Mathematics – Logic
Scientific paper
Dec 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011agufm.p33h..03f&link_type=abstract
American Geophysical Union, Fall Meeting 2011, abstract #P33H-03
Mathematics
Logic
[5410] Planetary Sciences: Solid Surface Planets / Composition, [5464] Planetary Sciences: Solid Surface Planets / Remote Sensing, [5480] Planetary Sciences: Solid Surface Planets / Volcanism, [6225] Planetary Sciences: Solar System Objects / Mars
Scientific paper
Constraining the volume, style and timing of volcanism on Mars is important for understanding its climatic and magmatic history. Early geomorphic mapping efforts using Mariner and Viking data identified numerous isolated occurrences of late Noachian/early Hesperian "ridged plains" or "smooth plateau material" (e.g. Hr, Hpl3) in the cratered uplands. The origin of these units was interpreted to be a combination of volcanic, sedimentary or impact materials with unknown proportions. We present new evidence for the volcanic origin of some of these materials, and constrain their areal extent, volume and general style (e.g., flood basalt as opposed to pyroclastic). Using THEMIS, TES and CRISM data over a region of cratered uplands located between Syrtis Major and Hellas Basin, over one hundred isolated exposures of rocky materials with distinctively higher olivine abundance than surrounding intercrater plains materials were identified. The units are found in intercrater plains and in shallow, relatively flat crater floors, and comprise a total area of ~165,000 sq km. The thickness of individual exposures is estimated to be between 100-500 m, resulting in a total volume of 16,500-82,500 km3, far below that of major flood basalt provinces on Earth. The isolated exposures are dispersed throughout the entire study area (~2.4 million sq km), which is comparable in size to the Siberian flood basalts. The age estimate arises from the observation that many exposures coincide with areas previously mapped as Hpl3 or Hr. The units are interpreted to be primarily volcanically emplaced based on embayment relationships, textural appearance consistent with a relatively resistant morphology, and higher thermal inertia than surrounding materials. The lack of a clear sedimentary source region for the olivine-enriched material also precludes a dominantly sedimentary origin, though it may explain some occurrences of this unit. The lack of obvious lava flow fronts or source vents suggest that these represent low-viscosity flood lavas that buried their vents, similar to lunar mare. The morphologic similarities between the various occurrences of this unit suggest that they were likely emplaced nearly contemporaneously, which would imply relatively widespread magmatism that post-dates the formation of the primary crust. There is morphologic evidence for enhanced fluvial activity during this time period [Irwin et al., 2005, JGR-Planets]; significant volcanism near this time period (such as that described here) may have provided the climatic conditions needed to enable intense fluvial activity. The distinct compositional difference between these volcanic materials and the olivine-poor materials they overlie raises the question of whether the older crust-forming materials were 1) relatively deficient in olivine at the time of crystallization, or 2) compositionally similar to the younger materials, but altered to remove olivine. Based on observations of crater ejecta that impact into the older materials, we present evidence suggesting that the older materials were indeed less mafic than the younger volcanic units, but also that they have experienced some surficial alteration.
Fergason Robin L.
Rogers David
No associations
LandOfFree
Evidence for widespread effusive volcanism near the Noachian-Hesperian transition in circum-Hellas cratered uplands of Mars does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Evidence for widespread effusive volcanism near the Noachian-Hesperian transition in circum-Hellas cratered uplands of Mars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Evidence for widespread effusive volcanism near the Noachian-Hesperian transition in circum-Hellas cratered uplands of Mars will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-871138