See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/282654312 B. N. Modie Thesis Presentation Research · October 2015 DOI: 10.13140/RG.2.1.2600.5202 CITATIONS READS 0 123 1 author: Benson N.J. Modie University of Botswana 13 PUBLICATIONS 252 CITATIONS SEE PROFILE 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 All content following this page was uploaded by Benson N.J. Modie on 08 October 2015. The user has requested enhancement of the downloaded file.
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.
KALAHARI KAROO BASIN 18 S OF BOTSWANA ∗ 20 KALAHARI KAROO BASIN 22 t u l a F n i e t n o f t e o Z 24 Karoo Supergroup 26 Exposures Fault 20 E 22 24 26 28
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 other 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 of 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) (Turner, 1999) CAPE OROGENY (Late Palaeozoic – Early Mesozoic) � Subduction of palaeo-Pacific plate under Gondwana Main Karoo Basin developed as retroarc foreland basin to CAPE FOLDBELT
Geodynamic setting (Kalahari and other basins in the north) Compressional - extensional tectonics associated with orogeny in the south � Intracratonic rift basins in the north. (ECL, 1998)
Stratigraphy DEPOSITIONAL LITHOLOGY STRATIGRAPHY AGE ENVIRONMENT LAVA GROUP STORMBERG Continental flood basalts Basalt >extensional tectonics related > amygdaloidal to on-set of Gondwana break-up. 181 Ma Arid continental palaeo-climate Red beds KAROO SUPERGROUP LEBUNG GROUP >Aeolian > sandstone Late Carboniferous - Early Jurassic >Fluvial >Lacustrine BEAUFORT > siltstone, mudstone > sandstone, rare c/glomerate Siltstone, mudstone, limestone Transitional >Lacustrine De-glaciation, and amelioration of the palaeo-climate. Sandstone, siltstone, carbonaceous mudstone, and GROUP >Fluvio-deltaic coal ECCA >Swamps >Lacustrine/marginal marine Mudstone Glacial palaeo-climate Mudstone, varvites, DWYKA GROUP >Subglacial siltstone, sandstone, >Glacio-fluvial and tillites >Glacio-lacustrine
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: 18 S ∗ NATA 20 N I S � All samples sourced A B O TLMB1 O R ML2 A from drill-cores at 22 CKP 6 ML1 K I R A H DGS. A STRAT 1 KG03 ME58 L A K 24 Distribution of the Karoo Supergroup 26 0 100 200 CKP9 Kilometers Borehole locations 20 E 22 24 26 28
Drill core
Core description ME58 DEPTH LITHOSTRATIGRAPHY LITHOLOGY SAMPLE NUMBER LITHOLOGICAL DESCRIPTION (M) 10 Sandstone; coarse-grained, cream-white, ECCA GROUP graded beds, broad laminae. Mosomane 20 Formation thin carbonaceous mudstone ME58BNM1P-03 and coal intervals. 30 ME58BNM2P-03 Carbonaceous mudstone; silty. ME58BNM3P-03 40 ME58BNM4P-03 Sandstone; pebbly and conglomeratic layers, ME58BNM5P-03 carbonaceous and coal layers. 50 Diamictite; matrix-supported, medium-coarse Formation ME58BNM6P-03 Manyelanong DWYKA (Prec. Basement) 60 sandstone matrix, angular to GROUP WATERBERG Dukwi rounded clasts, banded siltstone Formation with fine delicate laminae (rare). GROUP 70 ME58BNM7P-03 80 Sandstone; red with white patches/spots. Sampling (based on trial-run on initial 20 samples)
Sample preparations Laboratoire de Palaeontologie, Université de Bretagne Occidentale. Directed by: Dr. Alain LE HERISSE
Microscopy Palynomorphs: � Microscopic laesura descriptions length equatorial diameter (measurements, physical form) � Nomenclature corpus diameter � Classification Sedimentary organic matter: SPOR BRNE � Categories � Palynofacies
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