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Equatorial layered deposits in Arabia Terra, Mars; facies and process variability

Monica Pondrelli, Angelo Pio Rossi, Laetitia Le Deit, Frank Fueten, Stephan van Gasselt, Mihaela Glamoclija, Barbara Cavalazzi, Ernst Hauber, Fulvio Franchi and Riccardo Pozzobon
Equatorial layered deposits in Arabia Terra, Mars; facies and process variability
Geological Society of America Bulletin (March 2015) 127 (7-8): 1064-1089


We investigated the equatorial layered deposits (ELDs) of Arabia Terra, Mars, in Firsoff crater and on the adjacent plateau. We produced a detailed geological map that included a survey of the relative stratigraphic relations and crater count dating. We reconstructed the geometry of the layered deposits and inferred some compositional constraints. ELDs drape and onlap the plateau materials of late Noachian age, while they are unconformably covered by early and middle Amazonian units. ELDs show the presence of polyhydrated sulfates. The bulge morphology of the Firsoff crater ELDs appears to be largely depositional. The ELDs on the plateau display a sheet-drape geometry. ELDs show different characteristics between the crater and the plateau occurrences. In the crater they consist of mounds made of breccia sometimes displaying an apical pit laterally grading into a light-toned layered unit disrupted in a meter-scale polygonal pattern. These units are commonly associated with fissure ridges suggestive of subsurface sources. We interpret the ELDs inside the craters as spring deposits, originated by fluid upwelling through the pathways likely provided by the fractures related to the crater formations, and debouching at the surface through the fissure ridges and the mounds, leading to evaporite precipitation. On the plateau, ELDs consist of rare mounds, flat-lying deposits, and cross-bedded dune fields. We interpret these mounds as possible smaller spring deposits, the flat-lying deposits as playa deposits, and the cross-bedded dune fields as aeolian deposits. Groundwater fluctuations appear to be the major factor controlling ELD deposition.

ISSN: 0016-7606
EISSN: 1943-2674
Serial Title: Geological Society of America Bulletin
Serial Volume: 127
Serial Issue: 7-8
Title: Equatorial layered deposits in Arabia Terra, Mars; facies and process variability
Affiliation: Universita d'Annunzio, International Research School of Planetary Sciences, Pescara, Italy
Pages: 1064-1089
Published: 20150310
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 119
Accession Number: 2015-032347
Categories: Extraterrestrial geology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2015095
Illustration Description: illus. incl. sect., 1 table, geol. sketch map
Secondary Affiliation: Jacobs University Bremen, DEU, GermanyUniversite de Nantes, FRA, FranceBrock University, CAN, CanadaFreie Universitaet Berlin, DEU, GermanyRutgers University, USA, United StatesUniversita di Bologna, ITA, ItalyGerman Aerospace Center, DEU, GermanyIstituto di Scienze Marine, ITA, Italy
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: 201515
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