1. Lecture 12 General history of foraminifera and their applications

2. General history of foraminifera  Principle steps in the evolution of the foraminifera.  Although acritarchs are known from Upper Precambrian rocks, there are no examples of foraminifera of this age.  Ammodiscaceans resembling Bathysiphon and Tolypammina have been reported from Lower Cambrian rocks.  Foraminifera with hard tests were scarce until Devonian, during which period the Fusulina began to flourish, culminating in the complexly constructed tests of Fusulinacea in Late Carboniferous and Permian times.  This suborder died out at the end of the Paleozoic.  Miliolina first appeared in the Early Carboniferous, arising probably from the agglutinated Ammodiscacea.

3. The phylogenetic history of the Foraminiferida

4.  Important Mesozoic events include the appearance and radiation of the Rotaliina (largely from endothyracean stock), Miliolina and complex Textulariina in the Jurassic, followed by the appearance of the first planktonic foraminifera.  The planktonic Globotruncanidae became extinct at the end of the Cretaceous.  A relatively rapid radiation followed in the Paleocene with the appearance of the planktonic Globigerinidae and Globorotalidae and in the Eocene with development of nummulites and soritids in the Old World and orbitoids in the New World.  Orbitoides died out in the Miocene, since which time larger foraminiferal stocks have progressively dwindled in the distribution and diversity, mostly because of the climatic deterioration.  Planktonic have also diminished in diversity since Late Cretaceous time, the "boom" periods of the Eocene and Miocene corresponding with warmer climatic phases.

5. Changes in the specific diversity of planktonic foraminifera through time

6. Application of micropaleontology Commercial, or industrial micropaleontology is generally associated with: 1. Petroleum industry. 2. Exploration and mapping of surface and subsurface stratigraphic units. 3. Implication of recent coccolith sedimentation pattern for paleooceanographic studies. 4. Ostracodes are used as paleoenvironmental indicators. 5. Importance of benthic foraminifera which are associated with biogenic gas seep. 6. Application of micropaleontology in hydrocarbon exploration. 7. Micropaleontology is used also in engineering and economic geology.

8. Applications of Foraminifera  Foraminifera are in many respects ideal zonal indices for marine rocks, being small, abundant, widely distributed and often extremely diverse.  Planktonic foraminifera provide the basis of important schemes for intercontinental correlation of Mesozoic (especially Upper Cretaceous) and Cainozoic rocks.  Benthic foraminifera tend to be more restricted in distribution but provide useful schemes for local correlation and sometimes for intercontinental correlation.

9.  Environmental interpretations that use fossil foraminifera are founded mainly on comparisons with the numerous studies of Recent ecology.  For examples, changes in depth, salinity and climate can be traced in late glacial and post glacial raised beaches and beach deposits from studies of their foraminifera.  For studies of paleogeography and paleosalinity at more remote periods, Murray and Wright (1974) used the ratios between Textulariina, Miliolina and Rotaliina, as well as diversity studies of fossil populations. Applications of Foraminifera cont.

10.  The narrow temperature ranges of Recent planktonic species have become useful tools in paleoclimatology, especially of Quaternary sediments.  Plots of the changing proportions of warm-to cold-water species, of selected indicator species, or of coiling directions through a cored interval may allow the construction of paleotemperature curves in some shallow-water Recent sediments, the Quaternary of the deep sea or even for the whole Neogene.  Studies on the oxygen isotope ratios of calcareous foraminiferid shells can also yield information on paleotemperatures, such as the long Cainozoic history of climatic cooling and glaciations.  Estimates of the relative rates of sedimentation have been calculated by comparing the proportion of living to dead (or living to total) foraminifera in benthic populations. Applications of Foraminifera cont.