Subglacial drilling at Black Rapids Glacier, Alaska, U.S.A.: drilling method and sample descriptions

1999 ◽  
Vol 45 (151) ◽  
pp. 495-505 ◽  
Author(s):  
M. Truffer ◽  
R.J. Motyka ◽  
W.D. Harrison ◽  
K. A. Echelmeyer ◽  
B. Fisk ◽  
...  
Keyword(s):  
Pore Water ◽  
Alaska Range ◽  
Denali Fault ◽  
The North ◽  
Basal Ice ◽  
Secular Variations ◽  
Drilling Method ◽  
The Matrix ◽  
Black Rapids Glacier ◽  
Tectonic Boundary

AbstractWe employed a commercial wireline drill rig to investigate the subglacial conditions of Black Rapids Glacier, a well-studied surge-type glacier in the central Alaska Range. The four main goals were: to assess the capabilities of the commercial drilling industry for sampling subglacial material, to investigate the basal morphology, to determine the subglacial geology and to emplace borehole instruments. The drilling was done in an area where seasonal and secular variations in speed are large, and where seismic studies suggested the presence of a till layer. Four holes were drilled at three locations to a maximum depth of 620 m. Three holes yielded samples of basal ice and till, although recovery of the latter was generally poor. Bedrock was sampled in one or possibly two of the holes. In the area sampled, t he glacier is underlain by a till layer some 4–7 m thick, confirming the seismic interpretation. It consists of a sandy matrix at least 20–30% of which comprises larger clasts. Limited samples of the matrix indicate that near the top of the till the porosity is 40%, and t hat some of the pore water is frozen. Geologic studies suggest that the drilling area lies to the north of the Denali Fault, a major tectonic boundary followed by the glacier, and that most of the till is locally derived with transport distances of <2 km.

scholarly journals Subglacial drilling at Black Rapids Glacier, Alaska, U.S.A.: drilling method and sample descriptions

1999 ◽  
Vol 45 (151) ◽  
pp. 495-505 ◽  
Author(s):  
M. Truffer ◽  
R.J. Motyka ◽  
W.D. Harrison ◽  
K. A. Echelmeyer ◽  
B. Fisk ◽  
...  
Keyword(s):  
Pore Water ◽  
Alaska Range ◽  
Denali Fault ◽  
The North ◽  
Basal Ice ◽  
Secular Variations ◽  
Drilling Method ◽  
The Matrix ◽  
Black Rapids Glacier ◽  
Tectonic Boundary

Abstract We employed a commercial wireline drill rig to investigate the subglacial conditions of Black Rapids Glacier, a well-studied surge-type glacier in the central Alaska Range. The four main goals were: to assess the capabilities of the commercial drilling industry for sampling subglacial material, to investigate the basal morphology, to determine the subglacial geology and to emplace borehole instruments. The drilling was done in an area where seasonal and secular variations in speed are large, and where seismic studies suggested the presence of a till layer. Four holes were drilled at three locations to a maximum depth of 620 m. Three holes yielded samples of basal ice and till, although recovery of the latter was generally poor. Bedrock was sampled in one or possibly two of the holes. In the area sampled, t he glacier is underlain by a till layer some 4–7 m thick, confirming the seismic interpretation. It consists of a sandy matrix at least 20–30% of which comprises larger clasts. Limited samples of the matrix indicate that near the top of the till the porosity is 40%, and t hat some of the pore water is frozen. Geologic studies suggest that the drilling area lies to the north of the Denali Fault, a major tectonic boundary followed by the glacier, and that most of the till is locally derived with transport distances of &lt;2 km.

X-Ray and Optical Data for a Rare Earth–Poor Eudialyte from the North–Central Alaska Range

1990 ◽  
Vol 5 (2) ◽  
pp. 89-92 ◽  
Author(s):  
Neil E. Johnson ◽  
Mickey E. Gunter ◽  
Diana N. Solie ◽  
Charles R. Knowles
Keyword(s):  
Rare Earth ◽  
Powder Diffraction ◽  
Weight Percent ◽  
Optical Data ◽  
Alaska Range ◽  
North Central ◽  
X Ray ◽  
The North ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

AbstractPowder X-ray and optical data have been recorded for a sample of exceptionally rare earth-poor eudialyte (Na12(Ca, REE)6(Fe2+,Mn,Mg)3Zr3(Zr,Nb)x[Si9O27−y(OH)y]2[Si3O9]2(C1,F)z, with x = 0. 1–0.9, y = 1–3 and z = 0.7–1.4) from a pegmatitic vein associated with the peralkaline Windy Fork granite in the north–central Alaska range. The eudialyte is uniaxial positive with ω= 1.6062(2), ε= 1.6138 (3) and microprobe analyses indicate that the sum of REE + Yis less than 0.1 weight percent. Refined unit cell dimensions are: a = 14.2572(4), c = 30.1338(27), Dx= 2.67, F30= 128 (0.006, 42), M20= 76. An indexed powder diffraction pattern is given.

V.—Mr. Harkee and Mr. Debley on the Scandinavian Ice-Sheet

1894 ◽  
Vol 1 (11) ◽  
pp. 496-499
Author(s):  
Henry H. Howorth
Keyword(s):  
Ice Sheet ◽  
Good Effect ◽  
The North ◽  
The Matrix ◽  
Glacier Ice ◽  
Inductive Methods ◽  
The North Sea ◽  
Antarctic Continent ◽  
The Alps ◽  
The Difference

Mr. Deeley tells your readers that he has recently been to the summit of Mont Blanc, and has been studying the difference between névé and glacier ice. This is interesting; but we thought that a great many people had done the same thing during the last hundred years, and we thought that one of them, Forbes, had studied the famous Mountain and the phenomenoninquestion to good effect, not in a casual visit to the Alps, but in the course of many years of patient labour. Among other things we also thought he had shown that in a viscous body like ice, the slope of the upper surface necessary to make it begin to move is the same as the slope which, would be required to induce motion in the ice if its bed were inclined at an angle. He further collected considerable evidence to show what the least angle is upon which ice will begin to move. This is the slope, the least slope, available. It is nothing less than astounding to me that anyone should venture to postulate a Scand in avian ice-sheet in the North Sea until he had considered this necessary factor, and how it would operate.The Scand in avian ice-sheet was, I believe, the invention of Croll, who, sittinginhis arm-chair and endowed with a brilliant imagination, imposed upon sober science this extraordinary postulate. He did not dream of testing it by an examination of the coasts of Norway, or even of Britain, but put it forward apparently as a magnificent deduction. All deductions untested by experiment are dangerous. Thus it came about that the great monster which is said to have come from Norway, goodness knows by what mechanical process, speedily dissolved away on the application of inductive methods. Of course it still maintained its hold upon that section, of geologists who dogmatiseinprint a great deal about the Glacial period before they have ever seen a glacier at work at all; but I am speaking of those who have studied the problem inductively. First Mr. James Geikie, a disciple of Croll, was obliged to confess that this ice-sheet, which is actually said to have advanced as far as the hundred-fathom line in the Atlantic, and there presented a cliff of ice like the Antarctic continent, never can have reached the Faroes, which had an ice-sheet of their own. Next Messrs. Peach and Home were constrained to admit that no traces of it of any kind occur in the Orkneys, or in Eastern Scotland. They still maintained its presence in the Shetlands; however, this was upon evidence which is somewhat extraordinary. I do not mean the evidence as to the direction of the striation, which was so roughly handled by Mr. Milne-Home, but I mean the evidence they adduce that the boulders found on the islands are apparently all local ones, and that, contrary to the deposits of glaciers, they diminish in number as we recede from the matrix whence they were derived.

scholarly journals Alternating asymmetric topography of the Alaska range along the strike-slip Denali fault: Strain partitioning and lithospheric control across a terrane suture zone

Tectonics ◽  
2014 ◽  
Vol 33 (8) ◽  
pp. 1519-1533 ◽  
Author(s):  
Paul G. Fitzgerald ◽  
Sarah M. Roeske ◽  
Jeffery A. Benowitz ◽  
Steven J. Riccio ◽  
Stephanie E. Perry ◽  
...  
Keyword(s):  
Strike Slip ◽  
Suture Zone ◽  
Strain Partitioning ◽  
Alaska Range ◽  
Denali Fault

scholarly journals Supplemental Material: Secular variations of magma source compositions in the North Patagonian batholith from the Jurassic to Tertiary: Was mélange melting involved?

2021 ◽  
Author(s):  
A. Castro ◽  
et al.
Keyword(s):  
Magma Source ◽  
The North ◽  
Secular Variations

<div>Geochemical and geochronologic data.<br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div><div><br></div>

Age and Geochemical Studies of the Snyder Breccia, Coastal Labrador

1975 ◽  
Vol 12 (3) ◽  
pp. 361-370 ◽  
Author(s):  
Jackson M. Barton Jr. ◽  
Erika S. Barton
Keyword(s):  
Trace Element ◽  
North Atlantic ◽  
Layered Intrusion ◽  
Basement Complex ◽  
Fine Grained ◽  
The North ◽  
Isotopic Analyses ◽  
The Matrix ◽  
The North Atlantic ◽  
Geochemical Studies

The Snyder breccia is composed of angular to subrounded xenoliths of migmatites and amphibolites in a very fine grained matrix. It is apparently intrusive into the metasediments of the Snyder Group exposed at Snyder Bay, Labrador. The Snyder Group unconformably overlies a migmatitic and amphibolitic basement complex and is intruded by the Kiglapait layered intrusion. K–Ar ages indicate that the basement complex is Archean in age (> 2600 m.y. old) and that the Kiglapait layered intrusion was emplaced prior to 1280 m.y. ago. Major and trace element analyses of the matrix of the Snyder breccia indicate that while it was originally of tonalitic composition, later it locally underwent alteration characterized by loss of sodium and strontium and gain of potassium, rubidium and barium. Rb–Sr isotopic analyses show that this alteration occurred about 1842 m.y. ago, most probably contemporaneously with emplacement of the breccia. The Snyder Group thus was deposited sometime between 2600 and 1842 m.y. ago and may be correlative with other Aphebian successions preserved on the North Atlantic Archean craton.

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