Muddy sand and sandy mud on the distal Mississippi Fan; implications for lobe depositional processes

• Published in: Geosphere (Boulder, Colo.) Colo.), 2018-06, Vol.14 (3), p.1051-1066
• Main Authors: Fildani, Andrea, Clark, Julian, Covault, Jacob A, Power, Bruce, Romans, Brian W, Aiello, Ivano W
• Format: Article
• Language: English
• Subjects: Atlantic Ocean; Cenozoic; clastic sediments; cores; Deep Sea Drilling Project; deposition; DSDP Site 614; DSDP Site 615; DSDP Site 621; event stratigraphy; grain size; gravity flows; Gulf of Mexico; IPOD; laser methods; Leg 96; lithostratigraphy; marine sedimentation; marine sediments; Mississippi Fan; mud; North Atlantic; northern Gulf of Mexico; Pleistocene; Quaternary; Quaternary geology; sand; sedimentation; sediments; upper Pleistocene
• ISSN: 1553-040X; 1553-040X
• DOI: 10.1130/GES01580.1

We used laser particle size analysis (LPSA) to quantitatively analyze grain-size characteristics from distal Mississippi submarine fan deposits (Gulf of Mexico) and relate them to established depositional models along the spectrum of sediment gravity flows. One hundred and seventy-nine (179) sediment samples from 22 beds were obtained from cores of Deep Sea Drilling Project Leg 96 Sites 614, 615, and 621. The sediment from Sites 614 and 615 was deposited in lobes ∼500 km downstream from the Mississippi canyon head. Most samples were described as sand from visual inspection of cores, containing >75% volume of sand grains, with clay content 20% silt and finer grains, with generally higher clay content (3%-16%). However, LPSA data show that facies assignments from visual core description overestimated the proportion of sand grains: 15% of samples initially interpreted as sand contain