MicropaleontologyMicropaleontologyBy

Prof. Dr. Salah N. Ayyad

Introduction and the importance of

microfossils

Lecture 1

• The definition of micropaleontology is the study of microscopic fossils that they must be examined with a microscope.

• Most marine microfossils are protists (unicellular plants and animals), but others are multicellular or microscopic parts of macroscopic forms.

• The value of marine microfossils is enhanced by their:

- minute size.

- abundant occurrence.

- wide geographic distribution in sediments of all ages.

- and in almost all marine environments.

• Most planktonic and many benthic microfossils have wide geographic distributions that make them indispensable for regional correlations and comparisons, and paleooceanographic reconstructions.

Marine microfossils occur in sediments ofMarine microfossils occur in sediments of PrecambrianPrecambrian to to RecentRecent ages, lived in almost all marine provinces;ages, lived in almost all marine provinces; NeriticNeritic (littoral) province (inner, middle and outer) up to (littoral) province (inner, middle and outer) up to 200m,200m, BathyalBathyal (Oceanic) province (upper, middle and (Oceanic) province (upper, middle and lower) up to 2000m and lower) up to 2000m and AbyssalAbyssal (Oceanic) province up (Oceanic) province up to 5000m.to 5000m.

Type of ProtistaMineralogyGeologic RangeHabitatEcology

DinoflagellatesorganicSilurian? – Recentaquaticphotosynthetic/various heterotrophe/carnivorous

AcritarchsorganicPrecambrian –Recentmarineunknown

DiatomsOppaline silicaCretaceous– Recentany wetphotosynthetic

SilicoflagellatesOppaline silicaCretaceous – Recentmarinephotosynthetic/various heterotrophe

RadiolariansOppaline silicaCambrian – Recentmarinevarious heterotrophe

Calcareous nannoplankton

calciteJurassic – Recentmarinephotosynthetic

Benthic forams

organic, agglutinated, calcareous, some

other

Cambrian – Recentmarine

various heterotrophe, some with symbionts

Planktonic forams

organic, agglutinated, calcareous, some

other

Jurassic – Recentmarine

various heterotrophe

Microfossils include:

Radiolaria, silicoflagellates, calcareous nannoplankton, pteropods, foraminifera and diatoms are planktonic (free floating) and live in abundance from 0 to 200m in the open ocean.

Silicoflagellate, DictyochaRadiolarian Shells

Calcareous nannoplankton Pteropods

Planktonic Diatoms

Diatoms, radiolarians, and a silicoflagellate

Planktonic Foraminifera

Planktonic Foraminifera

Other groups as theOther groups as the ostracodes, bryozoa, and some foraminifera and ostracodes, bryozoa, and some foraminifera and diatoms diatoms are benthic (adapted to living on the bottom of the sea).are benthic (adapted to living on the bottom of the sea).

Crisia acropora Chorizopora brongniartii

ostracodes

Bryozoa

Benthic Foraminifera

Benthic Foraminifera

Benthic marine diatoms

Some forms, such as theSome forms, such as the dinoflagellatesdinoflagellates are known to are known to contain both planktonic and benthic phases in their contain both planktonic and benthic phases in their reproductive cycle and are useful tools inreproductive cycle and are useful tools in paleoecologypaleoecology..

Spores and pollenSpores and pollen, although derived from land plants, , although derived from land plants, are strongly are strongly climate-dependentclimate-dependent..

Thus, their presence and distribution patterns in near-Thus, their presence and distribution patterns in near-shore marine sediments allow interpretations of shore marine sediments allow interpretations of continental climates; and/or, like chemical traces, their continental climates; and/or, like chemical traces, their distribution can be used to monitor distribution can be used to monitor current movementcurrent movement..

The reason why Foraminifera are importantThe reason why Foraminifera are important - in oil exploration and - in oil exploration and - other subsurface work as index fossils - other subsurface work as index fossils

(indicators of a particular geological age) lies not (indicators of a particular geological age) lies not only in their abundance but equally in their only in their abundance but equally in their range of size. range of size.

This is generally between This is generally between 0.10 mm0.10 mm and and 1.001.00 mm mm in diameter and averages about in diameter and averages about 0.33 mm0.33 mm, equal , equal to the to the fine sandfine sand grade of sediments. grade of sediments.

Although some are macroscopic and exceed 5.00 Although some are macroscopic and exceed 5.00 mm in diameter, "mm in diameter, "Larger ForaminiferaLarger Foraminifera", and some ", and some are smaller than 0.10 mm, "are smaller than 0.10 mm, "Micro foraminiferaMicro foraminifera".".

Scope of Foraminiferal studies

The reasons for the particular value of The reasons for the particular value of foraminifera in stratigraphyforaminifera in stratigraphy

11 ( (They are abundant in mostThey are abundant in most marine sedimentsmarine sediments, in, in outer-outer-shelfshelf mudsmuds where several thousand specimens representing where several thousand specimens representing some fifty species frequently occur in a 10 ml volume samplesome fifty species frequently occur in a 10 ml volume sample..

According to Levine (1962) they constituteAccording to Levine (1962) they constitute 2.5%2.5% of the of the animalanimal kingdom and more thankingdom and more than half the known protozoahalf the known protozoa . .

A number of species belonging to different families also occurA number of species belonging to different families also occur inin brackish waterbrackish water but only members of the non-testatebut only members of the non-testate AllogromiidaAllogromiida occur inoccur in freshwaterfreshwater . .

Therefore, the occurrence of Foraminifera is an indication of Therefore, the occurrence of Foraminifera is an indication of marinemarine (high marine to brackish) conditions(high marine to brackish) conditions..

22 ( (The average aboutThe average about 0.330.33 mmmm in diameterin diameter (fine sand )(fine sand ) with with rangerange fromfrom 0.100.10 mmmm to to 1.001.00 mmmm. This means that. This means that they they escapeescape destruction during the ordinary process of rotary destruction during the ordinary process of rotary drillingdrilling..

3) Stratigraphic markers 3) Stratigraphic markers "tops""tops" based on the based on the first appearance first appearance of speciesof species and assemblages in ditch cuttings can be applied in and assemblages in ditch cuttings can be applied in correlation which can be carried out without expensive coring.correlation which can be carried out without expensive coring.

4) It has existed in abundance 4) It has existed in abundance since the Cambriansince the Cambrian, showing , showing well-marked evolutionary changes useful in stratigraphy. well-marked evolutionary changes useful in stratigraphy. Different familiesDifferent families mark the Eras and major time Periodsmark the Eras and major time Periods..

5) Many species are planktonic and of 5) Many species are planktonic and of worldwide occurrenceworldwide occurrence. . When this wide geographical range is combined with a short When this wide geographical range is combined with a short vertical time range they make vertical time range they make excellent index fossilsexcellent index fossils..

6) Many species are restricted in their habit and confined to a 6) Many species are restricted in their habit and confined to a particular ecological niche. They are thus particularly useful in particular ecological niche. They are thus particularly useful in interpreting the character of interpreting the character of ancient environments.ancient environments.

7) Foram-limestones (larger foraminifera) are well developed in 7) Foram-limestones (larger foraminifera) are well developed in the the Upper Paleozoic,Upper Paleozoic, The The Upper CretaceousUpper Cretaceous and in the and in the CenozoicCenozoic..

8) Classification is based on characters shown by the 8) Classification is based on characters shown by the fossilisable testfossilisable test. .

ForaminiferaForaminifera Scope of Foraminiferal studies.Scope of Foraminiferal studies. Collection, Preparation and Examination (Technical Collection, Preparation and Examination (Technical

methods).methods). The living Foraminifera.The living Foraminifera. Test morphology and composition.Test morphology and composition. Classification of the Foraminifera.Classification of the Foraminifera. The Agglutinated Foraminifera.The Agglutinated Foraminifera. The Fusulinida.The Fusulinida. The Miliolida.The Miliolida. The Nodosariida.The Nodosariida. The Buliminida.The Buliminida. The Robertinida.The Robertinida. The Rotaliida (smaller).The Rotaliida (smaller). The Rotaliida (larger).The Rotaliida (larger). The Globigerinida.The Globigerinida.