Intra-crater sedimentary deposits at the Haughton impact structure, Devon Island, Canadian High Arctic

Abstract

Abstract-Detailed field mapping has revealed the presence of a series of intra-crater sedimentary deposits within the interior of the Haughton impact structure, Devon Island, Canadian High Arctic. Coarse-grained, well-sorted, pale gray lithic sandstones (reworked impact melt breccias) unconformably overlie pristine impact melt breccias and attest to an episode of erosion, during which time significant quantities of impact melt breccias were removed. The reworked impact melt breccias are, in turn, unconformably overlain by paleolacustrine sediments of the Miocene Haughton Formation. Sediments of the Haughton Formation were clearly derived from pre-impact lower Paleozoic target rocks of the Allen Bay Formation, which form the crater rim in the northern, western, and southern regions of the Haughton structure. Collectively, these field relationships indicate that the Haughton Formation was deposited up to several million years after the formation of the Haughton crater and that they do not, therefore, represent an immediate, post-impact crater lake deposit. This is consistent with new isotopic dating of impactites from Haughton that indicate an Eocene age for the impact event (Sherlock et al. 2005). In addition, isolated deposits of post-Miocene intra-crater glacigenic and fluvioglacial sediments were found lying unconformably over remnants of the Haughton Formation, impact melt breccias, and other pre-impact target rock formations. These deposits provide clear evidence for glaciation at the Haughton crater. The wealth and complexity of geological and climatological information preserved as intra-crater deposits at Haughton suggests that craters on Mars with intra-crater sedimentary records might present us with similar opportunities, but also possibly significant challenges.

Geological overview and cratering model for the Haughton impact structure, Devon Island, Canadian High Arctic

“…Haughton structure (Fig. 4, map insert; Osinski and Lee 2005). emphasized that the present day plateau surface of Devon Island is being eroded by stream and marine processes, with frost and glacial action being responsible only for a modification of details.…”

“…The crater rim has been eroded away, along with much of the ejecta deposits, exposing other concentric normal faults not visible in the newly formed Haughton crater (h). Modified after Grieve (1987), Melosh (1989), French (1998), Osinski and Lee (2005), Osinski and Spray (2005) and Osinski et al (2005b). produced during impacts into sedimentary targets, as opposed to crystalline targets.…”

“…Processes that are intimately related to complex crater formation, such as the uplift of the crater floor and collapse of the walls, merge into normal geological processes such as mass movement, erosion, and so on. In addition, geographically localized processes, such as impact-induced hydrothermal activity (see Osinski et al , 2005b) and intra-crater sedimentation (Hickey et al 1988;Whitlock and Dawson 1990;Osinski and Lee 2005), occurred at Haughton immediately after its formation (Figs. 7f-h), with the latter continuing until the present day (Lim and Douglas 2003;Lim 2004;Osinski and Lee 2005).…”

Breccia dikes and crater‐related faults in impact craters on Mars: Erosion and exposure on the floor of a crater 75 km in diameter at the dichotomy boundary

“…4g for location; crater center toward bottom. stratigraphy reported in the Haughton impact structure in the Canadian High Arctic (e.g., Osinski et al 2005a;Osinski and Lee 2005).…”

The Haughton-Mars Project: Overview of science investigations at the Haughton impact structure and surrounding terrains, and relevance to planetary studies

“…The intra-crater sedimentary record at Haughton is the focus of a paper by Osinski and Lee (2005). In addition to the recognition of a series of new sedimentary units, this work shows that the Haughton Formation, a post-impact crater lake sequence, was deposited up to several million years after the formation of the Haughton crater and not in the immediate aftermath of the impact event.…”