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Legault J.M.,Geotech Ltd. | Wijns C.,FQM Ltd
EAGE/DGG Workshop on Deep Mineral Exploration 2016: Chasing Both Land and Sea Deposits | Year: 2016

The ZTEM natural field helicopter EM discovery of the Balboa Cu-Mo-Au porphyry, Panama, in 2010 is discussed. Balboa is the most recent of six copper deposits discovered at Cobre Panama since 1966 but had escaped detection by soil geochemistry and drilling due to burial below thick, conductive saprolite. The survey consisted of 831 line-km of ZTEM (z-axis tipper electromagnetics) and aeromagnetics, flown at 300 metre line-spacings. The ZTEM results mapped elevated conductivity closely associated with all the known porphyry orebodies and Balboa represented a similar, untested feature. Balboa's magnetic response was inconclusive due to lack of a similar magnetic low. Drill testing encountered mineralization, 60 m below surface, and led to the discovery of the Balboa orebody within 3 months of the ZTEM survey. 2D inversion results show the ZTEM conductor correlates directly with the higher grade zone, both spatially and at depth. A 2D synthetic model predicts that Balboa is potentially detectable below 750 metres of cover. Balboa is the first documented case of a porphyry copper discovery using ZTEM airborne electromagnetics.

Seki O.,Hokkaido University | Kawamura K.,Hokkaido University | Ishiwatari R.,Geotech Ltd.
Journal of Quaternary Science | Year: 2012

Compound specific hydrogen isotopic compositions (δD) of free and bound forms of n-fatty acids (FA) were measured throughout a 200m sediment core taken from Lake Biwa to assess application of biomarker δD values to paleoclimate study in this central Japan lake. The results of our study suggest that the sources of the C16 n-FA in the two forms are different, whereas both free and bound C28 n-FA originate from terrestrial plants. The δD of combined (free plus bound) C28 n-FA in the 200m sediment core shows a large variability, with relatively low and high values during the glacial and interglacial periods, respectively. Based on comparison of our record with other marine and lacustrine paleoclimate data, we found that the sedimentary record of C28 n-FA δD likely reflects the temperature-induced change in δD of summer precipitation. This finding suggests that δD values of C28 n-FA could be used as a proxy for summer paleotemperatures in the sediments of Lake Biwa and other lakes. © 2012 John Wiley & Sons, Ltd.

Wannamaker P.E.,Consultant | Legault J.M.,Geotech Ltd.
27th Symposium on the Application of Geophysics to Engineering and Environmental Problems 2014, SAGEEP 2014 | Year: 2014

The performance of two-dimensional (2-D) joint ZTEM/MT inversion was tested using synthetic brick structures below a hill and valley model. Subsequently, separate and joint inversion of coincident ZTEM and Titan dense array MT data over the Johnston Lake district, Saskatchewan, were performed. A result of this effort is that only very few (e.g., three) MT stations may be needed to correct for background resistivity effects in a ZTEM survey provided the MT sites are appropriately spaced.

Arbanas Z.,University of Rijeka | Arbanas Z.,Institut IGH d.d. | Mihalic S.,University of Zagreb | Grosic M.,Geotech Ltd. | And 2 more authors.
Rock Mechanics in Civil and Environmental Engineering - Proceedings of the European Rock Mechanics Symposium, EUROCK 2010 | Year: 2010

The Brus Landslide occurred in April 2005, near village Brus in Istria, Croatia. The Landslide is a typical translational block slide and the landslide body consists of practically unique flysch rock mass block, 150m long and 35m wide. Sliding occurred abruptly, without previous announcement signs of possible instability. The area of North Istria is composed of flysch deposits of Paleogene age. Superficial deposits are made of considerable thick packages, with alternating layers of siltstones, marls and sandstones. Landslide body is composed of flysch rock mass which is 10m thick. Sliding surface is formed through bedding planes of siltstone layers. The sliding was caused by the unfavorable dip orientation of deposit layers in the slope, and additionally by the river erosion in the toe in combination with unfavorable hydrogeological conditions. © 2010 Taylor & Francis Group.

Legault J.M.,Geotech Ltd. | Izarra C.,Geotech Ltd. | Prikhodko A.,Geotech Ltd. | Zhao S.,Geotech Ltd. | Saadawi E.M.,MAADEN
Exploration Geophysics | Year: 2015

Magnetic and electromagnetic (EM) results from two helicopter EM surveys, a time-domain (VTEM) and AFMAG (ZTEM), are compared over the Nuqrah sedimentary exhalative (SEDEX) massive sulphide deposits in the Western Arabian Shield of the Kingdom of Saudi Arabia. The magnetic and EM data from both surveys map the major controlling structures that host the Nuqrah North and South deposits. Neither Nuqrah deposits stand out as distinctive aeromagnetic anomalies, but both EM surveys define the massive sulphide mineralised vent and bedded portions of the SEDEX orebodies. ZTEM is interpreted to be more capable in defining the larger, lower conductance and less mineralised distal portions of the SEDEX system. The modelled ZTEM also defines a down-dip extension of the Nuqrah South zone below a depth of 750m. © ASEG 2015

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