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Duddar |
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Balukistan, Pakistan |
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Zn Pb
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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All papers now Open Access.
Available as Full Text for direct download or on request. |
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The Duddar zinc-lead deposits are located 140 km NNW of Karachi in the Isabella District of Baluchistan in Pakistan (#Location: 26°13'24"N, 66°50'11"E).
Duddar is one of a series of Zn-Pb occurrences stretching north from Karachi in a belt of Jurassic-Cretaceous carbonates and clastics preserved in the Paleocene-Eocene collision zone between the Indian and the Iranian/Afghani plates. Zinc-lead mineralisation occurs over a length of several hundred kilometres within this zone. The Duddar deposit itself is hosted by peri-platformal Jurassic limestones and mudstones, with mineralisation constrained (cut) by two Tertiary faults. Variable facies and debris flows within the host Duddar Member of this sequence indicate the onset of extensional rifting, possibly, coinciding with syn-diagenetic development of mineralisation. The stratigraphic sequences at Duddar are typified by rapid facies changes, with few internal consistent marker beds. The lithologies at Duddar consist primarily of carbonate-shale sequences with minor fine- to coarse-grained siliciclastics.
The mineralisation comprises sulphides and barite, and is layered and concordant on both a large and small scale. Banding in the sphalerite is collomorphous, and in the barite is dendritic and irregular. It is hosted by a predominantly clastic sediment sequence, and is composed of pyrite/marcasite, sphalerite and lesser galena within de-calcified mudstones and silicified limestones. A veined and disseminated sphalerite-galena-chalcopyrite stockwork mineralisation zone underlies and cross cuts the stratabound assemblage.
The deposit demonstrates a compositional variation, with the base of the ore zone characterised by Zn and Fe sulphides, passing up into the lower Zn-Pb zone, a nodular limestone and then into an upper pyrite rich zone, which is barium-rich mineralisation in the south, and iron-rich facies in the upper levels of the marcasite and pyrite dominant areas of the Pyrite and Zinc Zones.
The mineralisation at Duddar is associated with numerous faults, which indicate syn-depositional controls of mineralisation. Some faults limit the extent of mineralisation and hanging wall rocks. In the southerly up-plunge area, the mineralisation is hosted within the hinge of a syncline. To the north, the deposit is hosted within an easterly dipping monocline.
Resources (indicated + inferred) amount to 15.84 Mt @ 8.5% Zn, 3.1% Pb, 19.7 g/t Ag at Duddar (Pasminco, 1997), which is part of the Duddar-Gunga-Surmai group which contain 28 Mt @ 7% Zn, 3.2% Pb (Paksitan Geological Survey).
The most recent source geological information used to prepare this decription was dated: 1997.
This description is a summary from published sources, the chief of which are listed below.
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