UNIT 16

MOVEMENT OF THE INDIAN

PLATE

Structure____________________________________________________________________
16.1 Introduction 16.7 Tectonic Features of the Indian Ocean
Expected Learning Outcomes 16.8 Activity
16.2 Geotectonic History of the Indian Plate 16.9 Summary
16.3 Rift and Drift of the Indian Plate 16.10 Terminal Questions
16.4 India-Asia Collision 16.11 References
16.5 Evolution of the Himalaya 16.12 Further/Suggested Readings
16.6 Tectonic Divisions of the Himalaya 16.13 Answers

16.1 INTRODUCTION
The theory of plate tectonics states that the rigid lithosphere of the Earth is composed of seven
major plates and numerous smaller plates, all of which are in motion in different directions. Before
break-up, India was a part of the massive southern Gondwana supercontinent. During
fragmentation of Gondwanaland, India carved out its own independent identity and got rare
distinction to be named for a plate. This is owing to its outstanding position for understanding the
several aspects of global geotectonic model as India holds key information regarding the
fragmentation of Gondwana supercontinent, opening of new ocean such as the Indian Ocean and
creation of young fold mountains belt of world namely, the Himalaya. The Indian shield India is
made up of cratons, mobile belts, suture zones, shear zones and rift valleys. The shield area of the
Peninsular India experienced these tectonic activities during the Archaean and Proterozoic eons of
Precambrian times i.e. before fragmentation of Gondwanaland. The formation of rich mineral
deposits in the Peninsular India is also a product of ancient tectonism.
The Himalayan region and Indo-Gangetic Plain of India are a product of geologically much younger
tectonism, starting from Late Mesozoic Era onwards. Initially, Indian plate after splitting from
Gondwana, moved northward across the Tethyan Sea and finally, collided with the Asian plate. The
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movement of the Indian plate from its break-up from Gondwana to its collision
with the Asian plate produced many geotectonic features within the Indian
Ocean and formed the Himalaya in the north.
In this unit, we will discuss the separation of the Indian plate from Gondwana
supercontinent, northward drift of the plate and its ultimate docking with the
Asian plate. We will also discuss the geotectonic features of the Himalaya and
the Indian Ocean.

Expected Learning Outcomes___________________________

After reading this unit, you will be able to:
 define the Indian plate;
 discuss chronology of separation of the Indian plate from rest of
Gondwanan continents;
 describe northward drift of the plate and its collision with the Asian plate;
 explain evolution and tectonic features of the Himalaya; and
 elaborate on the main tectonic features of the Indian Ocean.

16.2 GEOTECTONIC HISTORY OF THE INDIAN

PLATE
The Indian plate is a major tectonic plate straddling the equator in the Northeast
Hemisphere (Fig. 16.1). It is bordered by four major plates. The Eurasian
(consisting of Europe and Asia) plate lies to the north, the Arabian plate to the
west, the African plate including Somali to the south west and the Australian
plate to the south east. The minor Burma plate lies to the east (Fig. 16.1).

Fig. 16.1: Schematic showing position of the India plate in the Northeast
Hemisphere.

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The geotectonic history of the Indian plate began with the starting of
fragmentation of the Gondwana supercontinentand completed with its collision
with the Asian plate. By studying theory of continental drift, it becomes clear
that the Indian plate was once an integral part of Gondwana during Late
Palaeozoic Era. It was also the time, when there was only a single
supercontinent named as Pangaea. In the Early Mesozoic Era, Pangaea
started to break into two supercontinents namely Laurasia located north to the
equator and Gondwana situated south to the equator. These two
supercontinents were partially separated by awedge-shaped equatorial sea
known as Tethys Sea (Fig. 16.2).

Fig. 16.2: Palaeogeographic map of Pangaea. (Source: simplified after Smith, 1992;
Verma and others, 2016)

The Gondwana supercontinent consisted of all past southern continents such

as South America, Africa, Antarctica, Australia, India, Madagascar and micro-
continents like the Seychelles. The Gondwana started to separate by the
development of rifts from Laurasia in the beginning of the break-up of Pangaea
during Late Triassic (i.e., about 215 Million annuals (Ma) ago). In the late Early
Jurassic (nearly 180 Ma ago), Gondwana was started to separate into two parts
such as East Gondwana and West Gondwana. It is noted that for much of the
Mesozoic Era, India resided in the Southern Hemisphere as a part of East
Gondwana. Antarctica, Australia, Madagascar, and the Seychelles were also
the parts of East Gondwana (Fig. 16.2). India began to separate first from Africa
during the Middle Jurassic (around 165-150 Ma ago) that was also the time of
initial split of between East Gondwana and West Gondwana. In the middle of
the Early Cretaceous (about 130-120 Ma ago), the Indo-Madagascar block
began to disperse from Antarctica-Australia.
During the Late Cretaceous around 88 Ma ago, the India-Seychelles block
separated and drifted away from Madagascar. The Seychelles separated from
India near the Cretaceous-Paleocene boundary (66 Ma ago). Lastly, the India
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plate collided with the Asian plate during the Eocene (i.e. around 50-35 Ma
ago). It is noted that the India-Asia collision produced the world’s youngest and
highest fold mountains belt on the Earth known as Himalaya. The extent and
height of the Himalaya is so huge that it changed global climate system and
established a distinctive monsoon system for the Indian subcontinent
(Chatterjee and others, 2013; Verma and others, 2016).

16.3 RIFT AND DRIFT OF THE INDIAN PLATE

You have already read about the mantle plumes. It is thought that mantle
plumes play an important role in the rifting and subsequent drifting of the plates
and large- scale volcanic eruption of basaltic flows. When a mantle plume head
rises upward from the lower mantle or mantle-core boundary, it generates huge
quantities of basaltic magma, simultaneously alters the upper mantle
connective cells and produces divergent plate setting that led to the initiation of
continents break-up and then, their drifting and spreading with associated
massive volcanic activity (Storey, 1995). It has been observed that the rifts
within the Gondwana continents were developed by the mantle plumes. For
example, the initial rifting between East and West Gondwana was developed by
the Bouvet mantle plume, between South America and Africa by the Tristan
mantle plume, between Indo-Madagascar and Antarctic-Australia by the
Kerguelen mantle plume (Storey, 1995) as shown in Fig. 16.3. The rifting phase
of India from Antarctic-Australia is related to the rise of the Kerguelen mantle
plume and the massive basaltic eruptions of the plume led to the formation of
the Rajmahal traps in the eastern India. The Marion mantle plume is
responsible for the spilt of India from Madagascar (Fig. 16.3). The basalts of
southern Madagascar are a product of basaltic eruption of the Marion mantle
plume. The Reunion mantle plume separated the Indian plate from the
Seychelles and formed massive Deccan traps in the peninsular India (Fig.
16.3).

Fig. 16.3: Palaeogeographic map of Gondwana supercontinent around 200 Ma

ago showing the location of mantle plumes. (Source: modified after
Storey, 1995)
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The drift history of the Indian plate is remarkable (Fig. 16.4). After separating
from Gondwana in a sequential manner, the Indian plate moved northeast to
north direction and got welded with the Asian plate after collision followed by
subduction (Fig. 16.4). The movement rate or velocity of the Indian plate was
not uniform throughout its entire northward journey. It is noted that after splitting
from Antarctica-Australia in the Early Cretaceous, the Indian plate drifted
northward at a speed of 3-5 cm per year. Surprisingly, this moving speed of the
Indian plate suddenly increased at a rate 20 cm per year from Late Cretaceous
(about 67 Ma ago) to Early Eocene (about 50 Ma ago).

Fig. 16.4: Drift and speed of northward moving Indian plate. (Source: Dèzes, 1999)
Arrow indicates direction of moving Indian plate.

At present, the Indian plate is moving at a speed of 4 cm per year (Fig. 16.4).
The point that needs attention is that the Indian plate witnessed a fast rate of
movement at which any plate has moved or it has a fast moving rate relative to
adjoining plates like the African plate. There are some possible explanations
behind the fast drift of the Indian plate.
When Indian plate was moving over the Reunion hotspot, the head of the
Reunion mantle plume might have generated a strong radial plate deriving
force that was synchronising with time of the Deccan traps eruption (69 to
64 Ma ago), this increased the drift motion rate of the India plate between
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67 and 52 Ma ago and afterwards plate movement was slowed down
between 52 and 45 Ma ago prior to the initiation of India-Asia collision and
this fall of speed was associated with waning of the plume force.
It is suggested that after moving over several mantle plumes such as
Kerguelen, Marion and Reunion in different Mesozoic times, the lithospheric
thickness of the Indian plate was reduced to a considerable extent. As a
result, the dragging force between the Indian lithosphere and underlying
asthenosphere also got reduced and thus, allowing the Indian plate to move
at a much faster rate until it collides with the Asian plate.
The drift velocity of the Indian plate was again decreased dramatically to
around 4 cm per year between 50 and 35 Ma ago. It is suggested that this
decrease in speed of the plate is associated with the onset of the India-Asia
collision. It is worth noting that the Indian plate completed its northward journey
between the two tectonic features such as Ninety-East Ridge to the east and
Owen-Chaman Fault to the west of the plate (Fig. 16.5).

Fig. 16.5: Map showing present day position of Ninety East Ridge and Owen-
Chaman Fault. (Source: simplified after Chatterjee and others, 2013)
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The Neo-Tethyan Sea was located to the north of the Indian plate. As the
Indian plate was started moving towards the Asian plate after separating from
Gondwana, the Neo-Tethyan Sea located to the north of the plate, was slowly
becoming narrow as the plate was progressing and finally, it got consumed at
the time of India-Asia collision. On the other hand, the Indian Ocean is created
on the southern portion of the Indian plate.

SAQ 1
a) Define Indian plate.
b) What are Pangaea, Laurasia and Gondwana?
c) When did India separate from Africa, Australia-Antarctica and Madagascar?

16.4 INDIA-ASIA COLLISION

The collision of the Indian plate with the Eurasian plate (including Asian plate)
led to the formation of the Himalaya and upliftment of the Tibetan plateau. It is
noted that India-Asia collision is not a single tectonic event, but it happened in
the phased manner. As you know that the Tethyan Sea was existed before the
collision of plates and opening of the Indian Ocean. Indeed, the northern
Laurasian supercontinent separated from the southern Gondwanan
supercontinent by the Tethyan Sea during Late Palaeozoic and Mesozoic eras
(Fig. 16.2). First, during the Late Permian (260-250 Ma ago), a block known as
Lhasa block broke-off from the Gondwana, this was consisting of present
Turkey, Iran and Tibet and that having Neo-Tethyan Sea in the southwest and
the Meso-Tethys in the northeast (Fig. 16.6). The Lhasa block separation is
marked by widespread occurrence of Permian Panjal volcanics in Kashmir,
India. Later, the Lhasa block moved northward and collided with growing Asian
continent in late Jurassic to earliest Cretaceous and its collision zone marked
by a suture known as Bangong-Nujiang suture (Chatterjee and others, 2013).

Fig. 16.6: Palaeogeographic map of Gondwana showing Neo-Tethyan Sea.

(Source: modified after Shah, 2018)
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During the Cretaceous period, an intra-oceanic island arc system (also known
as Neo-Tethyan arc system) was developed within the Neo-Tethyan Sea in
response to northward drift of the Indian plate that split the Neo-Tethyan Sea
into two oceanic plates (Fig. 16.7a). The first plate was situated between
northern margin of the Indian plate and the southern margin of intra-oceanic arc
system and second plate was located between northern margin of intra-oceanic
arc system and southern margin of the Asian plate. It may be noted that intra-
oceanic arc system represents a north dipping subduction zone (Fig. 16.7a)
and consists of Kohistan-Ladakh arc and terranes of Zedong, Dazhuqu and
Bainang of the today’s Lhasa block (Aitchison and others, 2000; Chatterjee and
others, 2013).

Fig. 16.7: India-Asia convergence and collision: a) Development of intra-oceanic

island arc system within the Tethyan Sea; b) Collision of the Indian
plate with intra-oceanic island arc system; and c) Final India-Asia
collision and formation of the Himalaya. (Source: simplified after Aitchison
and others, 2000; Chatterjee and others, 2013)

In order to accommodate the northward movement of the Indian plate towards

the Asian plate, the subduction took place at two north dipping subduction
zones forming Shyok trench along the northern margin of the Asian plate and
Indus trench along the northern margin of the intra-oceanic island arc system
between the Indian and Asian plates (Fig. 16.7a). The collision between India
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and Asia took place in two phases. First phase involves collision of intra-
oceanic island arc with the Indian plate along the Indus suture zone (Fig.
16.7b). It is still not clear whether the intra-oceanic island arc system first
collided with Asia or India. In fact, many researchers suggested various ages,
ranging from 95 to 50 Ma ago (Late Cretaceous to Palaeocene), in which this
tectonic event took place. In second phase, both intra-oceanic island arc and
the Indian plate moved northward and finally, collided with the Asian plate (Fig.
16.7c) during Eocene (i.e. around 50-35 Ma ago) along the Shyok suture zone
(Shah, 2018). It is to be noted that India-Asia collision is diachronous to which
the Indian plate first was subducted at northwestern margin and later collision
process continuously progressed towards southeast with change in direction of
movement of plate from north to northwest.
The India-Asia collision is a hard continent-continent collision that resulted to
the formation of the biggest and youngest fold mountains belt of the world
known as Himalaya. The fast-northward drift and collision of the Indian plate
with Asia first caused narrowing of Neo-Tethyan Sea and secondly, final
closure of Neo-Tethyan Sea at the time of collision of the Indian plate with Asia
during Eocene and thirdly, ceased fast northward movement of the Indian plate.
It is noted that the buoyant Indian plate did not subduct any further beneath the
Asian plate after the closure of Neo-Tethyan Sea. Thus, subduction process
became slow and subduction related igneous activity welded northern margin of
the Indian plate with southern margin of Asian plate along a suture zone known
as Indus-Tsangpo suture zone (Chatterjee and others, 2013). The presence
of ophiolites along the Indus-Tsangpo suture zone and in northern part of
Uttarakhand where they were described as “Exotic Blocks” of Malla, Johar and
Hundus are considered as the evidences of the consumed Neo-Tethyan Sea
floor during the subduction process. The Shyok suture is considered as collision
zone between Indian plate and intra-oceanic island arc system.

16.5 EVOLUTION OF THE HIMALAYA

The Himalayan mountain belt is 2400 km long and about 240 to 320 km wide,
situated between Indus River (Nanga Parbat Mountain in Pakistan) in the west
and Brahmaputra River (Namche Barwa mountain in Tibet) in the east. It is
located in the northern margin of the Indian plate. The Himalaya is a result of
many deformational phases of upliftment of its thick sedimentary succession
that accumulated in the Tethyan Sea and other older and younger basins
before and during the actively progressing India-Asia collision. Valdiya (1984)
proposed evolution (elimination of sea to present mountain shape) of the
Himalaya in four different phases and named them as Karakoram, Malla Johar,
Sirmurian and Siwalik phases.
Karakoram Phase: It occurred during the Late Cretaceous to Palaeocene
times and represents the continental convergence between India and Asia.
During this phase, an island arc-oceanic trench complex was evolved in the
southern margin of the Asian plate. A chain consisting of the Karakoram-
Kailas-Lhasa of the Asian continent came-up as a landmass from the
Tethyan Sea due to convergence of the Indian plate with the Asian plate.
This phase represents the upliftment of the Karakoram chain and marks the
subduction stage in the evolutionary history of the Himalaya.
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Malla Johar Phase: It took place during the Late Eocene to Oligocene
times and represents a collision and obduction stage in the evolutionary
history of the Himalaya. In this phase, the Indian plate collided to the Asian
plate and caused to the obduction of the oceanic material of the Tethyan
Sea. The pressure generated by converging Indian plate with the Asian
continent led to development of high pressure metamorphic rocks, mélange
zones, ophiolites and southward transportation of large blocks as nappes.
These features can be seen at Malla Johar in Kumaun and Tso Morari in
Ladakh.
Sirmurian Phase: It operated during Miocene times and marks an interval
of dramatic renewal of tectonic activity in the Himalayan mountains belt. The
main Himalayan tectonic features including Main Central Thrust were
developed during this phase. In addition, Himalayan mountains belt also
attained maximum complexity in its structural architecture.
Siwalik Phase: The Himalaya witnessed this phase during Pliocene to
Middle Pleistocene. In this phase, the Main Boundary Thrust was developed
between the Lesser Himalaya and the Outer Himalaya consisting of vast
sedimentary cover of the Siwalik sediments. The Siwalik sediments were
also uplifted and folded in this phase and a vast depression was developed
in front of uplifted Siwalik sediments where sediment derived from the rising
Himalaya are getting accumulated and thus, formed the Great Indo-
Gangetic plain of the northern India or Great Indian Molassic basin.

16.6 TECTONIC DIVISIONS OF THE HIMALAYA

The Himalayan mountains belt is one of the longest systems of mountain
chains in the world. It is an arcuate range with convexity to the south. It has two
major knee-bends one in the west around Nanga Parbat and the other in the
east at Namche Barwa, which are commonly referred to as hair pin or syntaxial
bends. The Himalaya can be linearly divided into five parallel ranges from north
to south (Fig. 16.8). And, each range is separated by a prominent tectonic
feature as shown in Table 16.1.

Table 16.1: Main tectonic features of Himalaya.

Trans Himalaya
------ Indus-Tsangpo Suture Zone ------
Tethyan Himalaya
------ Tethyan Thrust ------
Greater/Higher Himalaya
------ Main Central Thrust ------
Lesser Himalaya
------ Main Boundary Thrust ------
Outer Himalaya
------ Himalayan Frontal Thrust ------
Indo-Gangetic Plain

Let us discuss divisions and tectonic features of Himalaya.

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(i) Trans Himalaya: It consists of southern region of the Asian plate and
northernmost part of the India plate (Fig. 16.8). It is located north of the
Tethyan Himalaya and mainly developed in the northern Ladakh and the
northernmost Pakistan. It consists of Kohistan, Shyok, Karakoram regions.
The Trans Himalaya is also known as the Tibet Himalaya because its major
portion occurs in Tibet.
The Indus-Tsangpo Suture Zone is the tectonic suture lies between the
northern margin of the Himalaya and southern margin of the Asian plate
consisting of Trans Himalaya. This suture zone marks the collision zone
between the Indian and the Asian plates (Fig. 16.8).
(ii) Tethys Himalaya: It is the northernmost region of the Himalaya extending
partly into Tibetan plateau. It is given the popular geological name “Tethyan
domain” having more than 10 km thick sedimentary sequence Late
Proterozoic to Eocene age (Fig. 16.8).
The Tethyan Thrust is a tectonic feature that separates the Tethyan
Himalaya from the Greater Himalaya (Fig. 16.8) and somewhere it appears
as normal fault or detachment zone and in some locations contact is
gradational.
(iii) Higher/Greater Himalaya: It lies to the south of the Tethys Himalaya and is
the highest part of Himalaya. The tectonic feature termed as Main Central
Thrust demarcates the boundary between the Higher and the Lesser
Himalaya (Fig. 16.8). The Higher Himalaya is also given the Sanskrit name
Himadri means snow covered, this is due to presence of glaciers in this
region. It bears some of the highest mountain peaks including the Mount
Everest and Zanskar, Ladakh and Karakoram are the main mountain
ranges. Higher Himalaya is made up mainly of highly deformed
metamorphosed sedimentary and intrusive granitic rocks of many ages.
(iv) Lesser Himalaya: It lies to the south of the Greater Himalaya (Fig. 16.8).
The Pir Panjal, Dhauladhar, Nag Tibba and Mahabharat are common high
ranges of the Lesser Himalaya. The terrain is characterised by a complex
structure consisting of superimposed thrust sheets. The Main Boundary
Thrust demarcates the tectonic boundary between the Lesser and Outer
Himalaya (Fig. 16.8).
(v) Outer Himalaya: The southern-most part of the Himalaya is called Outer
Himalaya or Sub-Himalaya (Fig. 16.8). It comprises low hills of maximum
1500 m heights that merge finally with the Indo-Gangetic plains. Himalayan
Siwalik in some regions is treasure house of vertebrate animal fossils which
are highly useful for study of animal evolution. The tectonic boundary
between the Outer Himalaya and Indo-Gangetic plains is marked by the
Himalayan Frontal Thrust (Fig. 16.8).

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Fig. 16.8: Map showing major ranges of the Himalaya. (Source: simplified after
Kumar, 1988)

16.7 TECTONIC FEATURES OF THE INDIAN

OCEAN
As you have already learned that the break-up of the Gondwana and
subsequent northward drift of the Indian plate led to the origin of the Indian
Ocean towards the southern margin of the Indian plate. The Indian Ocean is
smaller than that of the Pacific and Atlantic oceans. It is unique ocean because
it is bounded by the shield areas of Africa and Arabia to the west, India to the
north, Australia to the east and Antarctica to the south. The volcanic arc of
Indonesian archipelago lies to northeast (Fig. 16.9). It joins the Atlantic Ocean
through the southern tip of Africa and its east and southeast margins mix with
the Pacific Ocean. The inverted Y-shaped Mid-Oceanic Ridge pattern of the
Indian Ocean formed by joining its main ridges divides the ocean into three
regions such as western, eastern and southern Indian Ocean (Naqvi, 2005; Fig.
16.9). The central portion represents central Indian Ocean. There are many
tectonic features developed within the Indian Ocean in response of northward
drift of the Indian plate and its collision with the Asian plate.
The main typical tectonic features are Mid-Indian oceanic ridge (Southwest
Indian Ridge, Southeast Indian Ridge and Central Indian Ridge), Carlsberg
Ridge, Chagos-Laccadive Ridge, Ninety-East Ridge, Broken Ridge and
Kerguelen Plateau (Fig. 16.9).

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Fig. 16.9: Map showing main tectonic features of the Indian Ocean. (Source:
simplified after Talley and others, 2011)

Mid-Indian Oceanic Ridge: It includes active oceanic ridge system of the

Indian Ocean namely, Carlsberg Ridge and Central Indian Ridge. The
Carlsberg Ridge is located in the western Indian Ocean and separates the
Arabian Sea from the Somali basin. The Central Indian Ridge is a north-
south orienting mid-oceanic ridge situated in the western Indian Ocean (Fig.
16.9). It is to be noted that at the southern end, the Central Indian Ridge
divided into two parts such as Southwest Indian Ridge and Southeast Indian
Ridge (Fig. 16.9). The Southwest Indian Ridge is situated in the south
western Indian Ocean and forms a divergent plate boundary between Africa
and Antarctica. The Southeast Indian Ridge lies in the south eastern Indian
Ocean and forms a divergent plate boundary between Australia and
Antarctica.
Chagos-Laccadive Ridge: It is situated in the Western Indian Ocean and
marks the western limit of the Central Indian Ocean (Fig. 16.9). It is about
2500 km long in north-south direction and consisting of islands Chagos,
Maldives and Laccadive. This ridge was formed by the volcanic eruption of
the Reunion mantle plume when the Indian plate passed over it.
Ninety-East Ridge: The strike of Ninety-East Ridge is nearly parallel 90°
longitude at the center of the Eastern Hemisphere. Therefore, it is also
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known as 90°E Ridge. This nearly 5000 km long and 150 to 250 km wide
aseismic ridge divides Indian Ocean into the Western and the Eastern
Indian Oceans. The northern margin of the ridge is submerged under the
sediments of Bengal fan in the Bay of Bengal and its southern margin joins
the Broken Ridge (Fig. 16.9). The Ninety-East Ridge is a product of volcanic
eruption of the Kerguelen mantle plume. Both, the Ninety-East Ridge and
the Chagos-Laccadive Ridge marks the traces of the progressive northward
movement of Indian plate after its separation from Africa, Antarctica,
Australia and Madagascar.
Broken Ridge: It is an oceanic plateau located in south eastern Indian
Ocean. It is about 1200 km long and 400 km wide orienting from northeast
to southwest direction. Its northwest margin is located in close proximity of
the southern end of the Ninety-East Ridge (Fig.16.9). Its origin is closely
related with the separation of Australia from Antarctica.
Kerguelen Plateau: It is an oceanic plateau and situated in the Southern
Indian Ocean near the northern margin of Antarctica continental block (Fig.
16.9). This plateau is a product of volcanic eruption of the Kerguelen mantle
plume, which marks the initiation of split between India and Australia-
Antarctica.
Before proceeding further, let us have a short break to check your progress.

SAQ 2
a) Himalaya is a product of -----------.
b) List four evolutionary phases of the Himalaya.
c) Name the main tectonic features of the Himalaya.
d) Write tectonic features of the Indian Ocean.

16.8 ACTIVITY
The map given in Fig. 16.10 is showing the Indian Ocean. Study the map and
demarcate and label the following tectonic features of the Indian Ocean:
Southwest Indian Ridge, Southeast Indian Ridge, Central Indian Ridge,
Carlsberg Ridge, Chagos-Laccadive Ridge, Ninety-East Ridge, Broken Ridge
and Kerguelen Plateau. You may consult Fig. 16.10.

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Fig. 16.10: Map of the Indian Ocean.

16.9 SUMMARY
Let us now summarise what you have read in this unit:
The Indian plate is a major tectonic plate straddling the equator in the
Northeast Hemisphere and is bordered by the Eurasian, Arabian, African
and Australian plates.
The geotectonic history of the Indian plate began with the starting of
fragmentation of the former supercontinent Pangaea.
India was first separated from Africa during the Middle Jurassic, from
Antarctica-Australia in the Early Cretaceous, from Madagascar during the
Late Cretaceous and finally, collided with the Asian plate in the Eocene.
The drift history of the Indian plate is remarkable. After separating from
Gondwana, the Indian plate moved northward with different velocity, initially
at 3-5 cm per year, which later increased at 20 cm per year before the
collision with Asia and now, it is moving at a speed of 4 cm per year.
The Himalayan mountains chain is a product of India-Asian collision that
took place in the Eocene and still progressing.
The Tethyan Sea was wholly consumed during India-Asian collision and its
oceanic material subducted and obducted and finally gave rise to Himalaya.
Himalaya evolved in four phases such as Karakoram, Malla Johar,
Sirmurian and Siwalik involved in the evolutionary history of the Himalaya.
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Tethyan Thrust, Main Central Thrust, Main Boundary Thrust, and Himalayan
Frontal Thrust are the main tectonic features of the Himalaya.
The southwest Indian ridge, southeast Indian ridge, central Indian ridge,
Carlsberg ridge, Chagos-Laccadive ridge, Ninety-east ridge, Broken ridge
and Kerguelen Plateau are the main tectonic features of the Indian Ocean.

16.10 TERMINAL QUESTIONS

1. Describe the geotectonic history of the Indian plate.
2. Give an account of India-Asia collision and origin of Himalaya.
3. Discuss the evolution of Himalaya.
4. Describe the tectonic features of the Himalaya and Indian Ocean.

16.11 REFERENCES
Aitchison, J.C., Badengzhu, Davis, A.M., Liu, J., Luo, H., Malpas, J.G.,
McDermid, I.R.C., Wu, H., Ziabrev, S.V., Zhou, M. (2000) Remnants of a
Cretaceous intra-oceanic subduction system within the Yarlung-Zangbo
suture (southern Tibet), Earth and Planetary Science Letters, 183: 231–244.
Chatterjee, S., Goswami, A. Scotese, C. (2013) The longest voyage:
tectonic, magmatic, and paleoclimatic evolution of the Indian plate during its
northward flight from Gondwana to Asia, Gondwana Research, 23: 238–
267.
Dèzes, P. (1999) Tectonic and Metamorphic Evolution of the Central
Himalayan Domain in Southeast Zanskar (Kashmir, India), Mémoires de
Géologie (Lausanne), 32: 1-150.
Kumar, R. (1988) Fundamentals of Historical Geology and Stratigraphy of
India, New Age International Publishers, New Delhi.
Naqvi, S.M. (2005) Geology and Evolution of the Indian plate (from Hadean
to Holocene – 4Ga to 4Ka), Capital Publishing Company, New Delhi.
Shah, S.K. (2018) Historical Geology of India, Scientific Publishers,
Jodhpur.
Smith, A.G. (1992) Plate tectonics and continental drift, In: Understanding
the Earth, Cambridge University Press, Cambridge.
Storey, B.C. (1995) The role of mantle plumes in continental breakup: case
histories from Gondwanaland, Nature, 377: 301–308.
Talley, L.D., Pickard, G.L., Emery, W.J., Swift, J.H. (2011) Descriptive
Physical Oceanography: An Introduction, Elsevier, New York.
Valdiya, K.S. (1984) Evolution of the Himalaya, Tectonophysics, 105: 229–
248.
Verma, O., Khosla, A., Goin, F.J., Kour, J. (2016) Historical biogeography of
the Late Cretaceous vertebrates of India: comparison of geophysical and
paleontological data, New Mexico Museum of Natural History and Science
Bulletin 71: 317–330.

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Unit 16 Movement of the Indian Plate
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16.12 FURTHER/SUGGESTED READINGS

Biyani, A.K. (2007) Dimensions of Himalayan Geology, Satish Serial
Publishing House, Delhi.
Valdiya, K.S. (1984) Aspects of Tectonics: Focus on South-Central Asia,
Tata McGraw-Hill, New Delhi.
Valdiya, K.S. (2016) The Making of India: Geodynamic Evolution, Society of
Earth Scientists Series, Springer International Publishing Switzerland.

16.13 ANSWERS
Self Assessment Question 1
a) The Indian plate is a major tectonic plate straddling the equator in the
Northeast Hemisphere (Fig. 16.1). It is bordered by four major plates such
as Eurasian (consisting of Europe and Asia) plate, Arabian plate, African
plate and Australian plate.
b) Pangaea: It was a supercontinent comprised Gondwana and Laurasia and
existed during Late Palaeozoic Era.
Laurasia: It is northern part of the Pangaea and composed of North
America, Europe and Asia.
Gondwana: It is southern part of the Pangaea and consisted of South
America, Africa, Antarctica, Australia, India and Madagascar.
c) India separated from Africa in the Middle Jurassic (around 165-150 Ma
ago), Australia-Antarctica in the Early Cretaceous (about 130-120 Ma ago)
and Madagascar during the Late Cretaceous around 88 Ma ago.
Self Assessment Question 2
a) India-Asia collision.
b) The four evolutionary phases of the Himalaya are Karakoram, Malla Johar,
Sirmurian and Siwalik.
c) The main tectonic features of the Himalaya are Tethyan Thrust, Main
Central Thrust, Main Boundary Thrust and Himalayan Frontal Thrust.
d) The major tectonic features of the Indian Ocean are Mid-Indian oceanic
ridge (Southwest Indian Ridge, Southeast Indian Ridge and Central Indian
Ridge), Carlsberg Ridge, Chagos-Laccadive Ridge, Ninety-East Ridge,
Broken Ridge and Kerguelen Plateau.
Terminal Questions
1. Please refer to section 16.2.
2. Please refer to section 16.4.
3. Please refer to section 16.5.
4. Please refer to section 16.7 and 16.7.

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Block 4 Plate Tectonics and Movements
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