Transcript Brasier, 1980

INTRODUCTORY MICROPALEONTOLOGY
Micropaleontology is concerned with microfossils and
nanofossils (the latter being smaller than 50 m), the
study of which must, of necessity, be carried out using the
light or electron microscope.
Such fossils are:
1- The remains of unicellular and multicellular microorganisms.
2-The dissociated elements and skeletal fragments of
macro-organisms.
Objective of micropaleontology
1- Study the fossils in terms of morphology, structure,
chemical and mineralogical components
2- Classification: discover their origin and systematic
affinities
3- Application: (oil) exploration, biostratigraphy,
palaeo-biology, paleoclimatology
4- Environmental inferences
Microfossils Groups
1. Foraminifera
Unicellular/ calcareous or agglutinated/ marine
environments/ planktonic and benthonic/
heterotrophic.
2. Ostracods
Multicellular/ calcareous or chitinous valves/
marine and fresh environments/ planktonic and
benthonic/ heterotrophic.
3. Coccolithophora
unicellular/ autotrophic/ calcareous/ planktonic
and benthonic/ marine and fresh environments.
4. Diatoms
unicellular/ autotrophic/ siliceous/ planktonic/ mainly
marine environments.
5. Radiolaria
unicellular/ heterotrophic/ siliceous/ planktonic/
marine environments.
6. Dinoflagellates
unicellular/ autotrophic or heterotrophic / cysts are
preserved (organic, calcareous or siliceous) motile and non-
motile stages/ marine and fresh environments.
Foraminifera
Phylum: Protozoa
Subphylum: Sarcodina
Class: Rhizopoda
Order: Foraminiferida
Foraminifera are single-celled animals protected by hard shells of different types of
materials (chitinous, calcareous, agglutinatd, and siliceous). They are microscopic in size,
and generally range from 0.1 to 1 mm. (approximately the size of a grain of sand or smaller).
However, in the geologic past, forams with test diameters greater than 10 cm. (4 in.) were not
unusual.
Animal consists of:
Cell (Soft parts of foraminifera) has:
Protoplasm (surrounded by membrane)
Protoplasm within the shell (test) = endoplasm (dark
and granulous) contains:
- 1 or more nuclei
- systems for cell-secretion (Golgi)

- systems for gas-exchange (Mitochondria)
- systems for protein-synthesis (Ribosomes)
- fluid or gas filled ‘ droplets’ (Vacuoles)
Protoplasm outside the test = ectoplasm (transparent)
forms pseudopodia

Pseudopodia
Long strings of ectoplasm (2-3 to 20 times test diameter)
Can branch very often, shaping web-like appearance
around the test. Surrounded by rather fluid layer
Functions:
1- Feeling  objects
 changes in chemistry of the environment
2- Food gathering and transport:
(food particles caught and incorporated in the
ectoplasm; transport of food to the endoplasm through
aperture; transport of waste-products outward)
3- Fixation and motion
Benthic forams sessile or motile.
Planktonic forams migrate without pseudopodiaaction---they move only by the effect of water current
and gas-volume variation.
4- Formation new chambers
• Notes: students should see foram movie!
Pseudopodia network: they are
dense and more frequent near
the opening of the test

Life style
Benthic forams live in/on sea floor sediments
Planktonic forams  free floating living in the sea surface water (0.0-200
m), occupying different depths; some occupy depths down to 700 m in the
water column.
Diagram showing live benthic foraminiferal style (Brasier, 1980)
Habitats of benthic foraminifera:
1. Epifaunal------(includes branched forms) from 0.0 to
1cm depth in the sediments.
2. Shallow infaunal-----from 1 to 2cm depth in the
sediments.
3. Intermediate infaunal-----from 2 to 3cm depth in the
sediments.
4. Deep infaunal----from 3 to 15cm depth in the
sediments.

Food
Foraminifera are heterotrophic (mostly omnivorous) organisms in
nutrition, some food examples: bacteria, coccolithophorids, diatoms,
dinoflagellates, radiolarians, algae, parts of other plants, and other
foraminifera.
Some species are very selective feeders.
Food generally digested in the endoplasm.
Species with small apertures digest outside the test (feeding-cyste).
Note: Spinose planktonic species are carnivorous/omnivorous and live close to
the surface oligotrophic (low nutrients) water.
Non-spinose planktonic species are herbivores live in deep water (below 200
m).
 Symbiosis
Foraminifera make symbiosis with photosynthetic organisms
(zooxanthellae) such as: Algae, Dinoflagellates and Diatoms.
Zooxanthellae are separated from protoplasm by membrane; and what is
its functions? Suggestions:
1- Zoo. supply O2 and carbohyderates, forams supplies CO2
2- Zoo. are for emergency ‘Lunch’
3- Zoo. consume excess Nitrogen-products
4-Zoo. gain ‘mobility’ and ‘protection’
Day-night migration of symbionts within the protoplasm of planktonic
forams, has been observed. Motion is along the spines, in/out via the
aperture.
Some benthic foraminifera (e.g. Sorites sp., Amphisorus
sp., Marginopora sp. and Permian fusulinids >10 cm)
attain large sizes by help of symbiotic associations.
The dinoflagellates continue to photosynthesize, as long
as they have light and nutrients. However, they do not
keep the products of photosynthesis for themselves. They
release almost all of it into the tissues of the host. The
host uses this energy as food, and typically has enough
energy to add more and more calcium carbonate into its
test.
Does the symbiosis affect the isotopic signature (δ18O &
δ13C) of the foraminiferal shells and then makes the
climatic inferences difficult?
Image of Marginopora vertebralis
Note the occurrence of symbionts (brown zone) in the inner
part of the test avoiding the external digesting area (white
zone).
Image of Orbulina universa
Note that the test is surrounded by dinoflagellate symbionts.
Juvenile trochospiral shells are visible in the center of the
transparent spherical chamber.
 Life cycle
Foraminifera resemble (certain) plants, having two
phases of reproduction (heterophasic):
1. Asexual reproduction (schizogony)----( Microspheric form with
numerous chambers = A-form)
- Give young Gamont with half of the chromosome of the parent
- Occurs in winter months
2. Sexual reproduction (gamogony)--------megalospheric (A-form)
-Give young Schizont with all of the chromosome of the parent
- Occurs in summer months
In planktonic foraminifera only sexual reproduction
occurs
Diagram of benthic foraminiferal life history (Brasier, 1980)
 Wall structure and composition
Chitinous wall:
foraminifera.
present
in
fresh-water
benthic
Agglutinated wall: -----only feature for benthic---foraminifer builds its test wall by cementing together
exogenous grains (e.g. sand grains, oolites, fine grains of
calcite or sponge spicule) by carbonate mineralization.
Wall is a simple layer that grades from fine grains inside
to coarse grains outside
Calcareous (Ca CO3) wall: present for both benthic and
planktonic foraminifera: (hyaline or porcelaneous)
Hyaline/glassy wall: transparent, perforate, crystals are
radial, with lamellae (laminations) that separated by
organic layers.
Porcelaneous wall: shiny, smooth, crystals randomly
arranged
Examples of wall structures in foraminifera (Brasier, 1980)
 Chamber growth and development
1- Protoplasm moves gradually whereas test develops
periodically at regular intervals
2- Protoplasm (pseudopodia) occupies the space of the
new chamber, then organic wall builds, then finally
agglutinated or calc. materials add in the outer side
or on both sides.
Foraminiferal tests may be unilocular or multilocular
In multilocular tests, if the last formed chamber does not
overlap the previous one, wall will be non-laminar. If the
last formed chamber overlaps the previous one, wall will
be bi or multilaminar.
Non-laminar and multilaminar walls in foraminifera (Brasier, 1980).
 General classification and test morphology
1- Suborder Allogromiina:
2- Suborder Textulariina:
3- Suborder Fusulinina:
4- Suborder Miliolina:
5- Suborder Rotaliina: (contains many superfamilies)
Superfamily: Nodosariacea
Superfamily: Buliminacea
Superfamily: Discorbacea
Superfamily: Orbitoidacea
Superfamily: Spirillinacea
Superfamily: Duostominacea
Superfamily: Robertinacea
Superfamily: Globigerinacea
Superfamily: Rotaliacea
Superfamily: Cassidulinacea
Superfamily: Carterinacea
Images of suborder Allogromiina: a) Allogromia; b) Shepheardella
Images of suborder Textulariina (superfamily Ammodiscacea): c) Rhabdammina;
d) Technitella; e) Sorosphaera; f) Saccammina and g) Tolypammina. From
Brasier, 1980.
Images of suborder Textulariina (superfamily Lituolacea): a) Coskinolina; b)
Cyclolina; c) Cyclopsinella; d) Dicyclina; e) Orbitolina. From Brasier, 1980.
Images of suborder Textulariina (superfamily Lituolacea): a) Reophax; b)
Hormosina; c) Miliammina; d) Cyclammina; e) Loftusia; f) Spirocyclina.
From Brasier, 1980.
Images of suborder Textulariina
(superfamily Lituolacea):
a)
Ammobaculite;
b)
Textularia;
c)
Bigenerina;
d)
Verneuilina;
e)
Trochammina. From Brasier, 1980.
Images of suborder Fusulinina (superfamily Parathuramminacea): a)
Saccaminopsis and b) Earlandinita. Superfamily Endothyracea: c)
Nodosinella; d) Palaeotextularia; e) Tetrataxia. From Brasier, 1980.
Foraminiferal bioenvironmental indicators
 PHYSICAL PROPERTIES:
1- Water depth ----indirect---organic matter (food) decreases
with increasing water depth
2- Temperature----indirect---increasing T° leads to salinity
increases---more stratification in the water column---then
less oxygen at deeper sites
3- Light---indirect---important for algae (photosynthesis) that
make symbiosis with foraminifera
4- Water currents directly inhibit the benthic foraminifera to
build their habitat in/on the sea floor.
 CHEMICAL PROPERTIES:
1- Salinity (‰ = parts per thousand) ---- foraminifera can live
in all aquatic environments such as:
- Fresh water (0.0-0.5‰)-----rivers and estuaries such as:
Allogromiidae.
- Brackish water (0.5-30‰)--- lagoons and marshes such
Ammonia and miliolids
- Normal sea water (35-45‰) is suitable for all other
as:
species.
-Hypersaline water bodies (up to 57‰)----closed seas, lakes,
lagoons and marginal bays. Such environment is lethal and
destructive for any kind of living foraminifera.
Notes:
High diversity and high abundance of benthic foraminifera occur
under normal seawater and the lower the salinity of an
environment, the lower the diversity of benthic foraminifera is
there.
2- Alkalinity (pH):

Normal sea water has pH of about 8.1 that favors the Ca
CO3 precipitation (foraminiferal shells) as a result of
availability of both Ca and CO3-2.

pH is governed by temperature, pressure and biological
activities.
 Alkalinity decreases with increases water depth (=
increasing CO2 pressure and decreasing T°), as a result
acidity increases leading to Ca CO3 dissolution.

pH of the euphotic zone increases during the day and
decreases during the night.

Stagnant water (high POM fluxes) is characterized by
acidic pH’s.
 The corrosiveness of a water mass toward Ca CO3
increases as it moves along the path of thermohaline
circulation.

CCD = Calcite compensation depth: rain rate of Ca CO3
(shell) equals the solubility (dissolution) of Ca CO3.
CCD in ocean waters after Haq and Boersma (1978).
3- Nutrients (food):

High amount of nutrients (food) = high numbers of
benthic foraminifera

An excess of nutrients is harmful on benthic
foraminifera as a result of uptake of dissolved oxygen in
remineralization processes.

High density and diversity of benthic foraminifera occur
at areas receiving more amounts of food and dissolved
oxygen.
4- Dissolved oxygen

Depends on ocean circulation and fluxes of organic
matter to the sea floor.
 High oxygen indicates good circulation and no excess of
organic matter. This conditions lead to high faunal
density and diversity.

Low oxygen indicates stagnant water with more fluxes of
organic matter on the sea floor. Thus conditions lead to
anoxia and then to low faunal density and diversity.

Amount of dissolved oxygen is inversely related with the
amount of the organic matter.
 BIOTIC VARIABLES:
 Predation: worms, crustaceans, gastropods, echinoderms
feed on foraminiferal tissues by boring holes into the
foraminiferal tests in order to extract the protoplasm.
 Symbiosis: algal symbionts help foraminifers to attain
very large sizes. During algal blooms, foraminifers are
abundant than any other seasons.
 Food availability (nutrients) and dissolved oxygen are
the most important variables at deep-sea environments.
High amount of nutrients (food) = high numbers of
benthic foraminifera. An excess of nutrients is harmful
on benthic foraminifera as a result of uptake of dissolved
oxygen in remineralization processes.
 High density and diversity of benthic foraminifera occur
at areas receiving more amounts of food and dissolved
oxygen.
Planktonic Foraminiferal bioenvironmental
indicators
1.
2.
3.


TEMPERATURE: planktonic foraminifers are
temperature indicators
- Spinose species live in shallow, warm surface water (075m).
- Non-spinose species live mostly in (colder) deeper
waters, down to some 500m.
HYDROGRAPHY: planktonic foraminifera flourish and
become more abundant at eddies, turbulent zones and
upwelling areas.
FOOD AVAILABILITY: plank. foram. are abundant
and diverse at areas of high nutrients (food) such as
eddies, turbulent zones and upwelling regions.
Spinose species prefer oligotrophic (low food) waters.
Non-spinose species prefer eutrophic (rich by nutrients)
water.
Distribution of planktonic foraminifera
It is geographically distributed and controlled mostly by
temperature, water circulation and food availability.
 Tropical (24-30ºC)
 Subtropical (20-24ºC)
 Transitional (10-18ºC)
 Subpolar (5-10ºC)
 Polar (0-5ºC)
Geographical distribution of planktonic foraminifera (Haq and
Boersma, 1978).
Geographical distribution of planktonic foraminifera (Haq and
Boersma, 1978).