Geosyncline

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2. CONTENT
INTRODUCTION
GEOSYNCLINES
 HISTORY OF GEOSYNCLINES
TYPES OF GEOSYNCLINES
MECHANISM OF MOUNTAIN FORMATION
CONCLUSION
REFERENCE
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3. Introduction
 Geosynclines refers to thick pile of sediments that
were deposited in a deep marine basin & subsequently
compressed, deformed& uplifted in to a mountain range
, with associated volcanism .
The filling of a geosynclines with tons of sediment is
accompanied in the late stages of deposition by
folding, and faulting of the deposits.
Intrusion of crystalline igneous rock and regional
uplift It is then transformed into a belt of folded
mountains.
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4. History of geosyncline
 The geosynclinal concept first developed by
American geologists James hall & J D Dana during the
 studies of Appalachian mountain.

They 1st
to convince the ideas of sinking
Geosyncline&their relation to orogeny
Dana was 1st
to use the term geosyncline
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5. Cont…
This concept was later developed E Haug (1900)
in Europe with some modification.
 Haug also established the existence of geosynclines
in the regions of the present day mountain ranges.
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6. Types of geosynclines
Broadly geosynclines are classified in to two:
Orthogeosynclines
Parageosynclines
Ortho geosyncline: These are elongated basins which
become filled with very great thickness of sediments,
which is subsequently deformed to form a fold
mountain chain. These are divided in to two:
Eugeosyncline
Miogeosyncline
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7. Eugeosyncline:
 These are found far away from continental crust. In
these geosyncline, the pile of sediments are found with
an abundance of volcanic rock; these are formed at some
distance from the shield area.
Eugeosynclinal rocks include thick sequence of grey
wack,chert,slate and sub marine lavas. Here the
deposits are more deformed and metamorphosed and
intruded by small to large igneous plutons.
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8. Miogeosynclines: A miogeosyncline develops along a continental
margin on continental crust and is composed of sediments with lime
stones, sandstones and shale.
 The occurrences of lime stones and well-sorted quartz, sandstones
indicate a shallow-water formation, and such rocks form in the inner
segment of a geosyncline.
 Modern examples include the continental shelf of the northern Gulf
of Mexico and the Atlantic coast of North and South America.
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10. 2.Para geosyncline: it is an opeirogenic geosynclinal
basin located within a craton having oval in
shape. It is less active than eugeosyncline and
having shorter lifes. Para geosynclines are
again divided in to 3.
 Exogeosyncline
Zeugogeosyncline
 Autogeosyncline
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11. Exogeosyncline: It is a parageosyncline that lies along the
cratonal border and obtains its clastic sediments from erosion of
the orthogeosynclinal belt outside the craton. It is also known as
delta geosyncline.
 Zeugogeosyncline: A geosyncline in a craton or stable area,
within which is also an uplifted area, receiving clastic sediments.
Also known as yoked basin.
Autogeosyncline: It is a parageosyncline located as isolated
depositional centre within a craton and gave sediments from distant
cratons.
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14. Charles schuchert(1923)has recognized three
types of geosynclines
 monogeosyncline: This is a long relatively narrow
sinking structural basin, similar to that postulated by Dana
&Hall situated either with continent or just on its borders. A
monogeosyncline gives rise to a single mountain ranges.
eg:appalchian geosyncline of America.
CHARLES
SCHUCHERT(1923)
classification
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15. Polygeosyncline: This is a complex of a
number of monogeosyncline whose axes are more
or less parallel to each other. Polygeosynclines are
relatively wider, long enduring & give rise to
mountain ranges.
e.g.: rocky mountain orogeny
Mesogeosyncline: This is a complex of
several monogeosyncline whose axes not parallel
to each other. They are very narrow elongated
mobile ocean basin bordered by continents.
e.g.: The Himalayan orogeny
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16. Mechanism of mountain
formation
(Geosynclinal Theory)
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17. Geosynclinal Theory
According to geosynclinal theory
Folded mountain originate in three phases over a very
long period of time of millions of years.
1.geosynclinal phase(evolution of geosyncline)
2.tectonic phase( revolution of geosyncline )
3.orogenic phase( collapse of geosyncline)
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18. Geosynclinal phase
formation of geosyncline & accumulation of
sediments in an elongated lens-like shape to
estimated thickness of 10000 to20000 m. As the
sediments get accumulated the floor of the
geosyncline begin to subside due to continuosly
increasing weight on it.
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19. Tectonic phase
when the sediment become deeply
buried in considerably warmer zone, their
strength gets reduced by heat & pressure and
become plastic and yield to deforming
compressive forces by folding.
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20. Orogenic phase
The elevated foreland slowly encroach on
the geosyncline like the jaws of a vice exterting
great horizontal compressive force on the
sediments. By this sediments get further folded
followed by igneous activity, emplacement of
dikes & batholiths and upheaval give rise to
mountain ranges of tens of thousands of meters
elevation.
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21. conclusion
Geosynclines is a subsiding linear trough that was caused
during accumulation of succeeding sediments and volcanic
rocks.
 sediments were deposited in a deep marine basin &
subsequently compressed, deformed& uplifted in to a
mountain range , with associated volcanism .
 The geosynclinal theory is of fundamental importance to
sedimentation, petrology, geomorphology, ore deposits,
structural geology, geophysics, and in fact all branches of
geological science.
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22. B S Sathya narayanaswamy (1994), structural geology , Dhanpat rai and sons
publications, p.p-168 to 170.
Girija bhushan mahapatra (2008), A text book of geology(with special
reference to India), cbs publications
,p.p-30 to32
• L U De Sitter (1956),structural geology, McGraw hill book company,p.p-
349-355
• Jean Aubouin(1965),geosyncline,ELSEUIER publisher company,p.p-18-
19,26-29
• Websites
www.goole.com
www.wikepedia .com
reference
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