Radar detection of subglacial sulfides

Geophysics ◽  
1991 ◽  
Vol 56 (6) ◽  
pp. 870-873 ◽  
Author(s):  
W. R. Hammond ◽  
K. F. Sprenke
Keyword(s):  
Mineral Exploration ◽  
Radar System ◽  
Perfect Conductor ◽  
Southeast Alaska ◽  
Radar Echoes ◽  
Anomalous Reflection ◽  
Reflected Power ◽  
Drill Holes ◽  
Lateral Variations ◽  
Ice Radar

Using an ice radar system, we detected anomalous reflection strengths over subglacial disseminated sulfide zones beneath the Mt. Henry Clay Glacier in southeast Alaska. The subglacial sulfide zones, which were verified by drill holes, were not detected by previous magnetic, helicopter EM, or ground‐based time‐domain EM surveys. The sulfide zones were mapped by measuring lateral variations in the strength of radar echoes from the ice‐bedrock interface at the base of the glacier. The reflected power from these disseminated occurrences ranged from 20 percent to 60 percent of the theoretically predicted reflected power from a perfect conductor at the base of the ice. The empirical results of this experiment suggest that ice radar may be a useful tool for direct mineral exploration in ice‐covered terrain.

scholarly journals A rich fauna of subterranean short-range endemic Anillini (Coleoptera, Carabidae, Trechinae) from semi-arid regions of Western Australia

ZooKeys ◽  
2021 ◽  
Vol 1044 ◽  
pp. 269-337
Author(s):  
Pier Mauro Giachino ◽  
Stefan Eberhard ◽  
Giulia Perina
Keyword(s):  
New Species ◽  
Leaf Litter ◽  
Western Australia ◽  
Short Range ◽  
Mineral Exploration ◽  
Great Majority ◽  
New Genera ◽  
Eastern Australia ◽  
Drill Holes ◽  
Semi Arid

Globally, the great majority of Anillini species are endogean, adapted to live in the interstices of soil and leaf litter, while the extremely low vagility of these minute ground beetles gives rise to numerous shortrange endemic species. Until recently the Australian Anillini fauna was known only from leaf litter in rain forests and eucalypt forests in the wetter, forested regions of eastern and south eastern Australia, as well as Lord Howe and Norfolk islands. The first hypogean Anillini in Australia (17 species in six genera) were described in 2016 from mineral exploration drill holes in iron-ore bearing rocks of the Pilbara region in Western Australia, representing the first finding of the tribe deep underground in a semi-arid climate region. A further eight new genera and 20 new species are described herein, mostly from the Pilbara region as well as the semi-arid Kimberley and Goldfields regions; all were collected in mineral exploration drill holes. The following new genera are described: Erwinanillusgen. nov., Gregorydytesgen. nov., Pilbaraphanusgen. nov., Neoillaphanusgen. nov., Kimberleytyphlusgen. nov., Gilesdytesgen. nov., Pilbaradytesgen. nov., and Bylibaraphanusgen. nov. The following new species are described: Erwinanillus baehrisp. nov.; Gracilanillus hirsutussp. nov., G. pannawonicanussp. nov.; Gregorydytes ophthalmianussp. nov.; Pilbaraphanus chichesterianussp. nov., P. bilybarianussp. nov.; Magnanillus firetalianussp. nov., M. sabaesp. nov., M. salomonissp. nov., M. regalissp. nov., M. serenitatissp. nov.; Neoillaphanus callawanussp. nov.; Kimberleytyphlus carrboydianussp. nov.; Austranillus jinayrianussp. nov.; Gilesdytes pardooanussp. nov., G. ethelianussp. nov.; Pilbaradytes abydosianussp. nov., P. webberianussp. nov.; Bylibaraphanus cundalinianussp. nov.; and Angustanillus armatussp. nov. Identification keys are provided for all Australian anilline genera, and Western Australian species. All the described species are known from a single locality and qualify as short-range endemics. The Anillini are recognised as a significant and diverse element making up part of Western Australia’s remarkable subterranean fauna, and whose conservation may potentially be impacted by mining developments.

An emerging shale gas play in the Northern Territory

2012 ◽  
Vol 52 (2) ◽  
pp. 672
Author(s):  
Ray Johnson ◽  
Geoff Hokin ◽  
David Warner ◽  
Rod Dawney ◽  
Mike Dix ◽  
...  
Keyword(s):  
Shale Gas ◽  
Oil And Gas ◽  
Mineral Exploration ◽  
Northern Territory ◽  
Gas Flows ◽  
Oil And Gas Resources ◽  
Unconventional Oil And Gas ◽  
Shale Reservoirs ◽  
Drill Holes ◽  
Live Oil

As attention to unconventional oil and gas resources increases, historical oil and gas flows in shale reservoirs across the world are being given renewed attention. Such is the case of the shaly and carbonate deposits of the McArthur and Nathan groups in the Northern Territory. The Batten Trough is a Proterozoic depocenter with potential for a shale gas play in the Barney Creek Shale and potential for conventional gas accumulations in the underlying Coxco Dolomite. This Barney Creek Shale gas play is evidenced by a number of mineral exploration drill holes that encountered live oil and gas shows within the McArthur Group. The most prominent was a mineral exploration hole drilled at the Glyde River prospect by Amoco in 1979. This well reportedly flowed gas and condensates at 140 psi for six months before it was sealed at the surface, which certainly shows permeability values greater than micro-darcies reported for many North American shale plays; thus, an exploration program of this prospective area has been planned by Armour Energy in EP 171 on several targets adjacent to the Emu Fault Zone near both Glyde and Caranbirini, along with other anticline related targets adjacent to the Abner Range. This extended abstract details how the targets were identified, the plan for data acquisition (e.g. seismic, drilling, logging and testing), and the proposed completion strategy to test this highly prospective target.

scholarly journals A Microprocessor Based Ice - Radar System For Surfaceprofiling

1992 ◽  
Author(s):  
R W Jacobel ◽  
S K Anderson ◽  
D F Rioux
Keyword(s):  
Radar System ◽  
Ice Radar

scholarly journals Determination of meteor-head echo trajectories using the interferometric capabilities of MAARSY

2013 ◽  
Vol 31 (10) ◽  
pp. 1843-1851 ◽  
Author(s):  
C. Schult ◽  
G. Stober ◽  
J. L. Chau ◽  
R. Latteck
Keyword(s):  
Middle Atmosphere ◽  
Radar System ◽  
Neutral Atmosphere ◽  
Plasma Irregularities ◽  
Radar Systems ◽  
Radar Echoes ◽  
High Kinetic Energy ◽  
Head Echo ◽  
Sporadic Meteors

Abstract. During the flight of a meteoroid through the neutral atmosphere, the high kinetic energy is sufficient to ionize the meteoric constituents. Radar echoes coming from plasma irregularities surrounding the meteoroids are called meteor-head echoes, and can be detected by HPLA radar systems. Measurements of these echoes were conducted with MAARSY (Middle Atmosphere Alomar Radar System) in December 2010. The interferometric capabilities of the radar system permit the determination of the meteor trajectories within the radar beam with high accuracy. The received data are used to gain information about entry velocities, source radiants, observation heights and other meteoroid parameters. Our preliminary results indicate that the majority of meteors have masses between 10−10 and 10−3 kg and the mean masses of the sporadic meteors and Gemenids meteors are ∼10−8 kg.

scholarly journals Analysis of the radar reflectivity of aircraft vortex wakes

2002 ◽  
Vol 463 ◽  
pp. 121-161 ◽  
Author(s):  
KARIM SHARIFF ◽  
ALAN WRAY
Keyword(s):  
Refractive Index ◽  
Vortex Pair ◽  
Normal Incidence ◽  
Radial Pressure ◽  
Far Field ◽  
Two Dimensional ◽  
Radar Echoes ◽  
Scattering Approximation ◽  
Weak Scattering ◽  
Reflected Power

Radar has been proposed as a way of tracking wake vortices to reduce aircraft spacing and tests have revealed radar echoes from aircraft wakes in clear air. The mechanism causing refractive index gradients in these tests is thought to be the same as that for homogeneous and isotropic atmospheric turbulence in the Kolmogorov inertial range, for which there is a scattering analysis due to Tatarski. In reality, however, the structure of aircraft wakes has a significant coherent part superimposed with turbulence, about whose structure very little is known. This work adopts a picture of a coherent (in fact two-dimensional) wake to perform a scattering analysis and calculate the reflected power. In particular, two simple mechanisms causing refractive index gradients are considered: (A) radial pressure (and therefore density) gradient in a columnar vortex arising from the rotational flow; (B) adiabatic transport of atmospheric fluid within a descending oval surrounding a vortex pair. In the scattering analysis, Tatarski's weak scattering approximation is kept but the usual assumptions of a far field and a uniform incident wave are dropped. Neither assumption is generally valid for a wake that is coherent across the radar beam. For analytical insight, an approximate analysis that invokes, in addition to weak scattering, the far-field and wide cylindrical beam assumptions, is also developed and compared with the more general analysis. Reflectivities calculated for the oval (mechanism B) are within 2–13 dB m2 of the measurements (≈−70 dB m2) of MIT Lincoln Laboratory at Kwajalein atoll. However, the present predictions have a cut-off away from normal incidence which is not present in the measurements. This implies that the two-dimensional picture is not entirely complete. Estimates suggest that the thin layer of vorticity which is baroclinically generated at the boundary of the oval is turbulent and this may account for reflectivity away from normal incidence. The reflectivity of a vortex (mechanism A) is comparable to that of the oval (mechanism B) but occurs at a frequency (about 50 MHz) that is lower than those considered in all the experiments to date. This result may be useful because: (i) existing atmospheric radars (known as ST radars) already operate at this frequency and so the present prediction could be verified; (ii) rain clutter is not a problem at this frequency; (iii) mechanism A is more robust because it is independent of atmospheric stratification.

scholarly journals Potential Impacts to Wetlands and Water Bodies Due to Mineral Exploration, Pebble Copper-Gold Prospect, Southwest Alaska

Environments ◽  
2019 ◽  
Vol 6 (7) ◽  
pp. 84
Author(s):  
Zamzow ◽  
Chambers
Keyword(s):  
Natural Waters ◽  
Mineral Exploration ◽  
Quality Criteria ◽  
Water Quality Criteria ◽  
Regulatory Oversight ◽  
Drilling Waste ◽  
Copper Gold ◽  
Exploration Drilling ◽  
The One ◽  
Drill Holes

There is little information in the literature about the impacts of mineral exploration drilling on natural waters. A copper-gold-molybdenum mining deposit in Alaska was heavily explored until 2012 and partially reclaimed; however, full reclamation of drill sites remained incomplete in 2016. Copper is sub-lethally toxic to salmon, a highly-valued resource in this area. Of 109 sites inspected, 9 sites had confirmed impacts due to un-reclaimed drill-holes or drill waste disposal practices. At seven sites artesian waters at the drill stem resulted in surface water or sediment elevated in aluminum, iron, copper, or zinc with neutral pH. Copper concentrations at artesian sites were <0.4, 0.7, 2, 7, 15, 76, and 215 µg/L; the latter four exceed water quality criteria. Drilling waste is known to have been disposed of in ponds and unlined sumps. At one of five ponds sampled, copper declined from 51 to 8 µg/L over nine years. At the one sump area with historical data, copper increased from 0.3 to 1.8 µg/L at a downgradient wetland spring over five years. This research identifies contaminant types and sources and can be used to guide future ecotoxicity studies and improve regulatory oversight.

Spatial relationship of visual arcs to auroral electrojets

1991 ◽  
Vol 69 (8-9) ◽  
pp. 1047-1054 ◽  
Author(s):  
Q. Pao ◽  
L. L. Cogger ◽  
D. D. Wallis ◽  
A. G. McNamara
Keyword(s):  
Electric Field ◽  
Electron Flow ◽  
Spatial Relationship ◽  
Radar System ◽  
Maximum Magnitude ◽  
Temporal Relationships ◽  
Radar Echoes ◽  
E Region ◽  
Relationship Of ◽  
Coherent Backscatter

Observations of the 5577 Å (1 Å = 10−10 m) emission detected with an all-sky imager are superimposed onto maps of auroral E-region coherent backscatter at 50 MHz made by the bistatic auroral radar system (BARS) to obtain the spatial and temporal relationships of stable visual arcs to auroral electrojets and the Harang discontinuity. At large aspect angles, characteristic of BARS, many eastward electron-drift velocities appear poleward of the visual arcs, in agreement with a recent proposed explanation that is based on refraction through auroral ionization structures in the E region. For some observations, the radar echoes are essentially co-located with the visual aurora. When the Harang discontinuity is present, the discrete arc separates the counterstreaming electron flow. Under these circumstances, the electric field in the E region associated with the stable arc agrees with the theoretical electric-field simulation, in which the electric field with a maximum magnitude of 40 mV m−1, reverses direction across the discrete auroral arc. It is also evident from the observations that there is often no obvious spatial correspondence between the visible aurora and the velocity vectors of the electron flow. In some cases there exists electron flow with a large southward component across the stable arc.

Lithostratigraphic Mapping Through Saprolitic Regolith Using Soil Geochemistry and High-Resolution Aeromagnetic Surveys.

2020 ◽  
Author(s):  
Helen Twigg ◽  
Murray Hitzman
Keyword(s):  
Carbonate Rocks ◽  
Democratic Republic Of Congo ◽  
Mineral Exploration ◽  
Geological Mapping ◽  
Geochemical Data ◽  
Soil Geochemistry ◽  
Residual Soils ◽  
Copper Zinc ◽  
Siliciclastic Rocks ◽  
Drill Holes

&lt;p&gt;The Neoproterozoic Central African Copperbelt located in southern Democratic Republic of Congo (DRC) and the northwestern Zambia and contains 48% of the world&amp;#8217;s cobalt reserves and significant resources of copper, zinc, nickel and gold. A good understanding of the geology is critical for successful mineral exploration. However, geological mapping is hindered by low topographic relief, limited outcrop, and a generally deep (10-100m) weathering profile developed since the Late Miocene.&amp;#160; Multielement soil geochemistry provides a means for conducting geological mapping.&amp;#160; &amp;#160;Areas with outcrop or containing drill holes and/or trenches were utilized to relate known geological lithologies with soil geochemical results using major element and trace element ratios.&lt;/p&gt;&lt;p&gt;The lithostratigraphy within a study area along the DRC-Zambia border can be geochemically sub-divided into three units. Mixed carbonate and siliciclastic lithologies of the lower portion of the local stratigraphy are typically characterised by elevated V, Ti, and Nb. Mudstones and siltstones are dominated by elevated Al, Fe and Ba. The upper portion of the local stratigraphy is geochemically neutral with regards to trace elements.&amp;#160; Lithological discrimination through analysis of soil geochemical data is limited in some areas by intense weathering. A A-CNK-FM diagram exhibits how complete weathering of carbonate rocks and carbonate-rich breccias (after evaporites) results in the somewhat counter intuitive outcome that residual soils above carbonate rocks are amongst the most aluminum rich in the study area with &gt;80% Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; (mol%) or &gt;80% combined Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; (mol%) and FeO + MgO (mol%). The weathering of siliciclastic rocks (siltstones, mudstones, and diamictites) result in a shorter weathering path across a A-CNK-FM diagram, probably due to their higher original proportion of resistate phases.&lt;/p&gt;&lt;p&gt;An area specific geochemical database of baseline lithostratigraphy weathering paths allows the identification of atypical geochemistry which could indicate facies change, alteration or mineralization.&lt;/p&gt;

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