Radiolarian Micropalaeontology: Collection and Examination Professor Simon K. Haslett Centre for...

Radiolarian Micropalaeontology:

Collection and Examination

Professor Simon K. HaslettCentre for Excellence in Learning and Teaching

Simon.haslett@newport.ac.uk

16th March 2010

Introduction

• Radiolaria are Sarcodine Protozoa (single-celled) that secrete microscopic silica (SiO2) tests (cf. shells).

• Radiolaria are marine holoplankton that first appear in Palaeozoic rocks.

• Radiolaria may be extracted for study from marine sediments and rocks.

Collection Techniques

• Radiolaria may be obtained from:– Plankton samples collected using nets, etc.– Surface sediments on the sea floor

collected using grab samplers, etc.– Subsurface deep-sea sediments collected

using coring technology.– Rocks collected on the seabed or on land

where marine rocks have been uplifted.

Collecting Oceanic Sediments

• Deep-Sea Drilling Project (DSDP)

• Ocean Drilling Program (ODP)• Integrated Ocean Drilling

Program (IODP)• Other institutional, national

and international coring programmes. JOIDES Resolution (ODP

vessel), San Diego, 1992.

Video: Collecting Radiolaria

Sampling Procedures

• For unconsolidated oceanic cores:– Core catchers for preliminary sampling.– Interval sampling downcore.– Sample size: usually 1 cc is adequate.– Label with Site, Core, Section and Interval.– Store in plastic vial, bag, or glass tube.– Refrigerate samples, but avoid freezing.

Processing Technique

• For unconsolidated sediments:– Wash sediment through nest of 150 and

63µm sieves to concentrate Radiolaria.– Wash 150-63µm fraction with dilute (10%)

Hydrochloric Acid (HCl) to dissolve calcareous microfossils and particles.

– Wash with buffered water (H2O) and collect, with water, in a beaker or vial.

Mounting Techniques 1

• Pipette the residue and some water onto:– Glass coverslip for transmitted light

microscopy (TLM), or– a stub for scanning electron microscopy

(SEM).– Allow to dry in a clean atmosphere, usually

on a hot plate set at a low temperature.

Mounting Techniques 2

• For TLM:– pipette a pea-sized amount of mounting

medium (e.g. Canada Balsam, Naphrax) onto cover slip and allow to spread (on a warm hot plate) until bubbles are expelled.

– Then place cover slip on a labeled glass microscope slide and allow to set.

• For SEM, coat with gold before viewing.

Video: Extracting Radiolaria from Sediment

Transmitted Light Microscope

Microscope-mounted camera attached to a computer.Eye pieces (optics).

Head of the microscope.

Objective lenses (various).

Microscope stage.

Focusing mechanism.

Iris diaphragm and condenser.

Light source.

Viewing Techniques

• For TLM:– Place slide on microscope stage and view

under low magnification to start, adjust iris diaphragm and light intensity controller.

– Focus through specimens to view internal anatomical structures to aid identification.

– Photographs may be taken with a microscope mounted camera.

Searching and Counting

• Search slides systematically for specimens, and count taxa up to pre-defined limit (e.g. 300 specimens).

• Adopt a consistent search and counting approach from slide to slide.

• Specimens may be place-referenced on a slide using an England Finder.

Video: Examining Radiolaria under the Microscope

Collating Data

• Tally up counts for each taxa.• Tabulate in a database e.g. Excel.• Calculate the total assemblage.• Convert to percentages:

– taxa count ÷ total assemblage x 100• Plot downcore graphs of individual taxa.

Example Excel Database

Example Excel Taxa Plot

1.7 1.75 1.8 1.85 1.9 1.95 2 2.050

5

10

15

20

25

Cycladophora davisiana

age (Ma)

ab

un

da

nc

e (

%)

Analysing Datasets

• Large datasets often result from radiolarian studies that can be analysed using a range of numerical techniques:– Principal Components Analysis– Factor Analysis– Correspondence Analysis– Detrended Correspondence Analysis

Video: Analysing Radiolarian Microfossil Data

Summary

• Radiolaria can be collected from oceanic sediments through ocean drilling, or extracted from marine rocks.

• Oceanic sediments may be washed through sieves, and treated with dilute Hydrochloric Acid (HCl).

• Residues are usually mounted for TLM or SEM.• Assemblage data may be collated on spreadsheets.• Graphs of individual species variation may be plotted.• Entire datasets may be numerically or statistically

analysed, using a range of techniques.

Further Reading

• Armstrong, H. A., Brasier, M. D., 2005. Microfossils (2nd Ed). Blackwell, Oxford.

• Dale, A. L. and Dale, B., 2002. Application of ecologically based statistical treatments to micropalaeontology. In S. K. Haslett (ed.) Quaternary Environmental Micropalaeontology. Arnold, London, pp. 259-286.

• Haslett, S. K. and Robinson, P. D., 1991. Detecting radiolaria in the field. Journal of Micropalaeontology, 10, p. 22.

• Integrated Ocean Drilling Program, 2009. Proceedings of the Integrated Ocean Drilling Program. Available through www.oceandrilling.org (with links to Deep Sea Drilling Program and Ocean Drilling Program publications).

This resource was created by the University of Wales, Newport and released as an open educational resource through the 'C-change in GEES' project exploring the open licensing of climate change and sustainability resources in the Geography, Earth and Environmental Sciences. The C-change in GEES project was funded by HEFCE as part of the JISC/HE Academy UKOER programme and coordinated by the GEES Subject Centre.

This resource is licensed under the terms of the Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales license (http://creativecommons.org/licenses/by-nc-sa/2.0/uk/).

All images courtesy of Professor Simon Haslett. However the resource, where specified below, contains other 3rd party materials under their own licenses. The licenses and attributions are outlined below:

1. The name of the University of Wales, Newport and its logos are unregistered trade marks of the University. The University reserves all rights to these items beyond their inclusion in these CC resources.

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Author Professor Simon K. Haslett

Research Assistant Jonathan Wallen

Institute - Owner University of Wales, Newport

Title Radiolarian Micropalaeontology: Collection and Examination

Description Collection of Radiolaria and subsequent examination techniques

Date Created 2010

Educational Level Higher

Keywords UKOER, GEESOER, Microfossil, Radiolaria

Creative Commons License Attribution-Non-Commercial-Share Alike 2.0 UK: England & Wales