Geology of Clays

Interstitial-Water Studies, Deep Sea Drilling Project Sites 415 and 416

“…These authors cite in particular the textural evidence that indicates authigenic growth intimately related to opal recrystallization. On the other hand, Mélières (1978) suggests that the palygorskite and sepiolite were redeposited at Site 415, inasmuch as these minerals occur in thick sections of similar age in the basins of the West African coast, e.g., the Senegal Basin (Millot, 1970). The interstitial-water data support the hypothesis of the formation of these minerals in an environment of brine-enhanced magnesium combined with dissolved silica supplied during diagenesis.…”

Clay minerals in cave sediments and terra rossa soils in the Montagnola Senese karst massif (Italy)

“…In fact, a typ i cal pedogenic evo lu tion con sists of the al ter ation of illite with the for ma tion of ver mic u lite, smectitic mixed lay ers, smectite, kaolinite and amor phous com pounds (Millot, 1970;Jack son, 1964;Chamley, 1989). How ever, kaolinite is re ported as a pri mary con stit u ent of the lime stone bed rock crop ping out in the Montagnola Senese (Gandin et al, 2000;Iacoviello and Mar tini, 2012) and for this rea son its oc cur rence in the cave-sed i ments does not pro vide any in for ma tion about the degree pedogenetic weath er ing.…”

Paleoenvironmental controls on mineral assemblages in a shelf sequence: Te Kuiti Group, South Auckland, New Zealand

“…(2) The extremely fine grain size (0.1-1.0 ).lm) of the smectite is suggestive of progressive development from colloidal material, demonstrated by laboratory synthesis (Beutelspacher & Van der Marel 1968;Millot 1970). (3) Lath-shaped aggregates (Fig.…”

“…Primary clay minerals of the Mesozoic basement rocks, plus secondary sericite and chlorite produced by weathering of feldspars and ferromagnesian minerals, are sequentially transformed during pedogenetic alteration according to the following general schemes (Millot 1970): The long period (about 50 m.y.) of subaerial exposure of Mesozoic rocks from the late Cretaceous to Eocene, the generally warm temperate to subtropical climatic conditions through this period (Fleming 1979), and the subdued relief and tectonically stable nature of the South Auckland region by the Eocene (Nelson & Hume 1977), together must have fostered a late Paleogene landscape dominated by chemical weathering and supporting a thick regolith rich in pedogenetic kaolinite, similar to that developed on Mesozoic greywackes over much of northern New Zealand at the present day (Fieldes 1968).…”

“…9C) supports authigenesis (cf. Jeans 1968;Millot 1970). Although smectite is the dominant clay mineral in most Te Kuiti Group sediments, there are local exceptions.…”