Abstract
Young rifts are shaped by combined tectonic and surface processes and climate, yet few records exist to evaluate the interplay of these processes over an extended period of early rift-basin development. Here, we present the longest and highest resolution record of sediment flux and paleoenvironmental changes when a young rift connects to the global oceans. New results from International Ocean Discovery Program (IODP) Expedition 381 in the Corinth Rift show 10s–100s of kyr cyclic variations in basin paleoenvironment as eustatic sea level fluctuated with respect to sills bounding this semi-isolated basin, and reveal substantial corresponding changes in the volume and character of sediment delivered into the rift. During interglacials, when the basin was marine, sedimentation rates were lower (excepting the Holocene), and bioturbation and organic carbon concentration higher. During glacials, the basin was isolated from the ocean, and sedimentation rates were higher (~2–7 times those in interglacials). We infer that reduced vegetation cover during glacials drove higher sediment flux from the rift flanks. These orbital-timescale changes in rate and type of basin infill will likely influence early rift sedimentary and faulting processes, potentially including syn-rift stratigraphy, sediment burial rates, and organic carbon flux and preservation on deep continental margins worldwide.
Highlights
Young rifts are shaped by combined tectonic and surface processes and climate, yet few records exist to evaluate the interplay of these processes over an extended period of early rift-basin development
New results from International Ocean Discovery Program (IODP) Expedition 381 in the Corinth Rift show 10s–100s of kyr cyclic variations in basin paleoenvironment as eustatic sea level fluctuated with respect to sills bounding this semiisolated basin, and reveal substantial corresponding changes in the volume and character of sediment delivered into the rift
Our ability to constrain in sufficient resolution temporal and spatial variations in basin paleoenvironment, sedimentation patterns or rift development, or the role of climate and sea level in moderating these factors is severely restricted
Summary
Young rifts are shaped by combined tectonic and surface processes and climate, yet few records exist to evaluate the interplay of these processes over an extended period of early rift-basin development. We infer that reduced vegetation cover during glacials drove higher sediment flux from the rift flanks These orbital-timescale changes in rate and type of basin infill will likely influence early rift sedimentary and faulting processes, potentially including syn-rift stratigraphy, sediment burial rates, and organic carbon flux and preservation on deep continental margins worldwide. Active continental rift zones generate rapidly subsiding basins with significant accumulations of sediments These settings are thought to be highly sensitive to the interplay of extensional tectonics, sedimentary processes, climate and sea level change[1,2]. Rift basins and other basins in active environments close to sea level are known to experience dramatic changes in environment due to glacio-eustatic fluctuations[3,4] Both pronounced environmental change and active faulting are thought to control sediment delivery and accumulation in active basins[1,2,3]. The transition from Phase 2 to 3 may mark the onset of repeated connection to the open ocean, earlier marine incursions are recognised onshore[21]
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