Different magma differentiation processes of post-onset collision adakitic rocks in the Gangdese Batholith: Evidence from zircon trace elements
Lu TY, He ZY, Klemd R (2023)
Publication Type: Journal article
Publication year: 2023
Journal
Book Volume: 620
Article Number: 121345
DOI: 10.1016/j.chemgeo.2023.121345
Abstract
The widespread adakitic magmatism in southern Tibet, which postdates the onset of the India-Eurasia collision, is usually considered to be derived from the partial melting of Lhasa thickened lower crust. However, less attention has been paid to the magma differentiation processes following the formation of the parental adakitic melts. Here, we use in situ zircon trace-element geochemistry, combined with whole-rock geochemical data, to gain insight into the magma differentiation and related mineralization of two phases of post-onset collision adakitic magmatism from the Nyemo location in the southern Lhasa subterrane. Systematic variations in zircon trace-element compositions record fractional crystallization of specific minerals (e.g., titanite, magnetite) for the ca. 30 Ma monzogranite and equilibrium crystallization for the ca. 15 Ma granodiorite. This is also supported by thermodynamic modeling, which revealed that the monzogranite and granodiorite magmas underwent weak differentiation (melt fraction up to ∼70%) or no differentiation, respectively. Progressively reduced oxygen fugacity conditions during magnetite fractionation in the monzogranitic magmas resulted in sulfide segregation, thereby removing sulfur and chalcophile elements such as Ni and Cu from the melt. Thus, we propose on the basis of in situ zircon trace-element geochemistry that magnetite fractionation within shallow to mid-continental crust may lead to the low Cu fertility of magmas, forming some of the Cu-poor post-onset collision adakitic rocks in the Gangdese magmatic belt.
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APA:
Lu, T.Y., He, Z.Y., & Klemd, R. (2023). Different magma differentiation processes of post-onset collision adakitic rocks in the Gangdese Batholith: Evidence from zircon trace elements. Chemical Geology, 620. https://dx.doi.org/10.1016/j.chemgeo.2023.121345
MLA:
Lu, Tian Yu, Zhen Yu He, and Reiner Klemd. "Different magma differentiation processes of post-onset collision adakitic rocks in the Gangdese Batholith: Evidence from zircon trace elements." Chemical Geology 620 (2023).
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