Masters Theses

Keywords and Phrases

Hydrous metasomatism; Ivrea-Verbano Zone; LA-ICP-TOF-MS; Magmatic sulfide deposit; Metal and volatile mass transfer; Ultramafic-mafic magmatism

Abstract

"Constraining the processes that control the transport and deposition of sulfides in the deep lithosphere is an important step in expanding ore deposit exploration search space to include exhumed lower crustal rocks. The ultramafic sulfide ore-bearing Valmaggia pipe in the Ivrea-Verbano Zone of NW Italy, an exhumed cross section of the overlying lower continental crust and subcontinental lithospheric mantle, gives critical insight into metallogenic processes in lower crustal settings. The ~300 m wide metasomatized pipe hosts Fe-Ni-Cu-(PGE±Co±Au) sulfide mineralization that is commonly associated with locally abundant carbonates and hydrous silicates (phlogopite, amphibole). Previous studies suggested that sulfides were physically transported into the pipe via vapor bubble flotation of sulfide droplets. In order to test this hypothesis, petrography is combined with electron microprobe analysis, and laser ablation time-of-flight ICP-MS trace element maps of sulfide/volatile relationships. Results show that sulfide textures vary between semi-massive to disseminated blebs that are commonly in textural or spatial relationship with volatiles. Carbonates and hydrous silicates exist in various and randomly distributed sizes, textures, orientations, and compositions in relation to sulfides. The data shows that bubble-pair transport cannot fully explain the variability of volatile orientations, or textural and compositional relationships. Instead, it is argued that the observed variability of the textures and chemical relationships in the pipe resulted from the co-precipitation of carbonates and sulfides from the same fluid/melt"-- Abstract, p. iii

Advisor(s)

Locmelis, Marek

Committee Member(s)

Hogan, John Patrick
Oboh-Ikuenobe, Francisca
Wronkiewicz, David J.

Department(s)

Geosciences and Geological and Petroleum Engineering

Degree Name

M.S. in Geology and Geophysics

Publisher

Missouri University of Science and Technology

Publication Date

Summer 2024

Pagination

xi, 244 pages

Note about bibliography

Includes_bibliographical_references_(pages 230-243)

Rights

©2024 Shelby Leann Clark , All Rights Reserved

Document Type

Thesis - Open Access

File Type

text

Language

English

Thesis Number

T 12441

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