Ann: Significant Copper Mineralisation in First Hole at Sandover, page-15

Couple more images
Ivanhoe's Kitoko early sections

Continuity of reasonable thicknesses, high grade and large areas obviously make IVN interested that something could be mined at these depths.
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Lumwana area



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Another area of sedimentary copper is in Poland/Germany. Link to source paper for the image below.




The Kupferschiefer of northern central Europe is not only one of the largest sediment-hosted accumulations of copper ores worldwide (largest 1% of deposits with >60 Mt contained Cu) but has also one of thelongest continuously documented mining histories, starting from at least 1,199 A.D. in the Mansfeld districtof Germany. Kupferschiefer ores are currently mined in Poland from several large underground mines withactive near-mine exploration and possible downdip extensions at a planning stage. Kupferschiefer mines inthe Mansfeld and Sangerhausen districts of Germany had been largely exhausted by 1990 but a new exploration campaign is currently targeting a major deep Kupferschiefer resource near Germany’s eastern borderwith Poland.
The Cu-rich part of the Kupferschiefer mineralization is dominated by chalcocite, chalcopyrite, and borniteand is hosted by several rock types including footwall sandstone and conglomerate, black shale, carbonate rocksin the immediate hanging wall, and anhydrite even higher in the hanging wall. Orebodies can range in thickness from 0.3 m, contained largely within the black shale of the Kupferschiefer sensu stricto, up to more than50 m, where sublevel stoping, backfilling, and pillar mining reflect the pervasive mineralization.

Mining depths have increased here and may ultimately reach @Specul8's deep shaft range.

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The size of the deposits mentioned above shows why exploration is even being considered at these depths. Less important for the "Dome Areas" in Zambia that contain Lumwana.