Wellington, New Zealand
Wellington, New Zealand

Time filter

Source Type

Falconer R.K.H.,Chatham Rock Phosphate | Castle C.,Chatham Rock Phosphate | McKenzie C.J.,Kenex Ltd.
OCEANS'11 - MTS/IEEE Kona, Program Book | Year: 2011

This paper briefly outlines proposals for the seabed mining of rock phosphate deposits on the Chatham Rise, some 240 nautical miles offshore and in 400 m water depth. An outline of the proposed mining method is presented, along with some of the key issues that arise with the proposal. © 2011 MTS.

Kreuzer O.P.,X plore Geoconsulting | Kreuzer O.P.,James Cook University | Kreuzer O.P.,Macquarie University | Miller A.V.M.,Kenex Ltd | And 7 more authors.
Ore Geology Reviews | Year: 2015

Mineral exploration is undertaken in stages, with each stage designed to get to the next decision point of whether or not to keep exploring a particular area based on the results at hand. As a general rule, each consecutive exploration stage is more expensive due to the progressively more drill- and study-intensive nature of the work required, in particular after discovery of a potentially economic mineral deposit. As such, the distribution of exploration activities and related expenditures essentially serve as a spatial measure of prospectivity as perceived by mineral exploration companies. In this study we compare historic (1980 to 2002) porphyry Cu-Au exploration activities and expenditures in part of the Ordovician to Early Silurian Macquarie Arc, Australia's most significant porphyry province with total resources greater than 80Moz of Au and 13Mt of Cu, to prospectivity modelling results from a weights of evidence (WofE) model. The outcomes of this spatial and statistical comparison indicate that at 2002 the Macquarie Arc was by no means a mature exploration destination and that past exploration investment outside the main mining areas was not necessarily effective. Moreover, no spatial correlation was apparent between areas of higher exploration expenditure and greater geological potential. For example, of the 692km2 of highly prospective ground covered by the exploration licences examined in this study, only 89km2 (c. 13%) have been explored effectively in that they received some form of drilling. Interestingly, the remaining area (603km2 or c. 87%) had not yet been effectively tested. As such, our analysis confirmed that despite a greater 100year exploration and mining history, much of the prospective ground within the study area remained untested. Taken as a whole, the results of our spatial and statistical comparison are important inputs for assessing the effectiveness of exploration investment and explanation maturity and, therefore, future exploration decision-making. The outcomes also have implications for strategic planning of future government legislation helping to manage and maximise the benefits from exploration investment. © 2014 Elsevier B.V..

Nielsen S.H.H.,Kenex Ltd | Cunningham F.,Kenex Ltd | Hay R.,Dampier Gold Ltd | Partington G.,Kenex Ltd | Stokes M.,Kenex Ltd
Ore Geology Reviews | Year: 2015

The Proterozoic Marymia Inlier is known for orogenic gold deposits along granite-mafic rock contacts within major bounding thrust planes, including the producing Plutonic mine. A 3D prospectivity model was built based largely on surface geology extended into the subsurface using geophysical data, confirmed by drill data when available. Because of the complexities of taking 2D data into 3D and the length of time to test spatial associations in 3D, a 2D weights of evidence prospectivity model was initially created to constrain the 3D predictive maps integrated into the 3D prospectivity model. The final 3D model used a ranked fuzzy logic technique, with the ranking adjusted from the 2D weights of evidence model that was used to constrain the development of 3D predictive maps. The study shows that 3D prospectivity modelling can be used to identify targets at significant depth and establish depths for drilling them. © 2015 Elsevier B.V..

Payne C.E.,Kenex Ltd | Peters K.J.,Kenex Ltd
Geochemistry: Exploration, Environment, Analysis | Year: 2015

Prospectivity modelling of epithermal gold mineralization has been completed over the Taupo Volcanic Zone (TVZ), North Island, New Zealand. The TVZ is unique in that it is a present-day analogue of the environment in which many epithermal ore deposits, such as in the adjacent Hauraki Goldfield in the Coromandel Volcanic Zone, are formed. The model utilizes compiled digital data including: historical exploration data; geological data from the Institute of Geological and Nuclear Sciences Quarter Million Mapping Programme over Rotorua, Hawkes Bay and Taranaki; recent Glass Earth Gold Ltd geophysical data; and historic exploration geochemical data from rock-chip and stream sediment samples. The weights of evidence modelling technique was used to determine spatial correlations between known gold prospects and predictive maps, created from the available data, representing each component of the currently accepted mineral system model for epithermal gold. Despite the limited coverage of several data-sets, the resulting prospectivity model over the TVZ confirms potential for gold mineralization. The most prospective areas are those associated with active and inactive hydrothermal systems represented by areas of hydrothermal alteration. The Rotokawa and Waiotapu hydrothermal centres have been identified as particularly prospective, suggesting these systems may represent modern analogues of epithermal gold mineralization. © 2015 AAG/The Geological Society of London.

Kaplan M.R.,Lamont Doherty Earth Observatory | Schaefer J.M.,Lamont Doherty Earth Observatory | Schaefer J.M.,Columbia University | Strelin J.A.,Instituto Antártico Argentino | And 12 more authors.
Quaternary Science Reviews | Year: 2016

We present a comprehensive 10Be chronology for Holocene moraines in the Lago Argentino basin, on the east side of the South Patagonian Icefield. We focus on three different areas, where prior studies show ample glacier moraine records exist because they were formed by outlet glaciers sensitive to climate change. The 10Be dated records are from the Lago Pearson, Herminita Península-Brazo Upsala, and Lago Frías areas, which span a distance of almost 100 km adjacent to the modern Icefield. New 10Be ages show that expanded glaciers and moraine building events occurred at least at 6120 ± 390 (n = 13), 4450 ± 220 (n = 7), 1450 or 1410 ± 110 (n = 18), 360 ± 30 (n = 5), and 240 ± 20 (n = 8) years ago. Furthermore, other less well-dated glacier expansions of the Upsala Glacier occurred between ~1400 and ~1000 and ~2300 and ~2000 years ago. The most extensive glaciers occurred over the interval from ~6100 to ~4500 years ago, and their margins over the last ~600 years were well within and lower than those in the middle Holocene. The 10Be ages agree with 14C-limiting data for the glacier histories in this area.We then link southern South American, adjacent South Atlantic, and other Southern Hemisphere records to elucidate broader regional patterns of climate and their possible causes. In the early Holocene, a far southward position of the westerly winds fostered warmth, small Patagonian glaciers, and reduced sea ice coverage over the South Atlantic. Although we infer a pronounced southward displacement of the westerlies during the early Holocene, these conditions did not occur throughout the southern mid-high latitudes, an important exception being over the southwest Pacific sector. Subsequently, a northward locus and/or expansion of the winds over the Patagonia-South Atlantic sector promoted the largest glaciers between ~6100 and ~4500 years ago and greatest sea ice coverage. Over the last few millennia, the South Patagonian Icefield has experienced successive century-scale advances superimposed on a long-term net decrease in size. Our findings indicate that glaciers and sea ice in the Patagonian-South Atlantic sector of the Southern Hemisphere did not achieve their largest Holocene extents over the last millennium. We conclude that a pattern of more extensive Holocene ice prior to the last millennium is characteristic of the Southern Hemisphere middle latitudes, which differs from the glacier history traditionally thought for the Northern Hemisphere. © 2016.

Payne C.E.,Kenex Ltd. | Cunningham F.,Kenex Ltd. | Peters K.J.,Kenex Ltd. | Nielsen S.,Kenex Ltd. | And 3 more authors.
Ore Geology Reviews | Year: 2015

A 2D prospectivity model of epithermal gold mineralisation has been completed over the Taupo Volcanic Zone (TVZ), using the weights of evidence modelling technique. This study was used to restrict a 3D geological interpretation and prospectivity model for the Ohakuri region. The TVZ is commonly thought of as a present-day analogue of the environment in which many epithermal ore deposits, such as in the Hauraki Goldfield, Coromandel Volcanic Zone, are formed. The models utilise compiled digital data including historical exploration data, geological data from the Institute of Geological and Nuclear Sciences Ltd. Quarter Million Mapping Programme, recent Glass Earth geophysics data and historic exploration geochemical data, including rock-chip and stream sediment information. Spatial correlations between known deposits and predictive maps are determined from the available data, which represent each component of the currently accepted mineral system model for epithermal gold. The 2D prospectivity model confirms that the TVZ has potential for gold mineralisation. However, one of the weaknesses of this weights of evidence model is that the studies are carried out in 2D, with an approximation of 3D provided by geophysical and drilling data projected to a 2D plane. Consequently, a 3D prospectivity model was completed over the Ohakuri area, constrained by the results of the 2D model and predictive maps. The 3D model improved the results allowing more effective exploration targeting. However, the study also highlighted the main issues that need to be resolved before 3D prospectivity modelling becomes standard practise in the mineral exploration industry. The study also helped develop a work flow that incorporates preliminary 2D spatial data analysis from the weights of evidence technique to more effectively restrict and develop 3D predictive map interpretation and development. © 2014 Elsevier B.V..

Nielsen S.H.H.,Kenex Ltd | McKenzie C.,Kenex Ltd | Miller A.,Kenex Ltd | Partington G.,Kenex Ltd | And 6 more authors.
Ore Geology Reviews | Year: 2015

After almost five decades of episodic exploration, feasibility studies are now being completed to mine the deep-water nodular phosphate deposit on the central Chatham Rise. Weights of evidence (WofE) and fuzzy logic prospectivity models have been used in these studies to help in mapping of the exploration and resource potential, to constrain resource estimation, to aid with geotechnical engineering and mine planning studies and to provide background geological data for the environmental consent process. Prospectivity modelling was carried out in two stages using weights of evidence and fuzzy logic techniques. A WofE prospectivity model covering the area of best data coverage was initially developed to define the geological and environmental variables that control the distribution of phosphate on the Chatham Rise and map areas where mineralised nodules are most likely to be present. The post-probability results from this model, in conjunction with unique conditions and confidence maps, were used to guide environmental modelling for setting aside protected zones, and also to assist with mine planning and future exploration planning. A regional scale fuzzy logic model was developed guided by the results of the spatial analysis of the WofE model, elucidating where future exploration should be targeted to give the best chance of success in expanding the known resource. The development work to date on the Chatham Rise for nodular phosphate mineralisation is an innovative example of how spatial data modelling techniques can be used not only at the exploration stage, but also to constrain resource estimation and aid with environmental studies, thereby greatly reducing development costs, improving the economics of mine planning and reducing the environmental impact of the project. © 2014 Elsevier B.V..

Loading Kenex Ltd. collaborators
Loading Kenex Ltd. collaborators