creataeceous of Trichinopoly (Stratigraphy).pptx

Cretaceous of Trichinopoly

1. Cretaceous of thirchinopoly 22UGL239216 GUNASEELAN G

2. INTRODUCTION The Cretaceous Tiruchinopoly (Tiruchirappalli) Formation is a significant geological unit located in the Cauvery Basin, primarily around the Tiruchirappalli district in Tamil Nadu, India. This formation dates back to the Middle to Late Cretaceous period, roughly between 100 to 66 million years ago. It is one of the key stratigraphic units that provide insight into the Cretaceous marine environments of southern India. The Tiruchinopoly Formation is part of the larger sedimentary sequence in the Cauvery Basin, a rift basin formed during the breakup of the supercontinent Gondwana .

3. The Cretaceous succession in the thirchinopoly area is broadly divided into four widely know group: Uttatur Thirchinopoly Ariyalur Niniyur ( Early paleocene sediments)

4. UTTATUR GROUP Statigraphy : The lower stage named after the village Uttatur , lying at the western margin of cretaceou Basin The uttatur sediments range in thickness from 300 to 600 m. Albian to Turonian have been recognised in the uttatur formation. The topography is charecterized by trellis drainage and exhibits badland topography. Lithology : The sequence mainly includes limestones , shales , and sandstones. These rocks were deposited in a marine environment, indicating that the region was underwater during the period of deposition. Limestone : Description: Predominantly calcareous, indicating a high content of calcium carbonate. Shales : Description: Fine-grained, layered sedimentary rocks composed mainly of clay minerals. Sandstones: Description: Coarse to medium-grained sedimentary rocks made up of sand-sized particles, often quartz.

5. Fossil contact : The Uttatur Formation is rich in fossils, especially ammonites, belemnites, and other marine invertebrates. These fossils help in dating the rocks and understanding the paleoenvironment .

6. TRICHINOPOLY GROUP Stratigraphy : Trichinopoly (modern-day Tiruchirappalli) is located in Tamil Nadu, part of the Cauvery Basin.
The Trichinopoly Group is from the Late Cretaceous period, roughly 100 to 65 million years ago.
The group unconformably rest over the uttatur .
Formation separated from each other Conglomerate bed. Lithology : The sequence includes sandstones, shales , and limestones , representing a mix of terrestrial and marine . Sandstones: Description: Coarse to medium-grained, often showing cross-bedding. Shales : Description: Fine-grained, layered rocks composed mainly of clay minerals. Limestones : Description: Composed mainly of calcium carbonate, often fossiliferous

7. Fossils : The Trichinopoly Group is known for its marine fossils, including ammonites, molluscs, and other marine invertebrates.

8. ARIYALUR GROUP Stratigraphy The rocks in Ariyalur belong primarily to the Cretaceous period, which is about 145 to 66 million years ago. Some key formations in Ariyalur include the Sillakkudi Formation, Kallankurichchi Formation, and the Ottakoil Formation, each representing different environments and periods within the Cretaceous. The sedimentary rocks suggest that during the Cretaceous period, Ariyalur was submerged under a shallow marine environment. The sequence of rocks typically shows an upward transition from deeper marine to shallow marine environments, indicating a regression of the sea over time. Thickness is 1200 m.

9. 079388 Sillakudi(500 m) Kallankurichi(40 m) Ottakovil(60 m) Kallamedu(100) LITHOLOGY : • Sandstones, grey, light brown and white colour have been traced to a total thickness of 1000 m. • The depositional environment appears to be high-energy transgressive tidal bars or shoals. FOSSILS : Faunal remains in the sediments includes those of reptiles, fishes, cephalopods, lamellibranchs, gastropods, echinoderms and corals.

10. Sillakudi formation: • Formation comprises ferruginised arkosic sandstone and limestone bands. The fossil records include large sized Nautilus, Inoceramus, rhynconellides, echinoids, ammonites and forameniferids. Kallankurichi Formation: • The age of this unit is Upper Campanian-Early Maastrichtian. • Resting unconfromably over the Sillakudi formation. • Massive rudist bivalve carbonate shell-bank of about 40 m thickness. • It is mined for cement industry. • Lithologically it is mainly made of bioclastic packstone, grainstone facies. Bivalves brachiopods, echinoids, ammonites, foraminiferids and ostracodes

11. Ottakovil Formation: • The overlying calcareous sandstones of about 60 m thickness. • The age is Maastrichtian. Ottakovil formation is overlain by white to grey, cross bedded thick sandstones intercalated with greenish grey to red clay. Which delimit the cretaceous succession. Echinoids, Alectryonia, Eubaculites, turritellids, bryozones and echanofossils. Kallamedu Formation: • The Kallamedu sedimentary sequence, one of the least investigated sedimentary formations in South India (Ariyalur District, Tamil Nadu State). Well known for the occurrence of dinosaur remains.

12. NINIYUR GROUP : . The cretaceous succession is unconformably overlain by a thick carbonate sequence. • The carbonate sequence is of about 60 m in thickness. • Lithologically this unit is divisible in lower fossiliferous limestone, middle crystalline shelly limestone. • Upper argillaceous gritty nodular limestone collectively known as Niniyur Formation. • The fossils present include algae, cephalopods, gastropods, foraminiferids, and ostracodes suggesting an early Paleocene age. • Beds equivalent to Niniyur formation are seen in vridhachalam and Pondicherry areas.

13. Fossil Fuel Resources: The Cauvery Basin, which includes the Trichinopoly region, has been a site of petroleum exploration. The sedimentary rocks from the Cretaceous period are potential reservoirs of hydrocarbons Mineral Deposits : The Cretaceous rocks in the Trichinopoly region are known for containing important mineral deposits, including limestone, which is used in cement production, and phosphorite , which is valuable for fertilizer manufacturing Agriculture: The weathering of these rocks contributes to the fertility of the soil in the region, supporting agriculture, which is a major economic activity in Tiruchirappalli and surrounding areas. economic importance: