scholarly journals Ice core drilling on a high-elevation accumulation zone of Trambau Glacier in the Nepal Himalaya

2021 ◽  
pp. 1-7
Author(s):  
Akane Tsushima ◽  
Morihiro Miyahara ◽  
Tetsuhide Yamasaki ◽  
Nao Esashi ◽  
Yota Sato ◽  
...  
Keyword(s):  
Ice Core ◽  
High Elevation ◽  
Nepal Himalaya ◽  
Core Drilling ◽  
Drilling Operation ◽  
Core Samples ◽  
Cold Room ◽  
Drill Site ◽  
Commercial Flight ◽  
Drill System

Abstract We drilled an 81.2-m-long ice core in the accumulation area (5860 m a.s.l.) of Trambau Glacier in the Rolwaling region during October–November 2019. The drilling operation was conducted with a lightweight electro-mechanical drill system after two reconnaissance fieldworks in 2017 and 2018, during which two shallow firn cores were drilled with a hand auger. The drill system and ice core samples were transported by helicopters at a high elevation of 6000 m a.s.l. A further challenging issue was the ice core transportation between Nepal and Japan, as no regular commercial flight was available for the frozen samples. The addition of dry ice imported from India immediately prior to leaving Nepal allowed the ice core samples to be successfully transported to a cold room in Japan, and remain in a frozen state. Stratigraphic observations during the drilling operation suggest the drill site has been affected by melting and refreezing.

scholarly journals The Berkner Island (Antarctica) ice-core drilling project

2007 ◽  
Vol 47 ◽  
pp. 115-124 ◽  
Author(s):  
Robert Mulvaney ◽  
Olivier Alemany ◽  
Philippe Possenti
Keyword(s):  
Melting Point ◽  
Ice Core ◽  
Ice Sheet ◽  
Austral Summer ◽  
Core Drilling ◽  
Drilling Operation ◽  
Drilling Technology ◽  
Pressure Melting ◽  
Small Team ◽  
Drilling Project

AbstractWe describe a project to retrieve a 948m deep ice core from Berkner Island, Antarctica. Using relatively lightweight logistics and a small team, the drilling operation over three austral summer seasons used electromechanical drilling technology, described in detail, from a covered shallow pit and a fluid-filled borehole. A basal temperature well below pressure-melting point meant that no drilling problems were encountered when approaching the bed and the borehole penetrated through to the base of the ice sheet, and sediment was retrieved from beneath the ice.

scholarly journals Production drilling at WAIS Divide

2014 ◽  
Vol 55 (68) ◽  
pp. 147-155 ◽  
Author(s):  
Kristina R. Slawny ◽  
Jay A. Johnson ◽  
Nicolai B. Mortensen ◽  
Christopher J. Gibson ◽  
Joshua J. Goetz ◽  
...  
Keyword(s):  
Ice Core ◽  
Ice Sheet ◽  
Austral Summer ◽  
Snow Surface ◽  
Scientific Interest ◽  
High Quality ◽  
Core Drilling ◽  
Core Samples ◽  
Drill Fluid ◽  
Drilling Operations

AbstractThe deep ice-sheet coring (DISC) drill was used for production ice-core drilling at WAIS Divide in Antarctica for six field seasons between 2007 and 2013. Continuous ice-core samples were obtained between the snow surface and 3405 m depth. During the 2012/13 austral summer, the DISC drill’s newly designed replicate ice-coring system was utilized to collect nearly 285m of additional high-quality core samples at depths of high scientific interest. Annual progress graphs are described, as well as milestones achieved over the course of the project. Drilling operations, challenges encountered, drill fluid usage, drilling results, and the drill crew’s experiences with the DISC drill and replicate coring system during production drilling are described and discussed in detail. Core-processing operations are described briefly, as well as the logistical undertaking of the DISC drill’s deployment to Antarctica.

Ultrasonic velocity experiments on ice cores to complement fabric measurements

2021 ◽  
Author(s):  
Sebastian Hellmann ◽  
Johanna Kerch ◽  
Melchior Grab ◽  
Henning Löwe ◽  
Andreas Bauder ◽  
...  
Keyword(s):  
Light Microscopy ◽  
Crystal Orientation ◽  
Ice Core ◽  
Ice Cores ◽  
Ultrasonic Waves ◽  
Thin Sections ◽  
Core Drilling ◽  
Core Samples ◽  
Ultrasonic Measurements ◽  
Polarised Light

<p>The ice crystal structure and in particular the crystal orientation fabrics (COF) provide valuable information about the deformation history of ice sheets and glaciers. Therefore, COF analysis has been among the standard measurement techniques for most deep ice core drilling projects in the last three decades. The analysis depends on carefully prepared thin sections of ice that are measured with cross-polarised light microscopy or electron backscattering and diffraction (EBSD). The preparation of thin sections is labour-intensive and therefore only a discrete number of samples along the ice core is usually analysed. Geophysical methods such as ultrasonic sounding along the ice core could be employed to complement the discrete fabric data by providing data to fill the gaps. A suitable method needs to be reasonably fast, ideally non-invasive and provides unambiguous information in combination with the established methods.</p><p>In our study, we demonstrate the feasibility of such ultrasonic experiments applied to an ice core to support the approved cross-polarised light microscopy method. Point-contact transducers transmitted ultrasonic waves into ice core samples from a temperate glacier. X-ray computer tomography measurements provide the required information to consider the effect of a two-phase medium (ice and air bubbles) in a porosity correction of the velocity. We determined the azimuthal variation of the seismic velocity. This variation is a result of seismic anisotropy due to the crystal orientation within the ice core volume. The measurements can be acquired within minutes and do not require an extensive preparation of ice samples.</p><p>In addition, the COF of adjacent ice core samples was measured with cross-polarised light spectroscopy. From this, we derived the elasticity tensor and finally calculated the associated seismic velocities for the same azimuth and inclination angle as for the ultrasonic experiments. We compare these two velocity profiles and discover a significant discrepancy in presence of large ice grains. However, with an increasing number of ice grains both methods provide similar results. Although the ultrasonic measurements reveal some ambiguities, these can be resolved when considering the information derived from the standard analysis.</p><p>We conclude that ultrasonic measurements along the ice core are suitable to support the established COF analysis for sufficiently small grains as found in polar cores. We recommend further exploration of the potential of the presented technique as it provides both the chance to obtain a continuous fabric profile and a direct link to large-scale seismic measurements in the vicinity of ice core drilling sites.</p>

scholarly journals Deep ice-core drilling performance and experience at NEEM, Greenland

2014 ◽  
Vol 55 (68) ◽  
pp. 53-64 ◽  
Author(s):  
Trevor J. Popp ◽  
Steffen B. Hansen ◽  
Simon G. Sheldon ◽  
Christian Panton
Keyword(s):  
Drilling Fluid ◽  
Ice Core ◽  
Borehole Diameter ◽  
Extended Version ◽  
Core Drilling ◽  
Drilling Operation ◽  
Design And Implementation ◽  
Drilling Performance ◽  
Drill Fluid ◽  
Drilling Operations

AbstractThe NEEM deep ice-core drilling in northwest Greenland was completed in summer 2010 after three seasons, which included establishing all drilling infrastructure. Normal drilling operations in the main borehole were declared terminated at 2537.36 m below the surface, when further penetration was stopped by a stone embedded in the ice in the path of the drill head. The design and implementation of the drilling operation strongly resembled the NGRIP drilling program. The NEEM drill was an extended version of the Hans Tausen (HT) drill, with specific modifications to optimize its use with the highly viscous Estisol-240/Coasol drill fluid used at NEEM. Modification to the drill and its performance in the new drilling fluid was largely satisfactory and successful. Throughout the drilling, special consideration was given to the way chips were transported and collected in a new chip chamber, including the consequences of drilling a larger borehole diameter than with previous drill operations that used the HT family of drills. The problems normally associated with warm ice drilling near the base of an ice sheet were largely absent at NEEM.

Byrd Station drilling 1966–69

2007 ◽  
Vol 47 ◽  
pp. 24-27 ◽  
Author(s):  
Herbert T. Ueda
Keyword(s):  
Ethylene Glycol ◽  
Ice Core ◽  
Ice Sheet ◽  
Austral Summer ◽  
Average Diameter ◽  
Diesel Oil ◽  
Core Drilling ◽  
Us Army ◽  
Drilling Operation ◽  
The Us

AbstractAfter completion of the drilling by the US Army Cold Regions Research and Engineering Laboratory (USA-CRREL) at Camp Century, Greenland, in July 1966, the operation was moved to Byrd Station, Antarctica, during the 1966/67 austral summer. The drill employed was an electromechanical cable-suspended drill that used ethylene glycol to dissolve the chips formed, producing a core with an average diameter of 114 mm. A mixture of diesel oil and trichlorethylene was used as a borehole fluid. Ice-core drilling at Byrd Station occurred from 2 to 18 February 1967 and from 12 October 1967 to 2 February 1968 when the ice sheet was penetrated at a depth of 2164 m. During the ensuing 1968/69 season the drill was lost, and ultimately the cable was severed in early 1969/70 at a depth of 1545 m. This brief report reviews the drilling operation and some of the problems encountered primarily during the 1967/68 season, with a focus on the last few days of drilling.

scholarly journals Agile Sub-Ice Geological (ASIG) Drill development and Pirrit Hills field project

2020 ◽  
pp. 1-14
Author(s):  
Tanner Kuhl ◽  
Chris Gibson ◽  
Jay Johnson ◽  
Grant Boeckmann ◽  
Elliot Moravec ◽  
...  
Keyword(s):  
System Development ◽  
Ice Core ◽  
Sediment Cores ◽  
High Quality ◽  
Core Samples ◽  
Rock Cores ◽  
The Us ◽  
Drilling System ◽  
And Performance ◽  
Drill System

Abstract A new drilling system was developed by the US Ice Drilling Program (IDP) to rapidly drill through overlying ice to collect subglacial rock cores. The Agile Sub-Ice Geological (ASIG) Drill system is capable of drilling up to 700 m of ice in a continuous manner. Intermittent ice core samples can be taken as needed. Ten-plus meters of subglacial bedrock and unconsolidated, frozen sediment cores can be drilled with wireline core retrieval. The functionality of the drill system was demonstrated in 2016–17 at the Pirrit Hills, Antarctica where 8 m of high-quality, continuous granite core was retrieved beneath 150 m of ice. The particulars of the drill system development, features and performance are discussed.

Antarctic ice core samples: culturable bacterial diversity

2013 ◽  
Vol 164 (1) ◽  
pp. 70-82 ◽  
Author(s):  
Sisinthy Shivaji ◽  
Zareena Begum ◽  
Singireesu Soma Shiva Nageswara Rao ◽  
Puram V. Vishnu Vardhan Reddy ◽  
Poorna Manasa ◽  
...  
Keyword(s):  
Bacterial Diversity ◽  
Ice Core ◽  
Core Samples

scholarly journals An automated GC-C-GC-IRMS setup to measure palaeoatmospheric δ<sup>13</sup>C-CH<sub>4</sub>, δ<sup>15</sup>N-N<sub>2</sub>O and δ<sup>18</sup>O-N<sub>2</sub>O in one ice core sample

2013 ◽  
Vol 6 (8) ◽  
pp. 2027-2041 ◽  
Author(s):  
P. Sperlich ◽  
C. Buizert ◽  
T. M. Jenk ◽  
C. J. Sapart ◽  
M. Prokopiou ◽  
...  
Keyword(s):  
Ice Core ◽  
Gold Catalyst ◽  
Isotope Ratios ◽  
Core Sample ◽  
Ion Source ◽  
Resolving Power ◽  
Published Data ◽  
Core Samples ◽  
Stable Conditions ◽  
Ch4 And N2o

Abstract. Air bubbles in ice core samples represent the only opportunity to study the mixing ratio and isotopic variability of palaeoatmospheric CH4 and N2O. The highest possible precision in isotope measurements is required to maximize the resolving power for CH4 and N2O sink and source reconstructions. We present a new setup to measure δ13C-CH4, δ15N-N2O and δ18O-N2O isotope ratios in one ice core sample and with one single IRMS instrument, with a precision of 0.09, 0.6 and 0.7‰, respectively, as determined on 0.6–1.6 nmol CH4 and 0.25–0.6 nmol N2O. The isotope ratios are referenced to the VPDB scale (δ13C-CH4), the N2-air scale (δ15N-N2O) and the VSMOW scale (δ18O-N2O). Ice core samples of 200–500 g are melted while the air is constantly extracted to minimize gas dissolution. A helium carrier gas flow transports the sample through the analytical system. We introduce a new gold catalyst to oxidize CO to CO2 in the air sample. CH4 and N2O are then separated from N2, O2, Ar and CO2 before they get pre-concentrated and separated by gas chromatography. A combustion unit is required for δ13C-CH4 analysis, which is equipped with a constant oxygen supply as well as a post-combustion trap and a post-combustion GC column (GC-C-GC-IRMS). The post-combustion trap and the second GC column in the GC-C-GC-IRMS combination prevent Kr and N2O interferences during the isotopic analysis of CH4-derived CO2. These steps increase the time for δ13C-CH4 measurements, which is used to measure δ15N-N2O and δ18O-N2O first and then δ13C-CH4. The analytical time is adjusted to ensure stable conditions in the ion source before each sample gas enters the IRMS, thereby improving the precision achieved for measurements of CH4 and N2O on the same IRMS. The precision of our measurements is comparable to or better than that of recently published systems. Our setup is calibrated by analysing multiple reference gases that were injected over bubble-free ice samples. We show that our measurements of δ13C-CH4 in ice core samples are generally in good agreement with previously published data after the latter have been corrected for krypton interferences.

scholarly journals At what depth is the Eemian layer expected to be found at NEEM?

2008 ◽  
Vol 48 ◽  
pp. 100-102 ◽  
Author(s):  
Susanne L. Buchardt ◽  
Dorthe Dahl-Jensen
Keyword(s):  
Flow Model ◽  
Accumulation Rate ◽  
Ice Core ◽  
Monte Carlo Analysis ◽  
Interglacial Period ◽  
Ice Flow ◽  
North West ◽  
Flow Parameters ◽  
Drill Site ◽  
Radio Echo Sounding

AbstractNo continuous record from Greenland of the Eemian interglacial period (130–115 ka BP) currently exists. However, a new ice-core drill site has been suggested at 77.449˚ N, 51.056˚Win north-west Greenland (North Eemian or NEEM). Radio-echo sounding images and flow model investigations indicate that an undisturbed Eemian record may be obtained at NEEM. In this work, a two-dimensional ice flow model with time-dependent accumulation rate and ice thickness is used to estimate the location of the Eemian layer at the new drill site. The model is used to simulate the ice flow along the ice ridge leading to the drill site. Unknown flow parameters are found through a Monte Carlo analysis of the flow model constrained by observed isochrones in the ice. The results indicate that the Eemian layer is approximately 60m thick and that its base is located approximately 100m above bedrock.

scholarly journals Brief Communication: New radar constraints support presence of ice older than 1.5 Ma at Little Dome C

2020 ◽  
Author(s):  
David A. Lilien ◽  
Daniel Steinhage ◽  
Drew Taylor ◽  
Frédéric Parrenin ◽  
Catherine Ritz ◽  
...  
Keyword(s):  
Flow Model ◽  
Ice Core ◽  
Austral Summer ◽  
Basal Region ◽  
Glacial Cycles ◽  
Ice Flow ◽  
Vhf Radar ◽  
New Instrument ◽  
Drill Site ◽  
Ice Core Record

Abstract. The area near Dome C, East Antarctica, is thought to be one of the most promising targets for recovering a continuous ice-core record spanning more than a million years. The European Beyond EPICA consortium has selected Little Dome C, an area ~35 km south-east of Concordia Station, to attempt to recover such a record. Here, we present the results of the final ice-penetrating radar survey used to refine the exact drill site. These data were acquired during the 2019–2020 Austral summer using a new, multi-channel high-resolution VHF radar operating in the frequency range of 170–230 MHz. This new instrument is able to detect reflections in the near-basal region, where previous surveys were unable to trace continuous horizons. The radar stratigraphy is used to transfer the timescale of the EPICA Dome C ice core (EDC) to the area of Little Dome C, using radar isochrones dating back past 600 ka. We use these data to derive the expected depth–age relationship through the ice column at the now-chosen drill site, termed BELDC. These new data indicate that the ice at BELDC is considerably older than that at EDC at the same depth, and that there is about 375 m of ice older than 600 ka at BELDC. Stratigraphy is well preserved to 2565 m, below which there is a basal unit with unknown properties. A simple ice flow model tuned to the isochrones suggests ages likely reach 1.5 Ma near 2525 m, ~40 m above the basal unit and ~240 m above the bed, with sufficient resolution (14±1 ka m−1) to resolve 41 ka glacial cycles.

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