Depositional Controls on Clay Mineral Abundances in Slope and Basin-Floor Submarine Fans

AAPG Bulletin ◽  
1993 ◽  
Vol 77 ◽  
Author(s):  
CLARK, MICHAEL S., ARCO Oil and Gas
1988 ◽  
Vol 25 (10) ◽  
pp. 1579-1594 ◽  
Author(s):  
S. Gardiner ◽  
R. N. Hiscott

The lower part of the Hadrynian Conception Group is exposed in coastal outcrops near Holyrood Pond, St. Mary's Bay. Deep-water sediments of the Mall Bay Formation (>800 m) are overlain by glaciogenic debris flows of the Gaskiers Formation (250–300 m) and then by renewed turbidite deposition in the lower part of the Drook Formation (1000 m examined; formation thickness 1500 m). The main facies in the Mall Bay and Drook formations are thinly to very thickly bedded sand stone–mudstone couplets (turbidites), amalgamated in the thicker and coarser beds, and graded-stratified siltstones–mudstones. These are interpreted as deposits on an extensive basin floor and on the lower and middle parts of small-scale submarine fans that prograded from fringing volcanic islands. Paleocurrent data indicate a complex paleogeography dominated by active volcanic islands, probably like some modern volcanic arcs. The Gaskiers Formation was generated by glaciation of these islands.The Malll Bay Formation contains lenticular and wavy bedded siltstones–mudstones interpreted as the deposits of bottom currents, perhaps flowing parallel to the contours of the volcanic islands. In Phanerozoic sediments, bottom-current deposits in this setting would probably be thoroughly bioturbated.


Author(s):  
W. W. Barker ◽  
W. E. Rigsby ◽  
V. J. Hurst ◽  
W. J. Humphreys

Experimental clay mineral-organic molecule complexes long have been known and some of them have been extensively studied by X-ray diffraction methods. The organic molecules are adsorbed onto the surfaces of the clay minerals, or intercalated between the silicate layers. Natural organo-clays also are widely recognized but generally have not been well characterized. Widely used techniques for clay mineral identification involve treatment of the sample with H2 O2 or other oxidant to destroy any associated organics. This generally simplifies and intensifies the XRD pattern of the clay residue, but helps little with the characterization of the original organoclay. Adequate techniques for the direct observation of synthetic and naturally occurring organoclays are yet to be developed.


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