Alteration products of shock metamorphosed basalt from a range of shock pressures

Details Alteration products of shock metamorphosed basalt from a range of shock pressures Alteration products of shock metamorphosed basalt from a range of shock pressures

Dec 2010

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010agufm.p53c1523w&link_type=abstract

American Geophysical Union, Fall Meeting 2010, abstract #P53C-1523

Other

[5420] Planetary Sciences: Solid Surface Planets / Impact Phenomena, Cratering, [5464] Planetary Sciences: Solid Surface Planets / Remote Sensing, [5470] Planetary Sciences: Solid Surface Planets / Surface Materials And Properties

Scientific paper

To investigate the possibility that shock metamorphosed basalt weathers at faster rates than unshocked protoliths, a petrographic study of weathering products in shocked basalts is necessary. Lonar Crater, India is a fortuitous impact ~550 ka [Jourdan et al., 2010] into Deccan flood basalt. Deccan basalt is an excellent spectral analog for Martian basalts [Bandfield et al., 2000], and hence Lonar basalt shocked to a range of pressures [Kieffer et al., 1976] are excellent samples to compare to shergottites and remote sensing data of Mars. Shocked basalt is found as clasts in a thin, ~1 m suevite breccia layer that drapes an ~8 m lithic breccia that comprises the majority of the Lonar ejecta blanket. The lithic breccia represents the “throw out” ejected over the crater rim and only consists of clasts of unshocked and Class 1 (fractured grains) shocked basalt. The suevite breccia or “fall out” consists of all classes of shocked basalt classified by Kieffer et al. [1976]. Petrography of these clasts from suevite breccia outcrops will be shown and discussed. Class 2 shocked basalt shows intense shattering and fracturing of clinopyroxene grains, and labradorite has been converted to maskelynite (Figure 1). Classes 3 and 4 can be differentiated from Class 2 as the labradorite glass shows evidence of flow and vesiculation (e.g., Class 4 in Figure 2), respectively. Petrographic images of impact melts (Class 5) exhibit schlieren and flow features similar to lechatelierite from Meteor Crater and other terrestrial impact melts. The growth of hematite (Figure 1), calcite, chlorite, and serpentine within shattered augite and augite-maskelynite boundaries will be shown with comparisons to these minerals in unshocked basalt. Also discussed will be the petrography of shocked basalt talus vs. that of the in-situ clasts, as this bias in sample collection is influenced by what shocked basalt remains after ~550 ka. Class 2 shocked basalt in plain and cross polarized light. Note augite, maskelynite (isotropic, absence of twinning), and hematite.
Class 4 shocked basalt in PPL. Plagioclase is shock melted to vesicular glass whereas augites are heavily fractured.

Affiliated with

Also associated with

No associations

Rating

Alteration products of shock metamorphosed basalt from a range of shock pressures 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 Alteration products of shock metamorphosed basalt from a range of shock pressures, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Alteration products of shock metamorphosed basalt from a range of shock pressures will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1499256