Exploring microbial diversity and function
within the granitic-basaltic deep crustal
system of Koyna-Warna (India) region
Pinaki Sar
Department of Biotechnology
Indian Institute of Technology Kharagpur
India
Collaborators
Sufia K Kazy, National Institute of Technology Durgapur, India
Sukanto Roy, National Geophysical Research Institute, Hyderabad, India
Deep biosphere within basaltic – granitic
(igneous rocks) systems
Igneous rocks constitute ~95% of the Earth’s crust
Basalt
Deep crustal system represents an Extreme Habitat
for Life
 Aphotic
 Devoid of Org C
 Subjected to high temperature/pressure at
some point in their history
 Granite
Oligotrophic
Image source : http://en.wikipedia.org/wiki/File:Igneous_rock_eng_text.jpg#file
Microbiology of deep, igneous crust seems
more intriguing,
though relatively less studied
Biogeochemical
importance;
Limits of life ?
 Newly generated (annually) and recycled (~
60 M yrs)
Who are they ?
 Upper
What are their function
(500 m), subseafloor basalts are
significantly porous and permeable,
hydrologically active
Microbiology of basaltic/grantic deep subsurface (marine/terrestrial)
 Largest potential microbial habitat
are less studied and mostly unexplored
Some more reports for ocean crust than terrestrial habitats
Unlike deep oceanic subsurface which may be partially dependent on
organic C and energy derived from photosynthetic process, life within
terrestrial crystalline rocks are independent to photosynthesis
What remained largely unexplored and poorly understood :
 Distribution and diversity of microbes in terrestrial igneous rocks
 Knowledge on their metabolic functions and their impact on global
C and nutrient cycles
Bacterial communities in different (sub-)sea floor habitats,
demonstrating that subsurface crustal bacteria are distinct from
the bacteria in other deep-sea environments; Wang et al 2013; Edward et al 2011
What powers deep microbiome ?
Extent of microbial catabolic potential within
deep igneous crust
 Abiogenic H2 driven metabolic pathways ?
 Role in C/N/nutrient cycling
 Rock weathering and climate change
In igneous rock systems
?
X
Acetogenic –Methanogenic metabolism with
abiogenic H2
Geomicrobial processes at a subsurface shalesandstone interface; Fredrickson and Balkwill, 2006
Abiotic processes
Temperature
H2 driven system
Denitrification/NH4
Anaerobic heterotrophic
oxidation
metabolism
Anaerobic lithoautotrophic N2 fixation
metabolism
SLiMEs (?)
Abiotic geogenic H2
Abiotic diagenetic
formation of
H2
low mw compounds
Radiolytic decomposition of water
Water-rock interaction
Diffusion from deeper levels
Methanogen
Small Org comp
The Deccan Traps
 The Deccan Traps are a large igneous province, on the Deccan
Plateau (west-central India (between 17–24N, 73–74E)
 One of the largest volcanic features on Earth
 Consist of multiple layers of solidified flood basalt [together
>2,000 m thick and cover an area of 500,000 km2 and a volume of
512,000 km3 (123,000 cu mi)]
 formed between 60 and 68 million years ago [end of
the Cretaceous period] linked to the Cretaceous–Paleogene
extinction event
Seismic activity in deccan Trap at Koyna-Warna
region
Reservoir triggered seismicity (RTS) record in past 38 years:
>10 earthquakes of Mz5;
>150 earthquakes of Mz4
>100,000 earthquakes of Mz0
soon after the impoundment of the Shivaji Sagar Lake created by
Koyna Dam in Western India in 1962
Drilling site at Koyna
Drilling is proposed up to nearly 7 KM, so far ~1.5KM drilling is done
Cores recovered so far revealed :
 Flood basalt pile with numbers of lava flow
 Each flow has vesicular / amygdaloidal layer unde lined by massive
basalt
 Microbial presence (successful extraction of DNA and amplification
of 16 S rRNA gene regions) from samples of 1300 M depth
 Low C environment
Core samples from borehole KBH-1 showing (a) massive basalt, (b) vesicular and amygdaloidal
basalt with large vugs filled with quartz and/or JOUR.GEOL.SOC.INDIA,
calcite
VOL.81, FEB. 2013
Major aim of the proposed work
 Delineating the environmental limit of life within the
terrestrial baslatic/granitic system
 Understanding the processes that potentially define
diversity /distribution of life in deep terrestrial crustal
system
 Possible modes of microbial interactions within such
environment affecting C and nutrient cycle, rock weathering
etc.
Objectives
Analysis of microbial diversity and composition within the
basaltic-, granitic- and transition zones from deep subsurface
environment of Koyna region: Combination of metagenome based
sequencing techniques and enrichment/isolation of bacteria (include virus
and fungi as well after this meeting )
Metabolic function and microbial role in biogeochemical cycling
of carbon, rock microbiome interaction (weathering); effect –
response of seismic activities: Metagenome and metatranscriptome
analysis, WGS analysis of predominant isolates, metabolic modeling, getting
ideas of novel metabolic routes running the biogeochemical reactions
Integration of geochemical/environmental data and comparative
metagenomic analysis of deep basaltic-granitic biosphere with
and without seismic activities: Assessment of the extent of microbial
distribution and diversity, potential involvement in C cycle
Work flow: implementaion
Elucidation of effect of seismic activity
and crustal properties on microbial
diversity and activity
Analysis of microbial function
Analysis of microbial diversity,
community structure, abundance
Obj . I
0
Obj . II
Time scale (year)
Drilling, sample
collection and
analysis
Molecular genomic
analysis
Obj . III
5
Data integration and
modeling
Deliverables
Deep carbon observatory goals :
 Elucidation of microbial diversity/distribution within carbon
limited, dark, deep terrestrial crust
 Better insight in understanding on survival strategies and role
under deep subsurface igneous rocks
Global
significance
primer
siteandoftheir
RTSinteraction
within
 Delineation
of limits: forGlobal
microbial
deep life
basaltic/granitic
crust cycling
with critical nutrient
Microbial role in rock weathering
Nutrient cycling, CO2 sequestration and other aspects of
climate change
Biomineralization; Bioremediation, Bioprospecting (Access of novel
microbes and enzymes for industrial application)
Budget Details (five years)
Particulars
Cost in USD
(approx)
Equipment (NG Sequencer)
3,20,000
Accessory equipment
Drilling
65,000
1,50,000
Chemicals/Consumables, contingency
2,00,000
Staff (01 PDF, 02 RF, 01 RA)
International/domestic travel, material
transport
1,20,000
45,000
Total
11,00,000
PDF: post doc fellow; RF: Research fellew /Ph D, RA: Research assistant
Thank You
Deep subsurface : the hidden and
unexplored habitat for microbes
The largest potential ecosystem on Earth, estimated to harbour
half of all the biomass; and 2/3 of all microbial biomass on
Earth (2.5-3.5 X 1030)
Depth of distribution: Functionally and taxonomically diverse
populations extending several kilometres underground
Adaptation : temperature limit 121 C, pressures of up to 1.6 Gpa
Function: fundamental role in global biogeochemical cycles
o
over short and long time scale
Edwards et al., Annu. Rev. Earth Planet. Sci. 2012
(Itavaara et al., FEMS Microbiol Ecol 77 2012)
The deep biosphere : an extreme
habitat for microbes
With increasing depth there are several constrains that affect
composition, extent, life habitats, and the living conditions in
deep subsurface
Increasing temperature and pressure
Nutrient limitation, limited porosity and permeability
Decreasing available carbon and energy sources
Rates of microbial activity in deep subsurface is slow (orders of
magnitude over that in surface environments)
With average generation times of hundreds to thousands of years
…and therefore defies our current understanding of the limits of life
The deep biosphere
The huge size
Largely unexplored biogeochemcial process driving the
deep biosphere
“Investigation of the extent and dynamics of subsurface
microbial ecosystems an intriguing and relatively new topic
in today’s geoscience research” ICDP, 2010
Widely disseminated deep biosphere
pose fundamental questions :
IODP
Nankai
Trough Seismogenic
Zone Experiment
1. kind
of microorganisms
? populate
the deep (NanTroSEIZE)
subsurface?
Natural
Earthquake Laboratory at Focal Depth (DAFSAM-NELSAM)
2. their extension and limits?
Taiwan
Chelungpu
Drilling
(TCDP)
3. metabolic
processes
? Project
carbon and
energy sources ?
4. survival strategies?
to early
lifeBasin
on Earth?
Lomonosov
Ridge in thelink
Central
Arctic
5. biological alteration of rock
Outokumpu
Fennoscandian
Shield
6. impact ondeep
the borehole,
global -biogeochemical
cycle
and climate?
1. Nature
of microbial communities and their function in active
seismogenic zone
2. Effect of fracturing (during earthquake) on microbial
communities
3. Interrelation between geochemistry, microbiology and
nature/location of fracture zones
ICDP 2010
Requirements of microbes in deep biosphere
‘Living space’
•Porosity
•Permeability
•Tectonostratigraphic setting
Liquid water
Energy and nutrients
•Electron donor
•Electron acceptor
•Carbon source
•thermodynamic potential
of chemical reactions
Microbial metabolism within deep
subsurface
Igneous
rocks
Sedimentary
rocks
• Little org C
• Lithoautotrophic metabolism
• Small org molecules are microbially
synthesized from H2 and CO2
• Independent of surface photosynthetically
derived mater
• Buried org C is the main C and e source
• Heterotrohic metabolism
• Depends on surface photosynthetically
derived mater
Scheme visualizing potential carbon and energy
sources of deep microbial ecosystems
OM = organic matter, mw = molecular weight
CH4
Methanogen
Biotic processes
Abiotic processes
Temperature
Organic
matter
deposition
Preserved OM
(Kerogen, Bitumen,
Humics
Acetate, CO2 and
H2
Syntrophic
fermentation
e
acceptor
limited
Anaerobic
microbial
metabolism
Thermal
activation
Abiotic diagenetic formation of
low mw compounds
Independent from primary
microbial degradation processes
Organic acids and
alcohols Fermentation
Soluble monomers
(sugar and amino
acids)
Complex polymers
(CH2 O, proteins)
What have we learned?
All Observations are consistent with the laws of
physics
 Extended known biosphere to 3 km, not limited by energy
 Revealed biomass, biodiversity, unusual traits & microbes
with indications of autotrophic ecosystems
 Slow rates of deep subsurface microbial activity but linked
with geological interfaces
 Deep subsurface biosphere not linked to the surface (?)
 Deep anaerobic communities fueled by subsurface abiotic
energy sources (?)(Likely)
Objectives
Analysis
of microbial abundance, diversity and
composition
within
the
deep
subsurface
environment of the seismic zone of Koyna-Warna
region
Elucidation
of functional role of indigenous
microorganisms within the seismic zone
The
effect of seismic activity on microbial
community and function
Work flow
Elucidation of effect of seismic activity
and crustal properties on microbial
diversity and activity
Analysis of microbial function
Analysis of microbial diversity,
community structure, abundance
Obj . I
0
Obj . II
Time scale (year)
Sample collection
and analysis
Molecular analysis
Obj . III
3
Data integration and
modeling
Work
Plan
Objective 1.:
Analysis of microbial
abundance,
diversity and composition
Metagenome
extraction
Sample collection from cores
Geochemical
analysis
Elemental
analysis (XRF, ICP)
TOC, TC, TS, TP
analysis
Anion analysis
Amplification of 16S
DGGE
rRNA
gene
analysis
Enumeration
of cell counts
Analysis of community
Library
Sanger
composition
preparation
sequencing
Sequencing
[NGS]
Sequence
analysis
EPMA analysis
Community diversity
and composition
Direct microscopic
count
MPN count (Tot, Sox
/ red & Feox / red ,
methanogenic and
hydrogen utilizing
bacteria)
Plate count
Objective 2
Analysis of microbial communities’ function
Total community
Analysis of genes
related to S, Fe, C, N
cycles
Analysis of
metabolic diversity
PM - Biolog system
NG sequencing of
complete
metagenome
S cycle: dsr
Fe cycle: Fur
C cycle: mcrA,
RuBisCO
N cycle: nif,
nirK, amoR
Objective 3
Effect of seismic activity on microbial community and function
Comparison of community structure across depth
Comparison of community function across depth
Integration of microbiological data with geochemical
and other relevant data on seismic activity within the
samples from various depths
Expected out come
1. Understanding the deep terrestrial biosphere with
seismogenic activity
2. Distribution, extent and composition of deep
microbial communities within the basaltic-granitic
subsurface
3. Impact of seismic activity and subsurface CO2, N2,
and H2 production on microbial community
structure and function, existence of SLiMEs?
4. Correlation of microbial activity, geochemistry/rock
systems and seismic activity within the zone of RTS
Recurring
Particulars
1st Year
(Rs)
2nd Year 3rd Year
(Rs)
(Rs)
Total
(Rs)
Manpower
Senior Research Fellow (01)
216000
216000
216000
648000
Technical Assistant (01)
144000
144000
144000
432000
Sub-Total
360000
360000
360000
1080000
Consumables
600000
800000
600000
2000000
Travel
200000
200000
100000
500000
Contingency
100000
100000
100000
300000
Overhead
752000
292000
232000
1276000
Sub-Total of Recurring
2012000
1752000
1392000
5156000
Grand Total
(Non-Recurring + Recurring)
4512000
1752000
1392000
7656000
Thank You
Justification of Equipment
Fluorescence Microscope
The fluorescent microscope is required for all microscopic
enumeration of bacteria, cell counts, FISHT etc. This
equipment is the major requirement for microbiological
analysis related to the project.
Incubator shaker
The temperature controlled shaker will be used for
molecular biology work.
Gel electrophoresis system
with accessories
The gel electrophoresis apparatus will be used for all
routine DNA work.
Work station for bioinformatics The computer will be required for all bioinformatics data
with accessories
analysis
Ultra deep fridge
Ultra deep fridge will be used to store the samples from
cores and other microbiological samples. Ion selective
electrodes will be required for the Orion multiparameter
meter to be used in the field.
Real time PCR machine
For all quantitative determination of rRNA and other
genes; monitoring of expression levels of various
functional genes this instrument is absolutely essential. In
the present work transcriptional analysis of selected
biogeochemical cycle relevant genes, abundance of
specific microbial groups, -dynamics will be studied using
this equipment. The proposed model is versatile and
highly efficient. For this project this equipment is
extremely essential
Justification of Manpower
Senior Research Fellow
One dedicated senior research fellow will be
essential to assist the PI and co PI for carrying out
the research work
Technical Assistant
One TA will be essential or field work, sample
collection, sample processing and other relevant
activities of the project.
Justification of Consumables
Consumables will be essential for carrying out culture independent RNA dependent and
metagenomic analysis of microbial communities. Cost for RNA/DNA extraction kits, cDNA
preparation, real time PCR reagents, primers, vectors and restriction enzymes, plasmid isolation
kits, gel extraction and sequencing kits are all included. For real time based transcriptomic
studies, cDNA kits and other reagents related to real time PCR (TaqMan probes, Syber green
dye, etc.), nucleic acid quantification kits (pico green), etc. will be needed. For fluorescent
microscopy and FISH analysis dedicated kite are required. Sequencing reagents, kits and other
charges are included under this head. For all routine works general chemicals, glass and plastic
ware are necessary. Bacterial type strains will be procured from National or international culture
collection.
Justification of travel
Field sampling and analysis; Project Several visits to fields and analytical labs for analysis;
meeting
Project meeting, if any
Field work and project presentation; Field work and project presentation at DBT, if any;
Seminar participation
Seminar participation
Travel to fields
Several visits to fields for survey and sample collection
Travel to other laboratories
Sample analysis
Justification of Contingency
DNA sequencing, fatty acid DNA sequencing, fatty acid analysis, GC content
analysis,
GC
content determination, Conference and meetings
determination, Conference and
meetings
Field expenditures, photocopy, Expenditures related to sample collections and other field
computational works, cost of gas work, cost of field labors, porters, gases for anaerobic
for AAS, anaerobic station
workstation (N2 and mix gas), computational work,
photocopying; charges for PLFA analysis, type strains and
genomic DNA samples (from DSMZ or ATCC or MTCC),
sequencing etc. and any unforeseen expenditures
Sample collection related costs, Sample collection related costs, Conference and meeting
Conference and meeting related related expenditures; Visit to other labs for analysis and
expenditures; DNA sequencing
data verification; Cost of DNA sequencing
Extra slides
Expedition to deep biosphere
Map of DSDP, ODP, and IODP Legs (indicated by their numbers) considering microbial or
deep microbial scientific objectives. b. Map showing completed and planned ICDP
projects containing biogeochemical objectives. Black dots indicate ICDP projects where no
biogeochemical objectives were included.
Microbial cells : the main
biogeochemical engines of Earth
Microbes: the janitors of Earth
The most ubiquitous, abundant, most diverse live form on
this planet
Occupy even most inhospitable niches
Vast metabolic and genetic repertoire
Responsible
for many geobiochemical processes that take
place deep in the Earth’s crust
Global prokaryotic biomass distribution, given in cell numbers
(after Whitman et al. 1998).
Environmental parameters defining the
dimensions of living space
•Tectonostratigraphic setting
•Distribution patterns, degree of sorting, lithology, etc.
•Porosity and permeability
•Subsidence, uplift and deformation of the basin fill control
pressure (lithostatic, hydrostatic),
•Modification in porosity and permeability of lithotypes.
•Basin style and evolution control temperature gradient
Living space
Pore space; pore types and degree of interconnection are
important factor controlling deep biosphere
microorganisms occupy only about one millionth of available
porosity
An adequate flux of liquids or gases through rock pores is required
to sustain life and this is governed by pore throat dimensions.
Permeability that regulates the pressure-driven transport of
electron donors, electron acceptors, and nutrients to sustain living
cells [Quartz arenites retain permeability to great depths and offer perhaps the
most stable living accommodation for microorganisms while high reactivity of unstable
volcanogenic sandstones
and their mechanical weakness make them
susceptible to rapid porosity and permeability loss, in some cases at relatively low
temperatures]
Fractures are orders of magnitude more permeable than pore
systems and often allow microbial growth and activity
Supply of food
Provision of food (electron donors) and oxidants (electron
acceptor, e.g., O2) is controlled by the thermodynamic
potential of chemical reactions, both organic and inorganic
The rate of microbially catalysed reactions can be up to 106
times higher compared to abiological rates
Depends on the rate of supply and removal of substrates and
products, the concentration (above minimum thresholds and
below toxic levels) and bioavailability of reactants and
environmental conditions.
Microbial distribution in geospheres
Greatest biomass inhabits within the surface/near surface lithosphere
and shallow hydrosphere: reliance on photosynthesis / derived food
chain
Microorganism make the major component of biosphere because
they can grow under diverse conditions and have different metabolic
pathways
Anaerobic organisms are dominant inhabitants of lithosphere ..
generally decrease with increasing depth
Because, organic matters are too recalcitrant to be degraded or water,
nutrients and TEAs can not be supplied or temporaries are too high
Surprisingly large
bacterial populations
with considerable
Extension
of the biosphere
on Earth diversity are
present at depths near and over 1000m
Out come of deep borehole studies by
ICDP and/or IODP
To be added in end
The lower depth limit of the biosphere has not been reached in
any borehole studies
and the factors that control the abundance and activities of
microbes at depth and the lower depth limit of life are still poorly
understood.
The largely unexplored deep biosphere must play fundamental
role in global biogeochemical cycles over both short and longer
time scales
Potential limiting factors for microbes
in deep biosphere
The original chemical composition of the sediment
Response
of microbes and its organic and inorganic
components to increasing temperature
Availability of liquid water
Increasing pressure during burial may not be a major limitation as
some microorganisms can cope well with high pressure (>100 Mpa)
and there is some evidence for metabolic activity at GPa pressures.
Microbiology of seismic zones
Molecular hydrogen, H2, is the key component to link
the inorganic lithosphere with the subsurface biosphere.
Geochemical and microbiological characterizations of natural
hydrothermal fields strongly suggested that H2 is an important
energy source in subsurface microbial ecosystems because of
its metabolic versatility. One of the possible sources of H2
has been considered as earthquakes: mechanoradical reactions
on fault surfaces generate H2 during earthquake faulting.
However it is unclear whether faulting can generate
abundant H2 to sustain subsurface chemolithoautotrophic
microorganisms, such as methanogens.
Wanger et al 2007
Culture dependent analysis
Isolation of pure culture
bacteria
(different enrichment cond.,
aerobic and anaerobic cond.)
Identification
(16S rRNA gene,
FAME, API, etc.)
Metal resistance
and transformation
studies
Metabolic
Characterization
What have we learned?
Novel indigenous microbes and communities
Novel and unusual deeply branched sequences may be
indicative of ancestral linkages, (early life?),
Novel products for biomed and biotech applications
image courtesy of Gordon Southam
1 mm
Novel Bacterial lineages unique to the SA
deep-subsurface:
South Africa Subsurface Firmicutes Groups
(SASFiG)
SASFiG-6
SASFiG-5
SASFiG-4
SASFiG-3
*
SASFiG-8
SASFiG-1
*SASFiG-9 (isolated)
Detected within a water-bearing
dyke/fracture at 3.2 Km depth.
strictly anaerobic; iron-reducer
optimal growth temperature = 60 oC
virgin rock temp = ~ 45 oC
*
SASFiG-7
SASFiG-9
SASFiG-2
Key Experiments: Culture-Independent Evidence for Deep Life
Genomic advancements
 Sequencing of a microbe required ~18
months in mid 90’s
 Currently >150 microbes have been
sequenced
 In 2004 TIGR discovers 1.2 million new
bacteria/archea genes in the Sargasso Sea
 By 2005 JGI could sequence 400 microbes per
year
Could early life in the subsurface have
survived the Hadean bombardment?
Earth’s subsurface microbial ecology
•The biosphere extends deep into the subsurface
•Limited by geothermal gradient and nutrient flux
•Biomass generally low relative to the surface
•Distribution is very patchy and hetergenous
•Rates of community metabolism very low
•Volumetrically largest part of the biosphere
Subsurface lithoautotrophic
microbial ecosystems (SLiMEs)
Basalt:
- Forms on the surface of the earth
- Because it forms on the surface it cools quickly and has a fine texture (mineral grains
are too fine to see with the naked eye).
- The source of this rock comes from partially melted material in the mantle.
- It usually leaves the mantle at mid-ocean ridges, where new seafloor is being formed.
That's why most of the ocean crust consists of basalt or gabbro (the intrusive version of
basalt).
- Because basalt comes from a mantle source, it's very mafic and consists of dark,
dense minerals rich in iron and manganese (usually olivine and pyroxene).
Granite:
- Forms underneath the surface of the earth.
- Because it forms under the surface the magma cools slowly, grains have time to grow
and therefore it has a coarse grained texture. Grains can be easily seen with the naked
eye.
- Granite forms when a part of the continental crust melts to form magma and solidifies
again. The heat needed for this to happen can come from different sources, for
example magma from the mantle which causes the crust to melt.
- Because of the above granite will be found on the continental crust (mostly at least).
- The crust consists of lighter minerals than deeper parts of the earth, and that is why
the minerals you will find in granite will be lighter, less dense and richer in SiO2 than
those found in basalt (granite is therefore a much more felsic rock). Minerals you will
typically find is quartz, orthoclase and plagioclase
Eon
Era
Cenozoic
Period
Extent, Million
Years Ago
Quaternary
(Pleistocene/Holocene)
2.588 - 0
Neogene
(Miocene/Pliocene)
23.03 - 2.588
Paleogene
(Paleocene/Eocene/Olig 65.0 - 23.03
ocene)
Phanerozoic
Mesozoic
Paleozoic
Neoproterozoic
Proterozoic
Mesoproterozoic
Paleoproterozoic
Cretaceous
145.5 - 65.0
Jurassic
201.3 - 145.0
Triassic
252.17 - 201.3
Permian
298.9 - 252.17
Carboniferous
(Mississippian/Pennsylv
anian)
358.9 - 298.9
Devonian
419.2 - 358.9
Silurian
443.4 - 419.2
Ordovician
485.4 - 443.4
Cambrian
541.0 - 485.4
Ediacaran
635.0 - 541.0
Cryogenian
850 - 635
Tonian
1000 - 850
Stenian
1200 - 1000
Ectasian
1400 - 1200
Calymmian
1600 - 1400
Statherian
1800 - 1600
Orosirian
2050 - 1800
Rhyacian
2300 - 2050
Siderian
2500 - 2300
History[edit]
The Deccan Traps formed between 60 and 68 million years ago,[2] at the end of
the Cretaceous period. The bulk of the volcanic eruption occurred at
the Western Ghats (near Mumbai) some 66 million years ago. This series of
eruptions may have lasted less than 30,000 years in total.[3]
The original area covered by the lava flows is estimated to have been as large
as 1.5 million km², approximately half the size of modern India. The Deccan
Traps region was reduced to its current size by erosion and plate tectonics; the
present area of directly observable lava flows is around
512,000 km2 (197,684 sq mi).
Effect on climate and contemporary life[edit]
The release of volcanic gases, particularly sulfur dioxide, during the formation of
the traps contributed to contemporaryclimate change. Data points to an average
drop in temperature of 2 °C in this period.[4]
Because of its magnitude, scientists formerly speculated that the gases
released during the formation of the Deccan Traps played a role in
the Cretaceous–Paleogene extinction event (also known as the K–Pg
extinction), which included theextinction of the non-avian dinosaurs. Sudden
cooling due to sulfurous volcanic gases released by the formation of the traps
and localised gas concentrations may have contributed significantly to mass
extinctions. However, the current consensus among the scientific community is
that the extinction was triggered by the Chicxulub impact event in Central
America (which would have produced a sunlight-blocking dust cloud that killed
much of the plant life and reduced global temperature, called an impact
winter).[5]
Core samples from borehole KBH-1 showing (a) massive basalt, (b) vesicular and amygdaloidal basalt
with large vugs filled with quartz and/or calcite, (c) flow-top breccia, (d) red bole bed and overlying
massive basalt, (e) vugs filled with zeolite, and (f) basement granite at 951 m depth.