exploration and evaluation of the economic mineral potentials and deposits of nagar parkar ‎area southern sindh‎

Abstract

The investigation of China clay deposits of Nagar Parkar area revealed that the clay is mainly ‎consisting of Kaolinite and quartz along with minor quantity of goethite, etc. This China clay ‎is generally covered by thin encrustation of hydrated iron. oxides and or top soil layer. The ‎clay zone is of varying thickness, i.e., the clay deposits are in pockets and are of lenticular ‎nature. ‎

The main areas where workable deposits have so far been proved are Paradhoro Dedhvero Dungri Dudwa Motijo Vandio

The total reserves proved in these areas are of the order of 3.5 mil1ion tons.‎

The writer collected about 75 samples during the two-field session spent there, for the ‎purpose of detailed analyses with the objective of establishing composition of clay and, more ‎importantly, to ascertain the genesis of these deposits which should prove helpful in directing ‎the future exploration programme.‎

In addition to study of clay deposits, the writer also mapped Karunjhar Hill outcrop of the ‎granites on a scale of 1:25000; this Helped in understanding the overall geological set up of ‎the area.‎

The laboratory studies of samples collected have proved that Kaolinite, established both by ‎X.R.B. and D.T.A. studies, forms on average about 20% of the crude clay. The remaining ‎coarser grained fraction consists mainly of quartz, released thorough decomposition of ‎feldspar of the parent granite. Besides, highly decomposed bed rock below the clay horizon ‎are also granites. This established the fact that genesis of these clay deposits is related to the ‎in site decomposition of acid igneous rocks.‎

The processes of decomposition of granite and neosynthesis of Kaolinite must have advanced ‎under conditions of lateritization and these deposits, in fact, represent lateritic clay ‎development.‎

The conditions necessary for the promotion of lateritization of granite and the acidic rocks ‎under which Kaolinite is produced are: Sufficient rainfall; moderate drainage with permanent ‎water table, and high temperature.‎

In the case of China clay deposits under investigation it has been deduced that these ‎conditions were established in the low ground between the Paradhoro-Dedhvero granitic ‎ridges in the east and Ranpur Dhingano-Chanida ridges in the west. It has been shown that ‎topography was the controlling factor in localizing these deposits in the areas mentioned ‎above.‎

Evidence has been presented to show that suitable climatic conditions were prevalent in the ‎area during the Plio-Pliestocene period when the area was uplifted as a block in response to ‎movement and collision of the Indian plate with the Eurasian & Arabian plates.‎

Based on the controlling factors in the genesis of these lateritic clays established in this study, ‎other possible areas of clay occurrences have been pointed out.‎