Cretaceous sedimentation in the Barmer Basin, Rajasthan, India.

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Feb 21, 2014 (3 years and 10 months ago)

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Cretaceous sedimentation in the Barmer Basin, Rajasthan, India.

S. M. Clarke
1
,

R. Raine
2
,
N
. Whiteley
3

and

J. Guttormsen
3


1
Basin Dynamics Research Group, School of Earth Sciences & Geography, Keele University, Keele, Staffordshire, UT5 5BG, U.K.

2

Ichron
, Century House, Gadbrook Business Centre, Northwich, Cheshire, CW9 7TL, U.K.

3
Ca
i
rn India PTY, 3
rd

Floor, Vipul Plaza, Sun City, Sector 54 Gurgaon 122 002, India




The
d
esert
of
Rajasthan with the
southern Karentia

Hills in the background


The
Barmer
Basin, India,

is a rift of late Mesozoic to Tertiary age representing the onshore northwards
termination of the Western Indian Rift

System
. The sedimentary
fill

of the Barmer Basin is dominantly
Tertiary in age
,

although
Mesozoic

continental sediments are preserved at outcrop on the basin margins.
The Tertiary basin fill is dominantly continental and comprises an early syn
-
rift
,

Palaeocene alluvial, fluvial
and coast
al

plain succession, overlain by l
acustrine, alluvial fan and fan
-
delta sediments. The late
Palaeocene to early Eocene succession comprises lowland continental and fluv
io
-
deltaic sediments,
overlain
unconformably by middle Eocene
marginal

marine to lagoonal
deposits
. Upper Eocene to lower Miocene
sediments are not preser
ved and the end of rifting is marked by a base Miocene unconformity. Post
-
rift, late
Miocene

and Plio
-
Pleistocene

continental sediments complete the basin fill.

The recognised petroleum
play

of the basin resides within the Tertiary strata and the basin fill is generally
considered to be dominantly Tertiary in age. However,
Mesozoic

strata are preserved
around

the basin
edge

and outcrop studies (Bow
y
er
, 2004;

Clarke
, 2011
) have identified
a
Cr
etaceous
,

fluvially
dominated
succession
preserved in normally faulted and rotated blocks

of the eastern basin margin
.
New s
eism
ic
interpretations of the basin by Cairn India
have suggested that seismic facies
below the Tertiary fill
,

and
previously interpreted as pre
-
rift basement rocks
,

display a seismic character
more readily
associated with
sediments
,

and may represent Mesozoic sedimentary strata preserved within the subsurface. I
n some
such
examples, reflectors show divergence towards
local faults that implies syn
-
rift deposition. Furthermore, the
forward modelling of gravity require
s

reasonable

thicknesses of pre
-
Tertiary sediments to be present
at
depth
as one possible solution
to fit

the observed gravity
profile

for the basin.

It is

therefore plausible that the sedimentary fill of the Barmer Basin preserves
appreciable

successions of
Mesozoic sediments
in the subsurface.
The
stratigraphy and
nature of the preserved
Mesozoic

sedimentary
succession, the structural and environmental controls upon its deposition, and its post
-
depositional
interactions with the present day structural configuration of the basin

are poorly understood


This work will characterise the
stratigraphy,
p
etrography, geometry and depositional environment
(s)

of the Cretaceous
Ghaggar
-
Hakra (formerly Sarnu)

Formation
sediments of the Barmer Basin, the
controls of structure,
sediment

supply and proven
an
ce upon their deposition
,
and
their interactions
with
post
-
depositional structuration
.




Background

Cropping out

on the eastern ba
sin margin at Sarnoo and Karent
ia,
the Cretaceous sediments of the
Ghaggar
-
Hakra

F
ormation
contain

a dominantly fluvial succession. Preliminary studies (
Bowyer, 2004;
Clarke, 2011
) have identified at least three channel
-
dominated successions interbedded with significant
thicknesses of pa
rallel
-
laminated

siltstones and fine
-
grained sandstones. The channeli
s
ed successions,
whilst demonstrably of
fluvial

origin, display
sedimentary features
that suggest that the fluvial systems were
dominated by significant variations in d
ischarge and sediment load;

hence competence, capacity,
sediment
supply
and climate
may be

dominant

controls
upon

the texture and

architecture

of the fa
cies
. The thickest
of
the fluvial successions has been interpreted previously as the product of a strongly braided system (
Bowyer,
2004
) on the basis of stacked channels and
a
lack of overbank material. However, the textural aspects of the
channel fill sug
gest a more mature system, and the presence of significant fine
-
grained
and parallel
-
laminated
material
,

preserved
as abundant
rip
-
up
clasts with
in channel fill
,

suggests significant overbank
development within the depositional system, if not preservation.

This in turn suggests that the depositional
environment may be somewhat more complex than t
hat of a simple braided system, and relationships
between

sediment

supply, local subsidence
,

fluvial style

(avulsion)

and climate
,

influence
d the

deposition,
preser
vation,

fluvial architecture

and petrography,

and
ultimately

reservoir potential.

The dominantly fine
-
grained and
parallel
-
laminated successions preserved
between the channel
-
dominated
strata may well represent overbank development, although their
relative thicknesses compared to the
channel
-
dominated successions are somewhat anomalous
. T
his
,

combined with coarsening and thickening
upwards trend
s

to the beds

of each succession

and the preservation of
a variety of sedimentary structures

within them
,

h
as

been used by previous authors
(Dean, 2003
; Bowyer, 2004
)
to suggest
possible
deposition
in a
broad

range of
non
-
fluvial
continental environments. The exact depositional nature
and environment(s)
of these
successions
,
and
their relationships to the
remainder of the Cretaceous

succession

of the basin,
are
very much
equivocal
.

Subsurface and gravity modelling studies, whi
l
st not conclusively demonstrating the presence of
Mesozoic

strata preserved in faulted blocks at depth, do suggest that if such stra
ta are present they may be syn
-
rift in
nature.
Such a

relationship between the
Cretaceous strata

and
contemporaneous

structure is not
immediately
obvious

from outcrop studies. Consequently,
the
structural control

on depositional
architecture
,
sediment routing, provenance and
petrography

of the
Ghaggar
-
Hakra

sediments remains u
nanswered,
and,
by implication, so

does the
extent of

Mesozoic rifting within the Barmer Basin.

This work will clarify many of these questi
ons by providing a detailed
stratigraphical
, sedime
n
tological and
petrographical

analysis of the
Ghaggar
-
Hakra

Formation

sediments. The work will draw together existing
subsurface, remotely sensed and outcrop data,
augmented

with new, extensive and detailed outcrop

and
laboratory

stu
dies of the succession,
to develop well
-
constrained three
-
dimensional
models

of the
depositional

setting
(s)

and the controls upon it
(them)
.
The model
s

will be set in the context of the post
-
Mesozoic structuration of the basin and they
will provide the basis for assessing the
contribution the
Ghaggar
-
Hakra

Formation may
have made
to
the development of the Barmer Basin as a whole
.


The work provides a timely vehicle with which to further understanding of the Mesozoic succession and its
role in the evolution of the Barmer Basin
. Recent and on
-
going studies into the structural geometry of
exposures of this part of the succession by Keele researchers provides the required detailed structural
framework in which to integrate this study and de
termine
those

relationships between
sedimentology

and
structure. Furthermore, this study
will contribute towards the on
-
going structural work by elucidating the pre
-

or syn
-
rift nature of the sediments and thus providing

additional

control upon
the
structu
ral interpretation.


The work will:



Undertake extensive and detailed sedimentological analysis of all
exposures

of
Ghaggar
-
Hakra

sediments within the Barmer Basin to characterise the
stratigraphy and
nature of the
succession,
the
environment of deposition
and its

evolution
.



Undertake detailed
petrographical

analysis of the sediments to
augment the sedimentological
interpretation and
examine the play potential of the succession.



Undertake a detailed study of palaeocurrent from field
exposures

to determine g
ross sediment
supply pathways.



Undertake a detailed study of the geometric
parameters

of
architectural
elements

within the
succession
to provide quantitative control on models.




Interpret
field

data
at the large scale
to provide stratig
r
aphical detail for the
Ghaggar
-
Hakra

F
ormation
,

and develop a stratigraphica
l scheme at sub
-
formation level that
facilitates

correlation
and
identification

of the strata from core.




Interpret field data and petro
graphical

analyses
to characterise the
importance

of sediment load,
capacity

and discharge variability on the
fluvial style within the depositional environment
.



Integrate field analysis, palaeocurrent

data

and
interpreted
controls on fluvial style with

seismic and

on
-
going

structural
work by ot
her Keele researchers
to
determine

the
structural

controls on
sedimentary architecture
and sediment routing, and elucidate the syn
-

or pre
-
rift nature of the
succession.




Integrate field studies, petro
g
raphical

analysis and palaoecurrent analysis with
seismic and
remotely
sensed
data to
elucidate

sediment supply pathways, routing

and
provenance
in
the large
r
scale
context of the development of the Barmer Basin.




Integrate all strands of research to produce quantitative three
-
dimensional depositional fa
cies
models for the formation, and integrate these models into those of post
-
depositional structuration.

Ultimately, the work will p
rovide a fully
integrated

and
quantitative

set of three
-
dimensional
depositional
facies
models for the
Ghaggar
-
Hakra

Formation

of the Barmer Basin, augmented with
geometric statistics for architectural
elements
,

petro
graphical
details
,

and relationships to
syn
-

and
post
-
depositional
structure,

that will provide the basis for
interpretation of

this part of the
succession.


The project will provide industry
-
relevant training in:

1)

Geological fieldwork

incorporating sedimentology, sampling, digital data capture, statistical
measurement and
basin analysis;

2)

Field and laboratory
-
based petro
graphical

analysis.

3)

Statistical

and stochastical
techniques

for
sedimentological interpretation and
hydrocarbon
exploration.

4)

Integration and
interpretation

of field data, seismic, structural modelling and remotely sensed data
using th
ree
-
dimensional, industry
-
standard modelling packages.

5)

Techniques

of sedimentological analysis for hydrocarbon exploration.

6)

The workflow and principal elements involved in basin analysis related to hydrocarbon exploration,
and an understanding of the limitations, uncertainties a
nd risk involved.


References cited:

Bowyer, S. 2004. RJ
-
ON
-
90/1 Contract area: Integrated field geology report. Cairn Internal Report ED/RJ
-
ON
-
90/GEO/04/1504

Clarke, S. M. 2011. Outcrop studies in the Barmer Basin: The Sarnu & Karentia hills, the Barmer H
ills & the
Fatehgarh Ridge. Commission
ed

report on behalf of Cairn India PTY. Keele University, Staffordshire.

Dean, 2003. Report on the
fieldwork

carried out in the Barmer Basin,
Rajasthan. Oxford Geoscience for

Cairn

Energy India PTY.


Funding

Half
-
funding for this project will be provided by the Keele University research collaboration fund (ACORN)
with the remainder of the funding provided by Cairn India PTY. The fieldwork costs and logistical support in
the field are provided by Cairn India PT
Y.

For further information on the project, eligibility and the application process please cont
act the lead author
(s.m.clarke@
esci.keele.ac.uk) in the first instance. Formal applications should be directed through the on
-
line Keele University Graduate Sc
hool application process (
http://www.keele.ac.uk/pgresearch/howtoapply/
).