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A widespread olivine-rich ash deposit on Mars

Christopher H. Kremer, John F. Mustard and Michael S. Bramble
A widespread olivine-rich ash deposit on Mars
Geology (Boulder) (July 2019) 47 (7): 677-681


The origins of olivine-rich rocks on Mars remain only partially constrained, with hypothesized deposition as lava flows, impact products, aeolian sand, and pyroclastic materials. These rock units' uncertain origins obscure their genetic relationships with each other and the contexts of their aqueous alteration. We synthesize geomorphic mapping and geomorphic and stratigraphic measurements with previous spectroscopic analyses to constrain the origin of the circum-Isidis Planitia olivine-rich unit, one of Mars' most widespread and mineralogically diverse olivine-rich rocks. We find that the unit most likely formed as an ash-fall deposit, with a probable origin related to volcanism in the greater Syrtis Major-Isidis Planitia region. This work corroborates hypotheses that some extensive outcrops of ancient bedrock are clastic and that a planet-wide transition from dominantly explosive to effusive volcanism may have occurred in the Hesperian. Our findings also highlight the likely diverse origins of olivine-rich martian rocks and provide key geologic context for the aqueous alteration of the unit and underlying ancient crust.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 47
Serial Issue: 7
Title: A widespread olivine-rich ash deposit on Mars
Affiliation: Brown University, Department of Earth, Environmental and Planetary Sciences, Providence, RI, United States
Pages: 677-681
Published: 201907
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 40
Accession Number: 2019-068709
Categories: Extraterrestrial geology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2019249
Illustration Description: illus. incl. geol. sketch map
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201936
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