scholarly journals Revised stratigraphy and sedimentology of the Paleoproterozoic Dubawnt Supergroup at the northern margin of Baker Lake Basin, Nunavut

2000 ◽  
Author(s):  
R H Rainbird ◽  
T Hadlari
Keyword(s):  
Lake Basin ◽  
Northern Margin ◽  
Baker Lake

scholarly journals Uranium geology in the central Baker Lake Basin, District of Keewatin

1979 ◽  
Author(s):  
A R Miller
Keyword(s):  
Lake Basin ◽  
Baker Lake

Alluvial, eolian and lacustrine sedimentology of a Paleoproterozoic half-graben, Baker Lake Basin, Nunavut, Canada

2006 ◽  
Vol 190 (1-4) ◽  
pp. 47-70 ◽  
Author(s):  
Thomas Hadlari ◽  
Robert H. Rainbird ◽  
J. Allan Donaldson
Keyword(s):  
Lake Basin ◽  
Half Graben ◽  
Baker Lake ◽  
Lacustrine Sedimentology

Sm–Nd fluorite dating of Proterozoic low-sulfidation epithermal Au–Ag deposits and U–Pb zircon dating of host rocks at Mallery Lake, Nunavut, Canada

2003 ◽  
Vol 40 (12) ◽  
pp. 1789-1804 ◽  
Author(s):  
William A Turner ◽  
Larry M Heaman ◽  
Robert A Creaser
Keyword(s):  
Linear Trend ◽  
Lake Basin ◽  
Age Difference ◽  
Lake Area ◽  
Epithermal Deposits ◽  
Intimate Association ◽  
Baker Lake ◽  
End Members ◽  
Host Rocks ◽  
Low Sulfidation

The Mallery Lake area contains precious metal-bearing quartz–chalcedony stockworks that are pristine examples of ancient low-sulfidation epithermal deposits. Fluorite extracted from these epithermal deposits define a Sm–Nd errorchron age of 1434 ± 23 Ma mean square of weighted deviates (MSWD) = 4.8. This date is interpreted to have age significance because (1) a simple linear trend does not exist between the 143Nd/144Nd ratios of the fluorite with respect to their 1/Nd concentrations as would be expected for mixing of two geochemical end members; (2) microthermometric studies indicate that the fluorite analysed in this study has an intimate association with a single high-salinity, calcic brinal fluid; and (3) the age determined from seven fluorite samples extracted from a single outcrop location yielded an identical age result (1434 ± 60 Ma; MSWD = 5.5) compared to the fluorite composite. Rhyodacites of the Pitz Formation and syenites from the Nueltin suite (intrusive equivalent to the rhyodacites) are the youngest volcanic–plutonic rocks that are observed in outcrop in the Mallery Lake area, and they were dated by U–Pb zircon analysis at 1760 ± 43 Ma and 1755.4 ± 1.8 Ma, respectively. The ~320 million year age difference between the epithermal deposits and the hosting rhyodacitic flows suggests that the epithermal stockworks may have formed by a regional hydrothermal event unrelated to this earlier Paleoproterozoic volcanic activity. Uranium deposits in the Thelon and Athabasca basins, to the northwest and south of the Baker Lake Basin, were determined to have similar ore emplacement ages with no evident heat source.

scholarly journals A new cycle of jökulhlaups at Russell Glacier, Kangerlussuaq, West Greenland

2011 ◽  
Vol 57 (202) ◽  
pp. 238-246 ◽  
Author(s):  
Andrew J. Russell ◽  
Jonathan L. Carrivick ◽  
Thomas Ingeman-Nielsen ◽  
Jacob C. Yde ◽  
Meredith Williams
Keyword(s):  
Peak Discharge ◽  
Accurate Information ◽  
Lake Basin ◽  
Field Surveys ◽  
West Greenland ◽  
Northern Margin ◽  
Lake Volume ◽  
Significant Attenuation ◽  
Dammed Lake ◽  
Lake Drainage

AbstractJökulhlaups in 2007 and 2008 from an ice-dammed lake at the northern margin of Russell Glacier, West Greenland, marked the onset of a renewed jökulhlaup cycle after 20 years of stability. We present a record of successive ice-dammed lake drainage events and associated ice-margin dynamics spanning ∼25 years. Robust calculations of lake volumes and peak discharges are made, based on intensive field surveys and utilizing high-spatial-resolution orthophotographs of the lake basin and ice margin. These data enable identification of controls on the behaviour of the ice-dammed lake and provide the first field-based examination of controls on jökulhlaup magnitude and frequency for this system. We find that Russell Glacier jökulhlaups have a much higher peak discharge than predicted by the Clague–Mathews relationship, which we attribute to an unusually short englacial/subglacial routeway and the presence of a thin ice dam that permits incomplete sealing of jökulhlaup conduits between lake drainage events. Additionally, we demonstrate that the passage of jökulhlaups through an interlinked system of proglacial bedrock basins produces significant attenuation of peak discharge downstream. We highlight that improved understanding of jökulhlaup dynamics requires accurate information about ice-dammed lake volume and ice-proximal jökulhlaup discharge.

The last 7500 cal yr B.P. of westerly rainfall in Central Chile inferred from a high-resolution pollen record from Laguna Aculeo (34°S)

2003 ◽  
Vol 60 (3) ◽  
pp. 284-293 ◽  
Author(s):  
Rodrigo Villa-Martínez ◽  
Carolina Villagrán ◽  
Bettina Jenny
Keyword(s):  
Southern Oscillation ◽  
Lake Basin ◽  
Herbaceous Plant ◽  
Pollen Record ◽  
Precipitation Regime ◽  
Abrupt Decrease ◽  
Central Chile ◽  
Northern Margin ◽  
Pollen Accumulation Rates ◽  
Amplitude Fluctuations

AbstractWe report multiproxy analyses of a sediment core obtained from Laguna Aculeo that spans the past 7500 years. Laguna Aculeo (33°50′S, 70°55′W) is one of the few natural inland lakes located in the Mediterranean zone of Central Chile, near the northern margin of the influence of the southern westerlies. The record shows elevated pollen counts of halophytes and seasonally drying of the lake basin prior to 5700 cal yr B.P., indicating severe aridity and warmer-than-present conditions. This was followed by the establishment of a fresh-water lake, along with an increase in arboreal and herbaceous plant diversity between 5700 and 3200 cal yr B.P. An intensification of this trend started at 3200 cal yr B.P., along with the abrupt decrease of halophytes until 100 cal yr B.P. Within this humid period, pollen accumulation rates show large-amplitude fluctuations, coeval with numerous turbidite layers, suggesting a highly variable and torrential rainfall pattern. This intense and variable precipitation regime is probably associated with the El Niño–Southern Oscillation (ENSO) phenomenon. We suggest that the modern Mediterranean climate of Central Chile was established at ∼3200 cal yr B.P. Paleovegetation and paleolimnological changes starting at 100 cal yr B.P. correlate with documented human activity surrounding the lake.

Evolution Features and Controlling Factors of Depositional Systems of Paleogene-Neogene in Maxian Area, the Northern Margin of Qaidam Basin

2011 ◽  
Vol 71-78 ◽  
pp. 3224-3228
Author(s):  
Rui Zhang ◽  
You Liang Ji
Keyword(s):  
Qaidam Basin ◽  
Low Frequency ◽  
Sedimentary Facies ◽  
River Delta ◽  
Lake Basin ◽  
Frequency Change ◽  
Braided River ◽  
Northern Margin ◽  
Core Logging ◽  
Depositional Systems

According to the comprehensive detailed analysis of data such as, drilling core, logging and outcrop section, four kinds of sedimentary facies, namely, proluvial fan, braided river, shallow water braided river delta, and oxidative lacustrine, are recognized in Paleogene-Neogene of Maxian area in the northern margin of Qaidam basin. The evolution features of the sedimentary systems were analyzed in details: at the early forming stage of the lake basin (Paleocene-Eocene), proluvial fan -braided river depositional systems were developed in the study area. At the middle flourishing stage of the lake basin (Oligocene-Middle Pliocene), the main sedimentary systems were braided river-shallow braided river delta-oxidative lacustrine. Then the study area was dominated by proluvial fan-braided river-oxidative lacustrine depositional systems in the regression stage of the lake basin (Late Pliocene). The range of the depositional systems in low frequency sedimentary cycle was controlled by the multi-cycle tectonic uplifts and squeezing action of mountains around the study area. Paleoclimate and ancient landform controlled the high frequency change of the lacustrine level and supplied an advantage for the development of shallow braided river delta and oxidative lacustrine facies.

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