scholarly journals Volcanic ash and lignite of the Lower Cretaceous Chaswood Formation, central Nova Scotia

2006 ◽  
Author(s):  
G Pe-Piper ◽  
A Okwese ◽  
D J W Piper
Keyword(s):  
Nova Scotia ◽  
Lower Cretaceous ◽  
Volcanic Ash

Volcanic ash in the Lower Cretaceous Chaswood Formation of Nova Scotia: source and implicationsGeological Survey of Canada Contribution 20100082.

2010 ◽  
Vol 47 (11) ◽  
pp. 1427-1443 ◽  
Author(s):  
Georgia Pe-Piper ◽  
David J.W. Piper
Keyword(s):  
Nova Scotia ◽  
New England ◽  
Lower Cretaceous ◽  
Volcanic Ash ◽  
Bulk Composition ◽  
Volcanic Rocks ◽  
Grand Banks ◽  
Ash Fall ◽  
Volcanic Source ◽  
Cretaceous Volcanism

Lignites and coals, because of their low sedimentation rates of terrigenous detritus, may preserve a record of volcanic ash fall. Lignite from the Lower Cretaceous Chaswood Formation in central Nova Scotia was studied to identify whether any volcanic ash is present and can be correlated to known Early Cretaceous volcanism in southeastern Canada and adjacent New England. The bulk mineralogy and geochemistry of lignite and lignitic mudstones was determined by X-ray diffraction and whole-rock geochemical analysis of ashed samples; selected samples were examined by electron microprobe and scanning electron microscope. Much of the terrigenous component of some lignites consists of detrital sediments. In some lignites, distinctive rare earth element patterns are due to leaching from monazite and concentration in organic matter. Some lignites, however, lack illite and (or) quartz indicative of detrital sources, but show unusual abundance of stable high-field-strength elements such as Nb, Ta, and Hf, suggesting a volcanic source. Wood or charcoal fragments appear mineralized and diagenetic talc is present. Most of any ash component has been altered to kaolinite. Bulk composition of original ash ranges from basaltic to rhyolitic and matches chemically with subalkaline volcanic rocks on the SW Grand Banks and Orpheus graben. Coeval volcanic rocks on the U.S. continental margin and the New England–Quebec igneous province are more alkaline. Altered ash in lignite in the lower member of the Chaswood Formation correlates with Neocomian volcanism on the SW Grand Banks; and in the middle and upper members with Aptian–Albian volcanism in Orpheus graben.

The texture of an english fuller's earth

Clay Minerals ◽  
1982 ◽  
Vol 17 (2) ◽  
pp. 255-258 ◽  
Author(s):  
R. H. S. Robertson ◽  
D. Tessier ◽  
J. L. White
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Lower Cretaceous ◽  
Volcanic Ash ◽  
Glass Fragment ◽  
Basaltic Glass ◽  
Fuller’S Earth ◽  
Scanning Electron

It is generally agreed that the English mid-Jurassic and Lower Cretaceous fuller's earths were derived from volcanic ash. In the Lower Cretaceous fuller's earth of Woburn, Kerr (1932) recognized partially decomposed relics of shards in a matrix of montmorillonite, and Grim (1933, 1935) described montmorillonite pseudomorphs after glass fragments in the Bath fuller's earth of Bathonian age. Jeans et al. (1977) published twenty-two SEM pictures of pyroclasts, including sanidine, sphene, trachytic pumice, and a basaltic glass fragment. Photomicrographs of the Lower Cretaceous fuller's earth show shard relicts ranging in length from 0·8-1·26 mm (median ∼1·12 mm) and in thickness from 5-15µm (Jeans et al., 1977, fig. 14a). However, much remains obscure about the shape, size and mode of packing of the argillized vitric particles which make up the bulk of fuller's earths. This note describes the texture of an English fuller's earth which was freeze-fractured (Tessier, 1978), prior to examination with a scanning electron microscope.

Foraminiferal inventory and lithologic description of the Lower Cretaceous (Albian) Hulcross Shale, Monkman area, northeastern British Columbia

1988 ◽  
Vol 25 (5) ◽  
pp. 793-798 ◽  
Author(s):  
C. R. Stelck ◽  
Dale Leckie
Keyword(s):  
British Columbia ◽  
Water Column ◽  
Lower Cretaceous ◽  
Volcanic Ash ◽  
Peace River ◽  
Low Degree ◽  
Bottom Waters

Correlation of an arenaceous microfauna of 41 species (44 subspecies) from the Hulcross Formation of the Monkman Pass area with that found in the Hulcross Shale on the Peace River has a further corroboration in matching spectra of volcanic ash beds at both localities. The Monkman Pass equivalents of both the basalmost portion and the upper part of the Hulcross beds on the Peace River are in sandy to continental facies. Diatoms are plentiful in the Monkman Pass section in the shaly facies.The foraminiferal genera include Bathysiphon, Thuramminoides, Psammosphaera, Hippocrepina, Saccammina, Reophax, Glomospira, Ammodiscus, Psamminopelta, Haplophragmoides, Ammobaculites, Trochammina, Textulariopsis, Pseudobolivina, Verneuilinoides, Uvigerinammina, Gaudryina, Eggerella, and Dorothia. Only Thuramminoides, Haplophragmoides, and Trochammina occur in abundance, indicating water of depth around 100 m at time of deposition and of salinity close to that of normal seawater. The low degree of bioturbation and the presence of Chondrites in the lower Hulcross suggest that poorly oxygenated bottom waters prevailed. Upwards, the diversity and abundance of bioturbation increase, indicating higher oxygenation contents caused by better circulation. As such, the Hulcross basin had a stratified water column.

Detrital muscovite geochronology and the Cretaceous tectonics of the inner Scotian Shelf, southeastern Canada 1This article is one of a series of papers published in this CJES Special Issue on the theme of Mesozoic–Cenozoic geology of the Scotian Basin. 2Geological Survey of Canada Contribution 20120142.

2012 ◽  
Vol 49 (12) ◽  
pp. 1558-1566 ◽  
Author(s):  
Peter H. Reynolds ◽  
Georgia Pe-Piper ◽  
David J.W. Piper
Keyword(s):  
Nova Scotia ◽  
Lower Cretaceous ◽  
Special Issue ◽  
Scotian Shelf ◽  
Single Grain ◽  
Meguma Terrane ◽  
Maritimes Basin ◽  
Uplift And Erosion

Geochronology of detrital muscovite from the Lower Cretaceous of the central Scotian Basin has shown predominant supply of Meguma terrane detritus, including muscovite with Alleghanian (mid-Carboniferous to Permian) ages from the inner Scotian Shelf. In this study, 87 detrital muscovite grains from five wells in the eastern Scotian Basin, representing depositional ages from Tithonian to Early Albian, were dated by single-grain 40Ar/39Ar techniques. Previous work shows that the provenance of this sediment was different from wells in the central Scotian Basin. Compared with the central Scotian Basin, the muscovite age populations from the eastern Scotian Basin have more (20% versus 7%) pre-Devonian ages, derived from inboard terranes of the Appalachians. In both the central and eastern Scotian Basin, most old grains are found in the Tithonian and the Aptian–Albian, with fewer in the Valanginian and almost none in the Kimmeridgian and the Hauterivian–Barremian. These data suggest rapid unroofing of the Meguma terrane in the Kimmeridgian and Hauterivian–Barremian and greater supply of sediment from Newfoundland to the eastern Scotian Basin in the Tithonian and Aptian–Albian. Compared with the central Scotian Basin, which has most ages in the range 340–300 Ma, the muscovite age populations from the eastern Scotian Basin have a higher proportion of 420–340 Ma and in particular 300–260 Ma ages. Such late Alleghanian overprinting of argon ages is very rare on land in Nova Scotia, but in the Maritimes Basin, this was the time of uplift and erosion of strata.

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