Banca de DEFESA: Mariana da Silva Gomes

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : Mariana da Silva Gomes
DATE: 21/12/2023
TIME: 14:00
LOCAL: Auditório do Instituto de Geociências
TITLE:

Granulometric and mineralogical characterization of mangrove sediments from Tinharé Island, Bahia, Brazil: a contribution to environmental management and the development of a depositional model.

KEY WORDS:

Bioclastic sediments; Halimeda; Cementation; Aragonite, Mg-calcite.

PAGES: 92
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Geologia
SUMMARY:

This work examines the granulometric and mineralogical features of sediments obtained from two mangroves—Pedarta and Garapuá—situated on Tinharé Island (BA). The distribution of granulometric classes and the shapes of grains are primarily influenced by tidal hydrodynamic energy and substrate conditions. Generally, both mangroves exhibit a prevalence of poorly sorted medium to very fine sand (0.5 to 0.125 mm), with Pedarta reaching up to 40%, and Garapuá exceeding 60%. The sediments consist of reworked bioclasts and siliciclastic grains, alongside authigenic minerals such as halite, gypsum, and carbonate cements. Bioclasts (Halimeda, mollusks, and others) grains are predominantly sub-rounded fragments and perforated, while siliciclastic constituents are sub-angular quartz, feldspar (albite, microcline), micas, and rare gibbsite grains. The mineral composition, determined through XRD analysis of the bulk sample from both mangroves, reveals the primary constituents in each: aragonite, halite, quartz, Mg-calcite, calcite, and kaolinite. Additionally, other minerals such as albite, microcline, gypsum, and gibbsite are present, contributing to the overall mineralogical diversity. The morphology and energy regime of the Pedarta mangrove do not favor the formation of Mg-Calcite composition cement in the bioclasts. In contrast, Garapuá, subject to wave action due to its morphology and coral reef discontinuity, revealed bioclasts cemented with high-Mg calcite cement.

COMMITTEE MEMBERS:
Externa à Instituição - JOSEFA VARELA GUERRA - UERJ
Interno - 1279072 - DERMEVAL APARECIDO DO CARMO
Externa à Instituição - EDI MENDES GUIMARAES - UnB
Interna - 1658822 - LUCIETH CRUZ VIEIRA