Lithogeochemical Study on the Diabase of the Shimokawa Mine, Hokkaido.
1973 Volume 23 Issue 118 Pages 153-161
Details
1973 Volume 23 Issue 118 Pages 153-161
Some geochemical features of the diabase intrusives and lavas associated with the bedded cupriferous iron sulphide deposits of the Shimokawa Mine are preliminarily studied to obtain the key for the method of lithogeochemical exploration of the area.
About 850 samples of hand specimens from underground workings and drill cores were analyzed for twelve elements such as B, Co, Cr, Cu, Pb, Mg, Mn, Mo, Ni, Ti, V and Zn by emission spectrography.
Some notable features of the several minor and trace elements of diabasic rocks are found. The outline will be described as follows;
1) There are no remarkable difference between the coarse grained ophytic diabase and the fine grained variolitic diabase, and also between the fresh diabase and the altered one in regared to the contents of above mentioned minor and trace elements.
2) On each diabase sill and lava, especially on the coarse grained diabase sheet, contents of cobalt, magnesium, manganese, nickel and some other elements are increased towards the upper surface of the sheet and vanadium is increased towards the bottom.
3) These behaviors of the elements are observed in all diabase sheets, whether the sheet is associated with ore or not and also whether the sheet located above the ore or below the ore. Therefore these features suggest that the elements may have disparsed syngenetically.
4) There are some differences between the diabase sheet above the ore and below the ore in regard to the contents of several elements. Namely cobalt, nickel, and manganese are concentrated in the diabase sheets above the ore and vanadium is concentrated in the sheets below the ore.
This distribution mentioned above suggests the effect of "primary epigenetic dispersion" of geochemical elements associated with mineralization.
Therefore this epigenetic pattern can be applied to recognize the ore-horizon of the bed-ded cupriferous iron sulphide deposits associated with diabase sheets. In other words the diabase sheets with ore may be determined among many of the same kinds of sheets by the geochemical method.
