Genesis Of The 1.45 Ga Kratz Spring Iron Oxide-Apatite Deposit Complex In Southeast Missouri, USA: Constraints From Oxide Mineral Chemistry

Author

Brandon Sullivan
Marek Locmelis, Missouri University of Science and TechnologyFollow
Bolorchimeg N. Tunnell
Cheryl M. Seeger, Missouri University of Science and Technology
Marilena Moroni
Sarah Dare
Ryan Mathur
Thomas Schott

Abstract

Seven major and numerous lesser Fe oxide occurrences within the 1.47 Ga St. Francois Mountains terrane in Missouri (USA) have previously been described as iron oxide-apatite (IOA) and iron oxide-copper-gold (IOCG) deposits. Researchers speculate that these contain significant amounts of critical minerals, most notably rare earth elements and cobalt. One of the less-studied deposits in the region is the 1.455 Ga Kratz Spring deposit. The deposit consists of two steeply dipping magnetite bodies beneath 450 m of sedimentary cover. The genesis of the Kratz Spring deposit and its relationship to nearby IOA-IOCG deposits remains poorly constrained. To better understand the formation of the Kratz Spring deposit, the authors integrated stratigraphic, petrographic, and bulk rock studies within situ trace element and Fe isotope chemistry of magnetite and hematite. These data show that the Kratz Spring deposit is hydrothermal in origin but is divided into two sub deposits according to different fluid sources and formation conditions: (1) a deep but cooler hydrothermal Kratz Spring South deposit with a juvenile fluid source and (2) a shallow but hotter magmatic-hydrothermal Kratz Spring North deposit with variable fluid sources. Our genetic model suggests the two Kratz Spring deposits are local expressions of the same mineralization system, i.e., the Kratz Spring South deposit is a distal, lower-temperature offshoot of the feeder system that formed the Kratz Spring North deposit. Understanding the magmatic-hydrothermal plumbing system that formed Missouri's IOA-IOCG deposits is important to guiding critical mineral exploration efforts in the region.

Recommended Citation

B. Sullivan et al., "Genesis Of The 1.45 Ga Kratz Spring Iron Oxide-Apatite Deposit Complex In Southeast Missouri, USA: Constraints From Oxide Mineral Chemistry," Economic Geology, vol. 118, no. 5, pp. 1149 - 1175, GeoScience World, Aug 2023.

The definitive version is available at https://doi.org/10.5382/econgeo.5003

Department(s)

Geosciences and Geological and Petroleum Engineering

Publication Status

Open Access

Comments

National Science Foundation, Grant 1944552

International Standard Serial Number (ISSN)

1554-0774; 0361-0128

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2023 GeoScience World, All rights reserved.

Publication Date

01 Aug 2023