Investigation of Shuttle Radar Topography Mission data of the possible impact structure at Serra da Cangalha, Brazil

Abstract

Abstract-The Serra da Cangalha crater structure in northeast Brazil, ∼13 km in diameter, has long been widely considered to be a confirmed impact structure, based on reports of shatter cone findings.Only very limited field work has been carried out at this crater structure. Landsat Thematic Mapper (TM) and Shuttle Radar Topography Mission (SRTM) data sets for the region around this crater structure are compared here with regard to their suitability to determine first-order structural detail of impact crater structures. The SRTM data provide very detailed information regarding drainage patterns and topography. A pronounced central ring of up to 300 m elevation above the surrounding area, two comparatively subdued intermediate rings of 6 and 10.5 km diameter, respectively, and the broad, complex crater rim of up to >100 m elevation can be distinguished in the Serra da Cangalha data. The maximum cratering-related regional deformation (radial and concentric features) seems to be limited to a radial distance of 16-18 km from the center of the structure. A first comparison of macrostructural information from several impact structures with that from Serra da Cangalha does not yield firm trends, but the database is still very small at this stage. The varied nature of the target geology strongly influences the development of structural features in any impact event.

The newly confirmed Luizi impact structure, Democratic Republic of Congo—Insights into central uplift formation and post-impact erosion

“…1). The occurrence of such types of intermediate inner rings is particularly rare on Earth, and they are generally interpreted, as in the case of the Haughton (Canada) and Serra da Cangalha (Brazil) structures, to represent the differentially eroded remnants of central uplifts formed in layered sequences of target rocks (Osinski and Spray, 2005;Reimold et al, 2006). We note that formation of these ring features should not be confused with the peak ring basin morphology of pristine impact craters, although the formation processes may actually be similar, as discussed in the following.…”

Omeonga—A possible large impact structure on the Eastern Kasai Province (D.R. Congo)?

“…Complex drainage patterns with both centripetal and concentric small rivers draining from a central uplift and external rim have been found also in the Brazilian tropical region (e.g., Engelhardt et al. 1992; Romano and Crósta 2004; Reimold et al. 2006).…”

The Jebel Hadid structure (Al Kufrah Basin, SE Libya)—A possible impact structure and potential hydrocarbon trap?

“…5b), as well as a distinct morphological similarity to the larger impact structures of Aorounga, Chad ($16 km in diameter; Becq-Giraudon et al, 1992;Koeberl et al, 2005a;Fig. 5c); Serra da Cangalha and Domo de Vargeão, Brazil (each $12 km in diameter; Cró sta, 1987;Cró sta et al, 2005;Reimold et al, 2006;Figs. 5d and e, respectively). We, therefore, propose that the Jebel Hadid structure might represent a possible complex impact structure.…”

“…We refer to Koeberl (2004), Reimold et al (2006), Buchner and Schmieder (2007), Reimold (2007), and Schmieder and Buchner (2007) for detailed discussions of suspected impact structures based on remote sensing. Field work and petrographic studies will be needed to search for shock metamorphic effects in rocks from the Jebel Hadid structure (such as shatter cones and shocked quartz grains providing evidence for shock metamorphism; e.g., French, 1998).…”

“…However, even the small impact structure of Viewfield, Saskatchewan, Canada ($2.5 km in diameter), produces significant amounts of oil and gas ($600 barrels of oil per day and $250 million cubic feet per day in gas; Grieve, 2005). The use of remotesensing techniques during the last decades has strongly supported the search for new possible impact structures (e.g., Koeberl, 2004;Buchner and Schmieder, 2007;Schmieder and Buchner, 2007) and research in impact geology (e.g., Koeberl et al, 2005a, b;Reimold et al, 2006). This paper provides a remote sensing study of a circular structure located in the Al Kufrah Basin, SE Libya-a region that is currently undergoing intense hydrocarbon exploration (e.g., Le Heron and Thusu, 2007).…”