Abstract: Not available.
Introduction
Geological Survey of Pakistan made a 'Borehole' near Jhang, Punjab, Pakistan. A suit of, Borehole core samples from 2297-2368 feet depth was provided to me for palynological studies. Samples were made at 3 feet intervals. The core samples yielded,plant cuticle, pteridophytic, pteridospermous and gymnospermoqs pollen grains/spores. There is no evidence for the presence of Bryophytic or Angiospermic grains. Out of thousand, isolated specimehs only 7960 spore/pollen have been included in this study which are split into following categories and has been produced at the Table 1.
| Table 1: | The samples obtained from (Geol. Sur. Pak.) borehole near jhang showing the depth and number of different pollen and spores |
Only above mentioned samples have plenty of pollen/spore while rest of the samples were free of these pollen/spore. The isolated 7960 specimens have been assigned to 54 genera and 124 species.
While studying the pollen/spore of different samples many new species have been found. They are redeposited during different studies in this area of Borehole. These are considered as new species. Some of them are found for the first time in Pakistan are:
New Species
Lundbladispora sp. nov.
Densosporites type A sp. nov.
Crybelosporites jhangi sp. nov.
Grandispora apiculata sp. nov.
Microreticulatisporites majus sp. nov.
Striomonosaccaties punjabensis sp. nov.
Plicatipollenites unicus sp. nov.
Florinites punjabensis sp. nov.
Platysaccus sp. Type A sp. nov.
Vestigisporites kosanki sp. nov.
Corisaccites juglansis sp. nov.
Striatopodocarpites tuberculatus sp. nov.
Schofipollenites sp. Type A sp. nov.
Retusotriletes punjabensis sp. nov.
Such as "Crybelosporites". Brenner (1963) illustrated this form its distribution throughout Cretaceous Potomac group of Maryland. This specimen has been isolated from the Borehole near Jhang, Punjab, Pakistan (Permian region) after a long time for the first time in Pakistan.
Lunbladispora initially recorded by Brenner (1963) from lower cretaceous Potomac group of Maryland. Again Balme (1963) found the dispersed spores of this type from the Triassic of Australia (Balme, 1963; Playford, 1965) and the late Pennsylvanian of Illinois (Pepper, 1964). Same is the presence of Retusotriletes, Punctatisporites, Microreticulatisporites are the elements which show their existence not only in Carboniferous but also in Permian era. All these species are found in the 'Borehole' near Jhang, Punjab Pakistan. They are considered to be very rarely present in the samples of Permian era.
By studying different samples from 2297-2330 it is found the percentage of Bissaccate is much large as compared to monosaccate and other types of pollen/spores. Bissaccate are evenly distributed in all strata.
Tiwari and Singh (1983) studied group of Bissaccate containing Illinites, Jugasporites, Sahnites and Vestigiosporites. They found that Gondwana forms Sahnites and Vestigiosporites show the presence of uniformly developed sexine all over the proximal face of the central body while in Jugasporites. Sexine is developed only on the lateral ends of the central body leaving a smooth unstructured area in the central body which bears the trilete marking. Many of the genera are redeposited.
Balme (1970) has recognised 3 microfloral assemblages within the Permian succession of Western Australia. But in Pakistan, Balme (1970) has studied palynologically 7 formations out of which Amb Formation is of lower Permian and is significantly comparable with the present microflora such as Alisporites, Cedripites and Lunatisporites.
Kosanke (1950) has described a number of pollen and spores from Pennesylvanian deposits of Illinois. Majority of them closely resembles with the assemblage isolated from the Borehole (Fig. 1). Bissaccate pollens are also important constituents of lower Gondwana assemblage. The grains exhibits a bilateral construction with a central body having two opposite sacci whichmay be small, equal or larger in size than the central body.
The Talchir formation of India and Tobra Formation of Pakistan is the oldest horizon of Lower Gondwana, where scar bearing bisaccate pollen grains are significantly distributed. They are insignificant in upper Permian and rarely known in Jurassic. Presence of Parasacites
and Plicatipollinites is an interesting complex whichis again known to occur in Lower Permian. Most probably there were 2 distinct climatic belts in Pakistan during Gondwana time and two different types of pollen spore flora complex are known to occur.
| Fig. 1: | Miospores of permian era from borehole near Jhang Punjab |
Bharadwaj (1964) made a comparative study of the miospores of some early Permian conifers with Potonisporites. He concluded that Vestigiosporits and Sahinites were the junior synonym of Potonisporites. But some workers have regarded these 3 genere having their independent importance. Disaccate pollen are also important constituents of lower Gondwana sporae dispersae. The general organization of these grains exhibit a bilateral construction with central body having two opposite sacci which may be smaller, equal or longer in size than the central body. For this reason terms haploxylonoid, diploxylonoid have been introduced. Many other characters like striation, grooves, vestigial trilete, scar, cappa and cappula morphology has made possible for the palynologists to go into greater details for the identification of Bisaccate pollen. The further details can be, however, borrowed from Hart (1965). Tiwari (1974) says, "recently Balme (1970) has given a comperhensive amount of palynological of Triassic and Permian from the Salt Range. Very recently Masood (1964) has presented certain palynostriatigraphical units which are somewhat similar to Balme (1970).
It is interesting to note that the microflora is predominately Gymnospermic with certain Pteridophytic spores. It closely resembles with the flora of Pennsylvanian deposites of Illinois and Talchir beds of India and stands at the junctions of Permocarboniferous boundary.