Exploración geológica de un yacimiento de placer de oro en la cuenca baja del río Marañón

Abstract

This thesis focuses on exploration geology for alluvial gold mining and under a system development methodology for an area located over the Peruvian Norwestern Amazon flood plain in Loreto, province of Datem and the Manseriche district, at the upper zone from lower Marañon basin, elevations relies between 100 to 400 masl and show geomorphologic unique features in the Amazon flood plain. The whole area averages 100 km². Geology of deposit is driven by quaternary fine sediments near surface and alluvial substratum beneath overburden consisting of rounded to sub rounded gravel with silty sand matrix, getting consolidated at depth. Outcropping rocks at the area are next to the Manseriche gorge and occasionally crops in the Campanquiz belt, that is a Mesozoic – Cenozoic folding rocks anticline, natural boundary from the Amazonas and Loreto regions. Gold placer is all around the researching area, where accumulates and distributes just beneath overburden in different levels and grades for the first mineralized layers of alluvial gravels, an average gold grade of 120 mg/ m³ over an expected 80 mg/ m³ gold grade cut off and mineralization anomalies up to 672 mg/ m³.

The area has been mined for long time by local miners at small scale; recovering gold with no control. Methodology explained in this dissertation gives rich details for a quick, simple and efficient exploration stage under a ruled sampling and drilling programs on prospecting zones already identified by satellite imagery and field reconnaissance. Mining activities of gold placers in Peru are no legal and strongly discriminates environment. These extracting processes, which result in low cost operations and easy going technical workings, where gold is recovered by gravimetric methods and excessive usage of mercury.