The pattern of Neoglacial glacier variations in the Okstindan region of northern Norway during the last three millennia

BOREAS Griffey, N. J. & Worsley, P. 1978 03 01: The pattern of Neoglacial glacier variations in the Okstindan region of northern Norway during the last three millennia (Okstindan Research Project Report 26). Boreas, Vol. 7, pp. 1–17. Oslo. ISSN 0300–9483.
Historical, lichenometrical and stratigraphical evidence is combined to establish a provisional history of Neoglacial glacier variation in a mountainous environment approx. 66^oN. Attention is focussed on end moraine chronology. At five sites, derived organic materials have been located within end moraines and at two others in situ palaeosols occur buried beneath distal slopes. Organic rich samples from all the sites have been radiocarbon dated and the results permit the recognition of three major glacier expansion episodes, each of which contributes to the diachronous nature of the Okstindan outer Neoglacial limit. A widespread 'Little Ice Age' event with a maximum extent of probable eighteenth century age is confirmed. Limited areas of older moraine ridges peripheral to the 'Little Ice Age' maximal limit appear to date from about 3000-2500 ¹⁴C years B.P. and a younger period tentatively dated as about 1250-1000 ¹⁴C years B. P. which agrees with recent data from Engabreen in northwest Svartisen. No evidence for any extensive glacial activity after the inlandice wastage approx. 9000 ¹⁴C years B. P. and prior to 3000 ¹⁴C years B.P. was forthcoming.     

Context of relict Wisconsinan glacial ice at Angus Lake, SW Banks Island, western Canadian Arctic and stratigraphic implications

Massive ice incorporating till beds and scattered erratic clasts exposed in a bimodal thaw slide displayed an association with the surrounding fluvioglacial and flow-till facies indicative of a consanguineous relationship. The massive ice cores a low ridge interpreted as a recessional moraine feature paralleling the Last Glacial Maximum advance limit. Both ice and sand wedges penetrate the massive ice and their tops are truncated by a thaw unconformity overlain by a diamicton. In a permafrost environment, relict glacial ice can persist for many millennia, and the timing of the thaw is largely determined by the vagaries of erosional processes. The age of related kettle landforms can display considerable diachronism.     

Timing of the last deglaciation in Belarus

We measured ¹⁰Be concentrations in boulders collected from the Orsha and Braslav moraines, associated with the Last Glacial Maximum extent and a recessional stage of the Scandinavian Ice Sheet (SIS), respectively, providing a direct dating of the southeastern sector of the ice-sheet margin in Belarus. By combining these data with selected existing radiocarbon ages, we developed a chronology for the last deglaciation of Belarus. The northeastern part of the country remained ice free until at least 19.2±0.2 cal. kyr BP, whereas the northwestern part of the country was ice free until 22.3±1.5 cal. kyr BP. A lobate ice margin subsequently advanced to its maximum extent and deposited the Orsha Moraine. The ice margin retreated from this moraine at 17.7±2.0 ¹⁰Be kyr to a position in the northern part of the country, where it deposited the Braslav Moraine. Subsequent ice-margin retreat from that moraine at 13.1±0.5 ¹⁰Be kyr represented the final deglaciation of Belarus. Direct dating of these moraines better constrains the relation of ice-margin positions in Belarus to those in adjacent countries as well as the SIS response to climate change.     

Late-stage calcites in the Permian Capitan Formation and its equivalents, Delaware Basin margin, west Texas and New Mexico: evidence for replacement of precursor evaporites

Comparison of Upper Guadalupian fore-reef, reef and back-reef strata from outcrops in the Guadalupe Mountains with equivalent subsurface cores from the northern and eastern margins of the Delaware Basin indicates that extensive evaporite diagenesis has occurred in both areas. In both surface and subsurface sections, the original sediments were extensively dolomitized and most primary and secondary porosity was filled with anhydrite. These evaporites were emplaced by reflux of evaporitic fluids from shelf settings through solution-enlarged fractures and karstic sink holes into the underlying strata. Outcrop areas today, however, contain no preserved evaporites in reef and fore-reef sections and only partial remnants of evaporites are retained in back-reef settings. In their place, these rocks contain minor silica, very large volumes of coarse sparry calcite and some secondary porosity. The replacement minerals locally form pseudomorphs of their evaporite precursors and, less commonly, contain solid anhydrite inclusions. Some silicification, dissolution of anhydrite and conversion of anhydrite to gypsum have occurred in these strata where they are still buried at depths in excess of 1 km; however, no calcite replacements were noted from any subsurface core samples. Subsurface alteration has also led to the widespread, late-stage development of large- and small-scale dissolution breccias. The restriction of calcite cements to very near-surface sections, petrographic evidence that the calcites post-date hydrocarbon emplacement, and the highly variable but generally ‘light’carbon and oxygen isotopic signatures of the spars all indicate that calcite precipitation is a very late diagenetic (telogenetic) phenomenon. Evaporite dissolution and calcitization reactions have only taken place where Permian strata were flushed with meteoric fluids as a consequence of Tertiary uplift, tilting and breaching of regional hydrological seals. A typical sequence of alteration involves initial corrosion of anhydrite, one or more stages of hydration/dehydration during conversion to gypsum, dissolution of gypsum and precipitation of sparry calcite. Such evaporite dissolution and replacement processes are probably continuing today in near-outcrop as well as deeper settings. This study emphasizes the potential importance of telogenetic processes in evaporite diagenesis and in the precipitation of carbonate cements. The extensive mineralogical and petrophysical transformations which these strata have undergone during their uplift indicates that considerable caution must be exercised in using surface exposures to interpret subsurface reservoir parameters in evaporitic carbonate rocks.     

The Ethics of Place and Environmental Change: Some Examples from the South Pacific

This paper concerns place and ‘placelessness’, and suggests links between those two and types of environmental ethic. An historical analysis of place based ethics and environmental degradation draws on examples from the Pacific basin. Finally, relationships between environmental ethics and traditional patterns of resource exploitation are proposed for several island societies.     

Recent status of bowhead whales, Balaena mysticetus, in the wintering grounds off West Greenland

Bowhead whales, Balaena mysticetus, belonging to the Davis Strait/Baffin Bay stock, have historically in Baffin Bay and Davis Strait, including waters along the west coast of Greenland in and near the entrance of Disko Bay. Aerial surveys of the Disko Bay region during late winter (1981, 1982, 1990,1991, 1993 and 1994) showed that it was still visited regularly by a few tens of whales. Commercial whaling on bowheads in Baffin Bay and Davis Strait ended in about 1915, but occasional killing continued until as recently as the 1970s. The low numbers of bowheads observed off West Greenland in recent years are consistent with the results of surveys of the summering grounds in the eastern Canadian Arctic, indicating that any recovery has been exceedingly slow. The only conclusion supported by the data is that the current stock size is a small fraction of what it was prior to commercial whaling.     

Early Holocene drowned lagoonal deposits from the Kattegat, southern Scandinavia

Shallow seismic profiling indicated the presence of a drowned lagoon-barrier system formed during the transgression of the southern Kattegat, and investigations of core material have confirmed this. Studies of plant and animal macrofossils show that the lagoonal sediments contain a mixture of marine, brackish, lacustrine, telmatic and terrestrial taxa, and analyses of foraminifers indicate brackish-water conditions. Low oxygen isotope values obtained on shells of marine molluscs also point to lowered salinity. The lagoonal sediments are situated at depths between 24 and 35 m below present sea level. They are dated to between c. 10.5 cal. ka BP and c. 9.5 cal. ka BP, and reflect a period characterized by a moderate relative sea level rise. The lagoonal sediments are underlain by lateglacial glaciomarine clay and silt, which are separated from the Holocene deposits by an unconformity. The earliest Holocene sediments consist of littoral sand with gravel, stones and shells; these sediments were formed during the transgression of the area before the barrier island-lagoon system was developed. The lagoonal sediments are overlain by mud, which contains animal remains that indicate increasing water depths.     

Magmatic Evolution and Ascent History of the Aries Micaceous Kimberlite, Central Kimberley Basin, Western Australia: Evidence from Zoned Phlogopite Phenocrysts, and UV Laser 40Ar/39Ar Analysis of Phlogopite-Biotite

The Neoproterozoic Aries kimberlite was emplaced in the centralKimberley Basin, Western Australia, as a N–NNE-trendingseries of three diatremes infilled by lithic-rich kimberlitebreccias. The breccias are intruded by hypabyssal macrocrysticphlogopite kimberlite dykes that exhibit differentiation toa minor, high-Na–Si, olivine–phlogopite–richteritekimberlite, and late-stage macrocrystic serpentine–diopsideultramafic dykes. Mineralogical and geochemical evidence suggeststhat the high-Na–Si, olivine–phlogopite–richteritekimberlite was derived from the macrocrystic phlogopite kimberliteas a residual liquid following extended phlogopite crystallizationand the assimilation of country rock sandstone, and that themacrocrystic serpentine–diopside ultramafic dykes formedas mafic cumulates from a macrocrystic phlogopite kimberlite.Chemical zonation of phlogopite–biotite phenocrysts indicatesa complex magmatic history for the Aries kimberlite, with theearly inheritance of a range of high-Ti phlogopite–biotitexenocrysts from metasomatized mantle lithologies, followed bythe crystallization of a population of high-Cr phlogopite phenocrystswithin the spinel facies lithospheric mantle. A further oneto two phlogopite–biotite overgrowth rims of distinctcomposition formed on the phlogopite phenocrysts at higher levelsduring ascent to the surface. Ultra-violet laser ⁴⁰Ar/³⁹Ar datingof mica grain rims yielded a kimberlite eruption age of 815·4± 4·3 Ma (95% confidence). ⁴⁰Ar/³⁹Ar laser profilingof one high-Ti phlogopite-biotite macrocryst revealed a radiogenic⁴⁰Ar diffusive loss profile, from which a kimberlite magma ascentduration from the spinel facies lithospheric mantle was estimated(assuming an average kimberlite magma temperature of 1000°C),yielding a value of 0·23–2·32 days for thenorth extension lobe of the Aries kimberlite. KEY WORDS: ⁴⁰Ar/³⁹Ar; diamond; kimberlite; mantle metasomatism; phlogopite–biotite