Publication Date

2015

Document Type

Honors Thesis

Department

Geosciences

Keywords

Martian craters, Mars (Planet)-Geology, Geologic mapping, Mars, Planetary science, Geologic history, Mapping, Craters

Abstract

Nicholson Crater is a 102 km diameter, closed basin, complex impact crater located at the Martian equator. It resides on the western edge of a pyroclastic and volcanic ash deposit (Medusae Fossae Formation) landform named Eumenides Dorsum. Nicholson is one of roughly 50 craters that contain a large central mound several kilometers thick. Gale Crater, which is currently being explored by the Curiosity rover for evidence of past habitability on Mars, has a central sedimentary mound composed of lacustrine deposits overlain by aeolian sediments morphologically similar to the mound in Nicholson Crater. This study focuses on characterizing geologic features in Nicholson, as well as on identifying the origin of its central mound in order to model the sequence of geologic events that shaped it. The age of Nicholson Crater is unknown, but the age of the substrate suggests it formed between 3.7 – 3.0 Gya. High-resolution images from within the crater reveal the oldest nonimpact related feature to be the 2.7 km high central mound. The erosion styles observed on the mound indicate its origin is likely the same as the Medusae Fossae Formation. The isolation and central location of the mound is the result of slope-enhanced wind erosion from katabatic winds entering the crater. Fan-shaped deposits, originating from alcoves on the crater rim, superimpose channels along the crater floor neighboring the central mound signifying a transition from a wet to dry environment and episodic groundwater activity. Mass-wasting lobate debris landforms along the base of the crater rim are the youngest depositional features in the crater and are commonly associated with glaciation on both Earth and Mars. This work expands the understanding of the similarity in mound morphology between Gale and Nicholson craters, despite differences in the mechanism of mound formation.

Language

English

Comments

50 pages : illustrations (chiefly color). Honors project-Smith College, 2015. Includes bibliographical references (pages 47-50)

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