‘Transverse Section across Jabal Nasaz near Gil’ [‎185r] (1/2)

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N E
Jdbol NaSoZ
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ft ad C/oy & Sa nds-fona S e. r /
Red Cloy & Sandstone Series
Jy cnsevarse. Section acaroSS Joioj IVasoz dear Gil
Sco/e. / Inch =/Mil&-
Fars outcrop, however, was still further narrowed by a large reversed fault which cut out part of
the S.W. limb. In fact an anticlinal structure cannot now be clearly demonstrated, but is deduced
by analogy with other areas. One here and there gets the impression of an arching over in the
central core of limestone. This admittedly may be the result merely of the upward thrust of the
beds, but, comparing it with less disturbed folds, I am more inclined to the view that the original
crestal area is present and that the faulting has taken place a little to the S.W. of this. Near Gil a
distinct S.W.’ ly dip flanking an arch can be seen. As already stated, in the complete N.E. limb,
the central core of limestone is succeeded by a thick bed of clay with locally some gypsum, then by a
thin limestone band, and finally by several hundred feet of red clays belonging to the lowest horizons
of the Red Clay and Sandstones Series. Dislocation in the S.W. limb would most naturally take
place along the junction of the hard central limestone core and the succeeding soft beds of Fars
clay, and this, I think, is what has happened along most of its length. The section will illustrate
this.
A traverse from N.E. to S.W. shews the following succession. Commencing about 4 miles
E. of Kani Qadir, we see the massive light brown clays of phase “ c ” of the Red Clays and
Sandstones dipping N.E. at 15. 3 Further S.W. sandstones become a little more frequent, and the
dip sinks to 13 and 9. The dip soon after begins to steepen, producing the “ ridging up ” referred
to ; 1 mile E. of Kani Qadir it is 23°, and at the Fars upper boundary it varies from 30° to 50 3
with locally still greater dips. The N.E. limb of the Fars outcrop is not unduly contorted—in
fact it shews comparative regularity—but the central core of the anticline is disturbed. This core,
what remains of the S.W. limb, and the reversed fault, are all largely concealed by gravel and
other detritus which have spilled over it from the jabal Nasaz above. Beyond the fault S.W3
wards are the conglomerates of phase “ d ” dipping at angles scarcely more than 2°-3° towards the
N.E. The missing beds cut out by the fault, therefore, include a small thickness of the Fars, and
the whole of the Lower Stage of the Red Clay and Sandstone Series, viz., phases “a,” “ b ” and
“ c.” Crossing the Jabal Nasaz the conglomerates are seen to overlie zone “ c ” which forms a
low flat anticline between the Jabal Nasaz and the Zindanah ridge, the latter consisting of zone
“ d ” much reduced in thickness. Still further S.W. comes the flat syncline of the Dasht-i-Patahi,
occupied by brown clays of phase “ e,” followed by a third belt of conglomerate near Balagah
Rashid, overlying beds forming the N.E. limb of the Tuz Khurmatu-Kifri anticline. The contact
of steeply dipping Fars beds with almost horizontal conglomerates along the fault is well shewn
in the banks of the Aq Su and a small tributary thereof. The more N.’ly sections shew gypsum
in contact with the conglomerate, while the more S.’ly shew red clays on both sides of the gypsum,
that on the S.W. being contorted and in contact with conglomerate dipping at about 3° towards
E.N.E. The Fars outcrop cannot be more than 20 or 30 feet across ; the hade of the fault is not
clear, but has the appearance of being steep and not very far from 45°. S. of Qawali the Fars
outcrop, the fault and the Jabal Nasaz, all swing round towards the S., and a section in a stream
shews a line of fault breccia inclined at 44°, so that the hade of the fault must be something
approximating 46°; its thrust or throw must be over l j> miles.
The Fars outcrop, although so narrow, is surprisingly continuous. It was not seen for about 4
mile half-way between Kani Qadir and the Aq Su, but may be concealed here ; small rounded
boulders of limestone are plentiful, but are neither larger nor more numerous than they are in the
conglomerates of the hills above, from which they may well have rolled. A line of springs occurs
along or very close to the fault.
PETROLEUM.
(i) Natural Indications .—Seepages of oil and sulphuretted hydrogen, accompanied by the
usual sulphur deposition, are very numerous, occurring between a point 2\ miles S.S.E. of Kani