Heterogeneous mush-dominated plumbing system and mantle sources of alkaline lamprophyres in Tuoyun Basin, SW Central Asian Orogenic Belt

Heterogeneous mush-dominated plumbing system and mantle sources of alkaline lamprophyres in Tuoyun Basin, SW Central Asian Orogenic Belt

WoS Article

Lamprophyres are spatially and temporally widespread in continental belts, but their magmatic differentiation process and melting dynamic mechanisms remain subjects of debate. In this study, we report mineral chemistry, bulk -rock compositions, and Sr-Nd-O isotopes of the alkaline lamprophyres (including monchiquite and camptonite) from the Tuoyun Basin of the southwestern Central Asian Orogenic Belt. Based on the P -T estimates, transcrustal magmatic reservoirs from the lower crust to upper crust are revealed for monchiquite and camptonite. These magmatic reservoirs were potentially connected, and the magmatic recharge and mixing processes that occurred were recorded by zoned clinopyroxene and amphibole. The diverse crystal populations are suggested to have originated from multiple batches of magmas, which were then involved in forming the subsequent magmas. The Sr-Nd isotopic compositions are relatively depleted, with ( 87 Sr/ 86 Sr) i = 0.70390- 0.70452 and epsilon Nd (t) = 5.46-6.49 for the monchiquite, while the values for camptonite are 0.70391-0.70463 and 4.71-5.02. Moreover, the olivine in situ O isotopes in the monchiquite show delta 18 O V-SMOW values of 4.81%0- 5.40%0, which are comparable to those of the mantle peridotite. Compared with the experimental melts, a hybridized mantle source of hydrous peridotite + silica -depleted pyroxenite is proposed, and partial melting of this component was induced by the upwelling asthenosphere. Ultimately, our study highlights the critical role of the magmatic plumbing system and hydrous mantle source in the formation of Tuoyun lamprophyres.

Lamprophyres are spatially and temporally widespread in continental belts, but their magmatic differentiation process and melting dynamic mechanisms remain subjects of debate. In this study, we report mineral chemistry, bulk -rock compositions, and Sr-Nd-O isotopes of the alkaline lamprophyres (including monchiquite and camptonite) from the Tuoyun Basin of the southwestern Central Asian Orogenic Belt. Based on the P -T estimates, transcrustal magmatic reservoirs from the lower crust to upper crust are revealed for monchiquite and camptonite. These magmatic reservoirs were potentially connected, and the magmatic recharge and mixing processes that occurred were recorded by zoned clinopyroxene and amphibole. The diverse crystal populations are suggested to have originated from multiple batches of magmas, which were then involved in forming the subsequent magmas. The Sr-Nd isotopic compositions are relatively depleted, with ( 87 Sr/ 86 Sr) i = 0.70390- 0.70452 and epsilon Nd (t) = 5.46-6.49 for the monchiquite, while the values for camptonite are 0.70391-0.70463 and 4.71-5.02. Moreover, the olivine in situ O isotopes in the monchiquite show delta 18 O V-SMOW values of 4.81%0- 5.40%0, which are comparable to those of the mantle peridotite. Compared with the experimental melts, a hybridized mantle source of hydrous peridotite + silica -depleted pyroxenite is proposed, and partial melting of this component was induced by the upwelling asthenosphere. Ultimately, our study highlights the critical role of the magmatic plumbing system and hydrous mantle source in the formation of Tuoyun lamprophyres.

monchiquite; camptonite; Sr-Nd-O isotopes; Tuoyun Basin

monchiquite; camptonite; Sr-Nd-O isotopes; Tuoyun Basin

CHENG, Z.; MARTIAL, M.E.; ZHANG, Z.; LI, J.; XU, L.; KRMÍČEK, L.

2025

06.07.2024

GEOLOGICAL SOC AMER, INC

BOULDER

0016-7606

GEOLOGICAL SOCIETY OF AMERICA BULLETIN

136

5-6

United States of America

1827

1845

19

https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/136/5-6/1827/628013/Heterogeneous-mush-dominated-plumbing-system-and?redirectedFrom=fulltext