Banca de QUALIFICAÇÃO: RENATO BORGES BERNARDES

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : RENATO BORGES BERNARDES
DATE: 02/10/2023
TIME: 14:00
LOCAL: Auditório do Instituto de Geociências
TITLE:

GEOLOGICAL MAPPING AND STRUCTURAL ANALYSIS OF THE ‘ARAGUAINHA DOME’ IMPACT STRUCTURE, CENTRAL BRAZIL

KEY WORDS:

Impact cratering; Impact structure; Araguainha; Geological mapping; Structural analysis.

PAGES: 102
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Geologia
SUMMARY:

The Araguainha impact structure (AIS) in central Brazil is a medium-sized (~40 km diameter), complex impact structure formed in a mixed crystallinesedimentary target. The structure is, despite significant erosion, still remarkably well preserved. Recent roadworks along the MT-100 state road crossing the entire AIS provided extensive new exposure for detailed structural analysis along this SW-NE transect. The structure offers an opportunity to document the structural effects associated with complex crater formation at various scales, which assists in further developing our understanding of the kinematics of crater formation and impact-induced strain patterns, as well as refining crater diameter estimates and investigating (a)symmetry of this impact structure. Field campaigns for geological and structural mapping of the AIS and its environs were undertaken between January 2021 and July 2023, totaling more than 50 days of fieldwork. Virtually all accessible outcrops along the MT-100 and GO-194 roads up to a radial distance of ~33 km to both SW and NE from the assumed center of the structure were described and measured in detail. The promising results allow building a ca. 70-km-long SW-NE geological-structural profile across the whole structure and beyond. The observations may indicate that previously undescribed mechanisms operated in the outer rim region, related to the formation of the Passa Dois Group inliers, and probably related to the modification stage of cratering. Moreover, there is evidence of asymmetry of structures between the SW and NE sectors of the outer central uplift, which may point to asymmetry during crater formation (oblique impact) and/or collapse of the central uplift. Preimpact target structure appears to have played a significant role in the resulting AIS morphology. Post-impact regional geological overprint can be identified and has heterogeneously acted in different sectors of the structure. Many other observations are presented in the text, with a synthesis of the project's current state, including what has been achieved, problems encountered so far, what still needs to be done, and how to achieve the proposed objectives in time.

COMMITTEE MEMBERS:
Externa à Instituição - EDI MENDES GUIMARAES - UnB
Externo ao Programa - 2156153 - ELDER YOKOYAMA - nullExterno à Instituição - JOSE OSWALDO DE ARAUJO FILHO
Externa ao Programa - 1732336 - TATI DE ALMEIDA - nullPresidente - 3043135 - WOLF UWE REIMOLD