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The x-ray identification and crystal structures of clay minerals
01 Jan 1961-
About: The article was published on 1961-01-01 and is currently open access. It has received 966 citations till now. The article focuses on the topics: Clay minerals.
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TL;DR: In this paper, chemical, differential thermal and X-ray analyses are given and discussed with particular reference to a clay-size chlorite from weathered pumice-tuff.
Abstract: Calcareous volcanic ashes (pumice–tuffs) occur among Ordovician rocks in Snowdonia, North Wales. The clays of these rocks and of the ecologically important soils derived from them are found to be almost mono-mineralic and to consist of chlorites. Chemical, differential thermal and X-ray analyses are given and discussed with particular reference to a clay-size chlorite from weathered pumice–tuff. There is no evidence for pedogenetic clay mineral transformations in the range of soils studied.
8 citations
TL;DR: In this paper, petrographic investigations of the Upper Cretaceous-Eocene succession exposed at Bahariya Oasis resulted in the recognition of different litho- and biofacies associations, mostly of the carbonate rock type.
Abstract: Detailed petrographic investigations of the Upper Cretaceous-Eocene succession exposed at Bahariya Oasis resulted in the recognition of different litho- and biofacies associations, mostly of the carbonate rock type. The litho- and biofacies characters of the Eocene strata reveal comparatively shallow, quiet marine conditions, interrupted by agitated, high energy intervals. During the Maastrichtian age, deeper quiet marine conditions prevailed. The Upper and Lower members of the Campanian strata were deposited under deep quiet marine conditions, relative to shallower agitated conditions that prevailed during the deposition of the middle member. The Lower Cenomanian sediments were deposited under an alternating high and low energy fresh water environment, interrupted with saline (fluviomarine) periods, relative to the comparatively deeper marine conditions that prevailed during the Upper Cenomanian age. The main diagenetic processes recorded are: cementation, aggrading neomorphism, silicification and dolomitization.
7 citations
7 citations
Journal Article•
TL;DR: In this paper, three kinds of flow units in aqueous bentonite suspension were postulated: non-Newtonian, thixotropic and non-thixotropic.
Abstract: The theological properties of aqueous suspensions of Black Hills bentonite were measured by using a Couette-type viscometer. Three kinds of flow units in aqueous bentonite suspension were postulated. Each has a different average relaxation time, one Newtonian. One of the non-Newtonian types is thixotropic, and the other is non-thixotropic. The thixotropic non-Newtonian unit is transformed to a Newtonian unit by shear stress. If the stress is relieved, the transformed unit returns to its original state. Two flow equations were derived by introducing chemical kinetics consideration for such a transition into the generalized theory of viscous flow. One equation describes the "upcurve," a diagram of rate of sheat versus shear stress, obtained by increasing the rate of shear, and the other relates to the "downcurve" obtained by decreasing the shear rate. The equations satisfactorilly describe the experimental thixotropic hysteresis of bentonite suspensions. The equations also were successfully applied to the flow curves of the suspensions containing various amounts of monovalent electrolyte (KCI).
7 citations
TL;DR: Petrographical comparison and palaeocurrent analysis support correlation of the Lower Palaeozoic sediments cropping out along the coast between Gatehouse and Creetown, Kirkcudbrightshire, with the Carghidown Beds (Hawick Rocks,? Telychian) of the adjacent Whithorn area as mentioned in this paper.
Abstract: Synopsis Petrographical comparison and palaeocurrent analysis support correlation of the Lower Palaeozoic sediments cropping out along the coast between Gatehouse and Creetown, Kirkcudbrightshire, with the Carghidown Beds (Hawick Rocks,? Telychian) of the adjacent Whithorn area. The succession consists of a thick development of medium-grained turbidites, which display regional metamorphism in the lowest-grade greenschist facies, related to the first (f 1 – f 1 a ) episode of deformation. Superimposed on this is a carbonate metasomatism which may be related to the emplacement of the Cairnsmore of Fleet pluton, and a later episode of iron replacement which is associated with major strike-faults, and is probably connected with the Permo-Carboniferous weathering cycle. Eroding currents flowed mainly from the ENE. and depositional currents from the NNW., indicating derivation of the sediments from the tectonic landmass of Cockburnland. The petrography of these sediments suggests that in Telychian times Cockburnland may have consisted largely of Dalradian metasediments intruded by soda-granites, in association with a Cambro-Ordovician ophiolite complex with restricted outcrop. The sequence forms the basal part of a pile of flysch which ultimately filled in the Southern Uplands Trough.
7 citations