An Example of Stepwise Refinement of Distributed Programs: Quiescence Detection
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CHAPTER - 1
INTRODUCTION
1.1 GENERAL
The long period of quiescence that ruled the landmass since the dawn of
Proterozoic ended with the initiation of sedimentation in three newly formed
depressions (basins), on or close to the margins of the craton. They are Cuddapah
Supergroup, Pakhal Supergroup and Neo Proterozoic Groups such as Kurnool,
Penganga and Bhima groups.
Sedimentary basins have not received as much attention as they deserve. The
variety of sediments deposited in these basins, have sampled the continental crust of
that period and have, therefore, a great deal to tell us of the condition of the
atmosphere and hydrosphere and the nature of the weathering prevailing then.
The term Proterozoic is synonymous with Algonkian (USA), which is widely
used to represent late Precambrian. A variety of rocks are found in Precambrian
terrains, and each continent differs little from another in this regard. They are
represented by all kinds of sedimentary rocks, extensive lava flows and some still
relatively undeformed and unmetamorphosed. The name ‘Purana’ was given by
Holland (1907) to the group of unfossiliferous rocks lying unconformably over the
highly metamorphosed schists and gneisses of assumed Archaean age. Since there is
no precise age limit assigned for rocks falling with in this group, Dhaundiyal has
advocated dropping the term altogether in preference to the well defined chrono-
stratigraphic name “Proterozoic” with its proposed 3 divisions into early, middle and
late Proterozoic. The name Purana, however, is a most convenient term applicable to
sediments deposited in the middle to late Proterozoic, somewhat equivalent to the
Riphean of Russia. Proterozoic rocks in the form of least disturbed platform
sediments in India are younger than 1600 ma.
The Precambrian sedimentary formations are very well developed throughout
India. The Peninsular India offers a better scope for the study of these sedimentary
formations. The Kurnool sediments, which rest unconformably on the denuded edges
of the Cuddapah Formation, forms one of the sedimentary basins of the Precambrians
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(Purana) in the southern part of the Peninsular India, and are exposed in two basins
one in Kundair valley and the other in the Palnad tract. The Kurnools have been
broadly classified by King (1872) into four major divisions: Banaganapalle,
Jammalamadugu, Paniam and Kundair Formations, of which the first two are grouped
under lower Kurnools and the other two under upper Kunools.
This thesis deals with the stratigraphy, lithology, structure, sedimentology,
geochemistry, provenance and depositional environment of the Palnad sediments
(Kurnool Group). The sequence of rocks studied is exposed in Guntur, Krishna and
Nalgonda district of Andhra Pradesh. The area is found to be of particular interest,
since the Kurnools are very well exposed and their actual contact with the underlying
Archaeans and Cuddapahs is quite distinct, providing a continuous geological
succession, enabling to establish the detailed lithostratigraphy of the area.
1.2 LOCATION AND COMMUNICATION
The Kurnool Group of rocks are well exposed in Kurnool, Cuddapah, Guntur,
Krishna, Nalgonda and Mahabubnagar districts of Andhra Pradesh. The exposures can
be noticed in two basins, one in the Kurnool basin and the other in the Palnad Sub
basin. The Kurnool basin, extends between the latitude 14°30" - 16°00" and longitude
77°58" -78°45", covering an area of about 14,500 sq Kms The Palnad Sub basin
which is found in the North-Eastern part of Cuddapah basin extends between the
latitude 16°18" - 16°55" and longitude 79°18" -80°26" covering an area of about 3600
sq. Kms (Survey of India toposheets : 56 P/6, 7, 8, 10, 11 and 65D/1 and 2). The
location map of the area is shown inFig1.1.
The area is accessible from Hyderabad, Kurnool and Vijayawada. Two major
towns in the area, Macherla in Guntur district and Jaggayyapeta in Krishna district are
very well connected by rail and road network. There are good metalled roads
connecting railway stations, district and taluk headquarters. Also, the villages are very
well connected by metalled roads. The communication network, both by rail and
road, has enabled Guntur and Krishna districts in the development of few cement
factories such as Andhra cements Ltd., (Dachepalli, Piduguralla) KCP Ltd,
(Macherla), Bhavya cements, (Tangeda), Sri Durga cement works (Old Guntur), JK
white cement works, (Old Guntur), Madras cements Ltd., (Jayanthipuram),Ramco
cements Ltd., (Jayanthipuram) situated at Macherla and Jaggayyapeta.
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Fig 1.1 LOCATION MAP OF THE STUDY AREA
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1.3 GEOMORPHOLOGY
The geomorphology of the area is essentially a reflection of the lithology and
structure of underlying rocks. Therefore a brief account of the same is presented as it
could help in deciphering the continuity of lithounits and their structural disposition.
The terrain in the South-western part of the basin ie, around Macherla,
Veldurti and Dwarakapuri is made up of either steep slopes or scarps and flat topped
hillocks of quartzites. Hillocks run roughly in east-west direction covered by
Kandlagunta, Mandadi and Veldurti Reserved forest. In the North – Eastern part of
the basin ie, around Jaggayyapeta town the terrain is a broad flat plain consisting of
carbonate rocks.
1.4 DRAINAGE
The drainage is mostly sub-dendritic to sub parallel (Vaidyanadhan, 1964).
Krishna riveris the northern boundary of the study area. Chandravanka which is
perennially flowing from south to north, is a tributary of Krishna river. A few small
streams flow in the area, important among them being Edibogulavagu and
Bottalavagu. All these streams are affluent and join Chandravankariver. Numerous
seepages are observed at the contact between quartzites and limestones. There are
waterfalls on the Chandravankariver with a fall of 20 mts at Ettipotala. These falls are
exactly at the contact of quartzites with limestones.
The drainage patterns of the study area varies considerably. A combination of
angulate, dendritic, rectangular and trellis drainage patterns have been noticed in
many parts of the study area. The important river draining the area is Krishna and a
multipurpose dam is constructed across this river 20 kms NW of Macherla town (Fig
1.2).
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Fig 1.2 PANORAMIC VIEW OF NAGARJUNASAGAR DAM ACROSS RIVERKRISHNA
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1.5 CLIMATE AND RAINFALL
The climate is the day-to-day variations in weather of a locality and it includes
the following elements as temperature, precipitation, humidity, sunshine and wind
velocity. Palnad area enjoys a warm summer and dry winter. The hot season
commences early in March and ends up sometime in June, when the monsoon starts.
The minimum annual temperature varies from 16°C to18°C. The maximum
temperature is around 40°C. The average annual rainfall varies from 100 to 125 cms.
Area receives rainfall both during SW monsoon and NE monsoon. Often the NE
monsoon brings out floods causing severe damage to human life. Periodically, the
rainfall is precariously low or unseasonal, causing drought and famine.
1.6 MINERAL RESOURCES
The area is endowed with a fairly large number of mineral deposits, important
of which are asbestos, barites, copper, steatite, lead and diamond(Fig1.3). Although
the Kurnool Formations do not contain metalliferous deposits, they contain clays,
ochres, limestones and dolomites, besides excellent building stones and raw materials
for cement. There are also a few deposits of high grade calcareous tufa and
efflorescence of earth salts and soda.
Old workings for diamond are noticed in basal Banaganapalle conglomerates
in numerous localities. Yellow ocherous shales occur in pockets in the Owk shale
member. This material can be used in colour wash distempers and also possibly in the
cement industry for making coloured cements. Small deposits of white clays are
exposed in the Owk Shales and are used as a filler.
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Fig 1.3 MINERAL MAP OF ANDHRA STATE
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1.7 GEOLOGY
The foundations of the geology of the area were laid by several workers
during the last part of 19th
century and the early part of 20th
Century. The rock types
constituting the Kurnool Group of rocks in Palnad Sub basin are mainly of quartzites,
shales and limestones. The generalized geological succession or stratigraphy of the
area was first given by King (1872).
The Kurnool strata cropout in two isolated areas, namely in Kurnool basin and
the other in the Palnad Sub basin. The lowermost formation of the Kurnool is the
Banaganapalle conglomerate, sandstone and quartzite. The conglomerate being
occasionally diamondiferous. It is succeeded by the Narji massive or flaggy limestone
with shale and quartzite intercalations. This is well developed in both the basins,
where huge reserves of limestone suitable for the manufacture of cement exist. The
Narji is succeeded by the Owk Shale. The Owk shale is overlain by the Paniam
quartzite, which in turn is overlain by earthy siliceous Koilkuntla Limestone, followed
by purple calcareous Nandyal Shale with thin intercalations of limestone.
1.8 SOIL AND AGRICULTURE
Soil quality is an important factor in the crop yield. The area is characterized
mainly by three types of soils, namely black cotton soil, red loamy soil and dark
brown soil. Most part of the research area is covered by black cotton soil, and are
found in areas where limestones are occurring. The red loamy soil is formed due to
the weathering and erosion of quartzites. Another type of soil is dark brown in colour
and is covering the area between Mandadi and Mutukuru. This colour is due to the
weathering of purple coloured shales of Kundairs.
The dry climate in Guntur and Krishna district is not conducive for a good
vegetational cover. The most fertile and rich tract of land bordering the banks of the
river Krishna is however intensely cultivated. The main crops cultivated in the area
are Chillies, Jowar, Ragi, Paddy, Blackgram and cotton. Except for the green strips of
vegetation along the valleys, the flat topped hills are not covered by vegetation. The
vegetation is dry savannah and poor steppe. The drought resisting xerophytes, thorny
bushes and scrubs along with grass grow over the hill tops and along the slopes. The
region is characterized by open spaced short trees of acacias and euphorbias, with an
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under growth of thorny shrubs and grasses. Grasses grow rapidly during the rainy
season. The reserve forest in the area is reported to contain bear, leopards, wild hogs,
hares, porcupine, hyena, deer, rabbits, snakes and few sambars.
1.9 PREVIOUS WORK
The Cuddapah Group of rocks are overlained by a set of predominantly
sedimentary rocks called Kurnools and the two groups are separated by an angular
unconformity. These sedimentary rocks belong to the upper Proterozoic. It is
significant to note, while reviewing the literature on Kurnools that much of the
contributions in the early periods come from the officers of the Geological Survey of
India. The earliest work on Kurnools dates back to 1794 by Mackenzie, who focused
his attention on the lithology of this tract. During further attempts emphasis was
mostly on economic evaluation of the area, particularly for diamond and iron by
Heyne (1814) and by Voysey (1825). Four other contemporary workers, namely
Cullen (1827), Christie (1828), Malcolmson (1836) and Newbold (1836) for the first
time started describing various rock types of Cuddapahs and Kurnools. Carter (1854),
attempted to secure a position for Cuddapahs and Kurnools in the geological scale of
formations. None of these writers has dealt with the stratigraphy and structure of these
rocks and their account on lithology is also very brief. A pioneering geological work
was carriedout by trio geologist Sir Thomas Oldham (1786), William King(1872) and
Robert Bruce Foote(1892). A very comprehensive treatise on the Kurnool group came
off from King (1872). This memoir still remains a valuable geological document on
the Kurnools. His greatest contribution to the geology of the Kurnools is the first ever
formulation of comprehensive stratigraphy of the entire basin. By the test of
superposition he classified Kurnools into four major lithological units, each of which
comprising several subunits named after the predominant rock type. The four major
lithological formations are Banaganapalle, Jammalamadugu, Paniam and Kundair.
Though, the earliest geological work in the area is by King (1872) but, the first to
record about the geology of the area is Bruce Foote whose notes were freely quoted
by King (1872) in his memoir.
After the monumental work of King (1872), there was a period of lull and only
during the last fifty year or so substantial amount of work has been turned out on
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various aspects of Kurnools. It is significant to note that the original stratigraphy
proposed for Kurnools by King, however, stands undisputed throughout.
The Kurnool formations of the northern part of the Kurnool district were
mapped by Roy (1945-46 & 1946-47). Venkatesh (1947-48 & 1948-49) and
Madhusudhana Rao (1950-51). Balasundaram (1944-45) and Venkatram (1945-46)
examined the limestone in this area belonging to Kurnool Group.
As regard to the geomorphology of the basin, no detailed work has been
carriedout till 1955. Dutt (1955) described various geomorphological features and
carriedout extensive work on Geology of the Kurnool sediments. Again in 1962, 1975
and 1986 mapped the Kurnool formations and reported flux grade and cement grade
limestones from the basin. He recognized a disconformity at the base of the Paniam
Quartzite and identified Kurnool as a group.
The evidence for finding out life during upper Proterozoic times was
carriedout in detail by Saluja et al., (1972). They had done detailed palynological
investigations and reported some of the micro-planktons for the first time from the
Kurnool shales. On the basis of this investigation they assigned late Precambrian to
Cambrian age for these sediments and inferred that the Kurnool sediments are
deposited under shallow marine conditions. Later Sharma and Shukla (1973) reported
carbonaceous mega remains from the Owk Shales and inferred the Neoproterozoic
age for it. Also, Crawford and Compston (1973) worked on the age factor of
Cuddapah and Kurnool Group of rocks.
Subsequently, Reddy and Vijayam (1974, 76) have studied the lithology and
tectonic framework of sedimentation of the Kurnool sediments in the Western part of
Palnad basin, besides studied in detail clay minerals in Owk and Nandyal Shales and
inferred the marine depositional environment for these shales. Also, they have made a
detailed study on microstylolites in Narji Limestones and discussed in detail the
diagenetic aspects of limestones and inferred the tectonic activity in the area.
Natarajan and Rajagopalan Nair (1977) have reported post Kurnool thrust and
other structural features (primary and secondary) in the north-eastern part of the
Palnad basin, Krishna district, which constitutes a very important factor in
interpreting the tectonic history of the area. They have done detailed work on pressure
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solution structures (stylolites) in Narji Limestones from Jaggayyapeta area and
described their nature and types, megascopic and microscopic features and tectonic
effects on them. They have discussed in detail the usefulness of stylolites in
recognizing the bedding planes and their importance in estimating the thickness of the
limestone units.
Later Arya and Rao (1979) worked on the Narji Limestones and reported
bioturbation structures from the Narji Formations. A detailed work on structural
aspects of Cuddapahs and Kurnools has been carriedout by Rajurkar (1977). From the
analysis of structural patterns and other details, it is concluded that the Cuddapah
orogeny resulting in severe deformation of the Cuddapah is of Pre Kurnool age. There
has been another period of deformation in the post Kurnool period, where in the
Cuddapahs and Kurnools suffered very little folding, but extensive faulting. Besides,
reported discoidal impressions akin to Fermoria, from the Owk Shales of Kurnool
Group by this author.
Later, Kamal (1982) carriedout detailed petrographic studies and on the basis
of the types of cementing material, authigenic products and replacement textures, it is
inferred that the Paniam sands deposited in beach to dune environments, subjected to
shallow to medium burial and involved in redexomorphic to locomorphic stages of
diagenesis. Besides, Kamal and Vijayam (1982) have reported intraformational
conglomerate from this group and attempted to discuss mode of origin.
Rao and Dasari (1989) has worked in detail on the isotopic variations in
limestones (Narji and Koilkuntla). Observed a progressive increase of δ O18
values for
Narji Limestones from basal to top horizons and inferred that the gradation of δ O18
value is due to interaction of various horizons with fresh water in the later geological
periods and possible consequent exchange.
Venkatachalapathy et al., (1992) have carried out detailed work on
palynological aspects of Kurnool Group and reported some of the microplanktons
from this group. From this study they inferred Precambrian-Cambrian age for the
Kurnool Group of sediments and also attributed shallow marine intertidal depositional
environment for these sediments.
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Lakshminarayana et al., (1999) studied in detail the Paleocurrent pattern of the
Banaganapalle Formation in the Kurnool sub basin and inferred the provenance as
mainly the intrabasinal tract occupied by lower Cuddapah sediments, igneous
intrusive and the basement located to the west.
Grururaja et al., (2000) recognized a boundary strata separating Precambrian
from the Cambrian in the Cuddapah basin.
Patil. D.J et al., (2002) carriedout Carbon, Oxygen and strontium isotope
geochemistry of carbonate rocks from Kurnool Group and inferred the open system
diagenetic trends for the carbonate rocks of Narji Formation and for Koilkuntla
Formation does not show any definite alteration trends.
Harish et al., (2003) worked on the petrography and fluid inclusion studies on
Palnadsiliciclastics and suggested that the Archaean granites, granitic gneisses and
sedimentary formations belonging to Cuddapah Group are the source rocks for the
Palnadsiliciclastics.
Saha and Chakraborty (2003) studied in detail the deformation pattern in the
Kurnool and Nallamalai groups in the NE part (Palnad basin) of the Cuddapah basin.
Subsequently Saha et al., (2006) carriedout a detailed work on sedimentary sequences
in Palnad and Kurnool subbasins and interpreted their paleogeographic and tectonic
implications.
Jeyagopal, A.V et al., (2006) worked on the geology of the Julakallu area,
Guntur district, Palnad sub-basin. The geological studies have brought out the
presence of unknown Cumbum shale/phyllite in the Julakallu-pinneliare within the
Palnad sub-basin. Cumbum shale/Phyllite and quartzite was found to rest above the
Narji Limestone.
Later Butchi Babu et al., (2008) estimated the thickness of limestone
formation in Kurnool sub basin by Aeromagnetic anomalies.
Subsequently Babu (2011) carriedout provenance studies by U-Pb-H-L-O
isotopic composition of Zircons from the conglomerates and Sharma (2011) reported
Neoproterozoic and Ediacaran paleobiological remains in the purana basins of
Peninsular India and inferred the age of Kurnool, Bhima and Vindhyans.
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Joy et al., (2012) worked on geology of the Banaganapalle conglomerate of
Kurnool Group and inferred the diamond provenance for the sequence. Saha and
Tripathy (2012) worked on Tuff beds in Kurnool sub basin and inferred the felsic
volcanism in Proterozoic intracratonic basins. Sharma and Shukla (2012) reported
helically coiled microfossil in the Owk shale of Kurnool Group and discussed their
significance.
Bickford et al., (2013) carriedout a detailed work on U-Pb ages of Zircons in
the Owk Shales and inferred the age and the provenance for the Owk Shales.
Paul. A.K et al., (2013) carriedout a detailed study on mineral chemistry of
radioactive uranium deposit of Koppunuru area in Palnad basin. The study has
revealed the potential for multi-episodic epigenetic U-mineralisation in basement
granitoids and the overlying Banaganapalle Formation.
Singh, R.V et al., (2013) also has reported uranium mineralization in
Koppunuru area of Guntur district in Palnad basin. They have reported uranium
mineralization in the granitic rocks which forms the basement for Palnad sediments.
1.10SCOPE OF THE WORK
A survey of previous literature indicates that many of the aspects were either
largely regional or limited to report some salient and specific occurrences. As such no
attempt had been made to know the characteristics of the Kurnools. This status has
remained so because of the very large size of the basin and the voluminous amount of
work needed to achieve the desired goal.
In line with the aforesaid objective, this work has been primarily oriented on
lithostratigraphy, sedimentary structures associated with the lithotypes and their
significance in the interpretation of the paleo environmental conditions of deposition.
The detailed study of the sedimentology helps in understanding the media of
transportation, depositional environment and provenance. The geochemical studies of
shales and limestones helps to evaluate the sedimentary environment under which
they were deposited and the reconstruction of ancient environmental conditions. Also
a detailed study of the diagenetic effects in the area helps to reveal the environment of
deposition as well as post-depositional textural and mineralogical modifications.
Besides, the clay mineralogy, XRD and staining technique have also been applied in
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this study, which may throw a better light as to the geological setting and the nature of
deposition of the sediments. The aspects like stratigraphy, structure, sedimentology,
geochemistry diagenesis are particularly chosen for the following reasons.
1. No detailed work regarding the above said aspects is on record.
2. The basin presents contrasting lithotypes having mainly sedimentary rocks
1.11 OBJECTIVES OF THE WORK
1. Construction of lithostratigraphical column.
2. Sedimentological studies including Textures, Modal Analysis, Petrography and
Structures.
3. Detailed Study of Carbonates and argillites by XRD and Staining technique.
4. Study of Provenance and depostional environment of the rocks based on
Geochemistry, Pre and post diagenetic effects in the area.
1.12 METHODOLOGY
Survey of India Toposheet (Scale 1:50,000) are used for field work to collect
the basic data required to know the geological history of the area. The main purpose
of field work is to construct the lithostratigraphic sequence of the study area (Palnad
Sub basin), along with a detailed study of lithounits. The basic data collected in the
field includes the study of primary and secondary structures, variation in colour and
thickness of the arenites carbonates and argillites, contact between the different litho
units within the stratigraphic divisions, the significance of paleo environmental and
depositional evidences. The different methods and techniques applied in investigating
research problem is as follows:
1. Lithostratigraphical columns of the rocks of Palnad Sub basin were constructed
using measured outcrops.
2. About 200 samples were collected from different lithological units for studying
the petrographical and textural characters and compositional variations.
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3. The Sedimentological work of quartzarenites includes grain size analysis,
petrographic study, modal and heavy mineral analysis with a view to understand
their genesis and environmental significance.
4. Quartzarenites are studied in detail as to their associated structures (cross
stratification, ripple marks, desiccation cracks) and in conglomerate orientation
of pebbles, pebble counting, matrix study were also carried out.
5. The macro and micro stylolites associated with the carbonates have been studied
in detail which helped in understanding the probable tectonic influence in the
area.
6. The colour and nature of the shales are used for classifying the Owk Shale into
lower and upper divisions and in the like manner the colour and nature of the
limestone are used for classifying the carbonates of Kurnool Group.
7. As the limestones of the group are cryptocrystalline in nature it is difficult to
carryout petrographic studies, hence staining technique is applied to differentiate
calcite and dolomite among the carbonates.
8. Separated clay minerals from shales using 1/10 N HCL by suspension method
and identified the clay mineral by obtaining the XRD curves. Illite is the
dominant clay mineral, the presence of which indicates the marine alkaline
environment for the shales. Besides, determination of pH substantiates that the
shales are deposited in marine alkaline environment.
9. Carbonates of the Kurnool Group are cryptocrystalline in nature and is difficult
to study their petrography. Hence, X-ray diffractogram analysis is used in the
identification of minerals, which revealed that calcite and quartz are the dominant
constituents.
10. The major and trace element analysis of arenites, argillites and carbonates were
carried out by Calorimetric, Titrimetric and by wet chemical analysis through
ICP.
11. Pre and post diagenetic effects in the area were studied in order to reveal the
environment of deposition.