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Research · October 2015

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1 author: Some of the authors of this publication are also working on these related projects: THE PALAEOZOIC PALYNOSTRATIGRAPHY OF THE KAROO SUPERGROUP AND PALYNOFACIES INSIGHT INTO PALAEOENVIRONMENTAL INTERPRETATIONS, KALAHARI KAROO BASIN, BOTSWANA View project Benson N.J. Modie University of Botswana

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PALYNOSTRATIGRAPHIE DU PALAEOZOIQUE DU SUPER-GROUPE DU KAROO, BASSIN DU KAROO-KALAHARI, BOTSWANA, ET INTERET DES PALYNOFACIES POUR LES INTERPRETATIONS PALAEOENVIRONNEMENTALES. THE PALAEOZOIC PALYNOSTRATIGRAPHY OF THE KAROO SUPERGROUP AND PALYNOFACIES INSIGHT INTO PALAEOENVIRONMENTAL INTERPRETATIONS, KALAHARI KAROO BASIN, BOTSWANA. Benson N. Modie

Tuteurs: Dr. Alain LE HERISSE - Directeur de Thése

• Dr. Bernard LE GALL - Co-directeur
• Dr. Jean-Jacques TIERCELIN - Co-directeur

27 April 2007 BREST

PRESENTATION OUTLINE

• BACKGROUND
• INTRODUCTION
• BACKGROUND GEOLOGY
• METHODOLOGY
• RESULTS
• CONCLUSIONS
• RECOMMENDATIONS

BACKGROUND NDP8 mineral development programme policy. Policy aim: to increase economic benefit from the development and exploitation of mineral resources. Project formulation:

Botswana host one of the largest coal deposits

in the region.

Not much economic benefits comparable to

resource magnitude e.g. one coal mine.

CBM; an alternative way of obtaining maximum

benefits from coal, but indirectly.

BACKGROUND Project objective defined :

To assess the availability and the potential

to develop natural gas resources associated with the coal-bearing sequences of the Kalahari Karoo Basin in Botswana. No local expertise on CBM at DGS:

External source Consultants Coalbed Methane Project

BACKGROUND

Second project objective:

To establish a database on stratigraphy and

develop a correlation system that characterises the coal-bearing sedimentary sequence of the Kalahari Karoo Basin in Botswana.

Karoo Basin Stratigraphy Project.

Overall Project: Coalbed Methane and Karoo Basin Stratigraphy Project.

CBM Project completed December 2003. KBS Project completed April 2007.

INTRODUCTION Kalahari Karoo Basin host important resources:

Coal Coal-bed Methane Clay deposits Groundwater aquifers

Stratigraphy: a pertinent subject.

24 18 S 20 22 24 26 20 E 22

Fault

KALAHARI KAROO BASIN

KALAHARI KAROO BASIN OF BOTSWANA

∗

Karoo Supergroup

26 28

Exposures

Z

• e

t f

• n

t e i n F a u l t

INTRODUCTION

There is hardly exposed geology in the Kalahari Karoo Basin :

Stratigraphy poorly constrained.

Purpose:

Introduce biostratigraphy i.e. palynostratigraphy

to enhance correlation during geological mapping.

Eventually to improve resource management,

their exploration and exploitation.

INTRODUCTION

Biostratigraphy:

A study of the relative arrangement of strata or

rock bodies with regard to their fossil content. Kalahari Karoo Basin:

Lack of extensive surface exposure hinders the

identification of macrofossils.

Stratigraphic investigations based on borehole

sections; only microfossils are suitable.

INTRODUCTION

Palynology:

Tool of investigation in the Kalahari Karoo Basin. A study of plant microfossils and the remains of

• ther living micro-organisms retrieved from the

digestion of clastic sedimentary rocks with various acids.

Remains collectively termed palynomorphs.

Palynostratigraphy: stratigraphic subdivision on the basis of palynology.

INTRODUCTION

Pollen and spores:

Palynomorphs of choice in the Kalahari Karoo

Basin.

Continental sequence.

Pollen

Multicellular male reproductive cells of all seed-

producing plants, form part of life cycle.

Pollination – fertilization of a seed plant.

Spores

Unicellular reproductive cells that form part of

the life cycles of some plants.

Develop independently into new organisms.

INTRODUCTION

Palynology: a tool for geological correlation.

Fundamental base for correlation stems from the

evolution of plants through geological time.

Various forms of palynomorphs deposited with

sediments.

Palynomorph assemblages from different levels

• f strata likely to be different, allowing

sequences to be differentiated. Palynology applied extensively in the oil and gas industry; to determine levels of drilling (production).

INTRODUCTION Palynology: other applications Geochronology/age dating

Palynomorphs represents parts of the life

cycles of plants and animals that have at times evolved rapidly.

Evolution of a fairly narrow time range,

and hence useful for age dating.

INTRODUCTION

Palynology: other applications Palaeoecology Palynomorphs can be indicators of palaeoenvironments and the source of sediments.

Dinoflagellates > marine > indicators of ancient

biological environment of organism.

Spores or pollen > Continental > indicate

presence of source vegetation.

Vegetation (spore/pollen) > indicators of

continental environments > palaeoclimate.

INTRODUCTION Palynofacies:

A body of rock defined on the basis of

particulate Sedimentary Organic Matter (SOM) retrieved during palynological sample preparations.

SOM dominated by the remains of land

plants i.e. fragmented parts of tree trunks, branches, and leaves.

Includes all palynomorphs retrieved.

Palynofacies bound by significant horizons; form basis for correlation at local scale.

BACKGROUND GEOLOGY Regional Setting Kalahari Karoo Basin form one of several contemporaneous basins of southwestern Gondwana:

Basins active in Permo-Carboniferous times. Earliest deposits laid down during a major glacial

event (i.e. Late Palaeozoic).

Sedimentation in Karoo basins was interrupted

and halted by basaltic volcanism in early Jurassic times (c.185 – 177 Ma)

Volcanism associated with extensional tectonics

marking the on-set of Gondwana break-up.

Regional disposition

(ECL, 1998)

Geodynamic setting (Main Karoo)

CAPE OROGENY (Late Palaeozoic – Early Mesozoic) Subduction of palaeo-Pacific plate under Gondwana Main Karoo Basin developed as retroarc foreland basin to CAPE FOLDBELT

(Turner, 1999)

Geodynamic setting (Kalahari and other basins in the north)

Compressional

• extensional tectonics

associated with

• rogeny in the south

Intracratonic rift basins

in the north.

(ECL, 1998)

Stratigraphy

BEAUFORT DWYKA GROUP AGE STRATIGRAPHY

Late Carboniferous - Early Jurassic

ECCA GROUP LEBUNG GROUP

STORMBERG LAVA GROUP

KAROO SUPERGROUP

Basalt > amygdaloidal

181 Ma

Mudstone Mudstone, varvites, siltstone, sandstone, and tillites Red beds > sandstone > siltstone, mudstone > sandstone, rare c/glomerate Siltstone, mudstone, limestone LITHOLOGY Sandstone, siltstone, carbonaceous mudstone, and coal >Aeolian >Fluvial >Lacustrine Transitional >Lacustrine De-glaciation, and amelioration

• f the palaeo-climate.

>Fluvio-deltaic >Swamps >Lacustrine/marginal marine Glacial palaeo-climate >Subglacial >Glacio-fluvial >Glacio-lacustrine Continental flood basalts DEPOSITIONAL ENVIRONMENT >extensional tectonics related to on-set of Gondwana break-up. Arid continental palaeo-climate

METHODOLOGY Nature of study

Aim of study:

The use of Palynology in stratigraphic

correlation i.e. Palynostratigraphy. Main activities:

Determination and identification of

palynomorphs, and their stratigraphic ranges.

Determination of the stratigraphic

distribution of sedimentary organic matter.

Sample source Investigation area poorly exposed:

All samples sourced

from drill-cores at DGS.

Distribution of the Karoo Supergroup

K A L A H A R I K A R O O B A S I N

∗

Drill core

Core description

Sampling (based on trial-run on initial 20 samples)

ECCA GROUP ME58

WATERBERG GROUP (Prec. Basement)

Manyelanong Formation DWYKA GROUP Dukwi Formation

Mosomane Formation

40 60 70

50

80 30 20 10 DEPTH (M) LITHOLOGY LITHOSTRATIGRAPHY SAMPLE NUMBER LITHOLOGICAL DESCRIPTION

ME58BNM1P-03 ME58BNM2P-03 ME58BNM3P-03 ME58BNM4P-03 ME58BNM5P-03 ME58BNM6P-03 ME58BNM7P-03

Diamictite; matrix-supported, medium-coarse sandstone matrix, angular to rounded clasts, banded siltstone with fine delicate laminae (rare).

Sandstone; coarse-grained, cream-white, graded beds, broad laminae. Carbonaceous mudstone; silty.

Sandstone; red with white patches/spots.

thin carbonaceous mudstone and coal intervals.

Sandstone; pebbly and conglomeratic layers, carbonaceous and coal layers.

Sample preparations Laboratoire de Palaeontologie, Université de Bretagne Occidentale. Directed by:

• Dr. Alain LE HERISSE

Microscopy Palynomorphs:

Microscopic

descriptions (measurements, physical form)

Nomenclature Classification

Sedimentary organic matter:

Categories Palynofacies

equatorial diameter laesura length corpus diameter

BRNE SPOR

RESULTS

• Sample yields
• Systematic descriptions
• Palynofacies categories
• Palynostratigraphy
• Correlations
• Palaeoenvironments

Distribution of the Karoo Supergroup

K A L A H A R I K A R O O B A S I N

∗

Sample yields

Borehole Samples submitted Samples yielding palynomorphs Samples barren *STRAT 1 120 113 7 *CKP6 95 78 17 CKP9 10 9 1 TLMB1 12 2 10 ML1 5 2 3 ML2 5 5 KG03 8 6 2 ME58 7 7 NATA 8 2 6 Totals 270 219 51

Systematic descriptions 68 genera

30 Spores 29 Pollen 4 Acritarchs 4 Prasinophytes 1 Chlorophyte

Punctatisporites Protohaploxypinus Veryhachium Tasmanites Botryoccocus

Systematic descriptions

184 species

89 Spores (31 open-

ended, 9 new combinations)

76 Pollen (18 open-

ended, 1 new combination)

11 Acritarchs (5 open-

ended, 5 uncertain)

7 Prasinophytes (5

• pen-ended)

1 Chlorophyte (open-

ended)

Horriditriletes gondwanensis Divaricrassus minor Cristatisporites inconstans Potonieisporites congoensis Hamiapollenites bullaeformis Pakhapites fusus

Sedimentary Organic Matter Palynofacies categories:

• Phytoclasts
• Amorphous organic matter (AOM)
• Palynomorphs

Palynofacies categories Phytoclasts

Brown equi-dimensional

(BRNE)

Brown lath-shaped

(BRNL)

Black equi-dimensional

(BLKE)

Black lath-shaped (BLKL) Cuticular and

Membranous Tissues (CAMT)

BRNE BRNL BLKE BLKL CAMT

Palynofacies categories Amorphous organic matter (AOM)

No test to determine

source.

Considered terrestrial

(i.e. degradation of land plants)

Palynofacies categories Palynomorphs

Pollen (saccate pollen

– SAPO, plicates – PLIC)

Spores – SPOR Phytoplankton

(Acritarchs – ACRT, Prasinophytes – PRSN, Chlorophytes - CHLR

SAPO PLIC SPOR ACRT PRSN CHLR

Palynostratigraphy Qualitative analysis

Stratigraphic subdivision involved the creation of Biozones

Delineated based on definitions of Murphy and

Salvador (1999). International Stratigraphic Guide

• --- An abridged version.

Biozones described as:

Bodies of strata that are defined or

characterised on the basis of their fossil content.

Palynostratigraphy

Qualitative analysis

The following procedure was adopted for the determination of biozones:

• 1. Data presented in

species range charts

First and last

• ccurrences.

T 1

LITHOLOGY

Converrucosisporites pseudoreticulatus (49) Converrucosisporites irregularis (50) Raistrickia crenata (47) Punctatisporites ubischii (9) Horriditriletes curvibaculosus (43) Cristatisporites menendezii (76) Arabisphaera bellula (178) Retusotriletes diversiformis (11) Lophotriletes rarus (32) Cristatisporites inconstans (71) Lundbladispora gracila (83) Divaricrassus minor (29) Apiculatisporis unicus (23) Concavisporites mortonii (2) Cristatisporites spinosus (75) Cymatiosphaera gondwanensis (180) Didecitriletes ericianus (28) Laevigatosporites plicatus (87) Laevigatosporites vulgaris (86) Horriditriletes brevis (39) Lophotriletes rectus (30)

Palynostratigraphy

Qualitative analysis

• 2. Delineation of

biohorizons

Stratigraphic

boundaries, surfaces

• r interfaces,

showing significant change in biostrat character e.g. species diversity.

Converrucosisporites irregularis (50) Cristatisporites microvacuolatus (73) Horriditriletes tereteangulatus (41) Horriditriletes curvibaculosus (43) Converrucosisporites pseudoreticulatus (49) Cirrabaculisporites plumsteadiae (36) Horriditriletes gondwanensis (44) Cymatiosphaera gondwanensis (180) Retusotriletes golatensis (12) Apiculatisporis parmatus (26) Apiculatisporis cornutus (22) Apiculatisporis levis (24) Cristatisporites lestai (72) Granulatisporites trisinus (17) Cristatisporites menendezii (76) Cristatisporites inconstans (71) Arabisphaera bellula (178) Divaricrassus minor (29) Lophotriletes rarus (32) Apiculatisporis unicus (23) Retusotriletes diversiformis (11) Lophotriletes rectus (30) Lundbladispora gracila (83) Concavisporites mortonii (2) Cristatisporites spinosus (75) Foveosporites karrooensis (62) Didecitriletes ericianus (28) Horriditriletes brevis (39) Laevigatosporites vulgaris (86) Calamospora aplata (1)

Palynostratigraphy

Qualitative analysis

• 3. Delineate biozones

Identification of taxa

specific to sections of strata.

Biohorizons helped

select suitable boundaries.

Illinites spectabilis (109) Vittatina foveolata (146) Striatopodocarpites pantii (141) Marsupipollenites striatus (159) Alisporites australis (117) Alisporites potoniei (118) Protohaploxypinus haigii (132) Striatopodocarpites fusus (140) Platysaccus papilionis (120) Hamiapollenites saccatus (125) Lueckisporites virkkiae (128)

2 S1 - 3 b a b c d

Protohaploxypinus perexiguus (135) Marsupipollenites triradiatus (160)

S1 - 4 BIOZONES Subzones

Florinites eremus (90)

Palynostratigraphy Types of biozones

• 1. Range Zone (Concurrent, Taxon)

Body of strata representing known

stratigraphic and geographic range of

• ccurrence of a particular taxon or

combination of two taxa of any rank.

• 2. Assemblage Zone

Body of strata characterised by an assemblage

• f three or more fossil taxa that, taken

together, distinguishes it in biostratigraphic character from adjacent strata.

Otshe ECCA

Malo- gong

DWYKA Khuis

Middlepits

Kobe

GROUP FORMATION DEPTH (M)

STRAT 1

LITHOLOGY S1 - 3 S1 - 2 S1 - 1 S1 - 4 BIOSTRATIGRAPHIC UNITS Biozones Range Zones

Converrucosisporites pseudoreticulatus (49) Converrucosisporites irregularis (50) Raistrickia crenata (47) Punctatisporites ubischii (9) Horriditriletes curvibaculosus (43) Cristatisporites menendezii (76) Arabisphaera bellula (178) Retusotriletes diversiformis (11) Lophotriletes rarus (32) Cristatisporites inconstans (71) Lundbladispora gracila (83) Divaricrassus minor (29) Apiculatisporis unicus (23) Concavisporites mortonii (2) Cristatisporites spinosus (75) Cymatiosphaera gondwanensis (180) Didecitriletes ericianus (28) Laevigatosporites plicatus (87) Laevigatosporites vulgaris (86) Limitisporites rectus (110) Vittatina foveolata (146) Horriditriletes brevis (39) Illinites spectabilis (109) Lophotriletes rectus (30) Potonieisporites congoensis (108) Hamiapollenites bullaeformis (123) Caheniasaccites flavatus (105) Striomonsaccites crucistriatus (92) Marsupipollenites triradiatus (160) Protohaploxypinus perexiguus (135) Florinites eremus (90) Alisporites potoniei (118) Alisporites australis (117) Protohaploxypinus haigii (132) Striatopodocarpites pantii (141) Platysaccus papilionis (120) Hamiapollenites saccatus (125) Lueckisporites virkkiae (128) Striatopodocarpites fusus (140) Potonieisporites congoensis

• Converrucosisporites irregularis

Concurrent-range Zone Retusotriletes diversiformis

• Divaricrassus minor

Concurrent-range Zone Lophotriletes rectus

• Concavisporites mortonii

Concurrent-range Zone Platysaccus papilionis Taxon-range Zone

STRAT 1 RANGE CHART Significant taxa Concurrent-range Zones TRZ

CKP 6

• Cyclogranisporites gondwanensis

• Pachytriletes splendens

• Cristatisporites morungavensis

CKP 6 RANGE CHART Significant taxa Concurrent-range Zones Taxon-range

ECCA

Otshe Kobe

DWYKA

Middlepits Khuis Malo- gong

GROUP

FORMATION DEPTH (M) LITHOLOGY

STRAT 1

Cristatisporites morungavensis (74) Cristatisporites microvacuolatus (73) Cyclogranisporites gondwanensis (13) Hamiapollenites bullaeformis (123) Striatopodocarpites cancellatus (139) Punctatisporites parvus (8) Deltoidospora directa (4) Raistrickia crenata (47) Lophotriletes rarus (32) Didecitriletes ericianus (28) Weylandites magmus (154) Limitisporites rectus (110) Vittatina scutata (147) Alisporites ovatus (116) Horriditriletes ramosus (40) Lophotriletes rectus (30) Alisporites potoniei (118)

KK 1 KK 2 KK 3

Biozones Assemblage Zones Platysaccus papilionis Assemblage Zone

Potonieisporites novicus (106)

Cyclogranisporites gondwanensis Assemblage Zone Hamiapollenites bullaeformis Assemblage Zone BIOSTRATIGRAPHIC UNITS

Punctatisporites gretensis (6) Punctatisporites ubischii (9) Punctatisporites gracilis (7) Densosporites rotundus (80) Apiculatisporis parmatus (26) Retusotriletes diversiformis (11) Cycadopites follicularis (164) Potonieisporites brasiliensis (107) Caheniasaccites flavatus (105) Lundbladispora braziliensa (82) Indotriradites australensis (69) Granulatisporites papillosus (15) Protohaploxypinus limpidus (134) Vestigisporites ventrisaccatus (115) Striatopodocarpites fusus (140) Platysaccus papilionis (120) Lueckisporites virkkiae (128)

GROUP

CKP 6

FORMATION DEPTH (M) LITHOLOGY

BIOSTRATIGRAPHIC UNITS Biozones

KK 3

Platysaccus papilionis Assemblage Zone

Assemblage Zones

Hamiapollenites bullaeformis Assemblage Zone

KK 1

Cyclogranisporites gondwanensis Assemblage Zone

KK 2

Palynostratigraphy

Quantitative analysis Stratigraphic subdivision involved the delineation

• f palynofacies horizons (STRAT 1):

Based on counts of the palynofacies categories. Counting procedures followed descriptions of

Traverse (1988) and Tyson (1995).

Results presented as relative abundance (%)

charts depicting stratigraphic distributions.

F E A B C D

STRATIGRAPHIC DISTRIBUTION OF THE TOTAL SEDIMENTARY ORGANIC MATTER (TSOM)

Relative abundances as %TSOM. Palynofacies horizons represent major changes in relative abundances. Horizons can be correlated with those from the qualitative analysis. Marker horizons for correlation in local basin.

AOM PHYTOCLASTS PALYNOMORPHS

DWYKA Khuis Malo- gong Middlepits

ECCA Kobe

Otshe

STRAT 1 BOREHOLE Log10 blke/brne Log10 tphe/tphl

• 1.5 -0.5 0

DWYKA GROUP ECCA GROUP

Log10 blke/brne

DWYKA – ECCA BOUNDARY BLKE dominant BRNE dominant

• 1. Lower rates of degradation and oxidation

associated with the cold climate.

• 2. Local derivation and immediate cover i.e.

short distance to depositional basin.

• 1. Well-oxygenated environments due to

warmer climate.

• 2. Oxidation during prolonged exposure in

transportation.

• 3. Significant rates of degradation.

Palynostratigraphic correlations

• Local
• Regional and

Gondwana-wide

Distribution of the Karoo Supergroup

K A L A H A R I K A R O O B A S I N

∗

Local Present study STRAT 1 (reference section):

CKP6 yielded data suitable for

comparative analysis and can be correlated on the basis of assemblage zones.

CKP9; general comparisons All other boreholes yielded inadequate

• ccurrence data.

Local

Species range comparisons:

Younging of glacial

sequence to southwest.

CKP6 to STRAT 1 STRAT 1 to CKP9

Glacial migration!

Distribution of the Karoo Supergroup

K A L A H A R I K A R O O B A S I N

∗

CKP6 STRAT 1 CKP9

Local

Correlation with previous work:

Only broad comparisons possible Most previous work without taxa range data Commonly based on narrow sections; difficult to

distinguish short from long range taxa.

Regional and Gondwana-wide Comparison with previous studies

Generally common taxa; evidence for comparison. Limiting factors related to levels of details;

• i. disparities in sampling details (e.g spacing,

stratigraphic range etc.)

• ii. type of analysis and presentation format (e.g.

range charts, abundance charts, written account)

First Things First: Upgrade knowledge on the local basins first.

South America

SOUTH AMERICA (Souza and Marques Toigo, 2003, 2005; Souza, 2006) Lueckisporites virkkiae Interval Zone Vittatina costabilis Interval Zone STRAT 1 (This Study) S1-4 KK3 S1-3 KK2 S1-2 KK1 S1-1

Close similarity:

Comparison based on common taxa Different kinds

• f biozones

Potential for future studies!

Late Palaeozoic Palaeogeography

(Turner, 1999)

Age The Karoo sequence is largely terrestrial in nature

Lack of marine fossils Radiometric age determinations scarce

Age control for the assemblages described is poorly constrained

Age ranges are only inferred from comparison

with other Gondwana palynofloras.

Remains tentative.

Age

LATE PERMIAN

Roadian

S1 - 4 EARLY PERMIAN

Kungurian Artinskian

• Asselian

S1 – 3 c, d S1 – 3a, b S1 – 2 S1 - 1 LATE CARBONIFEROUS

Gzhelian

• Kasimovian

Basal section

Wright and Askin, 1987; Farabee

• et. al., 1991; Hankel, 1992;

Lindström, 1995a; Souza, 2006. Stephenson and McLean, 1999; Souza, 2006. MacRae, 1988; Dolby, 1990; Souza, 2006.

SYSTEM STAGE STRAT 1 REFERENCES

Palaeoenvironmental Interpretations Qualitative analysis

Species occurrence

data Quantitative analysis

Palynofacies data

Distribution of the Karoo Supergroup

K A L A H A R I K A R O O B A S I N

∗

Palaeoenvironmental Interpretations

Qualitative analysis

Some general observations considered diagnostic

• f the palaeoenvironmental setting include:
• 1. Increase or decrease in diversity of some taxa,

and species initiations and terminations.

Influenced by palaeoclimatic changes

• 2. Variations in the frequency of occurrence of

taxa (i.e. consistent to non-consistent).

Linked to the depositional history of the

sedimentary sequence e.g. facies controlled.

Facies distribution may be influenced by the

palaeoclimate i.e. variations in sediment supply.

Palaeoenvironmental Interpretations

Qualitative analysis

ECCA DWYKA

• 1. Notable observations

Monosaccates Bisaccates Cristatisporites

COLD WARM

• -Previous studies--

Dominance of monosaccates pollen and trilete spores widely reported in Permo-Carboniferous glacigene Gondwana sequences – Kar, 1976; MacRae, 1988. Proglacial – periglacial settings e.g. glaciolacustrine Wet and humid conditions for spore reproductive cycle. Support monosaccate pollen vegetation.

Palaeoenvironmental Interpretations

Qualitative analysis

• 2. Notable observations

ECCA DWYKA

• -Kobe Fm.--

Remarkable species disappearance

• -also a drop in frequency of occurrence--

Sand influx Not entirely facies control!! Probably dry, non-humid climatic conditions. Compare: Indian Barren Measures Low taxa abundance Dry-arid environment (Sah and Kar, 1969)

Palaeoenvironmental Interpretations

Qualitative analysis

ECCA DWYKA Kobe Otshe

• 3. Notable observations

ACRITARCHS Dominate the marine environment e.g. Downie, 1973; Cramer,1979; Martin, 1993. Veryhachium spp. MARINE INCURSION

Eurydesma Shallow marine bivalve e.g. Ellis, 1979. High AOM Deepening water Suboxic-anoxic Transgressive System

Palaeoenvironmental Interpretations

Quantitative analysis

Cluster analysis (in PAST)

Dendrograms Ternary plot Fields of depositional

environments (e.g. Tyson, 1995; Duringer and Doubinger, 1995)

VI VII VIII IX 50

II

I

(after Tyson, 1995)

50 IV V III 50

AOM PALYNOMORPHS PHYTOCLASTS

1 20 30 40 50 60 70 80 90

• 900
• 800
• 700
• 600
• 500
• 400
• 300
• 200
• 1

00 Similarity

32P 53P 39P 40P 23P 61P 26P 78P 80P 62P 63P 73P 35P 48P 33P 34P 41P 55P 65P 51P 45P 54P 70P 72P 56P 71P 31P 50P 46P 38P 52P 57P 58P 59P 13P 49P 15P 37P 47P 12P 16P 20P 8P 10P 29P 42P 97P 96P 7P 86P 91P 6P 95P 92P 3P 25P 89P 88P 5P 94P 81P 83P 90P 27P 2P 14P 1P 21P 22P 9P 43P 36P 77P 85P 87P 4P 74P 76P 93P 24P 69P 28P 82P 79P 98P 100P 30P 84P 44P 75P 66P 64P 60P 11P 68P 67P

AOM – TPH – TPA

1 2

1A 1B 2A 2B 2Bi 2Bii

3

DWYKA GROUP ECCA GROUP

1 2 4 5 6 7

Otshe Formation Kobe Formation Middlepits Formation Khuis Formation Malogong Formation

TOTAL SEDIMENTARY ORGANIC MATTER CLUSTER DIAGRAM

VI VII VIII IX 50

II

I

(after Tyson, 1995)

50 IV V III 50

AOM PALYNOMORPHS PHYTOCLASTS

50 50 50

AOM TPH TPA

CLUSTER CODE

B

A

1 A

ii

B

i

2

(a) (b)

TSOM CLUSTERS IN TERNARY PLOT PALYNOFACIES FIELDS AND ENVIRONMENTS Notable proximal-distal trends: I. Highly proximal setting

• High phytoclast supply
• III. Heterolithic oxic proximal setting

Low AOM Oxidation and reworking common Phytoclast abundance relative to proximity to fluvio-deltaic supply

• IV. Proximal – distal

transitional setting

• V. Oxic distal setting

50 50 50

100%SPORE

100%MICROPLANKTON

100%POLLEN CLUSTER CODE

2 1 A B

i ii

50

SPORES DELTAIC

50

MICROPLANKTON O F F S H O R E

NEARSHORE

(after Duringer and Doubinger, 1985; Traverse, 1988; Tyson, 1995)

Theoretical regressive trend

50

POLLEN

MICROPLANKTON-SPORE-POLLEN PLOT ONSHORE-OFFSHORE ENVIRONMENTS

Notable observations: Distinctive segregation or clustering Spore segment dominant Negligible microplanktons Active fluvial supply Variations in the depositional setting Continental setting Overall Depositional Environment

• DELTAIC

85 m

Proximal Highly proximal Distal

PALAEOENVIRONMENTAL CYCLES %TPh %TPa

AOM TPH TPA

50 50 50

A

2 B 1 i ii

VERTICAL STRATIGRAPHIC TRENDS STRAT 1

SHIFTS IN DEPOSITIONAL SETTINGS

fluctuations in water levels e.g. transgressive-regressive. changes in depositional conditions e.g. energy, chemistry.

CORRELATION POTENTIAL

Local basin multi-sections Marker horizons

AUGMENT LITHOSTRATIGRAPHY

(c.f. down-hole geophysics)

MIDDLEPITS

CONCLUSIONS

• Palynomorph yields

and preservation

• Biozonation
• Correlations
• Age
• Palaeoenvironments
• Other observations

Distribution of the Karoo Supergroup

K A L A H A R I K A R O O B A S I N

∗

CONCLUSIONS

Overall, the study has demonstrated the potential in Palynology for Biostratigraphy in the Karoo Supergroup (Lower Karoo) of the Kalahari Karoo Basin, in Botswana.

Alternative method for geological

investigations by the DGS.

CONCLUSIONS

• 1. Palynomorph yields and preservation status

There is an overwhelming presence of pollen

and spores.

Palynomorphs show variable preservation

status, but adequate for analysis.

There is need for detailed procedures e.g.

narrower sampling intervals, sample-specific preparations etc.

CONCLUSIONS

• 2. Biozonation

Taxa range analysis revealed the occurrence of

long, medium, and short range species (STRAT1, CKP6).

Three Concurrent-range zones and a Taxon-

range zone have been erected (STRAT 1, CKP6).

Three Assemblage zones were erected (STRAT1,

CKP6).

STRAT 1 subdivided into palynofacies horizons

that can be correlated with palynomorph biohorizons.

CONCLUSIONS

• 3. Correlations

No direct correlation of the concurrent-range

zones (STRAT 1, CKP6).

The Taxon-range zones reveal limited direct

correlation (STRAT1, CKP6).

A direct correlation is attainable on the basis of

the Assemblage zones (STRAT 1, CKP6).

There is limited comparison and broad

correlation with other previous studies (local, regional, gondwana-wide).

CONCLUSIONS

Age

Age control for the zonation schemes erected is

inferred from comparison with similar assemblages from previous Gondwana studies.

Ages remain tentative. Overall age range: Late Carboniferous

(Kasimovian-Gzhelian) to earliest Late Permian (Roadian).

CONCLUSIONS

Palaeoenvironments

Interpretations based on general taxa diversity

indicates changes in the palaeoclimatic conditions in the Lower Karoo sequence from cold to warm, corresponding to the trend shown by the lithofacies (i.e. glacial – postglacial).

Rare but significant occurrences of acritarchs

and prasinophytes, which typically dominate marine environments, indicate the possibility of a marine incursion.

CONCLUSIONS

Palaeoenvironments (cntd.)

Palynofacies analysis based on comparison of

the relative abundance of phytoclasts reflect changes in the palaeoenvironment from cool climatic conditions of typically poorly-oxygenated waters (Dwyka Group – brown phytoclasts) to warm palaeo-climates (Ecca Group – black phytoclasts) that generated a well-oxygenated environment with high rates of oxidation.

The overall data on total sedimentary organic

matter reveal a strong lineage towards a proximal palaeo-depositional setting e.g. deltaic.

CONCLUSIONS

Other important observations

The Dwyka – Ecca boundary can be

delineated on the basis of contrast in the relative abundances of brown and black phytoclasts.

The Karoo Sequence can be rapidly

distinguished from older sedimentary sequences on the basis of sedimentary

• rganic matter.

RECOMMENDATIONS

Future Projects

Karoo basin has great

potential for future investigations.

Distribution of the Karoo Supergroup

K A L A H A R I K A R O O B A S I N

∗

RECOMMENDATIONS

• 1. Biostratigraphy and palaeoenvironments (as in

KBS – preliminary)

Future studies can consider additional sections

across basin (i.e. target sub-basins)

Carry out detailed sampling for systematics

and palynofacies. Aim: Populate database to enhance local and regional correlations, and eventually global correlations. Potential researchers:

Local e.g. DGS, UB. etc. International e.g. Universities, Coal exploration

companies, other research centers etc.

RECOMMENDATIONS

• 2. Palynology of the Upper Karoo (mid-

Mesozoic).

Determine palynological characteristics of

the “Red Beds” (often neglected due to poor yields; consider suitable methods). Aim: Age determination and correlation. Potential researchers:

Local e.g. DGS, UB. etc. International e.g. Universities and other

research centers etc.

RECOMMENDATIONS

• 3. Palaeobotany

Sporomorphs; taxonomy and botanical affinity. Phytoclasts; study anatomical structure and

determine plant type. Aim: Determine palaeo-vegetation to assess palaeo-ecology and palaeoclimates (e.g Savanna, Swamp forest, Rain forest etc) Potential researchers:

Local e.g. UB etc. International e.g. Universities, other research

institutes etc.

RECOMMENDATIONS

• 4. Karoo vs pre-Karoo phytoclasts analysis

Target Karoo strata in diamond

exploration Aim: Distinguish Karoo from pre-Karoo sedimentary sequences. Potential researchers:

Diamond exploration companies

THE END/ LA FIN

Thank you all!!! Merci a tous!!!