Neotectonism in Pondicherry

8/19/2019 Neotectonism in Pondicherry

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Curiosity about a

RavineAn attempt to unlock the mystery!


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Welcome to Pondicherry University


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Observation 1

Elevation profile along the path show


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Problem Statement 1:

▪Why such an irregularity in the elevation profile and topograph

▪ Pondicherry is in the Eastern Coast of India and there shouldn’t change in elevation profile near the sea coast.

▪ What are the possible causes for such irregularity?


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Observation 2

Presence of a huge crack as seen frGoogle Earth


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Field observation of the crack


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Inference:

▪

On field observations suggest that this crack is a “deeply incisedshaped Ravine.”

▪ This ravine seems to be extending from the central area of theuniversity to almost near the sea.


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Problem Statement 2:

▪ How did the Ravine form?

▪ What are the probable causes for it’s formation?

▪ The valleys and ravines are usually a function of gradient i.e., mthe gradient, deeper is the valley or the ravine.

▪ Coastal areas are known for very low gradients.

Need for an Explanation??


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Observation 3:


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Observation 3:


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Inference:

▪

Presence of Alternate Sandstone and conglomerate layers.

▪ Lithology of Pondicherry: Cuddalore Sandstone as the supracrcovered by marine/fluvial deposits as regolith.

▪ Conglomerates are deposited in a area where they are not usuafound.

▪ Presence of rounded angular fragments in the conglomeritic lay


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Answer Statement 3:

▪ Conglomerate deposits => High gradient and high velocity.

▪ It is a well known as that the South Western part of the Indian

Subcontinent is well elevated than the South Eastern Part.

▪ The conglomerates should be deposited somewhere in the cenpart.

▪ There must be a “Shift in the slope” in the South Eastern Partled to the deposition of the Conglomerate.


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The Grand Reconstruction


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Answer Statement 2 & 1:

▪ There could be a syn-sedimentary upliftment in the Eastern coa

This explains the deposition of the conglomerate in the area.

▪ After the consolidation of the rock mass, there could be anotheupliftment in the area.

▪ The torrential rain or stream flow in the area eroded the weak-zof the rock carving a beautiful ravine.


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Clear indication of neo-tectonic acti

▪ Evidences:

1. The ravine is the major evidence to support our theory.

2. Conglomeritic Deposits also provides an indirect evidence poito a change in slope of the area.

3. Recent seismic activity indicate a re-activated thrust fault syst

Pondicherry causing a M 5.5 earthquake in 2001.


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Pondicherry Area Remodelled using DE


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Evidence of Seismicity in Pondicher


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References

▪ DEM Data Courtesy: Mr. Lakshmi Ramprasath, Research ScholDept. of Earth Sciences, Pondicherry University.

▪ Murthy, G P S., Subrahmanyam, AS., Murthy, K S R., Sarma, K VS., 2012, Evidence of fault reactivation off Pondicherry coast fromarine geophysical data, Current Science, 1446-1449.

▪ Ravine’s Picture courtesy :https://sruthinlal.wordpress.com/2014/10/18/a-ravine-and-an-adventure-one-day-at-pondy/


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THANK YOU!

A presentation by:

G N S SREE BHUVAN andC VENKATESWAR REDDY

Integrated M.Sc. (Applied Geology) 2nd year.

Neotectonism in Pondicherry

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