1. Paleozoic era
BY:
THOMAS CHINNAPPAN .A ,
M.SC.APPLIED GEOLOGY,
PERIYAR UNIVERSITY,
SALEM.

2. THE PALEOZOIC ERA AT A GLANCE

3. SALIENT FEATURES OF PALEOZOIC ERA
Started at about 542 Ma and lasted for ~290 My and culminated at about 252 Ma
Occupies ~6% of the total time of the life of the earth
Provides better geological environment for coal formation which is the main
source of energy
Suitable time for organic evolution (both flora and fauna)
Rocks are less deformed and hence provide good sections for research
In India, Paleozoic rocks occur mainly in the Himalayan region and that too most
of them in the Tethyan basin, extending from Kashmir in NW to Bhutan in the east.
Apart from this, grabens in peninsula too preserve Paleozoic rocks

5. Rocks of Paleozoic Era have been exposed in different isolated basins along the
Himalayan regions. It is thought that an earlier single basin has been divided into many
due to deformation and erosion
The stratigraphy of the Himalayan terrain was worked out mainly based on observations
made during traverses along the river sections across the mountain ranges
Due to difficulties in terrain accessibility, inadequate thickness, lack of habitations for the
formations to be named after, only regional lithostratigraphic nomenclature have been
adopted.

6. Tethyan Basin
It comprises the Paleozoic and younger sediments in the Himalayan domain, north of
the Main Central Thrust (MCT) and its analogous extent from Kashmir in the NW to
Arunachal Pradesh in SE.
The Kashmir, Bhadarwah-Chamba, Zanskar-Spiti-Kinnaur, Gharwal-Kumaun, Nepal-
Sikkim-Bhutan-Arunachal Pradesh are the individual segments of the vast spread
Tethyan Basin.
Conspicuous feature in this area are unconformities at Late Cambrian, Late
Carboniferous and Middle Permian

8. Kashmir sub-basin: It trends NW-SE and covers 18,000 km2 area and is separated
from the adjacent Spiti-Zanskar sub-basin by crystalline rocks. The Lidder valley forms
a part of the sub-basin and is situated in the SE part where an excellent section of the
sub-basin has been exposed as Lidder anticline composed by Paleozoic as well as
Triassic sequence.
Bhadarwah-Chamba sub-basin: It lies SE of the main Kashmir sub-basin. It exposes
the Permo-Triassic sediments overlying the Panjal volcanics

10. Spiti-Zanskar and Kinnaur sub-basin: The Paleozoic and Mesozoic sequence in the
south Ladakh of J & K and Spiti and Kinnaur area of Himachal Pradesh occur in two
isolated synclinoria. These two isolated basins were together and later separated due to
erosion of the central structural axis. The Spiti-Zanskar basin of the Indus Himalayas
exposes a spectacular section.
Anticlinal valley

11. Gharwal- Kumayun Tethyan Sub-Basin: It is mainly seen in the Malla Johar and
northern Kumayun area. This sequence composed of a thick sequence of Proterozoic
and Phanerozoic rocks. But the most significant features of the area is, though the
basins are situated close to each other, but the thickness of sediments from one place to
other vary considerably and it is probably due to the effect of paleogeography of the
region.

12. PRECAMBRIAN-CAMBRIAN BOUNDARY
Precambrian-Cambrian boundary is marked by major biotic changes (emergence of soft-
bodied Ediacaran fauna and their subsequent extinction, emergence of fauna and their
hard part or chemical changes, particularly variation of C and Sr isotopes in carbonates).
These evidences are used to correlate the terminal Proterozoic and Early Cambrian
strata
Nutrient Enriched Water mass (NEW) with high level dissolved phosphate and silica with
low level of oxygen left a clear imprint in fossil record in the Pc/C boundary
Explosion of life in the Pc/C boundary saw variety of animals as builders, binders and
encrusters in various build-ups.
Around 544 Ma during the Early Cambrian, there was an evolutionary explosion called
“Cambrian Big Bang” which extended up to Middle Ordovician.

13. But some people by the study of nucliotide (an organic matter constitutes Purine and
Pyrimidine) sequence studies, put the origin and diversification of major phyla between
1000-2000 Ma. But lack of fossils to support the theory is probably supports the origin of
organism as soft bodied.
Stromatolites: Stromatolites are blue green algae. These are believed to be present in
the world at 3.77 BY ago. In India these have been reported in rocks from Sandur,
Simoga, Chitradurga in Karnataka state dated 2.9 BY. These are not body fossils , these
are the sedimentary structures build by bacteria (cyanophytus and microscopic algae)
and only rare do they contains remaining of organisms.

14. These are also reported in Raisi Group of Jammu Himalayas,, Gharwal-Kumaon
Himalayas, Himachal Himalayas, Nepal, Sikim, Arunachal Pradesh Himalayas.
In all the reported places both in peninsular and Extrapeninsular, the
stromatolites represent Precambrian sequences except in Tal Formation of Uttarakhand,
where stromatolites occur in Early Cambrian
Pc/C Boundary in The Himalayas
The sedimentation of the terminal Proterozoic-Cambrian succession
commenced with a wide spread marine transgression in response to
global warming after the Varangian glaciation at about 610-590 Ma.
Salkhala Group and parts of Haimanta Group represent Neo-and
Terminal Proterozoic in Lahaul-Spiti and Himachal Himalayas. The
transgression was terminated by the Pan-African orogeny in Late
cambrian. The sediments are now exposed in Krol belt, Lesser
Himalayas, in Kashmir basin in Higher Himalayas and Spiti-Zanskar and
Kumayun basins. Blainia-Krol-Tal sequence is considered as the
standard Pc/C boundary in the Himalayas which can be correlated with
global standards

15. Cambrian stratigraphic sections with ages of strata and positions of trilobite fossil recovery. Data source:
1—Garzanti et al. (1986), Myrow et al. (2006a); 2—Brookfield (1993), Myrow et al. (2006b); 3—Kumar
(1985), Brookfield (1993); 4—Zhang (1988); 5—Searle et al. (2003). Inset map shows position of sections
and adjacent tectonic zones.

18. Pc/C boundary in Rajasthan
The Nagaur-Ganganagar evaporite intra cratoinc basin exposes marine sediments of
Late Precambrian-Cambrian age over the basement of Malani volcanic suit between
Kalu and Kaksar
Over the Malani volcanic suit, the evaporites of Jodhpur, Bilara, Hanseran evaporites
represent Terminal Proterozoic, which is followed by Birmania Formation of Cambrian
age.
In the Himalayas, the Pc/C boundary is well known but in the Aravali-Vindhyan belt it is
tentative

19. PALEOZOIC LIFE
Plant Life
Acritarcha are unicellular micro phytoplankton of organic composition and with a known
life cycle is the first appearance of plant life in marine environments started at
Precambrian and continued to Recent. They appeared their acme period during
Ordovician-Devonian
Vascular plants appeared in Cambrian

20. Though vascular plants came into existence in Cambrian, but further diversified and
advanced during Devonian
Luxuriant plant life is noticed in Carboniferous which ultimately gave rise vast coal
deposits world wide, but a few representative in the Himalayas. However, in Peninsular
India, environment was suitable for coal deposits. Many families of plant in Gondwana
strata are of Permian age.

21. Animal Life
 Early life seems to have been essentially marine and particularly most of the
invertebrate fauna and their lineage known today (whether living or fossil), existed in
some part or other of the Paleozoic
 Unicellular organisms are quite common

22.  Foraminifers were present from the
Cambrian but they assumed some
importance during the Carboniferous
 Sponges, one of the simplest
multicellular organism and essentially
marine, increased in number only in
carboniferous
 Corals came into prominence in
Ordovician and Silurian and continued
further, they are the main carbonate
builder in the marine environment

23.  Echinoderms were flourished through out the
Phanerozoic but, prominent in Ordovician and
Silurian and were extinct by Permian
 Brachiopods (bivalves) shows one of the
longest range of existence and were survived
up to Tertiary. Since most of them are
calcareous shells, these are well preserved and
are used in stratigraphic classification.
(Lingulella, Obolus Wastonia and Obolela
Atlantica are well preserved in Cambrian in
Spiti)

24. Pelecypods appeared in Cambrian
and also live in Holocene
These can live in fresh, brackish and
marine water
 Gastropods appear in Cambrian,
represented by few species in
Ordovician-Silurian and occur in
considerable numbers in Permian. They
can live in all types of environments
from marine to mountain

25. Cephalopods, which are
exclusive marine, are
represented by few
species in Ordovician
And a few more in Permian.
After that they flourished
Ostracods are known from Paleozoic. These
are very important in petroleum exploration

26. Trilobites are index fossil in Lower Paleozoic specialy during Cambrian
and almost extinct by the end of Permian
Conodonts appeared in Cambrian and
extended up to Triassic. Due to their lack of
facies restriction and world wide distribution
these are used in correlation.

27. MAGMATIC ACTIVITIES
There was invasion of granitic magma on large scale throughout the Himalayan province
from Manshera in northern Pakistan to Manaslu in Nepal and beyond during 525 to 475
Ma. The intrusion of granitic magma caused low grade metamorphism to the invaded
Proterozoic rocks

28. The period was established by Adam Sedgwick, who named it after Cambria, the Latin
name for Wales, where Britain's Cambrian rocks are best exposed
Cambrian Period/System

29. Strata belong to the Cambrian occur in the Tethys Himalayas and in Lower
Himalayas in the state of Jammu and Kashmir, Himachal Pradesh and
Uttarakhand.
In the Lower Himalayas, the Cambrian strata are separated by profound
unconformities from the overlying Permians but in the Tethys Himalayas there is
almost continuous with Mesozoic and Cenozoic with occasional minor
unconformities.
The Upper most Cambrian strata are absent in the entire Himalayas indicating a
major hiatus
THE CAMBRIAN PERIOD
The Cambrian strata does not show any profound unconformity from the lower lying
Proterozoic succession and hence it is difficult to mark the boundary sharply. However,
on the basis of the faunal appearance, it is demarcated in many places. Another
problem is that, the fossils in the Cambrian are too varied that their first appearance is
doubted. It is apparent that some of them have been evolved over a long period of
time.

30. Cambrian in Jammu & Kashmir
Cambrian strata occur in Jammu-Kashmir and in Zanskar-Spiti sector. Of all the known
strata of the age, the Kashmir succession is by far the most accessible and complete.
Good sections are exposed in Lidder valley, Basmai anticline in Sind valley.

31. Cambrian in Himachal Pradesh
Cambrian strata occur both in Tethys Himalayas and Lesser Himalayas in Himachal
Pradesh. The Kunzun La is the principal Cambrian Formation in Lahaul-Spiti-Kinnaur
sub-basin in the Tethys Himalayas of HP. It comprises greenish grey shale, siltstone,
slate, quartzite and dolomite.
In the Lesser Himalayas, the Cambrian is represented by Tal basin
Cambrian in Uttarakhand
Excellent exposure of Tal Formation lying over Krol formation is found in the Mussoorie
syncline in Uttarakhand. The rocks consists from bottom to top are Chert Phosphorite
Member, argillaceous, arenaceous, calcareous, quartzitic and limestone. Presence of
phosphorite at the base of Tal Formation establishes the Global Cambrian
Phosphogenic Province in the Indian subcontinent.

32. ORDOVICIAN AND SILURIAN
There are difficulties to separate the rocks of Ordovician and Silurian because:
1. Due to considerable thickness of unfossiliferous strata
2. Paucity of fossils to distinguish
3. The cyclicity of sedimentation in rocks of both ages
So there are no means by which the rocks of these two different rocks can be separated
and hence are clubbed together
Jammu & Kashmir Region:
In Jammu and Kashmir, Ordovician and Silurian rocks are exposed in Doda, Poonch,
Anantnag and Baramulla districts.
Rocks are represented by volcanics, slate, phyllite etc.
In Shans Abria syncline, a large exposure of variegated slate with numerous distorted,
crushed and obliterated fossils is found overlying the blue clay of Cambrian age.

33. In Anantnag district, the entire sections exposed representing from Late Cambrian to
Silurian is grouped under Hapatnagar Group
But the Late Cambrian is absent here as in the other parts of the Himalayas too
Himachal Pradesh region:
The Thango Formation is represented by basal conglomerate followed by
quartzite, doleranite and slate and characterized by typical purple colour and shows a
rugged topography. Shale partings in between preserve well preserved trace fossils
Numerous small sills of gabbro-norite affinity are observed within this Formation
The sedimentation of Thango Formation was started by fluvial material reworked in
beach and passed through essentially tidal zone with storm episodes where wave action
was prominent. Toward the terminal phase there was decrease in energy level, possibly
due to relative deepening of the basin. The entire sedimentation was taken place under
oxidizing condition

34. Takche Formation: Takche Formation is rich in carbonate and is easily distinguishable
from distance by its brown colour
Small transgressive sills of dolerite composition are intruded into the Takche Formation.
The rocks of the Takche Formation are represented by Sandstone to shale to limestone
to dolomite with a lot of facies changes in between giving rise to mudstone, packstone,
floatstone etc. Besides these there have been considerable reef build-ups by corals,
stromatopods and solenoporoids.
Uttarakhand Region:
In Uttarakhand, the Ordovician and Silurian successions are represented by Upper
Garbyang, Shiala and Young Limestone Formations. Lithologically these are
representing variegated shale, crinoidal breccia and sandy limestone lies above the
Garbyang Formation
All the three Formations are rich in fossils.
The presence of age marker Acritarch reveals the Ordovician-Silurian boundary lies in
the Shiala Formation

35. DEVONIAN
The characteristic litho unit of this age is Muth Quartzite, which is white colour, hard and
compact and can be easily distinguished from areal photograph. It extends from Kashmir
valley to Kumayun
Jammu and Kashmir region:
Muth Quartzite is the marker horizon and occurs repeatedly due to folding.
Rare plant remains are reported from this litho unit. Pre-Devonian plant life is recorded
in India
Himachal Pradesh region:
The Muth Quartzite rests on Takche Formation sharply indicating a break in
sedimentation in Spiti area. In Spiti area it is more or less uniform thickness. At places,
olive green shales and conglomerates are associated with it along minor amount of
dolomites. The presence of trace fossils, herringbone cross bedding, subaquous-
subaerial mud cracks indicates littoral zone of deposition. It is overlain by Lipak
Formation

36. Uttarakhand:
In Kumayun, Devonian is represented by Quartzite and dolomite layers. It is overlain by
the Quartzite typical of Muth Formation
CARBONIFEROUS
In some part of the world, Carboniferous is represented by both terrestrial and marine
sediments, some of them are rich in coal seams.
Marine sediments are confined in the Himalayan region (J & K, Spiti-Zanskar-Kinnaur in
HP, Kumaun in Uttarakhand) with a hiatus in Upper Carboniferous. But the Upper
carboniferous sediments are preserved in Peninsular India and forms the base of the
Gondwana Supergroup. Glaciation was initiated in the Upper Carboniferous. Towards
Lower Carboniferous, there was marine transgression in Peninsular India and hence
intercalation of marine sediments with Gondwana sediments. This gives a clear
evidence of paleogeography of Peninsular India

37. Jammu and Kashmir:
In Kashmir sub-basin, Carboniferous is represented by Tannaki Conglomerate,
Syringothyris Limestone and Fenestella Shale

38. Himachal Pradesh:
Carboniferous strata in HP is represented by Kanwar Group having three Formations i.e.
Lipak, Po and Ganmachidam Formations
Lipak Formation: It starts with dirty white grey locally cross bedded sandstone followed
by grey shale inter bedded with limestone and sandstone in middle and local shale with
lenticular gypsum bed in the upper part. Depositional environment change is well noticed
in sedimentary sequences.
Po Formation: It is composed of dark grey, pale green shale, siltstone and white grey
sandstone with shale predominantly in the middle part of the sequence. Burrows, sole
marks, ripple marks are present in quartz arenite.
Ganmachidam Formation:
It is composed of pebbly mud stone, pebbly sandstone, pebbly siltstone, conglomeratic
sandstone and black shale alternations. The entire sequence is unfossiliferous

39. Uttarakhand:
In Uttarakhand the Carboniferous is represented by Kanawar Group having two
Formations
Po Formation
Lipak Formation
These are the continuation from Spiti area
PERMIAN
In Peninsular India, after a great hiatus since the Precambrian, terrestrial deposition
commenced with pockets of glacial tillites of Upper Carboniferous followed by deposition
of terrestrial strata of the Gondwana Supergroup extending Lower Cretaceous.
In the Himalayan terrain, after the deposition of the Muth Quartzite, there was a hiatus
Frequent volcanism and intercalated plant fossils are reported in Pir Panjal Range

40. Extensive marine sedimentation is a conspicuous feature in Himalayan terrain. Marine
incursion in Permian within Peninsular India is also recorded in Rajasthan, Madhya
Pradesh and Bihar.
Permian in Jammu and Kashmir:
Panjal Volcanics: The rocks of this Group are prominently visible on the summits of Pir
Panjal range hill masses. This volcanic suits forms the central axis of the range.
Relation between successive flows indicate less time gap between successive flows.
Without erosion surface and fused nature of contact supports less time gap between
successive flows. The flows are basaltic to andesitic in nature.
Zewan Formation:
Marine fossiliferous rocks of Permian age known as Zewan Formation in Kashmir
stratigraphy are well exposed in Zewan valley in Vihi district.
Khunamuh Formation:
Dominated by Permian brachiopods and foraminifers

41. Himachal Pradesh:
Permian in HP is represented by
Kukti Formation: Carbonaceous phyllite, thin-bedded limestone calcareous phyllite,
calcarenite and pebble bed
Salooni Formation: Black shale, slate, calcareous slate and lenticles of limestone
Gechang Formation: Brown to grey, pale grey, coarse-grained weakly bioturbated
cross-bedded, calcareous sandstone with local conglomerate and/or shale lag at base.
Gungri Formation: Black shale, calcareous silty shale, phosphatic cherty calcareous
nodules and thin limestone with coquina lenses.

42. Uttarakhand Permian:
Kuling Formation : Rich in plant fossils
Arunachal Pradesh: Arunachal Himalayas remained a landmass of no sedimentation
from Neoproterozoic to Carboniferous. Paleozoic is represented by Lower Permian
rocks of Lower Gondwana Supergroup.
PENINSULAR INDIA:
Marine incursion in southern belt of Himalaya in Early Permian took place possibly
through rift valleys in Indian shield. These together with salt range through light on
paleogeography of Central India during Permian.
Umaria marine Bed:
About 3m thick marine strata occurs intercalated in Lower Gondwana strata in Umaria,
Madhya Pradesh. This bed overlies on the Talchir Boulder Bed and passes gradually
into Barakar rocks of Lower Gondwana. The marine bed is composed of sandstone and
clays with numbers of marine species like Productus, Spiriferina, Reticulariia and
Athyris.

43. It is inferred that an arm of sea was extended from the west up to Umaria and a little
beyond leading to the deposition of these sediments
Mahendragarh Marine Bed:
A marine bed of about 5m thick associated with the basal member of Talchir Formation.
This marine bed starts with shale followed by conglomerate, blackish shale, green
splintery shale and an upper member of green sandstone. Fossils are mainly confined in
the basal conglomerate bed. The faunal assemblage and their similarity with Bihar,
Darjeeling, Rajhara, West Bengal, Sikkim, Arunachal Pradesh indicate the marine
incursion from north.
But in Umaria, the faunal assemblage resembles to Salt Range, Badhaura,
Rajasthan indicate the marine incursion from west probably through the Narmada rift.
The faunal record indicate the two marine beds were deposited in different times during
Early Permian.