Statistical Association of Gold Occurrences with Landsat-Derived Lineaments, Timmins-Kirkland Lake Area, Ontario

Abstract

RESUME Une methode de mesure de l'association spatiale entre un ensemble de points et un ensemble de lignes est decrite ici et appliquee 0 la question suivante: est-ce que les indices de mineralisation d'or dans la region du lac Timmins-Kirkland sont associes a) aux failles, b) aux lineaments resultant de l'interpretation d'images de teledetection? Les indices de mineralisation d'or tires de Hodgson (1983) sont compares a) avec des failles numerisees 0 partir d'une carte geologique 0 l'echelle 1 po = 4 mi, et b) avec des lineaments numerises 0 partir d'une carte produite par Touborg (1983). Bien que les failles soient moins nombreuses que les lineaments et qu 'elles se superposent peu souvent 0 ces derniers, une comparaison statistique des orientations des failles et des lineaments montre une forte correlation. Ceci laissesupposer que chaque ensemble de lignes reflete un point de reference semblable sur la roche de fond. 11 est demontre que la distribution en frequences des distances entre un indice de mineralisation d'or et la ",me faille la plus rapprochee differe de facon significative de la distribution prevue et que cette difference s'accroit proportionnellement 0 k. Les distributions prevues sont obtenues a) par une simulation de Monte Carlo, et b) 0 partir d'un modele de Bermann (1977), qui suppose que les lignes repondent oune distribution de Poisson et qu 'ellessont spatialement independantes. En pratique, cette condition n 'est pas remplie; les simulations ne sont utilisees qu'a des fins de comparaisons avec les valeurs observees. Une mesure de la relation spatiale entre les points et les lignes, fondee sur Ie test Kolmogorov-Smirnov, montre que les failles orientees dans certaines directions sont plus significatives que d'autres. L 'association des indices de mineralisation d'or avec les lineaments est beaucoup plus faible que leur association avec les failles, 0 l'exception des lineaments orientes dans des directions comprises entre NE et E, lesquels montrent une association forte. Ceci laisse supposer que la presence aurifere se manifesterait en association spatiale avec des failles et des lineaments d'orientations NE 0 E. Dans certains cas, l'association des indices de mineralisation d'or avec des failles peut tout simplement etre attribuable 0 une activite cartographique plus importante autour des campements en secteurs auriferes. SUMMARYA method for measuring the spatial association between a set of points and a set of lines is described, and applied to the question: are gold occurrences in the Timmins-Kirkland Lake area associated: a) with faults; and b) with lineaments interpreted from remote sensing imagery? Gold occurrences from Hodgson (1983) are compared: a) with faults digitized from a 1" = 4 mile geological map; and b) with lineaments digitized from a map produced by Touborg (1983). Although the faults are fewer in number than the lineaments, and show very little overlap with them, statistical comparison offault and lineament orientations show a strong correlation. This suggests that both...

Spatial statistical analysis applied to rare-element LCT-type pegmatite fields: an original approach to constrain faults-pegmatites-granites relationships

“…Some of the classic spatial statistical tests that can be used include: i) frequency analysis of the shortest distance measured between faults or shear zones (lines) and deposits (points), ii) frequency analysis of the shortest distance measured between intersections of the faults (points) and deposits (points), iii) frequency analysis of the faults (or shear-zone) spatial density at location of the individual deposits, iv) frequency analysis of the shortest distance measured between geological unit boundaries (lines) and deposits (points), and v) frequency analysis of crosscutting relationships between the different types of geological units (polygons) and deposits (points). Techniques for the analysis of the distance frequency distribution, quantifying spatial associations between objects, have already been formalized and applied (Berman 1977(Berman , 1986Bonham-Carter 1985;Carranza and Hale 2002). Following such approach and for each test, the frequency distribution of the computed parameters is analyzed in order to bring out any potential control of the object considered on the spatial distribution of the pegmatites; this is illustrated in the rather simple synthetic example.…”

“…Techniques have been proposed to compare observed distributions with reference ones (e.g. Bonham-Carter 1985;Carranza 2009a).…”

Control of style-of-faulting on spatial pattern of earthquake-triggered landslides

“…This method has only been used recently by to study landslide controls, but it has been employed extensively in studies of mineralization controls (e.g. Bonham-Carter 1985;Carranza and Hale 2002;Carranza et al 2008a). In the present study, we applied distance distribution analysis not only because it is a probabilistic method but also because (a) distance to fault is suitable for ground motion attenuation analysis (Campbell 1981(Campbell , 1997, (b) variations in ground motion are influenced by the style of earthquake faults (Campbell 1981;Bommer et al 2003) and (c) ground motion is a factor of ETLs (Jibson and Keefer 1993;Miles and Ho 1999).…”

Entropy of Shortest Distance (ESD) as Pore Detector and Pore-Shape Classifier

“…The idea can be easily extended to three kinds of randomly distributed objects ("ellipses", "lineaments", "points"), see Figure 3. Of course other, metric approaches are also possible [12,18], based on the actual values of the shortest dot-to-line distances, their distribution, mean, their normality, etc. Still, as discussed previously, by Fischer's [5] Theorem only the entropy can be considered as an objective measure.…”

“…and the presence of proved mineral occurrences [18][19][20][21]. A hypothetical case is shown in Figure 2 where the lineaments (green lines) are apparently related to mineral occurrences (yellow dots).…”