Clay mineralogy of cubits gap crevasse splay, Mississippi delta
The relative abundances of clay species in the < 2-..mu..m fractions were determined for the three lithofacies identified in a 5-m core from the proximal part of Cubits Gap crevasse splay, Mississippi delta, to determine the control of depositional mechanics on clay-mineral composition. Proximal splay lithofacies, defined by sedimentary structures and the relative abundance of cohesive (mud) vs noncohesive (silt and sand) sediments, are (1) suspension-deposited mud, (2) interlaminated current-deposited silt and suspension-deposited mud, and (3) current-deposited sand. The weight percentages of sand, silt, and clay (s:slt:cly) in these lithofacies, defining discrete fields in a ternary grain-size plot, are (1) suspension-deposited mud (6 samples), 0-9:40-68:28-60 wt. %; (2) interlaminated silt and mud (6 samples, 1-30:60-98:0-31 wt. %; and (3) current-deposited sand (2 samples), 79-100:0-17:0-4 wt. %. The range in relative peak-height percentages of illite, smectite, and kaolinite plus chlorite (I:S:K+C), calculated using modified methods of Griffin, are (1) suspension-deposited mud, 33-41:35-50:18-26%; (2) interlaminated silt and mud, 31-39:43-52:17-20%; and (3) current-deposited sand, 43:38:19%. These results overlap with the observed range of illite, smectite, and kaolinite in Mississippi River suspended sediment reported by Johnson and Kelley, but are richer in smectite and depleted in kaolinite relative to clay abundance in sediment on the Louisiana continental shelf.
- Research Organization:
- Louisiana State Univ., Baton Rouge
- OSTI ID:
- 7152772
- Report Number(s):
- CONF-8610199-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Vol. 70:9; ISSN AAPGB
- Country of Publication:
- United States
- Language:
- English
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