Sedimentary organic matter accumulation provinces in the Santos Basin, SW Atlantic: insights from multiple bulk proxies
The organic matter (OM) of surface sediments (0–2 cm) from the Santos Basin was characterized by employing elemental (C, N, P), isotopic (δ13C and δ15N), biochemical (total carbohydrates, proteins, and lipids), and pigment (chlorophyll-a and phaeopigments) proxies, as part of the Santos Project – T...
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| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Instituto Oceanográfico da Universidade de São Paulo
2024-04-01
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| Series: | Ocean and Coastal Research |
| Subjects: | |
| Online Access: | https://www.journals.usp.br/ocr/article/view/222922 |
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| Summary: | The organic matter (OM) of surface sediments (0–2 cm) from the Santos Basin was characterized by employing
elemental (C, N, P), isotopic (δ13C and δ15N), biochemical (total carbohydrates, proteins, and lipids), and pigment
(chlorophyll-a and phaeopigments) proxies, as part of the Santos Project – The Santos Basin Regional Environmental
Characterization (PCR-BS) – coordinated by PETROBRAS. Samples were collected in a regional scale throughout
the entire basin, including 11 isobaths from eight cross-margin transects ranging from 25 to 2,400 m water depths,
and 12 additional samples obtained from the São Paulo Plateau. The aims of this study were two-fold, namely,
to identify the major oceanographic and depositional processes driving OM transport and accumulation and to
provide information on OM origin and availability to benthic secondary producers. The multiple employed proxies
and the use of machine learning allowed to categorize distinct OM accumulation provinces displaying two major
regional features: shallow sediments (< 50-m isobaths) are OM-poor (TOC < 2.0 mg g−1) but the available amount
is readily hydrolysable, and mid-shelf deposits (75-m and 100-m isobaths) throughout the entire basin present
muddy and OM-rich sediments (TOC ranging from 7.0 to 14.0 mg g−1) seemingly available to heterotrophs. Similarly,
relatively OM-rich deposits are found at depths ranging from 700 to 1,300-m isobaths throughout the basin, but their
composition and nutritional value (as suggested by biochemical indicators) are not related to mid-shelf deposits.
The general overview of OM accumulation and composition provided herein validated the selected organic
geochemical proxies for benthic ecology studies at the shelf and deep ocean sectors of the studied region.
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| ISSN: | 2675-2824 |