3.2.2. Main Predictive Bases


Precambrian metamorphic rock series and the Mesozoic granitoids, are favorable ore-hosting parts;

d. Geophysical bases. The efficiency of geophysical methods on gold prospecting is obvious [51–60]. The main geophysical indicators of gold prospecting in the Jiaodong Peninsula include the following aspects. <sup>1</sup> Linear gradient zones of gravity anomalies. Favorable metallogenic parts mainly include the edges of zones with low gravity (i.e., the transition zones between gravity highs and gravity lows could indicate fossil hydrothermal zone with dissolved rocks) and the contact zones between large-scale gravity lows and gravity highs, especially the turning parts of the gradient zones. The favorable metallogenic parts of deep-seated gold deposits include moniliform and elongate zones with high-amplitude magnetic anomalies, especially the bending parts of magnetic anomaly contours (protruding and concave parts), the edges of blocky gravity and magnetic anomaly zones, and the edges of small-scale blocky and moniliform positive magnetic anomaly zones. The magnetic anomaly would be associated to magnetite/pyrrhotite minerals often associated to gold mineralization. <sup>2</sup> The boundaries between high- and low-resistance electric fields. On the apparent resistivity sections, the sparse and wide contour lines that synchronously bend downward and show U- or V-shaped low resistance mark the parts favorable for the occurrence of gold deposits. Boundaries between low/high resistivity zones could be linked to the presence of conductive minerals such pyrite often pathfinder minerals for gold mineralization.
