T21 Tectonic, Volcanic, and Volcanotectonic Processes on Rocky Planetary Bodies

Sunday, 25 September 2016
8:00 AM - 12:00 PM
Room 201

VOLCANOTECTONIC PROCESSES NEAR MARS’ DICHOTOMY BOUNDARY

Paper number: T21-4
Program: Technical Sessions
Time: 8:35 AM – 8:50 AM

Authors

Abstract

The formation of widespread late Hesperian chaotic terrain and extensional fractures to the east of Tharsis has frequently been attributed to the interaction between intrusive volcanism and a thickened post-Noachian cryosphere [e.g. 1, 2], suggesting that magmatism was intimately involved in both tectonics and fluid outflow during this period. However, evidence for associated surface volcanism is limited [3], casting doubt upon these connections.

We show widespread evidence for flat-topped deposits with steep, lobate margins intimately associated with Hesperian to Amazonian extensional fractures across the Margaritifer Terra region, particularly within the Ladon basin and floor-fractured impact craters. The morphology and inferred mineralogy of these deposits is most consistent with lava flow sourced from the fractures. A volcanic interpretation is supported by the discovery of several constructive edifices around the margin of the Ladon basin associated with diffuse-margined material with a similar spectral signature, which we interpret as pyroclastic. The lava deposits overlie Noachian sediments scoured by fluid outflow from the fractures and are themselves eroded by such fluids, indicating a complex history of fracture-sourced volcanic and aqueous activity. Thus, we show that volcanic activity at Mars’ dichotomy boundary was indeed closely associated with extensional tectonics and fluid outflow, supporting a genetic relationship between these three processes.

[1] Chapman, M. & Tanaka, K. (2002) Icarus, 155:2, 324-339. [2] Rodriguez, J.A.P. et al. (2005) Icarus, 175, 36-57. [3] Meresse, S. et al. (2008) Icarus, 194, 487-500.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-283458

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