Morfologia dos recifes afogados na plataforma continental interna, adjacente à praia de Tamandaré-PE, pelo método batimétrico interferométrico

Abstract

The present work was carried out on the internal continental shelf adjacent to the municipality of Tamandaré-PE, in order to map the geometry and understand the formation of the region's drowned reefs, which are arranged in a conservation zone protected by the Environmental Protection Area (APA Costa of Corals). A geomorphological mapping was carried out using a bathymetric scanning system by interferometry (EdgeTech 4600), with the support of a small vessel at a speed of 5 knots. Data processing was done using Hypack 2014 software, for navigation and movement corrections, tides, sound speed and spurious data filtering, and ArcGis 10.3 georeferencing software, for digital terrain modeling. To perform the three-dimensional terrain modeling, the distance power interpolator (IDW) was used, with a 2x2 mesh in 50 m cells. The results show a field of reefs approximately 3.7 km long by 1.3 km wide, distributed parallel to the coast, surrounded by a flat bottom at depths of 31 m. The outer edge of the reef field has a higher gradient of 1:100 with positive elevations of up to 6 m high, while there is a smooth 5:15 gradient from the top of the reef towards the shore and lower slopes of 3 m at the shallow edge. of the reef body. Internally, the reefs are clustered in sets of ridges (knoll) and patch (patch) with heights ranging from 3 to 6 m and an average diameter of 35 m, and these clusters generally take a NE-SW orientation parallel to the coastline (Spalding, 2001; Leão et al., 2003, 2016). The reef field is cut in the E-W direction by a shallow paleovale 200 m wide and 40 m deep. The geometry of the reef field resembles fringing reefs, which suggests a development attached to the shoreline, while the distribution and dimensions indicate juvenile reefs drowned in low sedimentary input conditions.