Indicator minerals as guides to base metal sulphide mineralisation in Betul Belt, central India |
| |
| Authors: | Biswajit Ghosh M N Praveen |
| |
| Institution: | (1) Geological Survey of India, Operation: WB-SK-AN, Bhu Bijnan Bhawan, DK-6, Sector-II, Salt Lake, Kolkata, 700 091, India;(2) Geological Survey of India, Operation: TNPK, Kerala Unit, Dharani Bhawan, Manikanteshwaram, Thiruvananthapuram, 695 013, India |
| |
| Abstract: | Zn-bearing minerals that act as indicator minerals for base metal sulphide mineralization from the Proterozoic Betul Belt,
central India with special emphasis on their genetic significance have been discussed. Sulphide mineralisation is hosted by
the felsic volcanic rocks and has similarities with volcanic-hosted massive sulphide deposits in other parts of the world.
Synvolcanic hydrothermal alteration is crudely zoned with an inner high Mg-Ca core and an outer wider envelop of Al-Fe rich
mineral assemblage. Most of the prospects have strata bound, moderately to steeply dipping, multiple, sub-parallel sheet like
ore bodies composed of disseminated and semi-massive to massive ores. Zn-bearing spinel, staurolite, biotite and ilmenite
typically occur within the foot-wall alteration zones in close proximity to the sulphide mineralization. Zincian spinel is
ubiquitous irrespective of the nature of alteration zone. Zincian staurolite is nearly absent in Mg-Ca alteration zones but
commonly present in Al-Fe alteration zone along with zincian ilmenite. Zn-bearing biotite in intimate association with zincian
spinel is generally found in Mg-Ca alteration zone and in the transition to Al-Fe alteration zone. Most of these indicator
minerals can be considered as products of desulphidation of sphalerite during metamorphism. Mechanisms other than desulphidation
like formation of gahnite by overstepping of the zinc saturation limit of biotite during retrogression to chlorite and formation
of zincian staurolite at the expense of gahnite is also recorded. Field presence of these minerals has immense significance
in exploration in Betul Belt as they occur in close spatial relationship with the sulphide rich zones and therefore act as
direct vectors to ore. |
| |
| Keywords: | Gahnite zincian staurolite ecandrewsite hydrothermal alteration Betul Belt indicator minerals |
| 本文献已被 SpringerLink 等数据库收录！ |
|
