Paper No. 170-6
Presentation Time: 9:35 AM
DISTRIBUTED VOLCANISM PRESERVES THE TECTONIC RECORD ON MARS AND EARTH (Invited Presentation)
RICHARDSON, Jacob A.1, SUTTON, Sarah S.2, WHELLEY, Patrick L.3, DENG, Fanghui4, BLEACHER, Jacob E.5, CONNOR, Charles4, HAMILTON, Christopher W.2 and GLAZE, Lori S.6, (1)Department of Astronomy, University of Maryland, College Park, MD 20742; Planetary Geology, Geophysics and Geochemistry Lab, Goddard Space Flight Center, Greenbelt, MD 20771, (2)Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Blvd., Tucson, AZ 85721, (3)Planetary Geology, Geophysics and Geochemistry Lab, Goddard Space Flight Center, Greenbelt, MD 20771; Department of Astronomy, University of Maryland, College Park, MD 20742, (4)School of Geosciences, University of South Florida, 4202 E. Fowler Avenue, NES 107, Tampa, FL 33620-5550, (5)Planetary Geology, Geophysics and Geochemistry Lab, Goddard Space Flight Center, Greenbelt, MD 20771, (6)Planetary Science Division, NASA, Washington, DC 20024
The Tharsis Volcanic Province on Mars hosts not only the largest volcanic edifices in the Solar System, but also the largest concentration of small volcanoes that formed from distributed-style volcanism on Mars. These small volcanoes have diameters of 1-10s of km, an order of magnitude larger than their terrestrial counterparts, and their morphologies include isolated lava flows, shield volcanoes, and cinder cones. We have mapped over 1000 distributed volcanic vents within Tharsis, whose modeled eruptive dates span at least 3 Ga with the youngest vents forming within the past 100 Ma. These vents lie across Tharsis, both adjacent to the large central volcanoes and as distant, isolated volcano clusters. As ~90% of vents at Tharsis are elongate—and likely formed parallel to an underlying parent dike—distributed vents serve as timestamps of the stress regime of Tharsis when they each were formed through volcanic eruption. The wide range of time and space that these vents cover make them ideal for unraveling the history of a volcanic province that has repaved one-quarter of the martian surface. We identify clusters of these vents whose dominant orientations appear to be governed by 1) large central volcanoes, 2) regional fossae, or 3) Tharsis-wide fracture sets.
Field research at terrestrial analogs of distributed martian volcanism provides insight into how these vents form in relation to regional stress patterns and central volcanoes. Pliocene magmatism injected dikes in the San Rafael Swell (Utah, USA) that are subparallel to each other despite minimal deviatoric stress during their emplacement. Further south in the Springerville volcanic field (Arizona, USA), Quaternary vent locations are found to be related to Proterozoic crustal structure. In Iceland, the 2014-5 Holuhraun lava field erupted from a 1.5 km fissure that eventually coalesced into a single 500-m long spatter rampart. This NE fissure formed coaligned with an underlying dike that propagated radially from the Bárðarbunga volcano before realigning NE along the regional spreading center. We compare volcanism in these analog sites to the variety of distributed volcano clusters at Tharsis.
![[Visit Client Website]](/img/gsa/cfp_banner_2019am.png)