Carbonate/phosphate-dominated mineral deposits are abundant in the early Earth?s history but their occurrence is sporadic in the present day marine environment. These minerals usually form during the early diagenesis at near-surface organic-rich sediments. Although formed at different environmental settings, the role of organic or inorganic processes in controlling their formation are still debated and yet to be precized. In the XI plan we plan to work on Quaternary / Modern carbonate and phosphate deposits and identify the role microbial organisms in their formation.

Objectives:

• Origin of late Quaternary carbonates (aragonite and ferruginized ooids) along the western margin of India
• Origin of late Quaternary dolomites and phosphatic sediments of the Gulf of Kachchh
• Early diagenetic changes in near surface organic-rich sediments in sediment cores along the western margin of India and
• Establish linkages with ancient mineral deposits by showing Quaternary/modern analogues along the western margin of India.

General description: 

The Earth is believed to be 4.5 X 109 years old. The oldest known sedimentary rocks on the Earth’s surface are 3.4 X 109 years old and preserved traces of life in the form of microfossils, resembling the remnants of bacteria and blue-green algae. However the genetic link between microfossils and minerals has come to light only after the discovery of stromatolites dated 2.7 to 3.0 X109 years age.  The stromatolites are defined as laminated organo-sedimentary deposits form from sediment trapping and binding and precipitation because of metabolic activity, principally by cyanobacteria. The mineral deposits such as carbonates, phosphorites and iron, believed to be of stromatolitic origin are usually formed in shallow continental shelves in the early Earth’s history. The stromatolitic deposits were predominant and wide spread during early Palaeozoic and Precambrian, declined through time and are restricted to few locations such as Shark Bay, Australia and Bahamas in the present day. The microorganisms such as cyanobacteria exist even in the present day implying that their basic structure or biochemical functions may have been similar to those of their ancestors. However it is not understood why such mineral deposits are not wide spread in the present day? Are climatic/environmental conditions entire different? Moreover the early Earth’s conditions cannot be precisely assessed from the investigations of older deposits as they have undergone different degrees of metamorphism and cycles of reworking  If similar mineral deposits of Quaternary / Modern occur on continental margins one can work out detailed information regarding conditions and processes that controlled their formation. Therefore the need of the hour is to investigate the genetic aspects of Quaternary / Modern mineral deposits and see whether their environment of their formation can be linked to the ancient mineral deposits.

Scientific components and achievements:

To some extent phosphate deposits from  wide variety of marine topographic settings were investigated and identified the role of micro-organisms in their formation. Similar studies need to be carried out on carbonates (aragonites, dolomites and ooids)

Facilities available:

Basic facilities such as Scanning Electron Microscope,  X-ray diffractometer, ICP-AES, Mass spectrometer etc. are available in the Institute.