PRESENTATION ON MAGMATISM STAGES IN PAKISTAN COMPILED BY WASEEM KHAN
DEPARTMENT OF GEOLOGY
UNIVERSITY OF HARIPUR JANUARY,, 2016 JANUARY 2 016
Magm Ma gmat atis ism m De Defi fini niti tion on 1:- mo 1:molt lten en ma mate teri rial al be bene neat ath h or wi with thin in th the e ea eart rth' h'ss cr crus ust, t, fr from om whic wh ich h ig igne neou ouss ro rock ck is fo form rmed ed.. OR 2:-- Th 2: The e for forma mati tion on of igneous rock rock by by the solidification of magma. magma.
Magmatism
Pakistan contains a good record of magmatic rocks ranging from Early Proterozoic to Quaternary and almost all types of common igneous rocks have now been recognized.
In broad terms, most of the igneous rocks of Pakistan can be divided into three major paleo geographic regimes:
(1) Pre-Jurassic, related to various orogenic, crustal thinning and rifting processes in the Gondwanaland (2) Late Mesozoic, associated with spreading and hot spot processes, and (3) Cretaceous to Quaternary, related to convergent processes in the Tethys and at the edge of the "Asiatic" continent.
The Precambrian magmatic rocks of Pakistan can be divided into two groups :
(1)) Early Proterozoic granitic rocks with minor amphibolite, (1 amphibolite, in the Himalayan region, which are probably an extension of those of the Indian and Nepal Himalayas. (2) Late Proterozoic bimodal magmatic rocks in northern Punjab and southeastern Sindh, the latter being an extension of those of Rajasthan; and ultrapotassic volcanic in the Salt Range. During Early Paleozoic, several granitic plutons were emplaced in the Himalayan foothills. foothills.
Magmatism
Late Paleozoic rifting in the northwestern edge of the Indian plate ..-resulted in generally bimodal basic and acid (with some alkaline) magmatism in Kashmir, Hazara and Peshaw Peshawar ar region. region.
There are Jurassic-Cretace Jurassic-Cretaceous ous alkaline plutonic and volcanic rocks in Baluchistan which have been related to intraplate magmatism.
LATE ARCHEAN TO EARLY PROTEROZOIC
Igneous rocks of this age have recently been reported from the Nanga Parbat-Haramosh Parbat-Haramosh Massif (NPHM) and Besham area in northern Pakistan. Pakistan.
Nanga Nan ga Parbat Parbat-Ha -Haram ramosh osh Mas Massif sif
The N-S extending NPHM was considered as as a promontory (Wadia (Wadia 1933) or edge of a west-facing embayment (Madin et a1. 1989) of the Indian plate.
The northern part of the massif forms a N-S trending antiform.
The Indus Suture, along which rocks of the Cretaceous Kohistan magmatic arc were thrust over the Indian plate during Paleocene, appears to be folded around the NPHM in the form of a loop (Tahirkheli (Tahirkheli and Jan 1979). 1979).
There are young, generally undeformed, undeformed, granitic rocks in the NPHM.
These are dominant dominantly ly coarse-grained biotite-muscovite biotite-muscovite granite pegmatites locally mined for green tourmaline, aquamarine, aquamarine, topaz, topaz, and garnet (Kazmi et al. 1985).
Tourmaline granite and aplite Occur as dykes, lensoid bodies, and selvages selvages on the pegmatites pegmatites (Shams (Shams 1983, Madin et al. 1989).
Very young granitic rocks of Pliocene-Pleistocene age have been reported from the massif. These are probably related to very rapid uplift, and denudation which has' accelerated over the past 10 m.y. to a maximum of 7 mm/year mm/year (Zeitler 1985, Zeitler and Chamberlain Chamberlain 1991, Zeitler et al. 1993). 1993).
Besh Be sham am an anti tifo form rm
A window of Early Proterozoic basement, bounded by steep N-trending faults both on it eastern and western sides, is exposed in the Besham area to the south of the Indus Suture. Suture.
From oldest to youngest youngest they divide the rocks intofive groups:
1) The Besham Group, which forms the basement basement sequence, consists of metasediments, metasediments, quartzofeldspathic gneisses and sodic quartzo-feldspathic quartzofeldspathic quartzo-feldspathic gneisses formed in situ from a sedimentary protolithof variable composition. composition. The sodic gneisses are the equivalent of previously named Lahor Granite(Ashraff et al. 1980). Granite(Ashra 2) Mafic dykes in (1), now forming lenses and concordant layers commonly less than 2 m in width but reaching up to 50 m. Metamorphosed to epidote-bearing amphibolites, these are tholeiitic and have island arc geochemical geochemical affinities. However, However, Baig and Snee (1991) reported reported that some of of them are"basaltic komatiite, locally preserving preserving pillow structures. structures. 3) The third group of rocks consists of cogenetic, small granitic intrusions and associated pegmatites. 4) The Karora Group conglomerate, conglomerate, calcareous and carbonaceous carbonaceous metasediments, which form the cover sequence and provide evidence for more than one metamorphic event in the area. 5) Undeformed Undeformed leucogranites intrude both the Karora Group and the the Beshpm Group in two places in the form of small sills, up to 25 m thick.
LATE PROTEROZOIC
Kirana Kir ana Hil Hills ls
Some three dozen inliers of Precambrian basement, ranging from a few hundred square meters to about 20 kms in area, rise above the alluvial alluvial plain of the Punjab to the SE of Sargodha.
CAMBRIAN-ORDOVICIAN
The Lesser Himalayan granitic plutons of Lower Ordovician and Cambrian age occur in a belt stretching for 1,600 km from Kathmandu to the Indus (Le Fort et a1. 1980, 1983). Similar plutons also occur in the southern margin of the Tibetan slab and in the central mountains of Afghanistan.
Similar granitic rocks occur in other parts of the Himalayas of Pakistan, e.g.
Nanga Parbat, Besham, Swat, and Azad Kashmir, all of which are confined to the northern edge of the Indian plate to the south of the Indus Suture . Mansehra Manse hra Gran Granites ites :Covering more than 2,000 km2 area, these granites have been studied in detail by Shams and associates (1961a, 1966, 1969,1980, 1983).
They range from granite to granodiorite, are calc-alkaline in chemistry, and composed of quartz, albite-oligoclase, K-feldspar (orthoclase to microcline, mostly perthitic), biotite and small quantities of a number of other minerals, including garnet.
Mans Ma nseh ehra ra Gr Gran anit ites es
Swat Granitic Gneisses
these rocks are very similar similar to those of Mansehra Mansehra and their 515 Ma Ar-Ar biotite age confirms confirms that the the two are of the same age .
Like those of Mansehra, they also appear to have been emplaced in a sheet and tightly folded.
They are composed of quartz, two feldspars, two micas, opaques, opaques, epidote, apatite (± garnet) and, according to Shams (1983 ).
A younger tourmaline-bearing granite/gneiss granite/gneiss is a minor marginal variant of the Swat Granitic Gneisses (see also Di Pietro 1990). Wollastonit Wollastonite-bearing e-bearing calc-silicate rocks occur in contact marbles near Manglaur Mang laur (Sha (Shams ms 1961b) 1961b) and Pir Baba Baba..
Humayun (1985) divided the granitic granitic rocks in Lower Swat into :
(1) porphyritic porphyritic calcalkaline calcalkaline granodiorit granodiorite e gneisses with white white microline megacrysts,
(2) equigranular to porphyritic biotite granites of probable alkaline affinity and displaying local rapakivi texture, and
(3) equigranular, subsolvus, tourmaline-muscovite granites. granites .
Azad Kashmir
Several, relatively small granitic bodies have been reported from Azad Kashmir.
They are porphyritic, medium- to coarse-grained, coarse-grained, and deformed (gneissose) (gneissose) and undeformed undeformed types commonly commonly containing biotite and muscovite.
Nanga Parbat and Besham
The two-mica Shingus Gneiss in the Nanga Parbat Massif is a fine-grained, finely-laminated unit comprising a range of lithologies, but petrographic details are not available to us.
It has a V-Pb zircon age of 400-500 Ma,and is considered as a metamorphic metamorphic equivalent of the Mansehra Manseh ra Granit Granite e (Zeitler (Zeitler et a1. a1. 1989). 1989).
In Bes Besham ham are area a, there are small granitic intrusions of Cambrian age in the Early Proterozoic basement.
these the Shang and Duber bodies with associated pegmatites pegmatites are worth mentioning.
These are coarse-grained, with up to a centimeter long feldspar phenocrysts, deformed (especially on margins),and locally banded.
They range in composition from granodiorite to adamellite adamellite and consist of K feldspar, quartz, medium plagioclase, hornblende and/or biotite, opaque oxide, and traces of sphene, epidote, tourmaline, zircon and local garnet.
Western Karakoram
In upper Yarkhun Yarkhun Valley of northeastern northeastern Chitral, Le Fort et a1. (1994) and Tongiorgi et a1. (1994) reported pre-Ordovician granitoids occurring to the the north of the Karakoram Axial Batholith.
The granite body is 4 to 5 km wide.
Early Paleozoic granitoids have also been been reported from the neighboring region.
the darkest member of the Bumburet Pluton of Kafiristan in western Chitral (Le Fort et a1. 1994).
The occurrence of Early Paleozoic granites in the Karakoram Range suggests that the Karakoram plate is Gondw Gondwanic anic in origin origin and was probably contiguous to India before Permian.
LATE LA TE PALE PALEOZ OZOI OIC C - EA EARL RLY Y MESOZ MESOZOI OIC C
Based on the occurrence occurrence of alkaliae rocks in Warsak, Shewa-Shahbazgarhi Shewa-Shahbazgarhi (Coulson 1936), Koga (Siddiqui et a1. 1968) and Tarbela, Kempe and Jan (1970) suggested that an alkaline igneous province stretched across north Pakistan.
Subsequent geochemical and petrographic data on granitic rocks of Ambela (Ahmad and Ahmed 1974, Rafiq 1987) and Malakand (Chaudhry et a1.1974), and the discovery of carbonatite complexes complexes in Shilman (Jan et a1. 1981) and Sill Sillai ai Pat Patti ti (Ashraf and Chaudhry 1977) provided further support to the i dea that the Peshawar Plain alkalineigneous province (PAIP) extends extends for a distance of at least 150 km between the Indus River and PakAfghan PakAfg han borde border. r.
Field studies summarised in Kempe and Jan (1980) indicate that the alkaline complexes complexes are :
(1) generally emplaced along fault zones, and (2) restricted in occurrence to Paleozoic and Precambrian rocks.
the rocks of the alkaline igneousprovince igneousprovince are associated with Tertiary Tertiary rifting.
the total absence of these these rocks in the post-Paleozoic post-Paleozoic sedimentary sequence favour a Late Paleozoic age for the PAIP.
The later part of the Paleozoic and beginning of the Mesozoic appears to have been a fertile time for magma generation in this part of the subcontinent.
PAIP
PAIP
The Peshawar Plain Alkaline Igneous Igneous Province (PAIP) Of the three groups of rocks :
1. Loe ShUman ShUman,, Khyber Agency Agency
2. Warsak
3. Sill Sillai ai Patt Pattii
4. Malakand
5. Shewa-Shah bazgarhi
6. Ambela Gran Granitic itic Complex (AGe) (AGe)
7. Tarbela
The Peshawar-Hazara-Kashmir dolerites
Between the Indus Suture and the Main Boundary Thrust (MBT), there are numerous dolerite bodies in the Precambrian to Paleozoic rocks of NWFP and Kashmir.
Notable occurrences are those of the Attoc Attock-Ch k-Cherat erat Rang Range e (W (Wad adia ia 193 1931, 1, Tahirkhe Tahir khelili 1970) 1970),, Khyber Agency (Khan et aI., 1970, Shah et al. 1980), Hazara (Shams and Ahmed 1968, Calkins et ai. 1975), and Kashmir Kashmir (W (Wadia adia 1961, Pasco Pascoe e 1949).
JURA JU RASS SSIC IC - CR CRET ETAC ACEO EOUS US
The northeastern northeastern part of Balochistan shows several occurrences occurrences of alkaline rocks of Early Jurassic to Late Cretaceous age.
These constitute some 130 km long belt trending trending NE-SW betwe between en Zhob and NE of Quetta.
Include the name of area only because not the part of presentation :
1: Alkalic Alkalic rocks rocks of SpangarSpangar-Kozh Kozh Kach area. area. 2: Porali Porali suite suite 3: Pir Umar Umar Basalts Basalts 4: "Twin Sisters" soda dolerite, Muslimbagh.
CRET CR ETAC ACEO EOUS US - TE TERT RTIA IARY RY
belong ophiolitic complexes, commonly commonly thought thought of as traces of plate boundaries.
magmatism in Sindh, the Chagai arc, Kohistan arcs and Karakoram-Hindu Kush region. region. OPHIOLITES :
1) Ras Ras Ko Koh h Ran Range ge : The Ras Koh Range of west-central west-central Baluchistan is a tectonic block lying to the the south of the Chagai magmatic arc and to the west of the Cham an Transform Fault. The range is an E-W to NES~ trending anticlinorium both limbs of which are complicated by numerous folds and faults that trend generally in NE-SW direction. 2) The Bela-Zhob-Waziristan Bela-Zhob-Waziristan Suture Ophiolites 1.
Bela Ophiolite : Ultramafic rock, Mafic to silicic pl utonic rock, Dolerite dykes, Volcanic rocks
2.
Zhob Valley Ophiolite Ophiolitess :
3.
Waziristan Ophiolite :
3) The Indus Suture 0 phiolites 1.
Bajaur-Utmankhel:
2.
Skhakot-Qila Ophiolite Complex:
3.
Mingora-Shangla Mingora-S hangla 0 phiolite Melange:
4.
Allai Ophiolitic Melange:
5.
Allai Ophiolitic Melange:
6.
Burzill PassBurzi Pass-Dras Dras Ophio Ophiolitic litic Mela Melange nge
3) The Indus Suture 0phiolites : 1.
Bajaur-Utmankhel:
2.
Skhakot-Qila Skhakot-Qil a Ophiolite Complex:
3. Mingora-Sha Mingora-Shangla ngla
0 phiolite Melange Melange::
4. Allai
Ophiolitic Melange Melange::
5. Allai
Ophiolitic Melange Melange::
6.
Burzil Bur zil Pas Pass-D s-Dras ras Op Ophio hiolilitic tic Me Mela lange nge