Rb–Sr and U–Pb geochronology and setting of the Buffalo Head Hills kimberlite field, northern AlbertaThis article is one of a selection of papers published in this Special Issue on the theme Geology of northeastern British Columbia and northwestern Alberta: diamonds, shallow gas, gravel, and glaciers.

2008 ◽  
Vol 45 (5) ◽  
pp. 513-529 ◽  
Author(s):  
D. Roy Eccles ◽  
Robert A. Creaser ◽  
Larry M. Heaman ◽  
Jeff Ward

New Rb–Sr phlogopite and U–Pb perovskite age determinations for 12 of 38 known ultramafic bodies in the Buffalo Head Hills area of north-central Alberta show that kimberlitic magmatism occurred in at least two separate episodes during Late Cretaceous and Paleocene time. Nine kimberlites yield Coniacian to Campanian ages of between 88 ± 5 Ma (U–Pb perovskite, K5A) and 81.2 ± 2.3 Ma (Rb–Sr phlogopite, K252). A Danian U–Pb perovskite isochron age of 63.5 ± 0.7 Ma was obtained for the BM2 kimberlite, and Selandian Rb–Sr ages of 59.6 ± 2.8 and 60.3 ± 0.8 Ma were determined for the K1A and K19 bodies, respectively. These specific periods of magmatism correspond to characteristic intra-field features such as kimberlite spatial distribution, diamond content, rock classification, and mechanisms of emplacement. The ∼88–81 Ma group generally occurs in the northwestern part of the field and defines the diamond window for the Buffalo Head Hills kimberlite field. This volcanism is contemporaneous with sedimentary host rock deposition, which has important implications for the size and morphological complexity of the kimberlite bodies. The ∼64 Ma BM2 body represents the only known occurrence of hypabyssal-facies kimberlite in this field and is similar in terms of source composition to the ∼88–81 Ma kimberlites, but is not diamond bearing. The ∼60 Ma group occurs in the southwestern part of the field, is derived from a weakly diamondiferous – barren hybrid ultramafic source and features bodies that are eroded to present-day stratigraphic levels.

2008 ◽  
Vol 45 (5) ◽  
pp. 611-618 ◽  
Author(s):  
Richard J. Hebda ◽  
James A. Burns ◽  
Marten Geertsema ◽  
A. J. Timothy Jull

Dissected colluvial sediments on a Peace River terrace at Bear Flat, northeast British Columbia enclosed a late Pleistocene micromammalian faunule. The fossil remains, including a few loosely articulated skulls and mandibles, were dominated by taiga voles ( Microtus xanthognathus ). The Bear Flat site constitutes the second fossil occurrence in the region of this elusive species, which is unknown in British Columbia in historic times. The late Pleistocene age, determined by accelerator mass spectrometry directly on taiga vole bone collagen, is consistent with the ages of widespread taiga vole records peripheral to the Laurentide ice sheet in western, mid-western, and eastern North America. The presence of allo-chronous remains within a comprehensively dated sedimentary sequence provides a cautionary note about straightforward acceptance of relative stratigraphic dating.


2008 ◽  
Vol 45 (5) ◽  
pp. 577-591 ◽  
Author(s):  
Adrian S. Hickin ◽  
Ben Kerr ◽  
Derek G. Turner ◽  
Tom E. Barchyn

The relatively subdued topography of British Columbia’s northern interior plains does not reflect the irregular, buried bedrock surface. Many areas have been deeply incised by preglacial rivers that have subsequently filled with a succession of Quaternary sediments. In this study, oil and gas petrophysical logs, drill chip samples, water well logs, and surficial and bedrock outcrop maps were used to model the bedrock topography of the Fontas map sheet (NTS 94I). The modelled data produced several depressions that are interpreted to be paleovalleys incised into the soft Cretaceous shale of the Fort St. John Group. Understanding the geometry, thickness, and stratigraphy of the drift has considerable safety and resource management implications as artesian aquifers and natural gas were encountered in the drift during oil and gas well drilling. Four major paleovalleys are suggested. The most dominant paleovalley (Kotcho–Hoffard Paleovalley) is located south of the Etsho Plateau and trends west-southwest across the map area. A second depression occurs within the loop of the Hay River and may be a tributary of the Kotcho–Hoffard Paleovalley that links with the Rainbow Paleovalley in Alberta. A third paleovalley is mapped south of the Sahtaneh River (Kyklo Creek Paleovalley) and is either a tributary to, or crosscuts the Kotcho–Hoffard Paleovalley. The Niteal Creek Paleovalley is located between the Fontas and Sikanni Chief rivers. Its geometry is speculative as there are sparse data, but it may be a tributary of the Kotcho–Hoffard Paleovalley.


2011 ◽  
Vol 4 (2) ◽  
pp. 161-168
Author(s):  
Stela Manova

This special issue includes a selection of papers presented at the 2nd Vienna Workshop on Affix Order held in Vienna, Austria on June 4–5, 2009. The workshop was in honor of Wolfgang U. Dressler on the occasion of his 70th birthday. However, this special issue differs from the classical Festschrift dedicated to a renowned scholar and is ‘more special’ in two respects at least: 1) not all authors are Dressler's friends and colleagues, some of them are only indirectly related to him, through his students; and 2) since the papers were presented at a topic-oriented workshop, they are thematically uniform. In other words, this special issue is a kind of scientific genealogy in terms of affix ordering. Thus, the title Affixes and bases should be understood in two ways: literally – affixes and bases as linguistic notions, and metaphorically – affixes and bases as linguists related directly and indirectly to a prominent base: Wolfgang U. Dressler.


2003 ◽  
Vol 17 (1) ◽  
pp. 9-14 ◽  
Author(s):  
E. H. Robson

This special issue of Industry and Higher Education is devoted to a selection of papers and reports from tti2002, an international conference on technology transfer and innovation held at the International Convention Centre, Birmingham, UK in July 2002. In this introductory paper, the author provides the context of the conference, summarizes the presentations given by invited speakers and offers personal reflections on the event.


2021 ◽  
Vol 22 (14) ◽  
pp. 7560
Author(s):  
Julie A. Tucker ◽  
Mathew P. Martin

This special issue on Advances in Kinase Drug Discovery provides a selection of research articles and topical reviews covering all aspects of drug discovery targeting the phosphotransferase enzyme family [...]


Atmosphere ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 105
Author(s):  
Haider A. Khwaja

The five papers included in this Special Issue represent a diverse selection of contributions [...]


2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Elisabeth Gibert-Sotelo ◽  
Isabel Pujol Payet

Abstract The interest in morphology and its interaction with the other grammatical components has increased in the last twenty years, with new approaches coming into stage so as to get more accurate analyses of the processes involved in morphological construal. This special issue is a valuable contribution to this field of study. It gathers a selection of five papers from the Morphology and Syntax workshop (University of Girona, July 2017) which, on the basis of Romance and Latin phenomena, discuss word structure and its decomposition into hierarchies of features. Even though the papers share a compositional view of lexical items, they adopt different formal theoretical approaches to the lexicon-syntax interface, thus showing the benefit of bearing in mind the possibilities that each framework provides. This introductory paper serves as a guide for the readers of this special collection and offers an overview of the topics dealt in each contribution.


2008 ◽  
Vol 45 (2) ◽  
pp. 231-241 ◽  
Author(s):  
Jan Ove R. Ebbestad ◽  
Christopher A. Stott

Shell repairs resulting from presumed failed predation are documented in gastropods from the Late Ordovician (Cincinnatian; Richmondian) mid-to-upper Kagawong Submember of the Georgian Bay Formation on Manitoulin Island, Ontario, Canada. The bryozoan–mollusc biota and associated sediments generally suggest nearshore, shallow (<10 m), low energy (lagoonal), and perhaps mesotrophic to eutrophic conditions. Two sample sets from this unit have been studied for shell repair. One of the more commonly applied estimates of shell repair frequencies involves division of the number of individuals with at least one scar by the total number of individuals in the sample (the Individuals with scars method). Using this calculation, 207 specimens of Lophospira trilineata Ulrich and Scofield yielded a shell repair frequency of 4.8%; in 28 specimens of Trochonemella sp. the shell repair frequency was 35.7%. Repairs in Trochonemella occur primarily in the larger size class, suggesting that a size refuge was achieved by this species. Low repair frequencies in L. trilineata suggest predation with a higher success rate or fewer encounters. This study demonstrates that the paradigm of a standardized low level of shell repair in Ordovician and Silurian gastropods is oversimplistic and a range of frequency rates can be expected.


2006 ◽  
Vol 84 (4) ◽  
pp. 515-522 ◽  
Author(s):  
Preetinder K. Dhanoa ◽  
Alison M. Sinclair ◽  
Robert T. Mullen ◽  
Jaideep Mathur

The discovery and development of multicoloured fluorescent proteins has led to the exciting possibility of observing a remarkable array of subcellular structures and dynamics in living cells. This minireview highlights a number of the more common fluorescent protein probes in plants and is a testimonial to the fact that the plant cell has not lagged behind during the live-imaging revolution and is ready for even more in-depth exploration.


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