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SERRA DA CANGALHA, TOCANTINS, BRAZIL: INSIGHTS TO THE STRUCTURE OF A COMPLEX IMPACT CRATER WITH AN OVERTURNED CENTRAL UPLIFT. T. Kenkmann 1 , M. Vasconcelos 2 , A. P.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Reimold, Wolf Uwe |
| Copyright Year | 2010 |
| Abstract | Introduction: Serra da Cangalha in Brazil (8°5′S/46°52′W) was proposed as a possible impact structure because of its circular shape [1] and possible shatter cone occurrences [1-3]. A recent remote sensing study [4] revealed its great potential for structural analysis. Here we present results of a mapping campaign in the impact crater in May 2009. Methods: In the course of the field campaign 442 GPS referenced data points were taken with notation of lithology, bedding plane orientation and structure. The declination correction is -19°. Errors on GPS coordinates are usually 6 m, on strata orientations 5°. For mapping purposes we also used geo-referenced CBERS-2B/HRS (2.7 m res.) and WorldView-1 (0.5 m res.) satellite images. Geologic surveying and mapping were performed utilizing the ArcGIS 9.3 software package by ESRI. Geographic coordinates for datapoints, faults, and lineaments were transformed into radial coordinates to analyse concentric deviations and distances from the crater center. For details of data conversion and notations see [5]. Morphometry: The crater rim can be delineated from satellite images and ranges in diameter from 13400 to 14000 m, (mean Ø: 13730 m). The region outside the crater is represented by a table mountain land dissected by fluvial drainage systems. The crater rim is a concentrically trending monocline, whose inner limb dips towards the crater center. The moat between crater rim and central uplift is a depressed region with a concentric drainage system and subdued ring features [4]. The central uplift (Fig. 1) has a diameter of 5300 to 6500 m (mean Ø: 5800 m). The 200300 m high collar of the central uplift is 2650-3075 m in diameter (mean Ø = 2830 m). The collar has a somewhat quadrangular shape with an open part to the NNW. The central uplift is off-set to the WSW by ~550 m from the geometric crater center defined by the crater rim. Stratigraphy: The lowermost stratigraphic unit is formed by dark claystone of Devonian age (Longá Fm.) outcropping in the center (Fig.1; beige). They are surrounded by Carboniferous sandstones (Poti Fm; Fig. 1 stippled, Fig. 2), forming the collar of the central uplift. Piauí Fm. (Fig. 1 rosè) forms the periphery of the central uplift. The uppermost stratigraphic unit is the Pedra de Fogo Fm. mostly com sandstones. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://www.lpi.usra.edu/meetings/lpsc2010/pdf/1237.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
