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The Foelsche structure, Northern Territory, Australia: An impact crater of probable Neoproterozoic age
journal contribution
posted on 2023-05-16, 13:41 authored by Haines, P, Rawlings, DJThe Foelsche structure is situated in the McArthur Basin of northern Australia (16°40′S, 136°47′E). It comprises a roughly circular outcrop of flat-lying Neoproterozoic Bukalara Sandstone, overlying and partly rimmed by tangentially striking, discontinuous outcrops of dipping, fractured and brecciated Mesoproterozoic Limmen Sandstone. The outcrop expression coincides with a prominent circular aeromagnetic anomaly, which can be explained in terms of the local disruption and removal or displacement of a regional mafic igneous layer within a circular area at depth. Samples of red, lithic, pebbly sandstone from the stratigraphically lowest exposed levels of the Bukalara Sandstone within the Foelsche structure contain detrital quartz grains displaying mosaicism, planar fractures (PFs) and planar deformation features (PDFs). PFs and PDFs occur in multiple intersecting sets with orientations consistent with a shock metamorphic origin. The abundance and angular nature of the shocked grains indicates a nearby provenance. Surface expression and geophysical data are consistent with a partly buried complex impact crater of ∼6 km in diameter with an obscured central uplift ∼2 km in diameter. The deformed outcrops of Limmen Sandstone are interpreted as relics of the original crater rim, but the central region of the crater, from which the shocked grains were likely derived, remains buried. From the best available age constraints the Foelsche structure is most likely of Neoproterozoic age.
History
Publication title
Meteoritics and Planetary ScienceVolume
37Pagination
269-280ISSN
1086-9379Department/School
School of Natural SciencesPublisher
Meteoritical SocietyPlace of publication
Arkansas, USARepository Status
- Restricted