Mineralogical and geochemical characteristics of late Cretaceous bentonite deposits of the Kelkit Valley Region, northern Turkey

Clay Minerals ◽  
2000 ◽  
Vol 35 (5) ◽  
pp. 807-825 ◽  
Author(s):  
H. Yalçin ◽  
G. Gümüşer
Keyword(s):  
Volcanic Rock ◽  
Marine Environment ◽  
Late Cretaceous ◽  
Volcanic Ash ◽  
Clay Fraction ◽  
Geochemical Characteristics ◽  
Basal Spacing ◽  
Pyroclastic Rocks ◽  
Rock Fragments ◽  
Diagenetic Minerals

AbstractLate Cretaceous bentonitic clays in the Kelkit Valley region of Turkey are composed of an alternation of limestone lenses and silicified tuff nodule-bearing pyroclastic rocks and their alteration products. Quartz, feldspar, biotite, trace amounts of augite together with pumice and volcanic rock fragments comprise the volcanogenic components. Diagenetic minerals are represented by clay, calcite, opal-CT, zeoliteand dolomite. The clay fraction is dominated by smectite and lesser amounts of I-S, illite, chlorite and kaolinite. The d001 basal spacing of dioctahedral smectites ranges from 12.51 to 12.55Å in Na-smectites and 14.97 to 15.52 A˚in Ca-smectites. The CaO/Na2O ratio of smectites ranges from 0.15 to 19.50, and the interlayer Na and Ca contents are 0.22–0.30 in beidellitesand 0.02–0.09 while those in montmorillonites are 0.01–0.13 and 0.03–0.15, respectively. The data obtained indicate that bentonites formed in a marine environment by the alteration of volcanic ash of rhyodacitic/dacitic and intermediate/acidic composition.

The implications of reworking on the mineralogy and chemistry of Lower Carboniferous K-bentonites

Clay Minerals ◽  
1996 ◽  
Vol 31 (3) ◽  
pp. 377-390 ◽  
Author(s):  
T. Clayton ◽  
J. E. Francis ◽  
S. J. Hillier ◽  
F. Hodson ◽  
R. A. Saunders ◽  
...  
Keyword(s):  
Trace Element ◽  
Volcanic Ash ◽  
Clay Fraction ◽  
Trace Element Content ◽  
Element Content ◽  
Heavy Minerals ◽  
Lower Carboniferous ◽  
Greenish Yellow ◽  
Trace Element Contents ◽  
Plastic Clays

AbstractPotassium-bentonites have been found in the Courceyan Lower Limestone Shales near Burrington Combe and Oakhill, Somerset, consisting of thin, greenish yellow, plastic clays interbedded within a mudrock and limestone sequence. Mineralogically, the clay fraction is composed of virtually monomineralic interstratified illite-smectite containing 7–10% smectite layers. The clay fraction of the surrounding mudrocks, however, consists of an illite-chlorite dominated assemblage. Their mineral composition, trace element content, and the relative abundance of zircon crystals suggest an origin from burial of montmorillonite originally formed from volcanic ash. The presence of anomalously high trace element contents with both euhedral and rounded zircon grains in the Oakhill K-bentonites suggests a secondary or reworked origin for these samples. In contrast, the presence of a non-anomalous trace element content and large (>100 μm) euhedral zircon grains suggests that the Burrington K-bentonite is primary in origin. Modelling of whole-rock rare-earth element (REE) patterns shows that the Oakhill REE pattern can be derived from the Burrington pattern by the addition of small contributions from zircon and monazite, two major heavy minerals present. These K-bentonites probably represent the oldest Carboniferous K-bentonites so far recorded in the British Isles.

Late cretaceous pelagic sediments, volcanic ASH and biotas from near the Louisville hotspot, Pacific Plate, paleolatitude ∼42°S

1989 ◽  
Vol 71 (3-4) ◽  
pp. 281-299 ◽  
Author(s):  
Peter F. Ballance ◽  
John A. Barron ◽  
Charles D. Blome ◽  
David Bukry ◽  
Peter A. Cawood ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Volcanic Ash ◽  
Pacific Plate

Tracking compositional changes within the High Arctic Large Igneous Province using zircon Hf isotopes from altered volcanic ash layers of the Sverdrup Basin, Canada

2021 ◽  
Author(s):  
Michael Pointon ◽  
Michael Flowerdew ◽  
Peter Hülse ◽  
Simon Schneider ◽  
Ian Millar ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Volcanic Ash ◽  
Volcanic Belt ◽  
High Arctic ◽  
Ellesmere Island ◽  
Hf Isotope ◽  
Large Igneous Province ◽  
Volcanic Material ◽  
Igneous Province ◽  
Sverdrup Basin

<p>During Late Cretaceous times the Sverdrup Basin, Arctic Canada, received considerable air-fall volcanic material. This is manifested as numerous centimetre- to decimetre-thick diagenetically altered volcanic ash layers (bentonites) that occur interbedded with mudstones of the Kanguk Formation. Previous research on bentonite samples from an outcrop section in the east of the basin (Sawtooth Range, Ellesmere Island) revealed two distinct volcanic sources for the bentonites: most of the bentonites analysed (n=9) are relatively thick (0.1 to 5 m), were originally alkaline felsic ashes, and were likely sourced from local volcanic centres on northern Ellesmere Island or the Alpha Ridge that were associated with the High Arctic Large Igneous Province (HALIP). Two thinner (<5 cm) bentonites with contrasting subalkaline geochemistry were also identified. These were inferred to have been derived from further afield, from volcanic centres within the Okhotsk-Chukotka Volcanic Belt, Russia.</p><p>To better understand volcanism within the vicinity of the Sverdrup Basin during Late Cretaceous times, and further test the above interpretations, a larger suite of bentonite samples was investigated, drawing on samples from outcrop sections in the central and eastern Sverdrup Basin. Whole-rock geochemical analyses and combined zircon U-Pb age and Hf isotope analyses were undertaken. The vast majority of bentonites analysed to date have alkaline geochemistry and were likely sourced from proximal volcanic centres related to the HALIP. The combined U-Pb and Hf isotope data from these bentonites show a progression from evolved (-2 to 0) to moderately juvenile (+9 to +10) εHf<sub>(t)</sub> values between late Cenomanian and early Campanian times (<em>c</em>. 97–81 Ma). This is interpreted to record compositional change through time within the local HALIP magmatic system.</p>

The geochemical characteristics of marine volcanic rock

1996 ◽  
Vol 3 (1) ◽  
pp. 47-49 ◽  
Author(s):  
Xihua Chen ◽  
Yiqi Zhao ◽  
Lihua Xie
Keyword(s):  
Volcanic Rock ◽  
Geochemical Characteristics

Stratigraphie et paléogéographie d'un bassin d'avant-arc ordovicien, Estrie-Beauce, Appalaches du Québec

1994 ◽  
Vol 31 (2) ◽  
pp. 435-446 ◽  
Author(s):  
Pierre A. Cousineau ◽  
Pierre St-Julien
Keyword(s):  
Volcanic Rock ◽  
Accretionary Prism ◽  
Late Ordovician ◽  
Coarse Grained ◽  
Magmatic Arc ◽  
Rock Fragments ◽  
Felsic Volcanic Rock ◽  
Volcaniclastic Rocks ◽  
Felsic Volcanic ◽  
Quartz Grains

Two new formations, the Frontière and Etchemin formations, have been found to lie below the Beauceville and Saint-Victor formations, the two known formations of the Magog Group. The Frontière Formation, at the base of the group, is made up of centimeter-thick beds of medium- to coarse-grained litharenite and of greyish green mudstone; the sandstone, greyish green, contains abundant felsic volcanic rock fragments and chromite grains. The Etchemin Formation is composed mostly of centimeter-thick dusky yellow green siliceous mudstone; at the base, there is also a purple mudstone, and meter-thick beds of dusky green volcaniclastic rocks rich in intermediate to felsic volcanic rock fragments and crystals of feldspar and quartz occur near its top. The Beauceville Formation consists of interbedded centimeter-thick beds of black clayslate and centimeter- to meter-thick beds of black volcaniclastic rocks. The Saint-Victor Formation consists of classic turbidite beds with few meter-thick yellowish volcaniclastic rock beds similar to those of the Beauceville Formation; the sandstone is a litharenite rich in quartz grains and sedimentary rock fragments. Most rocks of the Frontière and Etchemin formations as well as the volcaniclastic rocks of the Beauceville and Saint-Victor formations were derived from a magmatic arc located to the southeast. However, the shale of the Beauceville Formation and the turbidites of the Saint-Victor Formation were derived from an orogenic source located to the northwest. The Magog Group is located between the Saint-Daniel Mélange and the Ascot Complex interpreted as remnants of an accretionary prism and a magmatic arc, respectively. The sediments of this group were thus deposited in a fore-arc basin active during the Taconian orogeny of the Middle to Late Ordovician.

Chathamirhynchia kahuitara, a new genus and species of Late Cretaceous rhynchonellide brachiopod from the Chatham Islands, New Zealand: shell structure, palaeoecology and biogeography

2007 ◽  
Vol 98 (3-4) ◽  
pp. 357-367 ◽  
Author(s):  
Daphne E. Lee ◽  
Neda Motchurova-Dekova
Keyword(s):  
New Zealand ◽  
Shallow Water ◽  
Volcanic Rock ◽  
Late Cretaceous ◽  
Shell Structure ◽  
New Genus ◽  
High Energy ◽  
New Genus And Species ◽  
Cardinal Process ◽  
Energy Environment

ABSTRACTA new rhynchonellide brachiopod has been collected from the Kahuitara Tuff (Campanian–Maastrichtian) of Pitt Island, Chatham Islands, New Zealand. Brachiopods are extremely rare in Cretaceous rocks from New Zealand, and this new genus and species is unlike any other rhynchonellide known from Australasia or elsewhere. Chathamirhynchia kahuitara is distinguished by its small size, strong ribbing, and well-developed sulciplicate folding, and internally by a large, robust cardinal process and raduliform crura. The shell structure of C. kahuitara is shown to be of typical fine fibrous ‘rhynchonellidine’ type. This brachiopod was probably strongly attached to volcanic rock or shells in a shallow-water, high-energy environment. Implications for the biogeography of brachiopods during the Late Cretaceous are briefly discussed.

An Unusual Chlorite as Revealed by the High Temperature X-Ray Diffractometer

Clay Minerals ◽  
1973 ◽  
Vol 10 (2) ◽  
pp. 71-78 ◽  
Author(s):  
K. Kimbara ◽  
S. Shimoda ◽  
T. Sudo
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Ethylene Glycol ◽  
Volcanic Rock ◽  
Small Proportion ◽  
Basal Spacing ◽  
Capillary Water ◽  
X Ray ◽  
Akita Prefecture ◽  
Dta Curve

AbstractAn unusual chlorite has been collected from amygdales in Miocene volcanic rock found at Taiheizan, Akita Prefecture, Japan. The mineral shows subtle variations from other chlorites and related minerals. These are: (a) no apparent expansion with water or ethylene glycol, (b) negligible or no collapse after NH4-saturation or heating at about 300°C, (c) a slow decrease in the basal spacing on heating from approximately 400°C to 760°C, (d) a small amount of low temperature or capillary water and (e) a DTA curve with a vermiculite-like system of peaks.The mineral is identified as a highly chloritic vermiculite with a small proportion of imperfect hydroxy interlayer.

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