Gondwana Flora

UG LEVEL GEOLOGY

1. Dr. C.P. Dorlikar GONDWANA FLORA

2. CONTENT Introduction Formation Content&microcontent Fossils in Gondwana Gondwana flora Summary Reference

3. INTRODUCTION Gondwanaland, is the name given to the more southerly of two supercontent . that were part of the Pangaea supercontinent that existed from approximately 510 to 180 million years ago . Gondwana formed prior to Pangaea, then became part of Pangaea, and finally broke up after the breakup of Pangaea. Gondwana is believed to have sutured between about 570 and 510  Mya , thus joining East Gondwana to West Gondwana .

4. Pangaea Map with Laurasia & Gondwana

5. FORMATION The assembly of Gondwana was a protracted process. Several orogenies led to its final amalgamation 550–500  Mya at the end of the Ediacaran , and into the Cambrian. These include the Brasiliano Orogeny , the East African Orogeny , the Malagasy Orogeny , and the Kuunga Orogeny . The final stages of Gondwanan assembly overlapped with the opening of the Iapetus Ocean between Laurentia and western Gondwana . During this interval, the Cambrian explosion occurred .

6. Azania: much of central Madagascar, the Horn of Africa and parts of Yemen and Arabia (Named by Collins and Pisarevsky (2005): "Azania" was a Greek name for the East African coast.) The Congo–Tanzania–Bangweulu Block of central Africa; Neoproterozoic India: India, the Antongil Block in far eastern Madagascar, the Seychelles, and the Napier and Rayner Complexes in East Antarctica. The Australia/ Mawson continent: Australia west of Adelaide and a large extension into East Antarctica Other blocks which helped to form Argentina and some surrounding regions, including a piece transferred from Laurentia when the west edge of Gondwana scraped against southeast Laurentia in the Ordovician This is the Famatinian block (named after Famatina in northwest Argentina) and it formerly continued the line of the Appalachians southwards. Content & microcontent

7. FOSSILS IN GONDWANA FLORA: - Brongniart , in the early 1880s, describe and illustrated Glossopteris browniana var. indica and Glssopteris angustifolia from the Raniganj coalfield. Ottokar Feistmantel not only undertook an exhaustive and intensive monograpfic study of Gondwana plants but also used the information for age determination and palaeobotanical zonation . The sparsely developed Triassic flora gave place to well developed Ptilophyllum flora seen in Rajmahal Hills and Jabalpur area .

8. Fig-A-Glossopteris angustifolia Fig-B- Gangamopteris Fig-C- Ptilophyllum flora Fig-D- Dicrodium GONDWANA FLORA:- Fig-E- Glossopteris flora

9. SUMMARY The Gondwana basin of India represents about 200 million year of Geological records of Peninsular India. The basin originally evolved as sag basins but later on switched over to fault controlled basins in response to large scale tectonic movments many of which are Pan-Gondwana land events. Gondwana flora support the continental drift concept. Gondwana fossils helps in Palaeoenvironment . Also, Gondwana fossils helps in the exploration of coal.

10. REFERENCE Krishnan, M.S.(1982) Geology of India and Burma, C.B.S. Publ. and Distributors, Delhi, PP-274-299 Vaidynadhan , R. and Ramkrishnan , M.(2008) Geological Society of India,Vol.2, Geology Society Of India, Banglore .

11. Thank you