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FORAMINIFERA: PART 1 - AN INTRODUCTION

FORAMINIFERA: PART 1 - AN INTRODUCTION. FORAMINIFERA. Single-celled Amoeba- like Testate & usually multichambered Net-like pseudopods Anastomosing & Reticulating Dimorphic life cycles are complex Nearly 4 000 genera known 60 000 species known!. LIVE FORAM.

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FORAMINIFERA: PART 1 - AN INTRODUCTION

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  1. FORAMINIFERA:PART 1 - AN INTRODUCTION

  2. FORAMINIFERA • Single-celled • Amoeba- like • Testate & usually multichambered • Net-like pseudopods • Anastomosing & • Reticulating • Dimorphic life cycles are complex • Nearly 4 000 genera known • 60 000 species known!

  3. LIVE FORAM • Note pseudopodia capturing food particles • Note multichambered calcareous skeleton

  4. MULTICHAMBERED FORAM SKELETON

  5. DIFFERENT SPECIES OF FORAMS

  6. FORAMINIFERA • 50 to 60 species of living planktic forams • Many thousands of living benthic species • ~1 000+ genera living • Up to 1 million individuals per square metre benthos • Movement-feeding categories: • Crawling: • Mudeaters (detritus feeders) • Micropredators • Herbivores • Burrowing mudeaters • Reclining suspension feeders • Encrusting suspension feeders

  7. Microscopes used in Studies • Transmitted light – whole mounts • Transmitted light – thin sections • Reflected light • SEM

  8. Sample Preparation • Study unconsolidated sediments as the 1st choice • Wash (heat & baking soda) any fines from sediments • Sieve coarse and separate sand fractions • Juveniles tend to look alike – even among different genera, so pick 0.125 mm fraction & above • Some shale can be broken down by heating in water & soaking in organic solvents. Then, treated as above. • Other rocks: Simply boiling crushed samples with baking soda helps to release some sediment • Thin sections may be resorted to, but usually thin section studies not very effective, except for fusulinids & a few other kinds of forams.

  9. Generalized History Based on Wall Composition & Structure • Note: • Early organic walled & arenaceous forams in Cambrian • Calcareous microgranular forams in Ordovician • Porcelaneous in Carboniferous • Hyaline in Permian • Planktic in Late Jurassic • Nummulitids = Late K to Early Cenozoic

  10. Review Early History of Forams

  11. Review Later History of Forams

  12. CHALK = FORAMS IN A "FINE-GRAINED MATRIX"

  13. Application of Foram Studies • Very useful indicators for • Biostratigraphy • Dating • Correlation • Paleoenvironments • Depths • Climates • Habitats • Paloeautecology (species) & paleosynecology (community) • Evolution • Gradualistic phenomena • Punctuated equilibrium examples

  14. CLIMATE CHANGES INTERPRETEDFROM DEEP-SEA CORES • Identification of planktic foraminiferal species • Date layers in deep-sea cores. • Plotting the abundance of cold and warm climate species from core samples indicates climatic changes through time.

  15. CLIMATE CHANGES INTERPRETEDFROM DEEP-SEA CORES • O18/O16 ratios from used to determine • Paleotemperature changes with planktic species & • Ice-volume changes with benthic species Triserial, planktic

  16. END OF FILE

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