Scholarlink

<p>The Brazilian Equatorial Margin is a critical ecological and economic region on the Atlantic, yet the physical and chemical processes that govern the sedimentation on its continental slope are not fully understood. Therefore, addressing this deficit is crucial for understanding deep-sea dynamics and ensuring effective management of these vulnerable marine environments. Here, we investigate the sedimentological and geochemical characteristics of surface sediments on the slope of the Ceará Basin. A total of 64 samples were collected for particle size and calcium carbonate content analyses. In addition, three representative specimens were selected for Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy (SEM-EDS), while twenty samples were analyzed using X-ray Diffraction (XRD). The sediments of the continental slope of the Ceará Basin exhibit a predominance of silt (59.37%), with sandy silt (23.45%), clayey silt (12.5%), and silty sand (4.6%) distributed across three sub-basins at depths ranging from 1358 to 2048&#xa0;m. The slope was classified as a mixed type with facies analysis revealing a west–east gradient from biosiliciclastic to siliciclastic dominance, with biogenic fractions composed mainly of mollusks, foraminifera, and bryozoans. XRD and SEM-EDS analyses confirmed high abundances of CaCO₃ phases such as calcite, aragonite, magnesian and dolomitic calcites, and accessory minerals such as zircon, siderite, barite, and ilmenite. The chemical analysis indicated a preponderance of calcium oxide (CaO), accompanied by significant concentrations of silicon dioxide (SiO2), aluminum dioxide (Al2O3), ferrous oxide (FeO), and magnesium oxide (MgO). The sedimentation observed on the continental slope of the Ceará Basin reveals significant physical and chemical diversity, reflecting the complexity of this deep environment. The presence of carbonate areas, which exhibit the most significant biogenic deposition, is linked to the activity of benthic organisms. Conversely, the presence of siliciclastic minerals such as quartz and zircon indicates sediment input from continental sources, transported via fluvial systems and submarine canyons. These findings underscore the dual biotic and abiotic origins of the slope sediments, shaped by a complex interplay of depositional processes, and provide valuable insights for environmental assessments, resource exploration, and regional marine spatial planning.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Sedimentological and geochemical characterization of the continental slope of the Ceará Basin, Brazilian equatorial margin

  • 期刊论文

  • 发表日期：

    2025年11月15日

查看全文
  • R. Medeiros Lima,
  • T. S. Sousa,
  • L. E. R. Oliveira,
  • N. Maia de Almeida

摘要

The Brazilian Equatorial Margin is a critical ecological and economic region on the Atlantic, yet the physical and chemical processes that govern the sedimentation on its continental slope are not fully understood. Therefore, addressing this deficit is crucial for understanding deep-sea dynamics and ensuring effective management of these vulnerable marine environments. Here, we investigate the sedimentological and geochemical characteristics of surface sediments on the slope of the Ceará Basin. A total of 64 samples were collected for particle size and calcium carbonate content analyses. In addition, three representative specimens were selected for Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy (SEM-EDS), while twenty samples were analyzed using X-ray Diffraction (XRD). The sediments of the continental slope of the Ceará Basin exhibit a predominance of silt (59.37%), with sandy silt (23.45%), clayey silt (12.5%), and silty sand (4.6%) distributed across three sub-basins at depths ranging from 1358 to 2048 m. The slope was classified as a mixed type with facies analysis revealing a west–east gradient from biosiliciclastic to siliciclastic dominance, with biogenic fractions composed mainly of mollusks, foraminifera, and bryozoans. XRD and SEM-EDS analyses confirmed high abundances of CaCO₃ phases such as calcite, aragonite, magnesian and dolomitic calcites, and accessory minerals such as zircon, siderite, barite, and ilmenite. The chemical analysis indicated a preponderance of calcium oxide (CaO), accompanied by significant concentrations of silicon dioxide (SiO2), aluminum dioxide (Al2O3), ferrous oxide (FeO), and magnesium oxide (MgO). The sedimentation observed on the continental slope of the Ceará Basin reveals significant physical and chemical diversity, reflecting the complexity of this deep environment. The presence of carbonate areas, which exhibit the most significant biogenic deposition, is linked to the activity of benthic organisms. Conversely, the presence of siliciclastic minerals such as quartz and zircon indicates sediment input from continental sources, transported via fluvial systems and submarine canyons. These findings underscore the dual biotic and abiotic origins of the slope sediments, shaped by a complex interplay of depositional processes, and provide valuable insights for environmental assessments, resource exploration, and regional marine spatial planning.