Abstract
Sedimentary beds of alternating red and green colour are commonly interpreted to reflect orbitally-forced cyclic climatic, syn-depositional conditions, although colour changes caused by post-depositional fluids are also documented. Results from IODP Hole U1502A marine sediments in the South China Sea exemplify post-depositional reducing fluid–rock interactions that locally changed the sediment colour from red to green. Petrographic, rock magnetic and paleomagnetic data on cores show that the red colouration originates from an early, basin-wide, pervasive diagenetic oxidation event (forming haematite), whereas the green colouration results from subsequent fluid-driven reduction (forming pyrrhotite-magnetite). The dense sulfidic stockwork in the basaltic basement underlying these sediments was the likely source of reducing fluids. Drilling deep holes into marine basin basements can thus provide useful information on fluid transfer from the basement to the overlying sedimentary layers.
Original language | English |
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Number of pages | 8 |
Journal | Terra Nova |
Early online date | 9 Jun 2023 |
DOIs | |
Publication status | E-pub ahead of print - 9 Jun 2023 |
Bibliographical note
Funding Information:Support was provided by Chinese 111 (HW), ECORD (SS), Korean IODP (DC), National Science Foundation (ECF), Natural Environment Research Council (SAB) and U.S. Science Support Program, Lamont‐Doherty Earth Observatory (ECF, PP). Marco Maffione, an anonymous reviewer, the Associate Editor and Max Coleman are kindly acknowledged.
Data Availability Statement
The data that support the findings of this study are available from the corresponding author upon reasonable request.Keywords
- hydrothermal
- IODP
- Miocene
- sediments
- South China Sea