Some Remarks on the Exploration of the Butrakhtinsky Deposit of Copper and Other Metals
Abstract Generated abstract
This paper reassesses the drilling-based evaluation of the Butrakhtinskoye deposit of copper and other metals, which had been downgraded after exploratory drilling despite earlier indications of industrial value. By comparing borehole positions with the inferred surface outcrops and probable ore-body geometry, the authors argue that many holes were planned according to an unsupported southwest-dipping model and therefore failed to reach the likely ore zones. The analysis suggests that several boreholes did intersect industrial-grade mineralization, that the main ore body may be steeply dipping or discontinuous, and that additional concealed bodies are possible. The authors conclude that the deposit’s industrial significance cannot yet be determined, but that it remains insufficiently explored and requires focused drilling beneath the surface outcrops.
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SOME REMARKS ON THE EXPLORATION OF THE BUTRAKHTINSKOYE DEPOSIT OF COPPER AND OTHER METALS
L. A. Pukhlyakov, I. M. Petrov
(Presented by Professor K. V. Radugin)
The exploration of the Butrakhtinskoye deposit of copper and other metals was first carried out by means of pits and other mining workings, and then with the aid of drilling. Before drilling began, the deposit was considered sufficiently valuable from an industrial standpoint, but afterward it was deemed unworthy of attention from the standpoint of its development.
Having studied the exploration materials for this deposit, the authors came to a different conclusion, namely: most of the exploratory boreholes were not carried through to the probable position of the ore body; that is, it remained insufficiently explored.
In fact, if one turns to Fig. 1, it can be seen that boreholes 19, 25, 29, and 39 encountered industrial copper contents precisely
Fig. 1. Outcrop of the ore deposit of the Butrakhtinskoye deposit of copper and other metals on the ground surface (shaded with dots), and horizontal projections of the boreholes laid out for its exploration. Circles indicate the collars of the boreholes. The short transverse straight lines correspond to zones of industrial mineralization penetrated by the boreholes.
in the zone that lies beneath the outcrop of the main ore body on the ground surface. And this means that the given ore body has a very steep dip (it occurs vertically). As for boreholes 34 and 43, which passed through the probable position of this ore body but did not encounter industrial contents of copper or other metals, this is apparently connected with the fact that the extent of this ore body
the body is limited or that it is discontinuous. In accordance with this is the fact that the width of its outcrop at the surface varies greatly and that the nearby surface outcrop of the second ore body is discontinuous.
The head of the Butrakhtinskoye exploration for some reason ignored the facts cited and adopted the assumption that the probable position of the ore body here dips to the southwest at an angle of about 60°, and laid out the boreholes in accordance with this hypothesis. As a result, of twenty-one boreholes whose materials were subjected to the analysis under consideration, only six reached the probable position of the ore body.
The situation is similar with the second deposit, namely: if the first of the hypotheses set forth is accepted, then the probable position of the ore body was intersected by boreholes 31, 48-a, 25, 43, 34, 45, 30, 26, 33, and 35. Half of them (boreholes 31, 48-a, 25, 26, and 33) encountered industrial-grade copper or other metals. Somewhat contrary to the hypothesis presented are the data from boreholes 35, 42, 37, and 41. They encountered industrial-grade copper or other metals in a zone displaced to the southeast from the surface outcrop of the ore bodies. However, this fact may be explained by these boreholes having encountered a third ore body, which has no outcrop at the surface.
For the time being it is difficult to say whether the Butrakhtinskoye deposit of copper and other metals has industrial significance or not; however, it can be asserted that it has remained insufficiently explored.
The latter becomes especially obvious if the body being explored is projected onto a horizontal plane. Here it is immediately apparent that only the upper and southeastern part of the deposit has been sufficiently explored. Throughout all the remaining area, the probable position of the ore deposit has been intersected by practically only one borehole (borehole 39), which, incidentally, encountered industrial-grade contents of useful components. In similar cases, negative conclusions are not drawn for gently dipping deposits. Apparently, at the Butrakhtinskoye deposit it is necessary to explore carefully, by drilling, the zone located directly beneath the surface outcrop of the ore body.