MICROFAUNA FROM THE EARLY PALAEOGENE LIGNITIC DEPOSITS OF BHAVNAGAR LIGNITE MINE, GUJARAT, INDIA
A DISSERTATION Submitted in partial fulfillment of the requirements for the award of the degree of MASTER OF TECHNOLOGY in GEOLOGICAL TECHNOLOGY
PRERNA VAID
Date c ►_ / T• ROORK~
X
DEPARTMENT OF EARTH SCIENCES INDIAN INSTITUTE OF TECHNOLOGY ROORKEE ROORKEE - 247 667 (INDIA) JUNE, 2012 INDIAN INSTITUTE OF TECHNOLOGY ROORKEE ROORKEE
CANDIDATE'S DECLARATION
I hereby certify that the work which is being presented in this Dissertation entitled "MICROFAUNA FROM THE EARLY PALAEOGENE LIGNITIC DEPOSITS OF BHAVNAGAR LIGNITE MINE, GUJARAT, INDIA" in partial fulfillment of requirements for the award of degree of MASTER OF TECHNOLOGY in GEOLOGICAL TECHNOLOGY and submitted in the Department of Earth Sciences, Indian Institute of Technology, Roorkee, is an authentic record of my own work, carried out during a period from August 2011 to April 2012 under the supervision of Dr. Sunil Bajpai, Professor, Department of Earth Sciences, IIT Roorkee and Dr. Abhayanand Singh Maurya, Assistant Professor, Department of Earth Sciences, IIT Roorkee.
The matter embodied in this Dissertation has not been submitted by me for the award of any other degree of this institute or any other Institute.
(PRERNA VAID)
This is to certify that the above statement made by the candidate is correct to the best of my knowledge.
â_- '- t-- (Dr. Sunil Bajpai) r. A. S. Maurya) (Supervisor) (Supervisor) Date : / / I Professor Assistant Professor
The Dissertation viva-voce examination of Ms. PrernaVaid, M.Tech student has been held on:
Signature of supervisor(s) Signature of external Examiner CERTIFICATE
I. Prerna Vaid, Student of M. Tech. (Final Year) Geological Technology
hereby solemnly declare that the dissertation that entitled "MICROFAUNA FROM
THE EARLY PALEOGENE LIGINITIC DEPOSITS OF THE BHAVNAGAR
LIGINITE MINE, GUJARAT, INDIA" being submitted by me towards partial
fulfillment of the award of Master of Technology in Geological Technology Degree is a
record of my own work and that I have not copied the work of any other person's
including published literature and material from any web site.
Where ever that work of other person's has been, it is been duly acknowledged and quoted with proper reference to the original work.
I fully understand that implications of plagiarism and that if at any stage the above statement made by me is found to be incorrect I shall be fully responsible for my acts.
Signature:
Name:
Place: ROORKEE
Date: 1'~r •I uN_F -aD I a ABSTRACT
The Cambay and Kutch basins of Gujarat, western India exposesome of the best developed Tertiary sequences in India. The succession includes several lignite deposits ofprimarilyEocene age, which are being commercially exploited at present in the form of open cast lignite mines in the state. In Cambay basin, Vastan lignite mine shows abundant microfaunal forms, which is been dated as of Eocene age. Recently, an open cast mine has come up in Bhavnagar district near Surkha village of Khadsaliya clays formation.
Previously in this area, an attempt on Palynostratigraphy is made resulting in a good frequency of pollen and spore taxa. The present dissertation is the first attempt aimed at the recovery, taxonomic identification and assessment of age and palaeoecology based on the microfossils from Bhavnagar lignite mine. The faunal assemblage recovered from the
Bhavnagar lignite mine includes fish otoliths, fish vertebra, bivalves, gastropods and ostracods. Some of the microfauna from Bhavnagar lignite mine shows affinities towards the respective microfaunal assemblages of the Vastan lignite mine, which is stated to be of early Eocene age. Fish otoliths includes "genus Ambassidarum", "genus
Apogonidarum", "genus Percoideorum" and Gobiidarumvastani, out of whichGobiidarumvastaniis an age diagnostic, of early Eocenefound in Vastan Lignite mine. Presence of both fresh water (Lepisosteus, Osteoglossidae) and shallow marine water (Enchodus, Egertonia and Stephanodus) fauna of fish vertebra and fresh water
(Cypridopsis) ostracods suggests that Bhavnagar lignite mine have an assemblage of admixed fauna. ACKNOWLEDGEMENTS
During the course of investigations and writing this volume embodying the
Dissertation work I have been accompanied and helped by many people. I feel privileged
in acknowledging all people who have been of valuable help to me in making of
successful Dissertation. It is to them that I owe my deepest gratitude.
It is my foremost privilege to express sincere gratitude to my supervisor Dr. Sunil
Bajpai and Dr. A. S. MauryaDepartcoent of Earth Sciences, Indian Institute of
Technology Roorkee, for their immense help, invaluable guidance and motivation
throughout my project work, without which this work would have been inconceivable.
Their wisdom, knowledge and support inspired and motivated me to the highest. It was an
honorable and great pleasure for me to work with them.
I am extremely grateful to Prof. A. K. Saraf, Head of the Department, Department
of Earth Sciences, Indian Institute of Technology, for providing me all the necessary facilities and administrative support required for the completion of this work.
I would like to express my thanks to Prof. G. J Chakrapani, O.C. Dissertation
(M.Tech., Geological Technology), Department of Earth Sciences.
The collection of fossils would not have been possible without the help and
support provided by the personnel of GMDC, Bhavnagar. I express my special thanks to
Mr Joshi (General Manager) and many others for providing access to the Bhavnagar
Lignite Mine.
I am thankful to Dr. Ramesh Chandra, Head,IIC, IITR and Ms. Archana (IIC,
IITR) and for their help during the SEM microphotography of the specimens described in this dissertation. Without their help it would not have been possible on my part to illustrate the entire faunal assemblage.
Among my seniors, I am thankful to Sanjay, Abhay and Nivedita (Research
Scholars) for constantly motivating and pushing me into completion of the Dissertation work. Also providing any help needed in the course of Dissertation work.
Last but not least I am thankful to my parents, teachers, classmates, seniors and beloved juniors who gave me the possibility to complete this Dissertation.
At the end, I extend my heartiest thanks and deep respect towards all those who have been of great help to me directly or indirectly in the successful completion of this
Dissertation Again I am also thankful to Dr. Sunil Bajpai and Dr. A. S. Maurya, whose peaceful guidance will always alive me for my bright future.
(PrernaVaid) CONTENTS
Title Page No.
ABSTRACT i_
ACKNOWLEDGEMENT ii
CONTENTS iv
LIST OF FIGURES vi
LIST OF TABLES vii
Chapter 1 INTRODUCTION 1
1.1 PREAMBLE 1
1.2 OBJECTIVES 2
1.3 BHAVNAGAR LIGNITE MINE (GUJARAT STATE
WESTERN INIDA) 3
1.3.1 Communication and location 3
1.3.2Geology 3
1.4 PREVIOUS WORK 4
1.5 COLLECTION TECHNIQUES 5
1.6 PHOTOGRAPHY 7
1.7 REPOSITORY OF THE MATERIAL 7
Chapter 2 GEOLOGICAL SETTING 8
2.1 GEOLOGY OF THE STUDY AREA 8
2.2 REGIONAL STRATIGRAPHY OF BHAVNAGAR 8
2.3 GEOLOGY OF CAMBAY BASIN ' 10
Chapter 3 SYSTEMATIC PALAEONTOLOGY 14
Chapter 4 DISCUSSIONS 32
iv
Chapter 5 SUMMARY AND CONCLUSION 35
REFERENCES 36
PLATES (1-10) LIST OF FIGURES
Figure 1.1 Satellite imageries showing the location of the Bhavnagar lignite mine,
Bhavnagar district, Gujarat, Western India (source www.googleearth.com)
Figure 1.2 Geological and location map of an area around Bhavnagar lignite mine,
Gujarat with reference to the Gulf of Cambay (Mathur et.al. 1968)
Figure 1.3 Lithocolumn of the Bhavnagar lignite mine, Gujarat, Western India.
Figure 2.1 Geological formation and lithology of an area with ages (CGM & GSI)
Figure 2.2 Stratigraphic correlation chart of the Cambay basin (after Chandra and
Chowdhary, 1969).
Photos 1 & 2 Photograph of the section and the panoramic view of the Bhavnagar lignite
mine, Bhavnagar district, Gujarat, Western India.
vi CHAPTER 1
INTRODUCTION
1.1 PREAMBLE
The Cambay and Kutch basins of Gujarat, western India expose some of the best developed Tertiary sequences in India. The succession includes several lignite deposits of primarily- Eocene age, which are being commercially exploited at present in the form of open cast lignite mines in the state. The most active site of mining in Cambay basin is at
Vastan Lignite mine where several studies have been conducted for the recovery of various microfaunal assemblages.
At the sites of lignite open cast mining, excellent exposures are available for collecting data on age, biotic affinities, and palaeoenvironments of the coal bearing successions in a geodynamic, pre-collisional setting. One such area is Bhavnagar Lignite
Mine in south Gujarat. The only record of microfossils from the Bhavnagar Lignite deposits is that of pollen and spores (Samant, 2000). The studies in the surrounding areas include those on the famous Vastan mine section which is highly fossiliferous comprising molluscs (bivalves, gastropods), ostracods foraminifers, fossil insects, dinoflagellates, pollen and spores Vertebrates (fish, amphibians, snakes, lizards, birds, and most importantly, mammals) (Bajpai, 2008 and the references therein).
The Paleocene-Eocene transition was a critical phase not only in the history of the
India-Asia collision but also for Cenozoic climate change. The Paleocene —Eocene boundary is an example of natural global greenhouse event in the history of the Earth which led to the diversification and evolution of many new fossils (mammals) (Gingerich,
2006). The terrestrial biotic record of the Paleocene-Eocene thermal maximum (PETM)
H demonstrates that climate change induces changes in the geographic distribution of terrestrial organisms. Migration appears to be dominant mechanism for the change within
PETM terrestrial ecosystems, especially in respect of mammals and plants (Slujis, A.
2007). It has been suggested that the Indian sub continental plate was the centre of origin/early evolution for several mammalian taxa which abruptly arrived in the northern continents after India collided with Asia (Krause & Maas, 1990) The importance of the lignitic deposits has to be understood in the context of India's collision with the Asiatic landmass (Sahni et al. 2008). In addition, the disruption of Neotethys palaeocurrent flow- through patterns after the India-Asia collision probably influenced the euxinity of the basins and the generation of coal deposits.
The present dissertation is mainly concerned with the microfossils collected from the Bhavnagar lignite mine near Surkha village of District Bhavnagar, Gujarat, Western
India. The microfaunal documented in this dissertation were recovered from the samples that come from the depth interval of 982-1342 cm situated just above the lignite seam B.
The fossiliferous samples (no. 20) from the lignite mine have been provided to me by
Prof. Sunil Bajpai and Dr. AS Maurya, Department of Earth Sciences, IIT Roorkee.
1.2 OBJECTIVES
In the recent years Commissionerate of Geology and mining has carried out detailed geological study in several areas of Gujarat for the exploration of lignite. Hence lignitic deposits and associated shales were exposed in several open cast mines of
Cambay basin and other areas of Gujarat. This dissertation is the first attempt to recover and study the microfauna from this section in order to depict the age and palaeoenvironment. The following major objectives were pursued during the present investigation:
2 ❖ Recovery and description of early Paleogene microfaunal assemblages from Bhavnagar Lignite Mine, (Gujarat state , Western India)
❖ To make faunal comparisons with other correlative lignite deposits of Gujarat
❖ To attempt tentative biostratigraphic age determination of the Bhavnagar section
❖ To reconstruct paleonvironmental reconstruction of the Bhavnagar lignitic sequence.
1.3 BHAVNAGAR LIGNITE MINE (GUJARAT STATE, WESTERN INDIA)
1.3.1 Communication and location
The Bhavnagar Lignite deposits of Cambay basin, Gujarat consists of Tertiary rock exposures. The lignite mine is close to Surkha village which is 15 km from
Bhavnagar city. The mine extends from latitude N 21°26', 21°43' and longitude E 72°7',
72°16' (Figure 1.1). The Tertiary exposures in this area cover an area of about 202 Km2, with an extension of 60-70 Km in length (N-S) and 2-3 Km in width (W-E). The total exploration area of the mine is 17.89 Km2. The nearest railway station and airport are in
Bhavnagar city. The exploration agencies involved in Bhavnagar Lignite mine are
Geological Survey of India, Commissionerate of Geology and Mining and GMDC.
1.3.2 Geology
Bhavnagar lignite mine is situated in Cambay basin of Gujarat, Western India see
figure 1.2 for detailed geology of the Cambay basin. The Commissionerate of Geology
and Mining (CGM), Gujarat and Geological Survey of India has carried out detailed
geological study of the mine area to form the generalized lithological sequence of the
area. Deccan traps form the basement of The Supratrappen which is overlain by
Khadsaliya clays, Gaj formation, Piram beds and at the top by the Recent deposits.
3 r :T
r•
1 '4 . 4
'. •1 /. :. :J-
j4:jj. .' -, k-- r_ Figure 1.1 Satellite imageries showing the location of the Bhavnagar lignite mine. Bhavnagar district, Gujarat, Western India (source www.googleearth.com) -I' Figure 1.2 Geological and location map of an area around Bhavnagar lignite mine, Gujarat with reference to the Gulf of Cambay (Mathur et.al. 1968) 1.4 PREVIOUS WORK
As already stated in the above paragraphs, this dissertation is a first attempt at the recovery and taxonomic identification of microfaunal assemblages from Bhavnagar lignite mine. Previously the study on palynostratigraphy of Bhavnagar lignite is done which produced a good frequency of pollen and spore taxa. Pollen assemblages consist of
66 genera and 85 species, palynoflora suggests deposition of this lignite during early
Eocene period under warm humid tropical climatic conditions (Samant, 2000).
But similar study on microfaunal assemblage has been conducted at Vastan lignite mine which lies in close proximity to Bhavnagar lignite mine. It is highly fossiliferous comprising molluscs (bivalves, gastropods), ostracods, foraminifers, fossil insects, dinoflagellates, pollen and spores Vertebrates (fish, - amphibians, snakes, lizards, birds, and most importantly, mammals) (Bajpai, 2008 and the references therein). The ostracods recorded from the Vastan mine include Alocopocythere abstracta Siddiqui,
Acanthocythereis vastanensis n.sp., Cytherellakimensis n.sp., Neocyprideis suratensis n.sp. and Phlycetenophora meridionalis (Lyubimova and Mohan), it suggests an early
Eocene age and sediments were deposited in marginal marine to very shallow marine environment (Bhandari et. al. 2005).Several dinoflagellate cysts from different levels in the lignite-bearing sediments were identified which are age diagnostic such as
Muratodinium fimbriatum, heteaulacaysta granulate, Operculodinium severinii etc.
depicts the ages between approx. 55-52 Ma. (Garg, et. al 2008).
Vastan lignite mine provide 20 teleost taxa in which nine were described as new
species of tropical, very shallow near shore habitats (Nolf, et. al. 2006). Here we record a
diverse assemblage of elasmobranch and teleostean fish, including the selachians Triakis,
Eogaleus, Abdounia, Rhizoprionodon and Eutrichiurides, which are new to the 4 subcontinent. The Vastan ichthyofauna has general affinities with the Palaeocene—
Eocene fish assemblages from northern Africa, Europe and Uzbekistan (Rana, et.al.
2004). The early Eocene (Ypresian) Cambay Formation of Vastan Lignite Mine in
Gujarat, western India, has produced a diverse assemblage of snakes including at least ten species that belong to the Madtsoiidae, Palaeophiidae (Palaeophis and Pterosphenus),
Boidae, and several Caenophidia (Rage et.al. 2008). The oldest fossil avian remains of the
Indian sub continental plate, from the early Eocene of the Vastan Lignite Mine in Gujarat,
India. Three incomplete coracoids and two scapulae are assigned to the new taxon
Vastanavis eocaena, gen. et. sp. Nov. (Mayr et. al, 2007).
1.5 COLLECTION TEChINIQUES
The microfossils described in this dissertation were recovered from the fossiliferous horizon by intensive, high resolution sampling on the southeast face of the
Bhavnagar Lignite mine. The samples approx. 500 grams were collected at close and occasionally constant stratigraphic intervals, with the minimum interval of 5 cm and the maximum of 20 cm.In order to avoid contamination, these samples were then transferred to the polythene labeled sampling bags. From the data provided by Prof Sunil Bajpai and
Dr. A.S.Maurya, the lithocolumn has been prepared in MS Excel as shown in figure 1.3 with the enlarged view of fossiliferous horizon.
1.5.1 Maceration using hydrogen peroxide or water
For the recovery of the microfossils 50 g of the dried sample was taken and soaked for at least 4 hours in distilled water or 20% of V/V (volume/volume) of H202
(hydrogen peroxide) to disintegrate or disperse the matrix to separate microfossils. This soaked sample is wet-sieved over nested sieves of mesh size 60, 120 and 230 with a pan
5 Systematic Lithocolurnn Litholgv level(cm) Laterite
Grey shale
3...1:
Fossiliferous shale
Lignite searr 3
Lignite seam A
Grey sha e
Base not exposed
Figure 1.3 Lithocolmmn of the Bhavnagar lignite mine, Gujarat, Western India. at the bottom and then dried in oven at about 50°C. The samples retained in the sieves of
125 pm and above were studied under the microscope for the recovery of microfossils.
1.5.2 Picking and mounting
The loose and dried material is sprinkled lightly and evenly over a set of picking trays and kept under the tube of stereoscopic binocular microscope. All the microfossils from the trays are then picked using the sable hair brush (000), one wax tipped needle and a small container of water is required. These microfossils are placed then placed carefully on the faunal slides also known as micropalaeontological slides. The microfossils are then picked under the stereoscopic microscope and separated according to various groups. A collection of more than 600 specimens (including both identifiable and unidentifiable) from 50g of sample preparation. Each group will be identified and counting will be done in order to present the relative abundances of microfossils.
1.6 PHOTOGRAPHY
The use of electron microscope in the study of microfossils is carried out through
Scanning Electron Microscope (SEM). For SEM photography numbers of stubs are prepared for mounting of microfossils. For this a double sticking tape is placed on the surface of the aluminum stub. Over this tape a circular piece of a film roll (used in ordinary cameras) is stuck. The selected fossil specimens picked from the macerated material are stuck onto the surface of the film using a water-based paper gum. The surface of the stub is then coated with a thin layer of gold (500 A in thickness). The stub is then placed inside an electron microscope. A beam of electron scans the object and its visual is displayed on a video screen. The desirable view, angle and magnification are selected and the object is then photographed. The microfossils recovered during the present work were photographed at the Institute Instrumentation Centre (IIC) IIT Roorkee.
1.7 REPOSITORY OF THE MATERIAL
All the microfossils described in this dissertation are catalogued in the
Paleontology laboratory, Department of Earth Sciences, Indian Institute of Technology,
Roorkee under the acronym IITR/PVBLM.
7 CHAPTER 2
GEOLOGICAL SETTING
2.1 GEOLOGY OF THE STUDY AREA
Commissionerate of Geology and Mining (CGM) Gujarat has carried out detailed geological study of the area. According to the CGM Deccan traps from the basement for the Supratrappen (Paleocene to Eocene) sequence. Supratrappens are unconformably overlain by Khadasaliya Clay Formation of Eocene age.. About 6-10 m thick lignite
sequence is a part of the Khadasaliya Clay formation. This formation is unconformably overlain by the Gaj formation of Miocene age, All these formations are concealed under the thick alluvial deposits of Sub-recent to Recent age. The generalized lithology for this
sequence is given in figure 2.1.
2.2 REGIONAL STRATIGRAPHY OF BHAVNAGAR AREA
Geology of this area is part of the Saurashtra peninsula, bounded by sea except on
NE where it is flanked by alluvial plains. The peninsula is bounded by N—S trending
Cambay Basin fault in the east, the extension of Narmada geofracture(a fault system) in
the south, E—W trending gulf of Kutch fault in the north, and the major WNW—ESE fault
(an extension of the West Coast fault system in the Arabian Sea) in the west (Thakur et.
al. 2010). As per Biswas (1980, 1987) and Merh (1995), the Aravalli trend in the SW
portion of the region splays out into three components. The main NE—SW trend continues
across the Cambay Graben into Saurashtra as a southwesterly plunging arch. Biswas and
Deshpande (1983) consider the Saurashtra region as a horst surrounded by rift graben and
demonstrate that central, southern and northern Saurashtra exhibit distinct volcano-
tectonic characteristics. On the eastern side of Saurashtra, a sharp contact of alluvium Foratiioi Soil & alluvium Coastal dunes Recent & Sub-recent beach sands
A flte bearing conglomerates Pleistocene to Sub-recent Ferruginous sandstone and loose sand
Fossiliferous conglomerates Uppermost Miocene to Grits and sandy days Pliocene
Variegated shales «ith G%psum Lower Miocene veinlets. sand stones marts & Conglomerates
Grey to Greenish grey clays Eocene Sandstones, lignite with or without iderite nodules
B entonite. Laterite and reworked Lower Eocene B entonitic clays
Plutonic masses and d-,i:es Cretaceous to Eocene intrusive in the trap flows
Figure 2.1 Geological formation and lithology of an area with ages (CGM & GSI) withbasalt is observed in the N—S direction, extending from the west of NalSarovar to
Bhavnagar.
The following description of the regional stratigraphy is based on literature survey, especially the following investigations: Thakur et al (2010), Samant (2000), Jain
(2002), GMDC Gujarat (2008) and DGH (2010). The present study area is located in the
Saurashtra region of Gujarat and is part of the western Cambay basin.
2.2.1 Deccan Traps
Deccan Traps forms the basement for the deposition of the Tertiary sediments that are exposedin this area.It consists of alternating basaltic flows and intervening sedimentary deposition. It consists of effusive grey to dark grey and greenish grey to hard columnar basalts. At places vesicles filled with zeolite, quartz and calcite are present.
Between different flows certain clastic beds of shales/clays, siltstones and sandstones occur locally as inter-trappean beds which are poorly fissile. Volcanic plugs present are also arranged in ENE-WSW direction. Deccan volcanics are present over a large part of the Indian Peninsula itself. Totally covers the Saurastra Peninsula, some parts of Cambay basin and is present throughout the western coast. Its thickness varies from a few hundred metres upto 2000m in the on land part. In the offshore its thickness is highly variable (as seen in the seismics) as no well has penetrated the volcanics fully in the offshore. Few fossils have been reported from the inter-trappens. This formation gives Upper
Cretaceous to Lower Paleocene age.
2.2.2 Supratrappeans
This formation overlies the Deccan Traps unconformably. The deposits mainly consists of bentonites, laterites and bentonitic clays which are formed after thedeposition
0 of Deccan volcanics. These deposits are considered to be of Lower Eocene age.
2.2.3Khadsaliya Clays
Lignite in the region occurs in Khadsaliya Clays Formation (Eocene), which is
never exposed on the surface. This green to greenish-grey clay formation, overlying the
Supratrappeans (Lower Eocene) and Deccan Traps(Cretaceous-Eocene) holds the lignite deposits together withcarbonaceous clay. This formation also consists of fossiliferous
horizon from which fossils described in this dissertation were recovered.
2.2.4 Gaj formation
The. Gaj Formation comprises mainly of the ash grey shales, dominantly gypsiferrous clay, shell limestone light yellow calcareous claystone, yellow, orange and
red marls, variegated clays and foraminiferal limestone.Rocks of this formation dip at
very low angles towards the northwest. The overall thickness of the Gaj formation is
about 65m. It lies unconformably over the Deccan traps and is .conformably overlain by
Piram beds at Bhavnagar lignite mine. The formation was deposited in transgressive shallow marine sedimentary environment which is of early Miocene in age.
2.2.5 Piram beds
This formation unconformably overlies Gaj formation and is unconformably overlain by Lankhanka formation in ' this area which consists of fossiliferous conglomerates, grits and sandy clays. It is upper Miocene to Pliocene in age.
2.2.6 Lankhanka Formation
This formation is also known as Agate Conglomerate Formation. The formation
10 Unconformably overlies the Piram beds and is unconformably overlain by Alluvium deposits. It consists of agate, conglomerate and associated ferruginous sandstone with intercalation of clays. It is of Pleistocene to Sub-recent in age.
2.2.7 Recent deposits
Alluvial, coastal dunes and Beach sands, mud flats, soil, etcdeposits overlies the
Lankhanka formation (Agate conglomerate). The Recent deposits are Recent to Sub- recent in age.
2.3 GEOLOGY OF CAMBAY BASIN
The Cambay rift Basin, a rich Petroleum Province of India, is a narrow, elongated rift graben, extending from Surat in the south to Sanchor in the north. In the north, the basin narrows, but tectonically continues beyond Sanchor to pass into the Barmer Basin of Rajasthan. On the southern side, the basin merges with the Bombay Offshore Basin in the Arabian Sea. The basin is roughly limited by latitudes 210 00' and 25° 00' N and longitudes 71° 30' and 73° 30' E. The evolution of the Cambay basin began following the extensive outpour of Deccan Basalts (Deccan Trap) during late cretaceous covering large tracts of western and central India. It's a narrow half graben trending roughly NNW-SSE filled with Tertiary sedimentswithrifting due to extensional tectonics. Seismic and drilled well data indicate a thickness of about 8 km of Tertiary sediments resting over the Deccan volcanics (DGH, 2010). The systematic description of the different subsurface rock units of the Cambay basin is outlined in Figure 2.2.
The formation of the Cambay Basin began following the extensive outpour of
Deccan basalts (Deccan Trap) during late Cretaceous covering large tracts of western and
11 central India. The NW-SE Dharwarian tectonic trends got rejuvenated creating a narrow rift graben extending from the Arabian sea south of Hazira to beyond Tharad in the north.
Gradually, the rift valley expanded with time.
During Paleocene, the basin continued to remain as a shallow depression, receiving deposition of conglomerate, trap conglomerate, trapwacke and claystonefacies,
especially, at the basin margin under a fluvio—swampy regime. The end of deposition of the Olpad Formation is marked by a prominent unconformity. At places a gradational
contact with the overlying Cambay Shale has also been noticed.
During Early Eocene, a conspicuous and widespread transgression resulted in the
deposition of a thick, dark grey, fissile pyritiferous shale sequence, known as the Cambay
Shale. This shale sequence has been divided into Older and Younger Cambay Shale with
an unconformity in between. In the following period, relative subsidence of the basin
continued leading to the accumulation of the Younger Cambay Shale. The end of Cambay
Shale deposition is again marked by the development of a widespread unconformity that
is present throughout the basin. Subsequently, there was a strong tectonic activity that
resulted in the development of the Mehsana Horst and other structural highs associated
with basement faults.
Middle Eocene is marked by a regressive phase in the basin and this led to the
development of the Kaloll Vaso delta system in the north and the Hazad delta system in
the south. Hazad and Kalol/ Vaso deltaic sands are holding large accumulations of oil.
Major transgression during Late Eocene-Early Oligocene was responsible for the
deposition of the Tarapur Shale over large area in the North Cambay Basin. The end of
this sequence is marked by a regressive phase leading to deposition of claystone,
sandstone, and shale alternations and a limestone unit of the Dadhar Formation. 12 The end of the Paleogene witnessed a major tectonic activity in the basin resulting in the development of a widespread unconformity.
During Miocene The depo-centers continued to subside resulting in the deposition of enormous thickness of Miocene sediments as the Babaguru, Kand and Jhagadia formations.
Pliocene was a period of both low and high strands of the sea level, allowing the deposition of sand and shale.
During Pleistocene to Recent, the sedimentation was mainly of fluvial type
represented by characteristic deposits of coarse sands, gravel, clays and kankar followed
by finer sands and clays, comprising Gujarat Alluvium.
Throughout the geological history, except during early syn—rift stage , the North
Cambay Basin received major clastic inputs from north and northeast, fed by the Proto-
Sabarmati and Proto—Mahi rivers. Similarly, the Proto—Narmada river system was active in the south, supplying sediments from provenance, lying to the east.
13 CHAPTER 3
SYSTEMATIC PALAEONTOLOGY
3.1 FISH OTOLITHS
Order: Perciformes
Suborder: Percoidei
Superfamily: Percoidea
Family: Ambassidae Klunzinger,1870
"genus Ambassidarum"sp. 1
Material: 4 sagittae
Horizon: Above lignite seam B (BH 103-106, with the depth interval 1002 cm -1062 cm, see Fig. 1.3)
Locality: Bhavnagar lignite mine, Gujarat
Description: This genus is characterized by robust, high otoliths with prominent rostrum and anti rostrum, also a strongly anterodorsal angle. Angular disposition of the ostial and caudal part of the sulcus i.e. line going straight from the rostrum to the center of the junction of the ostium and cauda always form an obtuse angle with the main orientation of the cauda. The cauda traces a general anterodorsal —posteroventral widening. The outer face is smooth, flat to slight concave in the antero-posterior direction and somewhat convex in the dorso-vental direction. The inner face is globally convex, with well incised sulcus and shallow depression just above the crista superior.
14 Remarks: The family Ambassidae is known from many the European euryhaline deposits
of Eocene-Miocene age (Nolf et al. 2006). The Bhavnagar specimens probably a new
species but formal erection of a new species is being deferred here for want of additional
specimens.
"genus Ambassidarum"sp. 2
Material: 2 sagittae
Horizon: Above lignite seam B (BH 103-106, with the depth interval 1002 cm -1062 cm,
see Fig. 1.3)
Locality: Bhavnagar lignite mine, Gujarat
Remarks: "genus Ambassidarum" sp. 2 differs from "genus Ambassidarum" sp. 1
inshape, the earlier one more or less oval to hexagonal in shape, cauda in more longer
than ostium while the latter is elongated rectangular in shape, ostium and cauda are equal
in length and the dorsal depression is more prominent.
Order: Perciformes
Suborder: Percoidei
Percoidei inc. sed.
"genus Percoideorum" sp. 1,
Material: 3sagittae
Horizon: Just above coal seam B (BH 101-113, with the depth interval 982 cm -1202 cm, see Fig. 1.3)
Locality: Bhavnagar Lignite mine, Gujarat
15 Description: This genus is characterized by oval shape rather elongate otoliths with an
expanded anterodorsal area, a clear posterodorsal angle, and a straight, well incised sulcus
with ostial and a caudal portions of about equal length. The ostium is twice as wide as cauda. The outer face has a smooth surface and a nearly flat. The inner face is regularly convex. The crista superior is very salient because of the strong incision of the sulcus and rather strong depression in the area just above the sulcus. Some of the specimens shows clear ventral furrow very near to the ventral rim.
Remarks: These otoliths show a mixture of Apogonid and Ambassid features and may either belong to one of those families or to an extinct pleisiomorph percoid group. This U genus is described by Samant et. al. 2001 of early Eocene age
Order: Perciformes
Suborder: Percoidei
Percoideiinc. sed.
"genus Percoideorum" sp.2,
Material: 6 sagittae
Horizon: Just above coal seam B (BH 101-113, with the depth interval 982 cm -1202 cm, see Fig. 1.3)
Locality: Bhavnagar Lignite mine, Gujarat
Remarks: "genus Percoideorum" sp.2, differs from other Percoideorum species in, pentagonal shape, sulcus is round-oval and straight.
Order: Perciformes
16 Suborder: Percoidei
Percoideiinc. sed.
"genus Percoideorum" sp.3
Material: 3sagittae
Horizon: Just above coal seam B (BH 101-113, with the depth interval 982 cm -1202 cm, see Fig. 1.3)
Locality: Bhavnagar Lignite mine, Gujarat
Remarks: "genus Percoideorum" sp.3, differs from other species in oval shape.
Order: Perciformes
Suborder: Percoidei
Superfamily: Percoidea
Family: Apogonidae
"genus Apogonidarum" sp.1,
Material: 2 sagittae
Horizon: Just above coal seam B (BH 102-109, with the depth interval 992 cm -1122 cm, see Fig. 1.3)
Locality: Bhavnagar Lignite mine, Gujarat
Description: These are the well preserved otoliths depicting the key features of the
Apogonidarum specimens. These specimens show distinct apogonid features of the otoliths oval shape, slightly crenulated rims in some species, rounded rostrum. The dorsal depression is shallow, well incised sulcus with caudal length is small, does not extend till
17 the posterior margin. antirodorsal portion is expanded much more than antiroventral portion.
- Remarks: Members of this family are reef associated, found in tropical bays with mangrove vegetation. This genus is described by Samant et. al. 2001 of early Eocene age.
Order: Perciformes
Suborder: Percoidei
Superfamily: Percoidea
Family: Apogonidae
"genus Apogonidarum" sp.2,
Material: 2 sagittae
Horizon: Just above coal seam B (BH 102-109, with the depth interval 992 cm -1122 cm, see Fig. 1.3)
Locality: Bhavnagar Lignite mine, Gujarat
Remarks: "genus Apogonidarum" sp.2, differs in Discoidal shape, dorsal depression is prominent, antero-dorsal margin is elongated and covers the antirostrum.
Order: Perciformes
Suborder: Percoidei
Superfamily: Percoidea
Family: Apogonidae
"genus Apogonidarum" sp.3,
Material: 2 sagittae
18 Horizon: Just above coal seam B (BH 102-109, with the depth interval 992 cm -1122 cm,
see Fig. 1.3)
Locality: Bhavnagar Lignite mine, Gujarat
Remarks: "genus Apogonidarum" sp.3, is elliptical in shape with straight sulcus.
Order: Perciformes
Suborder: Percoidei
Superfamily: Percoidea
Family: Apogonidae
"genus Apogonidarum" sp.4
Material: 2 sagittae
Horizon: Just above coal seam B (BH 102-109, with the depth interval 992 cm -1122 cm, see Fig. 1.3)
Locality: Bhavnagar Lignite mine, Gujarat
Remarks: "genus Apogonidarum" sp.4 is also elliptical in shape but the margins are lobed on all sides, cauda is more longer than ostium.
Order: Perciformes
Suborder: Gobioidei
Family: Gobiidae
"genus: Gobiidarum " Regan, 1911
Gobiidarum vastani Bajpai and Kapur 2001
19 Material: 40 sagittae
Horizon: Just above coal seam B (BH 101-113, with the depth interval 982 cm -1202 cm, see Fig. 1.3)
Locality: Bhavnagar Lignite mine, Gujarat
Description: These otoliths show some features, such as the appearance of a swollen collicular crest above the caudal crista inferior and the anterior closing of the ostium that can be considered as a gobioid. Narrow ostium and the separate ostial and caudal collicula, are not seen in modem gobiids. It is commonly sub-quandrangular is shape i.e. height and length is nearly equal. Ventral portion is thick, broadly rounded and slightly longer than the dorsal portion. Prominent postero-dorsal angle present on the dorsal rim with characteristic notch. Posterior constriction more prominent, sulcus located anteriorly along the midline but totally disconnected from anterior margin. Outer face is more convex than inner face. Ostium expanded antero-ventrally, shallow depression present just above the sulcus.
Remarks: The gobiid species from Bhavnagar lignite mine shows close resemblance with
Gobiidarum vastani described by Bajpai and Kapur (2001) from the Vastan lignite deposit of basal Eocene age (- 54 Ma) mine.
Order: Perciformes )G Ace N') 6 2 o9 ,.-'S' Suborder: Gobioidei
Family: Gobiidae •T onnR~F/ "genus: Gobiidarum " Regan, 1911
"genus Gobiidarum "sp 1
Material: 2 sagittae
20 Horizon: Just above coal seam B (BH 101-113, with the depth interval 982 cm -1202 cm, see Fig. 1.3)
Locality: Bhavnagar Lignite mine, Gujarat
Remarks: "genus Gobiidarum" spl differs from Gobiidarum vastani in shape, the earlier one is hour-glass in shape, the sulcus is not clearly visible but appears like round-oval in shape while the latter otoliths margin is squared in shape.
3.2 Fish vertebra
Teleost indet.
(P14-fig 1-9,P15—fig 1-9)
Material: 25 vertebrae
Horizon: Just above coal seam (BH 101-111, with the depth interval 982 cm -1162 cm, see Fig. 1.3).
Locality: Bhavnagar lignite mine, Gujarat
Description: The vertebra is mainly represented by the centrum. They are cylinder- shaped, slightly narrower in the middle and wider at the ends. The central of the vertebrae are short and they are composed of concentric layers of bones, which form a concave cavity on both the ends. The entire fish vertebra is doubly concave and almost parallel to each other, while some makes an acute angle. The dorsal and ventral arch bases fused with the centrum of the vertebrae are also preserved. The preservation of the bony element is poor and the entire vertebra is gypsified. The bones are altered by secondary gypsum.
21 Remarks: These fish vertebra are described as Teleost indet, because it is not possible to identify them precisely. These are of varying sizes and structure.
3.2.1 Fish teeth
Class: Chondrichthyes Huxley, 1880
Subclass: Elasmobranchii Bonaparte, 1838
Order: Myliobatiformes Compagno, 1973
Suborder: Myliobatoidei
Family: Dasyatidae D. S. Jordan, 1888
Genus: Dasyatis Rafinesque, 1810
Dasyatis sp. 1
Material: 1 tooth
Horizon: Just above the coal seam B seam (BH-101, with the depth at 982 cm see Fig.
1.3).
Locality: Bhavnagar lignite mine, Gujarat
Description: Isolated tooth of female individual, unique in having elliptical to quadrangular crested depression in upper part of lingual crown face and deep central notch in lower part of labial visor, labial crown face pitted or smooth, lingual crown face with a median ridge flanked by depressions, teeth from median rows have more elongated depression and narrower lingual visor. These teeth differ from all the known species of Dasyatis in possessing a prominent crested depression on lingual crown face.
Remarks: The present tooth shows close resemblance to Dasyatis sp.I described earlier by Rana et. al. (2005) from Giral lignite mine, Banner District Rajasthan. Subclass: Elasmobranchii Bonaparte, 1838
Material: 1 placoid scale
Horizon: just above coal seam B (BH-109, with the depth at 1122 cm see Fig. 1.3).
Locality: Bhavnagar Lignite mine, Gujarat
Description: Also called dermal denticles, placoid scales are found in the cartilaginous fishes: sharks, rays, and chimaeras. They are structurally homologous with vertebrate teeth ("denticle" translates to "small tooth. Placoid scales cannot grow in size, but rather more scales are added as the fish increases in size.
Remarks: Also known from Giral lignite mine, Distt. Barmer, Rajasthan (Rana et al.,
2005)
Superclass: Osteichthyes Huxley, 1880
Genus: Egertonia?
Material: 1 tooth
Horizon: Just above coal seam B (BH 110, with the depth of 1142 cm, see Fig. 1.3).
Locality: Bhavnagar Lignite Mine, Gujarat
Description: Tooth small and rounded, apex convex with a circular rim, smooth with translucent enameloid.
Remarks: The tooth is bullet shapedand is close to the teeth described as Egertonia by
Rana et. al. (2004). However the present assignment is tentative.
23 Class: Actinopterygii
Order: Perciformes
Family: Sparidae
Genus: Sparus Linnaeus, 1758
Sparus sp.l
Material: 6 teeth
Horizon: Just above coal seam B (BH 103-117, with the depth interval 1002- 1282 cm,
see Fig. 1.3).
Locality Bhavnagar lignite mine, Gujarat
Description: Teeth vary in size and shape, generally short and conical, slightly curved.
Apex small, pointed to blunt with smooth basal surface. Some have globular teeth with flat and smooth occlusal surface, are compared to Egertonia of Gujarat.
Remarks: Also known from Khuiala formation of Jaisalmer Basin (Kumar et.al., 2007)
Class: Actinopterygii
Subclass: Neopterygii
Order: Salmoniformes Bleeker, 1859
Suborder: tEnchodontoidei
Family: Enchodontidae
Genus: Enchodus Agassiz, 1835
Enchodus sp.l
Material: 5 teeth
24 Horizon: Just above coal seam B (BH 103-106, with the depth interval 1002-10622 cm, see Fig. 1.3).
Locality: Bhavnagar Lignite mine, Gujarat
Description: Teeth recurved, slightly compressed, long conical with lateral edges, lower part of the inner surface striated, outer surface smooth.
Remarks: Also known from Giral Lignite mine, Barmer District (Ranaet.al., 2005) and
Vastan Lignite mine, Surat District (Rana et.al., 2004).
Class: Actinopterygii Klein, 1885
Order: Osteoglossiformes L. S. Berg, 1940
Family: Osteoglossidae sp.1 Bonaparte, 1832
gen. et. sp. Indet.
Material: 7 teeth
Horizon: Just above coal seam B (BH-102-BH-104 with the depth interval of 992-1022 cm as shown in figure 1.3)
Locality: Bhavnagar Lignite mine, Gujarat
Description: Apical part of teeth small, acute, pointed and translucent enameloid, basal part long, cylindrical with smooth surface and blunt edges. Teeth conical, slightly curved or straight. Numerous squamules of scales were also found in association with isolated teeth.
Remarks: These are exclusively fresh water fishes, also known from Giral Lignite mine,
Barmer District (Ranaet.al., 2005) and Vastan Lignite mine, Surat District (Rana et.al.,
25 2004).
Class: Actinopterygii Klein, 1885
genus Stephanodus sp. 1
Material: 2 teeth
Horizon: Just above coal seam B (BH 103-112, with the depth interval 1002- 11182 cm, see Fig. 1.3).
Locality: Bhavnagar Lignite mine
Description: Teeth compressed and flat with a large, hook like principle cusp having a shelf-like structure near the base, a smaller secondary cusp and a fairly deep root.
Remarks: Similar genus has also been known from Giral Lignite mine, Barmer District
(Ranaet.al., 2005) and Khuiala formation, Jaisalmer basin (Kumar et.al., 2007).
Class: Actinopterygii Klein, 1885
Order: Lepisosteiformes O. P. Hay, 1929
Family: Lepisosteidae Cuvier, 1825
Genus: Lepisosteus Linnaeus, 1758
Lepisosteus sp.1
Material: 4 teeth
Horizon: Just above coal seam B (BH 103-112, with the depth interval 1002- 11182 cm, see Fig. 1.3).
Locality: Bhavnagar Lignite Mine, Gujarat
W Description: Teeth conical, without lateral edges slightly curved, apical part with smooth enameloid, basal part longer, vertically striped. Some teeth are longer, compressed apical part having lateral edges.
Remarks: This is also exclusively fresh water fishes, also found in Giral Lignite mine,
Barmer District (Rana et.al., 2005).
Teleost indet
(P1 7 fig 1, 12,13,15, 19 )
Material : 5 teeth
Horizon: Just above coal seam B (BH-101 — 116, with the depth interval of 982-1262 cm)
Locality: Bhavnagar lignite mine, Gujarat
Remarks: These teeth are presently not identifiable, hence they are placed in open nomenclature.
3.3 Molluscs
Class: Bivalvia Linnaeus, 1758
Order: Veneroida Gray, 1854
Family: Carditidae Lamarck, 1809
Genus: Cardita Bruguiere, 1792
Cardita sp. 1
Material: 8 specimens
Horizon: Just above coal seam B
27 Locality: Bhavnagar Lignite mine, Gujarat
Description: Elongate, anterior beaks, inner margins are dentate, cardinals long, relatively small, short, lunule not depressed. Transversally inequilateral, trapezoidal or modioliform
with nodulose radial ribs. Hinge with obliquely trigonal divergent cardinals in left valve and faint anterior laterals.
Remarks: It is one of the common species of bivalves.
Class: Bivalvia Linnaeus, 1758
Callista sp. 1
Material: 1 specimen
Horizon: Just above lignite seam B (BH- 102, with the depth of 992 cm as seen in figure
1.3)
Locality: Bhavnagar Lignite mine
Description: Triangular in shape, radial micro ornamentation.
Class: Gastropoda Cuvier, 1795
Superfamily: Naticoidea Guilding, 1834
Family: Naticidae Guilding, 1834
Natica Scopoli, 1777
Natica sp. 1
Material: 1 specimen
w Horizon: Just above the lignite coal seam B( BH-102, with the depth of 992 cm as shown
in figure 1.3)
Locality: Bhavnagar lignite mine
Description: Thick shell, globular with low spire, large last whorl and aperture entire.
Class: Gastropoda Cuvier, 1795
Indet.
Material: 6 specimens
Horizon: Just above lignite seam B (BH-105 — BH107, with depth intervals of 1042-1082
cm as shown in figure 1.3)
Locality: Bhavnagar lignite mine, Gujarat
Description: Short-spired, three spire, aperture entire and the last whorl is large.
3.4 Ostracods
Order: Podocopida Muller, 1894
Suborder: Podocopina Muller, 1894
Superfamily Cypridacea Baird, 1894
Family: Cyprididae Baird, 1845 •,
Subfamily: Cypridopsis Kaufmann, 1900
Genus: Cypridopsis Brady, 1868
Cypridopsis sp.
Material: 8 carapaces
Horizon: Just above the coal seam B (BH-101 with the depth of 982 cm) 29 Locality: Bhavnagar Lignite mine, Gujarat
Description: These are the most inflated of ostracods and are readily identifiable. The
material is well within the size range of adults. A large species of Cypridopsis, elongate •
ovate in shape, with maximum length below mid-height and rather narrowly rounded
anterior margin. Carapace surface covered with minute white normal pores.Irregularly elongate-ovate in lateral view.Regularly fusiform in dorsal and ventral views, without lateral compression of end margins. Anterior margin rather narrowly rounded with apex below mid-height and long, gently convex antero-dorsal slope without marked cardinal angle. Posterior margin bluntly pointed with apex below mid-height and without marked cardinal angles. Dorsal margin asymmetrically convex about an apex anterior of mid- length.Ventral margin with very gentle median concavity.
Remarks: Cretaceous to Eocene, fresh water also known from the Deccan intertrappean beds of terminal Cretaceous age (Whatley et al. 2003).
Order: Podocopida MUller, 1894
Suborder: Podocopina MUller, 1894
Superfamily Cypridacea Baird, 1894
Family: Cyprididae Baird, 1845
Subfamily: Herpetocypridinae Kaufmann, 1900
gen et sp. indet.
Material: 2 carapaces
Horizon: Just above coal seam B (BH105 & BH-108 with the depth of 1042 &1 102 cm)
Locality: Bhavnagar Lignite mine, Gujarat
~7 Description: Small, subarcurate to elongate subovate in lateral view. Subcylindrical in dorsal and ventral views. Anterior margin rather narrowly and asymmetrically rounded and with long convex antero-dorsal slope. Apex in most specimens below mid-height.
Dorsal margin narrow bluntly pointed, somewhat - downturned. Apex below mid- height.Dorsal margin gently and regularly accurate, ventral margin medianly concave.
Another species of this genus contain tubercles on the surface.
Remarks: The present species from Bhavnagar lignite mine shows resemblance with the fresh water ostracod described as Mongolianella from the Deccan intertrappeans beds of terminal Cretaceous age (Whatley et al. 2003). However, the Bhavnagar species is not being assigned this genus for want of additional specimens.
31 CHAPTER 4
DISCUSSION
This present dissertation seeks to work out to document the different microfaunal assemblages present in the lignite sequence in the Bhavnagar Lignite mine Gujarat state, western India. Emphasis was placed in this study on the Eocene micro faunal-bearing horizons including those associated with the lignite deposits in the open cast mines at
Bhavnagar. These recovered faunas found in these horizons are of global significance from the evolutionary and biogeography perspectives, hence their ages need to be better constrained using the micro paleontological data.
Although sampling has been done from the bottom to top about 28 meters by high resolution (up to —5 cm interval) but bottom grey shale layer, thin carbonaceous shale between first and second lignite seam and topmost part of upper grey shale layer has been found unfossiliferous only about six meter thickness of horizon studied for this dissertation is found fossilliferous overlying above the coal seam B.
The presently recovered microfauna include bivalves, gastropods, Ostracods, fish vertebra, isolated teeth are very frequent. The recovered fossil assemblage comprises:
Bivalve: Cardita sp., Callista sp.
Gastropods: Teinostoma aff., Natica sp, Indet.
Ostracoda: Cypridopsis sp., Hepetocypridinae gen. et.sp. indet,
32 Fishes: Ambassidarum sp., Percoideorum sp., Apogonidarum sp., Gobiidarum
vastani, Gobiidarum sp., Dasyatis sp., Placoid scales, Egertonia?, Sparus sp.,
Enchodus?, Osteoglossidae sp., Stephanodus sp., Lepisosteus sp., Teleost indet,
Whereas some of the recovered faunal remains are unidentified, majority of them
.are either typically fresh water (fishes Lepisosteus, osteoglossidsand ostracods)or shallow marine (fishes such as gobiids, Dasyatis, EnchodusEgertonia, Sparus,
Stphanodus, Ambassidarum, Percoideorum, Apogonidarum) are marine in nature. The occurrences of fresh water and shallow marine water fauna (admixed fauna)together indicates frequent incursions of fresh water. Their habitat varies to soft bottoms of coastal area to fresh water. The palaeoenvironmental implications of individual taxa of
Bhavnagar assemblageare given in Table 4.1.
This study reveals that the deposition of the Bhavnagar lignite succession took place essentially in a shallow bay of marine embayment which was surrounded by coastal marshes with luxuriant plant growth. The clastic material was essentially derived from weathered Deccan Traps of the area.The coastal marshes were frequently affected by freshwater incursions. The bays also witnessed events of sea-level rise causing reduced terrigenous clastic supply and increased molluscan population.
The Bhavnagar vertebrate fauna is dated as early Eocene based on the basis of
Gobiidarum vastani, This record is palaeobiogeographically significant because it represents the oldest record of the family Gobiidae in the world. Taken together with the presence of gobiids in the middle Eocene of Kutch and Vastan lignite mine, it clearly shows that the traditional idea of an `explosive' appearance of this family at the Eocene—
Oligocene boundary was probably an artifact of the fossil record, and that the gobiids
33 apui Isoaia~, X X 0 X X X X 0 X X X X x X X 0 X X x x I snalsosida1 X x x x X C XC x x X x x x x x X X x is o x aepIssDiholso X O x x x x x x x x x x x x X x x X x V OX
snpoungda1S x O O CV x x x x x x x x x VV XXX x x O
iuoiaV V V V V V V V VCVXXXxxxxx V x0
sniuds X x X XOV x x X x O x VX XXOV X x X X
snpogo j X V V V x 00 X x X x x C x x x x V x y' x 0
s[UL.CsE4 O x X x X V x X x X x X x X X X x x V x 00 y
cs 4apuJ000OCV VxxXxXxxxXxxxX
um tep►igoD O 000000 000 00 00 0 X x x x X X O y u
F.un.mptuoiiody X OOx X X xXOV
umioapioaiad V X O O x O x x X X x X x X X X X X X x X O
um.mp[ssegw~I V O O X x O x x X VV X XX V X x X x x x O
o o sis(Iopud;)o V i it /r V / V V;!r V VV /VOV 03
jptFI0 C C/ Y. / V/ Y. V V/ V Y. X% V/ V V I)
F'lSI L') % ^ % / % % % % % Y. V V / % V Y. / V V V X O O cz N > F>iFp~e~00 C CC C CCVVV>exx, V V V V V X C Q.. 1apul C 0 o 0 0 o 0 0 0 V X X X V X V X x x x E
-~ sng.IL'd1\i>>!XXXOOXVXXXXXxXXk XXXOX
O ~O ~iceuu>>sollm l 0 0 0 0 0 0 0 0 X ~C x X x X >C X X Y. ;~ O 1)U 0 g3111NxXXXXXXXXXXXXx0xXXxXXO
oN olduwlS 0C) T T T T T T T T Z T T T T T T T T T Z T cd mmmmmmmmmmmmmmmmmmmmc~.. H were already an important group in the early Eocene coastal marine fish ecosystems in
India (Bajpai and Kapur 2004)
The age of the Microfaunal assemblage of Vastan lignite mine- is early Eocene i.e.
55-52 Ma, and close similarity of Gobiids of Bhavnagar lignite mine suggests the same age i.e. early Eocene. More precise age determination must await the Sr-Sr dating of the molluscan fossils from Bhavnagar mine.
34 CHAPTER 5
SUMMARY AND CONCLUSION
The present dissertation is the first study of the microfauna from the Bhavnagar
lignite mine of Saurashtra region, along the western margin of Cambay basin. As discussed in the Chapter 4 we conclude with the following main points:
❖ The Bhavnagar fish fauna is essentially an admixed fauna with both freshwater and shallow marine taxa. This is a stark contrast with the better known Vastan fish
of the Cambay basin.
❖ The striking similarity of Bhavnagar otolith with the Vastan otolith assemblages show that the two somehow possibly fall within the same age range i.e. early
Eocene.
❖ Comparison of Bhavnagar ostracods with the Vastan Ostracods show that the two faunas differ strikingly, the Vastan ostracods are essentially marine whereas those
from Bhavnagar are possibly fresh water. This suggests significant freshwater
influx during depositionof the Bhavnagar deposit.
❖ Molluscs from Bhavnagar are diverse, and of shallow marine nature. The• preservation is very good and an attempt is being made to date them using Sr-Sr
method.
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Photos I & 2 Photograph of the section and the panoramic view of' the Bhavnagar lignite mine, Bhavnagar district, Gujarat, Western India. EXPALNATION OF PLATE 1
1. Ambassidarum sp.1 IITRJPVBLM/1 (bar=100µm)
2. Ambassidarum sp.2 IITR/PV/BLM/1 (bar=100µm)
3. Percoideorum sp. 1 IITR/PV/BLM/1 (bar=-100µm)
4. Ambassidarum sp.2 IITR/PV/BLM/1 (bar=200µm)
5. Apogonidarum sp.1 IITR/PV/BLM/1 (bar=100µm)
6. Apogonidarum sp.2 IITR/PV/BLM/1 (bar=100µm)
7. Apogonidarum sp.3 IITR/PV/BLM/1 (bar=100µm)
8. Apogonidarum sp.4 IITR/PV/BLM/1 (bar=100µm)
9. Apogonidarum sp.2 IITRIPV/BLM/1 (bar=100µm)
10.Percoideorum sp.2 IITR/PVBLM/1 (bar=100µm)
11.Indet. IITR/PV/BLM/1 (bar=100µm)
12.Percoideorum sp.3 IITR/PVBLM/1 (bar=100µm) PLATE 1 EXPLANATION OF PLATE 2
1. Gobiidarum vastani IITR/PV/BLM/2 (bar=30µm)
2. Gobiidarum vastani IITR/PV/BLM/2 (bar-=30µm)
3. Gobiidarum vastani IITR/PV/BLM/2 (bat=30µm)
4. Gobiidarum vastani IITR/PV/BLM/2 (bar=30µm)
5.. Gobiidarum vastani IITR/PV/BLM/2 (ba.=30µm)
6. Gobiidarum vastani IITR/PVBLM/2 (bar =30µm)
7. Gobiidarum vastani IITR/PV/BLM/2 (bar=30µm)
8. Gobiidarum vastani IITR/PV/BLM/2 (bar=30µm)
9. Gobiidarum vastani IITR/PVBLM/2 (bar=30µm)
10. Gobiidarum sp.1 IITR/PVBLM/2 (bar=30µm)
11. Gobiidarum sp.1 IITR/PV/BLM/2 (bar=30µm)
12.Gobiidarum sp.2 IITR/PVBLM/2 (bar=30µm) PLATE 2 EXPLANATION OF PLATE 3
1. Gobiidarum vastani IITR/PVBLM/2 (bar=30µm)
2. Gobiidarum vastani IITR/PV/BLM/2 (bar=30µm)
3. Gobiidarum vastani IITR/PVBLM/2 (bar=30µm)
4. Gobiidarumvastani IITR/PV/BLM/2 (bar=30µm)
5. Percoideorum sp.3 IITR/PV/BLM/2 (bar=30µm)
6. Indet. IITR/PVBLM/2 (bar=100µm)
7. Percoideorum sp. 3 IITR/PV/BLM/2 (bar=100µm)
8. Indet. IITR/PVBLM/2 (bar=3 0µm)
9. Indet. IITR/PVBLM/2 (bar=30µm)
10.Indet. IITR/PV/BLM/2 (bar=100µm)
11.Percoideorum sp. 2 IITR/PVBLM/2 (bar=30µm)
12.Percoideorum sp. 2 IITR/PVBLM/2 (bar=30µm)
13.Percoideorum sp. 2 IITR/PVBLM/2 (bar=100µm)
14.Percoideorum sp. 2 IITR/PVBLM/2 (bar=100µm)
15.Percoideorum sp. 2 IITR/PVBLM/2 (bar=30µm) PLATE 3 EXPLANATION OF PLATE 4
1. Fish Vertebra IITR/PV/BLMJ6 (bar=100µm)
2. Fish Vertebra IITR/PV/BLM/6 (bar=200µm)
3. Fish Vertebra IITR/PVBLM/6 (bar=100µm)
4. Fish Vertebra IITR/PVBLM/6 (bar=300µm)
5. Fish Vertebra IITR/PVBLM/4 (bar=100µm)
6. Fish Vertebra IITR/PV/BLMJ4 (bar=100µm)
7. Fish Vertebra IITR/PV/BLM/4 (bar=100µm)
8. Fish Vertebra IITR/PV/BLM/4 (bar=100µm)
9. Fish spine IITR/PV/BLM/6 (bar=200µm) PLATE 4 EXPLANATION OF PLATE 5
1. Fish Vertebra IITR/PVBLM/4 (bar=100µm)
2. Fish Vertebra IITR/PV/BLM/4 (bar=100µm)
3. Fish Vertebra IITR/PV/BLM/4 (bar=100µm)
4. Fish Vertebra IITR/PV/BLM/4 (bar=100µm)
5. Fish Vertebra IITR/PV/BLM/4 (bar=100µm)
6. Fish Vertebra IITR/PV/BLM/4 (bar=100µm)
7. Fish Vertebra IITR/PV/BLM/4 (bar=100µm)
8. Fish Vertebra IITR/PV/BLM/4 (bar=30µm)
9. Fish Vertebra IITR/PV/BLM/4 (bar=100µm) PLATE 5 EXPLANATION OF PLATE 6
1. Dasyatis sp. IITR/PV/BLM/5 (bar=30µm)
2. Placoid scale IITR/PV/BLM/5 (bar=30µm)
3. Egertonia ? IITR/PV/BLM/5 (bar=30µm)
4. Sparus sp. IITR/PVBLM/5 (bat=30µm)
5. Spine IITR/PV/BLM/5 (bar=100µm)
6. Enchodus ? IITR/PVBLM/5 (bar=100µm)
7. Sparus sp. IITR/PVBLM/5 (bar=30µm)
8. Sparus sp. IITRIPV/BLM/5 (bar=30µm)
9. Sparus sp. IITR/PV/BLM/5 (bat=30µm) PLATE 6 EXPLANATION OF PLATE 7
1. Teleost indet. IITR/PVBLM/5 (bar=30µm)
2. Osteoglossidae IITR/PV/BLM/5 (bar=100µm)
3. Stephanodussp. IITR/PV/BLM/5 (bar=100gm)
4. Osteoglossidae IITR/PVBLM/5 (bar=100µm)
5. Osteoglossidae IITR/PV/BLM/5 (bar=30µm)
6. Osteoglossidae IITR/PV/BLM/5 (bar=30µm)
7. Osteoglossidae IITR/PV/BLM/5 (bar=100µm)
8. Lepisosteus sp. IITR/PVBLM/5 (bar=100µm)
9. Lepisosteus sp. IITR/SBBH/5 (bar=100µm)
10. Lepisosteus sp. IITR/PVBLM/5 (bar=100µm)
11.Osteoglossidae IITR/PVBLM/5 (bar=30µm)
12. Teleost indet. IITR/PV/BLM/5 (bar=30µm)
13. Teleost indet. IITR/PV/BLM/5 (bar=30µm)
14.Stephanodus sp. IITR/PV/BLM/5 (bar=100µm)
15. Teleost indet. IITR/PV/BLM/5 (bar=100µm)
16. Enchodus sp. IITR/PV/BLM/5 (bar=100µm)
17. Enchodus sp. IITR/PV/BLM/5 (bar=100µm)
18. Enchodus sp. IITR/PV/BLM/5 (bar=100µm)
19. Teleost indet. IITR/PV/BLM/5 (bar=100µm) PLATE 7 EXPLANATION OF PLATE 8
1. Cardita sp. IITR/PVBLM/3 (bar=100µm)
2. Cardita sp. IITR/PV/BLM/3 (bar=100µm)
3. Cardita sp. IITR/PVBLM/3 (bar= 100µm)
4. Callista sp. IITR/PV/BLM/3 (bar=30µm)
5. Indet. IITR/PVBLM/3 (bar=30µm)
6. Indet. IITR/PV/BLM/3 (bar=30µm)
7. Cardita sp. IITR/PV/BLM/3 (bar=100µm)
8. Indet. IITR/SBBH/3 (bar=3 0µm)
9. Natica sp. IITR/SBBH/3 (bar=30µm)
10.Indet. IITR/PVBLM/3 (bar=30µm)
11.Indet. IITR/PV/BLM/3 (bar =100µm)
12. Indet. IITR/PV/BLM/3 (bar=100µm) PLATE 8 1. Indet. IITR/PV/BLM/3 (bar=30µm)
2. Indet. IITR/PV/BI1M/3 (bar=30µm)
3. Indet. IITR/PVBLM/3 (bar=100µm)
4. Teinostoma aff. IITR/PVBLM/3 (bar=30µm)
5. Teinostoma aff. IITR/PVBLM/3 (bar=30µm)
6. Teinostoma aff. IITR/PVBLM/3 (bar=30µm)
7. Teinostoma aff. IITR/PV/BLM/3 (bar=30µm)
8. Indet. IITR/PV/BLM/3 (bar=100µm)
9. Indet. IITR/PV/BLM/3 (bar=30µm)
10. Indet. IITR/PV/BLM/3 (bar=30µm)
11. Indet. IITR/PV/BLM/3 (bar=100µm)
12. Indet. IITR/PV/BLM13 (bar=100µm)
13. Indet. IITR/PV/BLM/3 (bar=100µm)
14. Indet. IITR/PV/BLM/3 (bar=30µm)
15. Indet. IITR/SBBH/3 (bar=20µm) PLATE 9 EXPLANATION OF PLATE 10
1. Cypridopsis sp. IITR/PV/BLM/8 (bar=30µm)
2. Herpetocypridinae Gen et sp.1 IITR/PV/BLM/3 (bar=30µm)
3. Herpetocypridinae Gen et sp. 1 IITR/PV/BLM/3 (bar=30µm)
4. Herpetocypridinae Gen et. sp. 2 IITR/PV/BLM/3 (bat=100µm)
5. Herpetocypridinae Gen et sp. 1 IITR/PV/BLM/3 (bar=30µm)
6. Cyprididae IITR/PV/BLM/3 (bat=30µn) PLATE 10 I - \ . Ap . -:j 4: •-- 1 !. ____ 1L• •- ---. __ --t - - • ui ' I a
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