Authors / CoAuthors
McInnes, D.
Abstract
From June 23rd to November 4th 2016 Geotech Ltd. carried out a helicopter-borne geophysical survey over part of East Isa in Queensland (figure 1). Operations were based at Cloncurry, Queensland. The traverse lines were flown in an east to west (N 90° E azimuth) direction with 2km and 2.5km traverse line spacings, with three Tie lines flown perpendicular to the traverse lines. During the survey the helicopter was maintained at a mean altitude of 76 metres above the ground with an average survey speed of 90 km/hour. This allowed for an actual average EM Transmitter-receiver loop terrain clearance of 38 metres and a magnetic sensor clearance of 68 metres. The principal geophysical sensors included a versatile time domain electromagnetic (VTEMTMPlus) full receiver-waveform system, and a caesium magnetometer. Ancillary equipment included a GPS navigation system, laser and radar altimeters, and inclinometer. A total of 15697 line-kilometres of geophysical data were acquired during the survey. The electromagnetic system is a Geotech Time Domain EM (VTEMplus) with full receiver-waveform streamed data recording at 192 kHz. The "full waveform VTEM system" uses the streamed half-cycle recording of transmitter current and receiver voltage waveforms to obtain a complete system response calibration throughout the entire survey flight. The VTEM transmitter loop and Z-component receiver coils are in a concentric-coplanar configuration and their axes are nominally vertical. An X-component receiver coil is also installed in the centre of the transmitter loop, with its axis nominally horizontal and in the flight line direction. The receiver coils measure the dB/dt response, and a B-Field response is calculated during the data processing. In-field data quality assurance and preliminary processing were carried out on a daily basis during the acquisition phase. Preliminary and final data processing, including generation of final digital data products were undertaken from the office of Geotech Ltd. in Aurora, Ontario. A set of Conductivity Depth Images (CDI) were generated using EM Flow version 3.3, developed by Encom Technologies Pty Ltd. A total of forty-five (45) dB/dt Z component channels, starting from channel 4 (21 µsec) to channel 48 (10667 µsec), were used for the CDI calculation. An averaged waveform at the receiver was used for the calculation since it was consistent for the majority of the flights with minor deviation from the average. Digital data includes all electromagnetic and magnetic data, conductivity imaging products, mulitplots plus ancillary data including the waveform.
Product Type
dataset
eCat Id
104700
Contact for the resource
Custodian
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
- ( Place )
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- East Isa
- ( Platform )
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- Geotech
- ( Product )
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- CDI
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- VTEM
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- VTEM Plus
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- AEM
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- Heliborne
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- versatile time-domain electromagnetic
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- geophysical survey
- Australian and New Zealand Standard Research Classification: Fields of Research
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- Earth Sciences
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- Cloncurry
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- Queensland
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- QLD
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- Mount Isa
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- Mt Isa
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- Conductivity Depth Image
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- EMflow
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- Published_External
Publication Date
2017-04-10T11:00:00
Creation Date
2017-03-16T16:00:00
Security Constraints
Legal Constraints
Status
Purpose
The data release and conductivity depth image information are intended for use by exploration industry stakeholders
Maintenance Information
asNeeded
Topic Category
geoscientificInformation
Series Information
Lineage
Data was acquirde by Geotech, final data processed by Geotech, Reviewed for quality and release by David McInnes of GA
Parent Information
Extents
[-22.75, -19, 139.75, 141.75]
Reference System
Spatial Resolution
NA
Service Information
Associations
Downloads and Links
Source Information