94 D10. Planetary Geology Potpourri: When One World Just Isn’t Enough (Posters)

Monday, 16 October 2023
8:00 AM - 5:30 PM
Hall B

INVESTIGATION OF SEDIMENTARY FAN DEPOSITS ALONG THE BEAGLE GAP TRAVERSE AT JEZERO CRATER, MARS

Paper number: 94-6
Program: Technical Sessions
Time: 8:00 AM – 5:30 PM

Authors

Abstract

In February 2023, the Perseverance rover ascended the Jezero sedimentary fan deposit that has been interpreted as an ancient river delta (~3.6-3.8 Ga). The ~1.2 km traverse up “Beagle Gap” climbed ~35 m in elevation over 10 sols (martian days). The route passed outcrop exposures up to 20 m higher than had been observed along the delta front drive. Image and compositional data add new information on fan sedimentology and stratigraphy, and indicate a complex history of depositional processes and paleoenvironments.

At five mounds along the route, 5-10 m thick, thin-bedded horizontal sandstone strata are present in the uppermost exposures. Locally, conglomerate beds are observed within these strata. This unit is interpreted as fluvial deposits in a delta top environment punctuated by episodic high discharge floods that transported cobble to boulder size clasts. Multiple outcrops of inclined strata are present, although these vary significantly in clast caliber, bedding thickness, and dip direction, which may indicate a range of deposit types. With the diversity in observed sedimentary attributes, a variety of depositional models are being evaluated, including deltaic foresets or lobes, and fluvial deposits.

Proximity science using the arm instruments was conducted at one location, “Jenkins Gap.” The poorly sorted, pebbly coarse sandstone has extensive porosity evident in WATSON images. Carbonate composition was identified in the matrix by both arm spectrometers. A candidate lake level (-2490 m) identified in the Kodiak outcrop passes through Jenkins Gap, supporting the interpretation of carbonate formation in a shore-marginal environment. Additionally, this outcrop is texturally similar to lacustrine shoreline ‘tufa’ deposits documented at the Provo level of Pleistocene Lake Bonneville in northeast Utah. Further investigation of the fan stratal geometry through correlation with Beagle Gap units will provide constraints on the relative timing and duration of lakes levels at Jezero crater.

Geological Society of America Abstracts with Programs. Vol. 55, No. 6

doi: 10.1130/abs/2023AM-393229

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