadvantages of each repair technology. It pointed out the need to develop scientific, efficient and comprehensive restoration management techniques.展开更多
In Tuoyun area of southwestern Tianshan, mantle and lower crust xenoliths are present In the volcanic rocks with ages of 101-123 Ma. Mantle xenoliths include mineral megacrysts such as kaersutite and pargasite, feldsp...In Tuoyun area of southwestern Tianshan, mantle and lower crust xenoliths are present In the volcanic rocks with ages of 101-123 Ma. Mantle xenoliths include mineral megacrysts such as kaersutite and pargasite, feldspar, biotite, and rare pyroxene and rock fragments such as perodotite, pyroxenite, amphibolite, and rare glimmerite. Lower crust xenoliths are mainly banded and massive granulite. The volcanic rocks were produced by within-plate magmatism. Occurrence of hydrous and volatile mineral megacrysts, amphibolite, and some pyroxenite containing hydrous and volatile minerals indicates that mantle metasomatism was intense. Undoubtedly, this discovery is very important to understanding of the crust-mantle structure and geodynamic background in depth in southwestern Tianshan and geological correlation with adjacent regions.展开更多
0 INTRODUCTION Initial subduction involves the complex process of oceanic lithosphere first inserting beneath oceanic or continental lithosphere(Chen et al.,2024;Yang et al.,2022;Stern and Gerya,2018).The modern Izu-B...0 INTRODUCTION Initial subduction involves the complex process of oceanic lithosphere first inserting beneath oceanic or continental lithosphere(Chen et al.,2024;Yang et al.,2022;Stern and Gerya,2018).The modern Izu-Bonin-Mariana(IBM)initial subduction system suggests that identifying the earliest ophiolites,arc igneous and metamorphic complexes(e.g.,blueschist,eclogites)can reconstruct ancient initial subduction systems(Yao et al.,2021;Ishizuka et al.,2011).However,knowledge of ancient subduction initiation is often limited due to poor exposures of rocks formed during the earliest stages of subduction(Chen et al.,2024;Cawood et al.,2009).展开更多
MUD crack is a common bedding-plane structure, but the zigzag mud cracks (figs. 1 and 2) are rare phenomena that were found beside G314 highway from Kaxgar to Taxkorgan in Xin-jiang, China. From the photographs we can...MUD crack is a common bedding-plane structure, but the zigzag mud cracks (figs. 1 and 2) are rare phenomena that were found beside G314 highway from Kaxgar to Taxkorgan in Xin-jiang, China. From the photographs we can find that there are footprints of a small animal at every top of zigzag. The zigzag cracks were controlled admittedly by the animal slightly disturbing just when they were breaking. There is a phenomenon worth researching further (fig. 1 ). Distributing equality of zigzags, the horizontal crack (F1) is cracked along the footprints strictly. The vertical one (F2) was not cracked regularly and confined by F1. The crack was展开更多
基金supported by GEMOC and the Department of Earth and Planetary Sciences,Macquarie University,Australia
文摘In order to distinguish the primary microstructures developed under mantle conditions from the secondary phenomena after xenolith entrainment in the host magma, this study intends to discuss the genesis of spongy, sieve-textured, and reaction rims on mineral grains of mantle xenoliths in the Cenozoic basalts from the western North China craton. The spongy rims on primary clinopyroxene show neither obvious compositional zoning nor preferential development towards the host basalt and probably suggest an origin via partial melting within the lithospheric mantle or pressure release as the xenoliths were carried upwards. The sieve-textured rims on primary spinel show clear chemical zoning with increasing Cr# and decreasing AI towards the host basalt. They are interpreted as the result of partial melting due to heating of the host basaltic magma and decreasing pressure during ascent proc- ess. Post-entrainment reaction mainly generated secondary minerals at contacts between the host ba- saltic melt and xenoliths. The secondary clinopyroxene in reaction rims develops on primary clinopy- roxene and has higher Ti, Ca, and Fe contents and lower Mg# and Si contents than primary one, while the secondary spinel on primary Cr-AI spinel is titanomagnetite. The secondary olivine and clinopy- roxene in the reaction rims on primary orthopyroxene are enriched in Fe, Al, and Ti. The occurrence of reaction rims in mantle xenoliths reflects disequilibrium processes after xenolith entrainment in the basaltic melt. The spongy rims on primary clinopyroxene may not be related to the interaction with thehost basaltic melt, while the sieve-textured rims on primary spinel and reactions rims on primary clinopyroxene, spinel, and orthopyroxene may result from post-entrainment reaction between the host basaltic melt and xenolith minerals.
文摘This paper focuses on the status quo of heavy metal cadmium pollution sites, analyzes and summarizes the physical, chemical and bioremediation technologies of cadmium contaminated soil, and carefully analyzes the advantages and disadvantages of each repair technology. It pointed out the need to develop scientific, efficient and comprehensive restoration management techniques.
文摘In Tuoyun area of southwestern Tianshan, mantle and lower crust xenoliths are present In the volcanic rocks with ages of 101-123 Ma. Mantle xenoliths include mineral megacrysts such as kaersutite and pargasite, feldspar, biotite, and rare pyroxene and rock fragments such as perodotite, pyroxenite, amphibolite, and rare glimmerite. Lower crust xenoliths are mainly banded and massive granulite. The volcanic rocks were produced by within-plate magmatism. Occurrence of hydrous and volatile mineral megacrysts, amphibolite, and some pyroxenite containing hydrous and volatile minerals indicates that mantle metasomatism was intense. Undoubtedly, this discovery is very important to understanding of the crust-mantle structure and geodynamic background in depth in southwestern Tianshan and geological correlation with adjacent regions.
基金supported by the special fund of the State Key Laboratory of Deep Earth and Mineral Exploration(No.KFDM2025203)the Natural Science Foundation of Liaoning Province(No.2025-MS-037)+2 种基金the National Natural Science Foundation of China(No.41972234)support provided by the China Scholarship Council(No.202306080045)the Geological Society Research Grants-Mike Coward Fund.
文摘0 INTRODUCTION Initial subduction involves the complex process of oceanic lithosphere first inserting beneath oceanic or continental lithosphere(Chen et al.,2024;Yang et al.,2022;Stern and Gerya,2018).The modern Izu-Bonin-Mariana(IBM)initial subduction system suggests that identifying the earliest ophiolites,arc igneous and metamorphic complexes(e.g.,blueschist,eclogites)can reconstruct ancient initial subduction systems(Yao et al.,2021;Ishizuka et al.,2011).However,knowledge of ancient subduction initiation is often limited due to poor exposures of rocks formed during the earliest stages of subduction(Chen et al.,2024;Cawood et al.,2009).
文摘MUD crack is a common bedding-plane structure, but the zigzag mud cracks (figs. 1 and 2) are rare phenomena that were found beside G314 highway from Kaxgar to Taxkorgan in Xin-jiang, China. From the photographs we can find that there are footprints of a small animal at every top of zigzag. The zigzag cracks were controlled admittedly by the animal slightly disturbing just when they were breaking. There is a phenomenon worth researching further (fig. 1 ). Distributing equality of zigzags, the horizontal crack (F1) is cracked along the footprints strictly. The vertical one (F2) was not cracked regularly and confined by F1. The crack was
