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Tectonics of the Dalrymple Trough and uplift of the Murray Ridge (NW
Indian Ocean)
Mathieu Rodriguez, Nicolas Chamot-Rooke, Philippe Huchon, Marc
Fournier, Siegfried Lallemant, Matthias Delescluse, S´ebastien Zaragosi,
Nicolas Mouchot
PII: S0040-1951(14)00450-8
DOI: doi: 10.1016/j.tecto.2014.08.001
Reference: TECTO 126408
To appear in: Tectonophysics
Received date: 2 April 2014
Revised date: 1 August 2014
Accepted date: 2 August 2014
Please cite this article as: Rodriguez, Mathieu, Chamot-Rooke, Nicolas, Huchon,
Philippe, Fournier, Marc, Lallemant, Siegfried, Delescluse, Matthias, Zaragosi, S´ebastien,
Mouchot, Nicolas, Tectonics of the Dalrymple Trough and uplift of the Murray Ridge
(NW Indian Ocean), Tectonophysics (2014), doi: 10.1016/j.tecto.2014.08.001
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Tectonics of the Dalrymple Trough and uplift of the Murray Ridge (NW Indian Ocean)
Mathieu Rodriguez
1*
, Nicolas Chamot-Rooke
1
, Philippe Huchon
2,3
, Marc Fournier
2,3
, Siegfried
Lallemant
4
, Matthias Delescluse
1
, Sébastien Zaragosi
5
, Nicolas Mouchot
6
(1) Laboratoire de Géologie de l'Ecole Normale Supérieure, CNRS UMR 8538, 24 rue Lhomond,
75005 Paris, France
(2) Institut des Sciences de la Terre de Paris, UMR 7193, Université Pierre & Marie Curie, case 129, 4
place Jussieu, 75005 Paris, France
(3) iSTeP, UMR 7193, CNRS, F-75005 Paris, France
(4) Département Géosciences Environnement, Université de Cergy-Pontoise, 5 mail Gay-Lussac,
Neuville/Oise, 95031 Cergy-Pontoise, France
(5) EPOC Université de Bordeaux, UMR 5805, avenue des facultés, 33405 Talence, France
(6) Beicip-Franlab, 232 Avenue Napoléon Bonaparte, 92500 Rueil-Malmaison, France
*Corresponding author: rodriguez@geologie.ens.fr
ABSTRACT
The Dalrymple Trough is a 150-km-long, 30-km-wide basin located at the northern termination
of the Owen Fracture Zone (OFZ), which is the present-day active India-Arabia plate boundary.
The Dalrymple Trough is closely associated with the Murray Ridge, a complex of prominent
bathymetric highs located on its eastern flank. Recent multibeam mapping of the connection
between the Dalrymple Trough and the OFZ revealed a horsetail structure, which suggests a
close relationship between geological histories of both structures. However, the 3-6 Ma age of
initiation of the OFZ contrasts with the commonly accepted Early Miocene emplacement of the
Dalrymple Trough. Recent seismic lines document a new tectonic history of the Dalrymple
Trough, involving two major episodes of deformation along the India-Arabia plate boundary at
~8-10 Ma and ~1.9 ± 0.9 Ma. The 8-10 Ma episode is marked by a system of folds linked to the
main uplift of the southern Murray Ridge and the first uplift of the northern Murray Ridge.
This episode is related to a global plate reorganization event in the Late Miocene, well expressed
by intraplate deformation in the Central Indian Ocean. The Dalrymple Trough opened at ~1.9 ±
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0.9 Ma subsequently to the formation of a stepover at the India-Arabia plate boundary, coeval
with the regional M-unconformity in the Oman abyssal plain, which marks a structural
reorganization of the Makran accretionary wedge, and the last uplift of the northern Murray
Ridge.
1. Introduction
The Dalrymple Trough consists of a series of basins forming the present-day loose boundary between
India and Arabia plates in the Arabian Sea, connecting the pure dextral strike-slip Owen Fracture Zone
(OFZ hereafter) to the sinistral Ornach-Nal Fault Zone in Pakistan (Fig. 1; McKenzie and Sclater,
1971; Minshull et al., 1992). The trough is located south of the Makran subduction zone, which
absorbs the convergence between the Arabian and Eurasian plates and has produced strong
earthquakes in the recent past (M
w
=8.1 for the 1945 event). The trough is flanked to the east by the
Murray Ridge complex, a series of bathymetric highs standing off India and Pakistan.
Seismicity along the entire India-Arabia boundary is scarce, but the strongest magnitude event
(M
w
=5.8) has been recorded in the Dalrymple Trough (Fig. 2) (Quittmeyer and Kafka, 1984; Gordon
and DeMets, 1989; Fournier et al., 2001). Kinematic models suggest that the present-day opening rate
of the Dalrymple Trough does not exceed a few millimeters per year (DeMets et al., 2010; Fournier et
al., 2011), with various amounts of transtension.
Multibeam mapping revealed a fault pattern at the southern part of the Dalrymple Trough typical of a
horsetail termination (Fig. 1, 2) (Fournier et al., 2011; Rodriguez et al., 2011). Few active horsetail
terminations have been documented so far in deep-sea environments. These include the northern
Andaman Sea at the termination of the Sagaing fault in SE Asia (Pubellier et al., 2005; Cattin et al.,
2009; Morley et al., 2013), and the North Aegean Trough at the termination of the North Anatolian
fault in the Aegean Sea (Laigle et al., 2000; Papanikolaou et al., 2002; McNeill et al., 2004).
Although the structure of the Dalrymple Trough has been well characterized by previous seismic
studies (Edwards et al., 2000, 2008; Gaedicke et al., 2002a,b), the way it connects to the OFZ and how
it relates to its tectonic history remain unknown. The main misfit concerns the Pliocene age of the
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OFZ (Fournier et al., 2008a,b; 2011; Rodriguez et al., 2011) and the inferred Early Miocene age of the
Dalrymple Trough-Murray Ridge system (Gaedicke et al., 2002a,b; Clift et al., 2001).
Here we present a set of recent seismic reflection data (OWEN-2 cruise) that documents a new
stratigraphic framework for the tectonic history of the Dalrymple Trough and the Murray Ridge in
close association with structural reorganizations of the India-Arabia plate boundary at ~8-10 Ma and
~1.9 ± 0.9 Ma. The origin of the M-unconformity in the Oman abyssal plain is revised in the light of
this new tectonic framework. The first objective of this study is to understand how rifting took place in
the Dalrymple Trough, and subsequently evolved into a large and complex stepover basin. The second
objective is to unravel the complex, poly-phased history of the Murray Ridge uplift, and identify
geodynamic changes that controlled it.
2. Geological background
2.1. Morphology and structure of the Dalrymple Trough and the Murray Ridge
The Dalrymple Trough is divided into two main segments (Edwards et al., 2000). The southern part of
the Dalrymple Trough (between 22-23°N) is a 150-km-long, 30-km-wide, 4200-m-deep basin, flanked
on its eastern side by the ~400-m deep southern Murray Ridge (Fig. 1, 2). The southern part of the
Dalrymple Trough abruptly ends at the Jinnah High at ~23°N (Burgath et al., 2002), which is formed
by the tilt of the Indus deposits of the Oman abyssal plain (Ellouz-Zimmerman et al., 2007a,b). The
Jinnah High marks the transition towards the northern part of the Dalrymple Trough, which is a ~120
km-long, ~40 km-wide stepover basin. The northern Murray Ridge (between 23°N and 23°40'N)
forms a normal faulted horst with a more subtle topographic expression than the southern segment
(about 1000-m high with respect to the surrounding seafloor, Fig. 1).
The pure strike-slip or transtensive character of a stepover basin depends on the colinearity between
the direction of relative motion and that of the strike slip fault (Wu et al., 2009). Because the
Dalrymple Trough deviates from the small circle defined by Fournier et al. (2011) (Fig. 2), the
structure is considered as transtensive, in agreement with focal mechanisms of earthquakes.
The basement of the Murray Ridge, although never sampled, is interpreted as continental in origin
according to seismic refraction data (Edwards et al., 2008). The Dalrymple Trough represents a very
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narrow ocean-continent transition, with abrupt crustal thickness variations from a ~14 km-thick
continental crust beneath the Murray Ridge to a 6 km-thick oceanic crust in the Oman abyssal plain
(Edwards et al., 2008). A set of volcanic reliefs, namely the Qalhat Seamount and the Little Murray
Ridge, are located west of the trough (Fig. 1, 2) (Edwards et al., 2000; Fournier et al., 2011).
2.2. Geological history
Kinematic and structural studies show that the present-day active OFZ is no older than 3 to 6 Ma
(Fournier et al., 2008; 2011; Rodriguez et al., 2011; 2013b). The exact location of the fossil India-
Arabia plate boundary remains debated (Whitmarsh, 1979; Mountain and Prell, 1990; Edwards et al.,
2000; Royer et al., 2002). The recent identification of a fracture zone buried under the Indus deposits
5-10 km east of the OFZ (Rodriguez et al., 2014), together with magnetic anomalies reconstructions
(Chamot-Rooke et al., 2009), suggest that the plate boundary remained close to the Owen Ridge since
at least the beginning of oceanic accretion in the Gulf of Aden in the Early Miocene (Fournier et al.,
2010). Buried, abrupt and sharp vertical fault offsets recognized on the eastern side of the Southern
Murray Ridge (Edwards et al., 2000) could correspond to the northward prolongation of the fracture
zone that used to form the Miocene India-Arabia plate boundary (Fig. 3).
As attested by Paleogene hemipelagites recognized on their top (Shipboard Scientific Party, 1989;
Gaedicke et al., 2002a,b), the Owen and Murray Ridges were part of a series of bathymetric highs
formed in Paleocene-Early Eocene times (Fig.1, 3) and subsequently rejuvenated during Neogene
times. Previous works (Gaedicke et al., 2002b) proposed two phases of uplift of the Murray Ridge
related to two coeval phases of subsidence in the Dalrymple Trough, in the Early and the upper Late
Miocene. In this framework, two regional angular unconformities, “U” and “M”, mark the episodes of
uplift and subsidence. Understanding the signification of these unconformities is critical to the
understanding of the formation of the Dalrymple Trough and Murray ridge, and how it relates with the
history of the OFZ.
2.3. Regional unconformities in the Arabian Sea
U-unconformity and the uplift of the Murray Ridge
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The U-unconformity is recognized over the entire Owen Basin and the Oman abyssal plain (Shipboard
Scientific Party, 1974; Whitmarsh et al., 1974; 1979; Rodriguez et al., 2014). According to ODP
(Ocean Drilling Project) and DSDP (Deep Sea Drilling Project) Sites, the U-unconformity marks a
highly diachronous transition between Upper Oligocene-Lower Miocene pelagic chalk and Upper
Oligocene-Lower Miocene turbidites coming from the Indus fan. The U-unconformity does not have a
tectonic origin, and simply reflects the transition from Oligocene pelagites to Lower Miocene
turbidites as the substratum of the Owen Ridge gets progressively buried under the Indus deep-sea fan
(Shipboard Scientific Party, 1989; Mountain and Prell, 1990). Therefore, the angular unconformity
marking the main uplift of the Murray Ridge recognized by Gaedicke et al. (2002) (picked in blue on
Fig. 3) is different from the U-unconformity recognized everywhere in the Owen Basin and the Oman
abyssal plain (Rodriguez et al., 2014).
According to an industrial well located in the Indus abyssal plain (Pak-G2-1), the unconformity
marking the uplift of the Murray Ridge is ~8-10 Ma-old (Fig. 3) (Calvès, 2008). The latter
unconformity is formed by 8-9 Ma-old channel-levee system adopting an onlap configuration over a
pre-10 Ma-old tilted series of channel-levee systems (Kolla and Coumes, 1987; Calvès, 2008).
This age contrasts with earlier estimations based on a correlation with the age of uplift of the Owen
Ridge (Gaedicke et al., 2002), first assessed at 15-20 Ma (Mountain and Prell, 1990). Actually, the
East Oman Margin, the Owen Basin, and the Owen Ridge show compressive deformation precisely
dated at 8.2-8.8 Ma at ODP Site 730 (Rodriguez et al., 2014) consistent with the age of the
unconformity marking the uplift of the Southern Murray Ridge. An erosive surface at the top of the
Owen Ridge, marked by large submarine failures (Rodriguez et al., 2012; 2013), and dated at 8-9 Ma
by ties with ODP Site 722, characterizes the younger uplift of the Owen Ridge (Rodriguez et al.,
2014).
M-unconformity
The M-unconformity in the Oman abyssal plain marks both an episode of subsidence in the Dalrymple
Trough, and an abrupt tilt of an uniform, 4 km-thick sequence composed of Indus channel-levee
systems lying on the subducting plate (Fig. 4) (Gaedicke et al., 2002; Smith et al., 2012). The
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overlying sequence adopts a wedge-shape geometry, with a maximal thickness of 3.5 km (Smith et al.,
2012). It is composed of turbiditic deposits coming from the Makran that onlap the M-unconformity
(Fig. 4). The latter is probably coeval with the last stage of uplift of the Murray Ridge, and the opening
of the Dalrymple Trough (Gaedicke et al., 2002).
This unconformity has never been drilled, which results in strong uncertainties in its age (Schlüter et
al., 2002). First related to a Messinian uplift event in the Zagros Mountain (Ross et al., 1986), it has
also been related to the onset of seafloor spreading in the Gulf of Aden (Schlüter et al., 2002),
estimated at 13 Ma when these studies were published (Cochran, 1981). The latter age cannot be
considered valid anymore according to recent magnetic anomalies studies that document the onset of
seafloor spreading in the Gulf of Aden as early as ~20 Ma (Fournier et al., 2010). Changes in the
regime of deformation in the Zagros suggest a 3-7 Ma-old kinematic change related to the Arabia-
Eurasia collision (Allen et al., 2004; Mouthereau et al., 2012) that may account for the M-
unconformity, but the existence of this kinematic change remains a matter of debate (Hatzfeld and
Molnar, 2010).
2.4. The Indus deep-sea fan
Tectonic deformation along the India-Arabia plate-boundary is well recorded by sediments belonging
to the Indus turbiditic system. At its thickest part the fan is more than 9-km thick, but its thickness
decreases when approaching the Owen-Murray Ridge (Fig. 3c) (Coumes and Kolla, 1984; Clift et al.,
2001). It forms a typical mud-rich, “passive margin fan” (sensu Reading and Richards, 1994), with
numerous inter-bedded pelagic layers (Shipboard Scientific Party, 1989). Indus Fan sedimentation
started during the Middle Eocene as the result of the onset of the India-Eurasia collision and
accelerated since the Early Miocene, coincident with a sharp increase in sedimentation rates related to
the uplift of the Himalaya and the onset of the Asian monsoon (Clift et al., 2001; Clift and Gaedicke,
2002; Clift et al., 2008). Seismic lines collected in the Indus deep-sea fan document the appearance of
well-developed channel-levee complexes since the Middle Miocene (Clift et al., 2001; Calvès, 2008).
In the Early Pleistocene, the Indus canyons underwent a southeast migration, leading to a major
episode of avulsion and concentration of Indus deposits on the southeastern part of the fan (fossil
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Indus canyons are mapped in Figure 1) (Kolla and Coumes, 1987; Bourget et al., 2013). This
migration resulted in dominantly pelagic deposits along the OFZ, allowing a good preservation of the
fault scarps morphology on the seafloor (Shipboard Scientific Party, 1974; Rodriguez et al., 2011).
3. Material and Methods
The new dataset presented in this study was acquired onboard the French Navy oceanographic vessel
Beautemps-Beaupré during the OWEN1 and 2 (2009 and 2012) surveys. Multibeam bathymetry was
collected using a Kongsberg-Simrad EM 120 echosounder (Fig. 2), and combined with previously
published data acquired during the MARABIE (Bourget et al., 2010) and CHAMAK cruises (Ellouz-
Zimmerman et al., 2007a,b). Seismic reflection profiles of the OWEN2 cruise were acquired at 10
knots using two GI air-guns (one 105/105 c.i. and one 45/45 c.i., fired every 10 seconds at 160 bars in
harmonic mode, resulting in frequencies ranging from 15 to 120 Hz) and a 24-channel, 600 m-long
streamer. Seismic profiles have a common mid-point spacing of 6.25 m and achieved a sub-surface
penetration of ~2s TWT. The processing consisted in geometry setting, water-velocity normal move-
out, stacking, water-velocity F-k domain post-stack time migration, bandpass filtering and automatic
gain control. All profiles are displayed with a vertical exaggeration of 8 at the seafloor.
Two-way travel time to seismic reflectors was converted to depth using a P-wave velocity between
1530 and 1730 m. s
-1
for lower and upper bounds. This range of values covers safely the
measurements performed in the area in the same pelagic sediments (Shipboard Scientific Party, 1974,
1989). The highest P-wave velocity of 1950 m.s
-1
has been measured in the Pliocene turbidites
underneath the pelagic cover (White and Klitgord, 1976; Kolla and Coumes, 1987). The reflectors
picked on seismic profiles have been selected based on seismic discontinuities that reflect lithological
changes, stratigraphic hiatuses or tectonic deformation. In the following, sedimentary series before the
opening of the Dalrymple Trough are referred to as the “substratum” of the Dalrymple Trough, which
is employed in the sense of “pre-rift” series, in order to avoid the confusion with the continental
basement of the Murray Ridge observed on several profiles.
4. Stratigraphic framework
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4.1. Criteria for the identification of sedimentary deposits
Turbiditic channels are characterized on seismic profiles by a typical lens-like architecture with a
concave-up lower boundary, and discontinuous, high amplitude reflection. The associated levees
display a wedge shape, with high amplitude, transparent seismic facies. Mass transport deposits
display the same chaotic to transparent seismic facies, but their geometry is more irregular. On the
other hand, pelagic deposits display well-stratified, continuous and conformable horizons on seismic
profiles. It is sometimes difficult to discriminate between turbiditic and pelagic deposits on seismic
profiles. Bottom-currents may influence the geometry of pelagic deposits, leading to typical pinched-
out, sigmoid geometries referred as contouritic drifts (Faugères et al., 1999). Figure 5 summarizes the
main criteria of sedimentary deposits identification.
4.2. Sedimentation rates
During turbiditic deposition (Late Miocene-Pliocene), the sedimentation rates ranged between 350 and
600 m Ma
-1
according to estimations at DSDP Site 222 located at the edge of the OFZ (Fig. 1; latitude
~20°N) (Shipboard Scientific Party, 1974). Turbiditic channels are sealed by a Plio-Pleistocene
pelagic drape according to ties with DSDP Site 222 (Shipboard scientific party, 1974; Rodriguez et al.,
2011; 2013). Several DSDP and ODP drillings are available along the Owen Ridge (Shipboard
Scientific Party, 1974; 1989), but the complete sedimentary sequence of the Murray Ridge has never
been drilled down to the basement (Schulz et al., 1998; Ziegler et al., 2010). All average Pleistocene
pelagic sedimentation rates estimated at different drilling sites along the Owen-Murray Ridge range
between 30 and 55 m Ma
-1
(Shipboard scientific party, 1974, 1989, and core KS07 in Bourget et al.,
2013), with the exception of rates of the order of 100 m Ma
-1
(Table 1) estimated from core MD 04873
(Ziegler et al., 2010). However, the nearby core S090-93KL (Schulz et al., 1998) (located only 40 km
away from the core MD 04873) (Fig. 2a) documents rates of about 50 m Ma
-1
, which suggests that
core MD 04873 has undergone core overpull (Skinner and McCave, 2003). There is consequently little
spatial variation of the Pleistocene pelagic sedimentation rates along the Owen Ridge, allowing large-
scale interpolation of these values in areas exclusively covered by pelagic deposits. However, these
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values cannot be extrapolated in areas where bottom-currents seem to have interacted with pelagic
processes, as observed at the edge of the OFZ and the Qalhat Seamount (Fig. 8, 9).
The thickness of the pelagic sediments overlying a reflector marking a geological event can be
converted into time using uniform sedimentation rates, therefore providing an age estimate of the
geological event. Two major sources of uncertainties are inherent to this approach. First, the estimated
pelagic thickness depends on the value of P wave velocity used to convert two way travel time
distance into meters. We estimate different pelagic thicknesses using P wave velocities ranging
between 1550 and 1730 m.s
-1
(table 1). The second source of uncertainty is the regional variability of
sedimentation rates, ranging between 30m.Ma
-1
and 55 m.Ma
-1
(Table 1). The conversion of the
pelagic thickness into time is done for the upper and lower estimates of the sedimentation rates,
providing the widest range of acceptable age estimates (Table 1). A last source of uncertainties is the
measurement of pelagic thickness on seismic profiles, considered in the order of 10 ms (TWT). Taken
all together, the uncertainties related to each age mentioned hereafter are of the order of 1 Myr for the
Plio-Pleistocene interval, providing valuable constrains at the time scale of tectonic processes.
5. Structure of the Dalrymple horsetail
The Southern part of the Dalrymple Trough is an asymmetric structure comparable to a half-graben
oriented N50°E bordered by a single normal fault to the southeast, and a complex set of antithetic
faults to the west (Fig. 1) (Edwards et al., 2000). The connection between the OFZ and the Dalrymple
Trough forms a complex horsetail structure (Fig. 2) composed of several normal faults trending
perpendicular to the OFZ, hereafter referred as "transverse faults" (sensu Ben Avraham and ten Brink,
1989). Focal mechanisms indicate a minor strike-slip component in transverse faults motion (Fig. 2).
Transverse faults are in the continuation of a dense network of right-stepping, en-échelon faults on the
northwestern side of the trough (labelled 1 on Fig. 2). Transverse faults delineate subsiding sub-basins
within the trough, whose lengths range between 10 and 20 km (Fig. 2). The trough forms a syncline
basin on seismic lines (Fig. 3, 6) (Edwards et al., 2000; Gaedicke et al., 2002 a,b). Although variable
in complexity, this syncline pattern is identified from sub-basin to sub-basin. In detail, the sedimentary
sequences that form the syncline basin display a series of angular unconformities (Fig. 6, 7), but the
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syncline itself is isopach, i.e. shows the same thickness throughout. Locally, a dense network of
transverse faults offset the syncline basin (Fig. 8). In the area of connection with the trough, the OFZ
is oriented N20°E, and forms a positive flower structure on seismic profiles, expressed by a pressure
ridge on the seafloor (Fig. 9, 10). There, contouritic drifts (Fig. 8, 10) mark the transition from
turbiditic to pelagic processes possibly related to a major avulsion episode of the Indus deep-sea fan
(Kolla and Coumes, 1987; Bourget et al., 2013). Since this transition, contouritic bodies at the edge of
the OFZ indicate the presence of a topography driving the bottom-current course.
At the entrance of the trough, the OFZ is bounded to the east by a set of ~N40°E en-échelon faults
(labelled 2 on Fig. 2), which merges northwards with the single normal fault bounding the eastern side
of the trough. Both the OFZ and the en-échelon fault system (2) cross cut a buried system of folds
observed on the seismic profiles (Fig. 9, 10). Two anticlines separated by a syncline are observed on
the eastern side of the OFZ (Fig. 9), whereas a syncline structure is observed on its western side (Fig.
10). The amplitude of the fold-system ranges between 1s (TWT) (Fig. 10) and 2s (TWT) (Fig. 9),
indicating bathymetric highs of the order of 700-1500 m before turbiditic covering. The top of one of
these anticlines is still forming a 700-m high arcuate relief at the latitude of 21°35'N (Fig. 2; 6). The
tilt of sedimentary layers on the eastern side of the arcuate relief indicates that some compression is
still active in this area (Fig. 9) and may represent an analog of the successive unconformities observed
in the sequence that was subsequently folded in the Dalrymple Trough (Fig.6). The system of folds
shows an isopach deformation at depth, followed by a gentle fanning configuration upward indicating
syn-tectonic deposition (Fig. 10). The seismic profile displayed in Fig. 10 highlights a contrast in the
deformation pattern on both sides of the OFZ, the syncline structure being observed solely on its
western side. The latter results from the right-lateral offset of the fold system, which moved the fold
initially located around the latitude of the profile in Fig. 10 to the latitude of the profile in Fig. 9.
The southern Murray Ridge follows a N60°E trend, and displays an asymmetric shape on seismic
sections, with a steeper flank facing the Dalrymple Trough (Fig. 3) (Edwards et al., 2000). The angular
unconformity marking the uplift of the southern Murray Ridge (picked in blue) is well identified on its
eastern side (Fig. 3) (Edwards et al., 2000; Clift et al., 2001; Gaedicke et al., 2002 a,b) and on its
western side (Fig.8).
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6. Age estimates of the deformation
Opening of the Dalrymple Trough, Northern Murray Ridge uplift, and M-unconformity
The age of opening of the Dalrymple Trough and of related geological events is estimated by using
turbiditic channel-levee systems as morphological markers of the deformation and by regional
correlations with ODP Site 722 at the Owen Ridge (Fig. 1).
Previously published multibeam bathymetric data reveal the presence of fossil meandering turbiditic
channels on the top of the Murray Ridge (Fig. 2) and the Jinnah High (Ellouz-Zimmermann et al.,
2007, Mouchot, 2009; Mouchot et al., 2008, 2010). Turbiditic channels are identified below ~4.1 s
(TWT) in the vicinity of the OFZ (Fig. 9, 10) and on the western flank of the Dalrymple Trough (Fig.
6). Perched turbiditic channels are also observed on the eastern flank of the trough (Fig. 6, 8).
All turbiditic channels in the area are blanketed by pelagites that preserved their seafloor expression,
but none of them are active anymore in the vicinity of the trough (Deptuck et al., 2003; Ellouz-
Zimmermann et al., 2007a,b; Rodriguez et al., 2011). Because of the steep and uneven slopes created
by the active thrusts of the Makran wedge, the turbiditic canyons cutting through the wedge do not
form any turbiditic channel at their mouth (Bourget et al., 2011). North of the Dalrymple Trough, the
Jinnah High acts as a topographic barrier for the turbiditic deposits coming from the Makran (Fig. 4).
The origin of the turbiditic sequence observed on both sides of the Dalrymple Trough and below the
M-unconformity is thus the Indus deep-sea fan (Gaedicke et al., 2002a,b; Ellouz-Zimmermann et al.,
2007a,b). Therefore, the youngest generation of channel-levee system in the area pre-dates the opening
of the Dalrymple Trough and the formation of the M-unconformity, and gives their maximal age. The
age of abandonment of the youngest channel-levee is estimated by the thickness of the overlying
pelagic cover, converted into time using uniform pelagic sedimentation rates in the area (30-55
m Ma
-1
).
Channel-levee systems (labelled A) observed both on the top of the Jinnah High (Ellouz-Zimmerman
et al., 2007) and west of the Dalrymple Trough (Fig. 6) are covered by ~0.3 s (TWT) of pelagic
deposits. Channel-levee systems A are therefore ~5.8 ± 2.2 Ma old (Table 1b). On the other hand, the
channel-levee system (labelled B on Figures 6 and 8) observed on the west side of the connection
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between the OFZ and the Dalrymple Trough is covered by a ~0.18 s TWT-thick pelagic cover, making
this channel the youngest in the area. This pelagic thickness indicates that turbiditic sedimentation
stopped in the area since at least 3.5 ± 1.4 Ma (Table 1b). This channel-levee system is dissected by
the transverse faults at the entrance of the trough, indicating that it predates this episode of
deformation (Fig. 8). The maximal plausible age of the Dalrymple Trough is therefore 3.5 ± 1.4 Ma.
Channel-levee systems in the area migrated southwards prior to their deactivation 3.5 ± 1.4 Ma ago,
which indicates that the Oman abyssal plain seafloor was not tilted towards the subduction zone before
that time (Mouchot, 2009).
The age of opening of the Dalrymple Trough can be refined by seismic correlations performed on the
profile transverse to the trough (Fig. 6, 7). The syncline basin forming the trough displays a seismic
facies typical of a turbiditic and pelagic layers succession (Fig. 6, 7). It further indicates that the
turbiditic sequence identified on both sides of the trough used to be connected before its opening (Fig.
6-8). An unconformable ponded sedimentary sequence, mainly composed of mass transport deposits,
seals the syncline basin (Fig. 7). The turbiditic series deformed by the syncline thus corresponds to the
substratum of the Dalrymple Trough, the top of which corresponds to the last sedimentary layer
deposited before its opening. The uppermost pelagic reflector of the syncline (Fig. 6, 7) correlates
fairly well with the sedimentary sequence west of the trough, where it is overlain by a 0.1 s (TWT)-
thick pelagic cover corresponding to 1.9 ± 0.9 Myr. The most probable age of opening of the
Dalrymple Trough is therefore 1.9 ± 0.9 Ma. About 1200-m of subsidence has been accommodated by
the trough since 1.9 ± 0.9 Ma.
On the other hand, the M-unconformity observed on Figure 4 can be correlated up to the Jinnah High.
Although indicating a tectonic tilt of the Indus channel-levee systems in the Oman abyssal plain, the
dip of the unconformity slightly changes at the approach of the Jinnah High. This change in dip is due
to the progressive transition from pelagic to turbiditic deposits as the Makran turbiditic system
progressively buries the M-unconformity. The thickness of pelagic deposits covering the M-
unconformity in the area uncovered by Makran turbidites is 0.1 s (TWT), which gives an age of about
~1.9 ± 0.9 Ma. Since the reflector marking the opening of the Dalrymple Trough (Fig. 6) and the M-
unconformity are sealed by the same thickness of pelagic sediments, both events are considered
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synchronous. Kolla and Coumes (1987) previously noticed the southeastward shift of the Pleistocene
Indus channel-levee systems that may relate to the Pleistocene uplift of the northern Murray Ridge..
Regional correlations of seismic lines show that the pelagic layer overlying the M-unconformity in the
vicinity of the Dalrymple Trough is also recognized in the vicinity of the 20°N pull-apart basin and at
the Southern Owen Ridge (Fig. 11). At the 20°N basin, the M-unconformity corresponds to a 2.5 ±1
Ma-old reflector marking the onset of contourite deposition on the western side of the basin
(Rodriguez et al., 2013b). There, the onset of contourite deposition may reflect local disturbance of
bottom currents following the opening of the basin (Rodriguez et al., 2013b). At the Owen Ridge, the
reflector corresponding to the M-unconformity is dated at 2.4 Ma at ODP Site 722 (Discoaster
pentaradiatus, sampled at a depth of 74 mbsf, Shipboard Scientific Party, 1989). The age of 2.4 Ma is
in the range of ages predicted by the extrapolation of sedimentation rates, and may represent the most
likely age of the last structural reorganization of the OFZ expressed by the coeval opening of both the
Dalrymple Trough and the 20°N Basin and the M-unconformity. Considering a steady India-Arabia
motion of 3±1 mm.yr
-1
(Fournier et al. 2008a,b; 2011), the Dalrymple Trough opened in response to a
limited amount of strike-slip motion, in the order of 5-10 km.
Late Miocene Murray Ridge uplift and buried folds
The use of the distribution of turbiditic channels as a marker of the evolution of the Murray Ridge
elevation is more problematic. The profile displayed in Fig. 3c shows that before its 1.9± 0.9 Ma
uplift, the northern Murray Ridge was almost totally buried by Indus turbidites. The paleo-location of
the Indus canyon in the northwestern extremity of the Indian margin prior to the Pleistocene (Fig.1,
Kolla and Coumes, 1987) implies that turbiditic channels simply bypassed the southern Murray Ridge
to flood the Oman abyssal plain. The southern Murray Ridge was thus a prominent high since 8-10 Ma
(age of the unconformity marking its uplift; Calvès, 2008), but did not act as a major barrier for the
Indus turbidites due to the paleo-location of the canyon (Fig. 1). The northern Murray Ridge, although
uplifted around 8-10 Ma (Fig. 4), was less prominent than the Southern Murray Ridge and had been
rapidly buried under Indus turbidites. The age of the buried folds identified on Figures 9 and 10 cannot
be estimated because of the large range of Late Miocene-Pliocene Indus sedimentation rates (Kolla
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and Coumes, 1987; Clift et al., 2001; Calvès, 2008), but they are probably coeval with the main uplift
episode of the southern Murray Ridge at 8-10 Ma. The N-S trend of the arcuate relief at ~21°35°N
implies a roughly E-W compression at the origin of the Late Miocene deformation.
7. Discussion
7.1. Mode of opening of the south Dalrymple Trough
The main structural characteristic of the Dalrymple Trough is the numerous transverse faults that form
the horsetail structure. Transverse faults are common structures within narrow (<15-km-wide)
stepover areas such as the Dead Sea Basin (Kashai and Croker, 1987; Ben Avraham and ten Brink,
1989; Lazar et al., 2006; Smit et al., 2008) or the 20°N Basin along the OFZ (Rodriguez et al., 2011,
2013). There, transverse faults form during the opening of the pull-apart basin and were shown to
transfer strike slip motion from one main bounding strike-slip segment to the other (Ben Avraham and
ten Brink, 1989). Stepovers at the origin of the Dalrymple Trough (>30 km), the North Aegean Sea
(>40 km), the Andaman Sea (>100 km) are far much wider, and emplaced in areas of strong crustal
thickness variations inherited from previous geological events. Complex structures such as the Jinnah
Seamount (Dalrymple), the North Cycladic Detachment Fault (Aegean Sea; Le Pourhiet et al., 2012;
Jolivet et al., 2013) or the Alcock Rise (Andaman Sea; Morley, 2013) prevent any connection between
bounding strike-slip faults at the extremities of the stepover. In this context, transverse faults cannot
result from the transfer of strike-slip motion between bounding strike-slip segments. Analog modeling
works (Basile and Brun, 1999) propose that in wide stepover areas, a divergent system composed of
normal faults trending perpendicular to the main strike-slip direction emplaces in the first stages of
strike-slip motion. As the amount of strike-slip motion increases, the main strike-slip fault connects
progressively the transverse normal faults. The first step of these analog models strikingly reproduces
the en-échelon fault system (2) observed at the Dalrymple Trough (Fig. 12). However, the full
connection of the strike-slip fault with the transverse normal faults implies a large amount of relative
motion in the model, which contrasts with the case of the Dalrymple Trough, where only ~5-10 km of
relative motion were accommodated since the first stages of opening ~1.9 ± 0.9 Ma. The ~5-10 km of
relative motion at the Dalrymple Trough drastically contrasts with its dimensions (150-km-long, 30-
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km-wide). This raises the question of the relationship between the size of a basin and the amount of
finite motion. The formation of a stepover in response to the structural reorganization of the strike-slip
fault system isolated a subsiding half graben of dimensions close to the present-day Dalrymple
Trough. The connection between the main strike-slip fault and the numerous transverse normal faults
may occur in the earliest stages of basin opening, and not progressively as suggested by analog
models. The numerous transverse faults individualized several sub-basins, and subsequently
accommodated distributed transtension corresponding to the ~5-10 km of India-Arabia relative
motion.
Moreover, the opening of the Dalrymple Trough enhanced the uplift of its flanks, and rejuvenated the
topography at the northern Murray Ridge and the westernmost part of the southern Murray Ridge,
similar to what is observed along the Dead Sea flanks (Basile and Allemand, 2002). On the other
hand, the southern Murray Ridge is outside the area affected by the flexure induced by the Dalrymple
Trough, and has probably been little affected by this uplift phase (Fig. 1d).
7.2. Tectonic history of the Dalrymple Trough-Murray Ridge system
The results above document at least two major deformation events (Fig. 13) : a first compressional one
(8-10 Ma-old) related to the folds observed on the sides of the OFZ (Fig. 9, 10) the main uplift of the
southern Murray Ridge, and the first uplift of the Northern Murray Ridge (Fig. 3) (Kolla and Coumes,
1988; Calvès, 2008); and a second one (1.9 ± 0.9 Ma-old) related to the subsidence of the Dalrymple
Trough, the uplift of its flanks (including the major uplift of the northern Murray Ridge), and the
formation of the M-unconformity in the Oman abyssal plain (Fig. 4, 6, 7). Compressive deformation
was still active in the area since 8-10 Ma. Whether stepover basins inception is coeval with the
inception of the OFZ is difficult to assess, as some stepover basins were shown to develop a few
million years after the initiation of the San Andreas Fault (e.g. Wakabayashi, 2007) and the Levant
Fault (Garfunkel and Ben Avraham, 2001). The alternative involves a third, intermediate episode, in
which the OFZ emplaced at ~6 Ma, and then underwent opening of stepover basins at 1.9 ± 0.9 Ma.
However, the location of the plate boundary for the 3-6 Ma time span is unknown. It is even possible
than India and Arabia were temporary coupled during this time span, both Carlsberg and Sheba ridges
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showing similar half spreading rates at ~3 cm.yr
-1
(Merkouriev and DeMets, 2006; Fournier et al.,
2010). This framework, summarized in Figure 13, contrasts with the two stages history (in the Early
and the Late Miocene) previously assessed (Gaedicke et al., 2002), and implies a new geodynamic
interpretative scheme of the Dalrymple Trough-Murray Ridge system.
Origin of the ~8-10 Ma-old compressional episode of deformation
The uplift of the Southern Murray Ridge is coeval with widespread deformation in the Owen Basin
(Rodriguez et al., 2014) and the ending of seafloor spreading rates deceleration at 8-11 Ma recorded
by magnetic anomalies at the Carlsberg Ridge (Mercuriev and DeMets, 2006). The Late Miocene
deformation in the Arabian sea coincides in time with a Late Miocene global plate reorganization
event, which is expressed in the Indian Ocean by the separation of Somalia from Africa (DeMets et al.,
2005; Mercuriev and DeMets, 2006) and intra-plate deformation in the Central Indian Ocean,
separating India from Australia (Weissel et al., 1980; Wiens et al., 1985; Bull and Scrutton, 1990;
1992; Chamot-Rooke et al., 1993; Henstock and Minshull, 2004; Delescluse et al., 2008; Krishna et
al., 2009; Copley et al., 2010). The increase in stress applied by the Miocene growth of the Himalayas
on India's plate boundaries has been tentatively proposed as the driver for this plate reorganization
event (Molnar et al., 1993; Molnar and Stock, 2009; Bull et al., 2010). However, the present-day
deformation west of the Chagos-Laccadive is extension rather than compression (Henstock and
Minshull, 2004). The compressive deformation at the India-Arabia plate boundary probably results
from complex tectonic interactions between both plates.
Origin of the ~1.9 ± 0.9 Ma-old transtensive episode of deformation
The M-unconformity records both the tilt of Indus series in front of the Makran and the opening of the
Dalrymple Trough, suggesting a common origin. This episode of deformation induced a second uplift
of the northern Murray Ridge. The opening of the Dalrymple Trough isolated the Makran from Indus
sediments, the only remaining source of sediments being the Makran turbiditic system. The younger
age of the M-unconformity implies that the erosion rates of the Makran accretionary wedge have been
strong during the Pleistocene, probably in the same order as current rates (>2 mm.yr
-1
, Bourget et al.,
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2011). Sedimentation rates control the temperature at the deformation front, high sedimentation rates
favoring shallow seismogenic rupture along megathrusts (Smith et al., 2012; 2013). This Late Pliocene
transition in the sedimentation regime may have affected both the structural organization of the wedge
and its seismogenic potential.
The reflector marking the opening of the Dalrymple Trough and the 20°N Basin being the same (Fig.
11) , the reorganization of the OFZ between 20°N and 24°N may be coeval with the last structural
reorganization of the Makran accretionary wedge marked by the M-unconformity.
8. Conclusions and perspectives
This study documents a Late Miocene compressive episode along the India-Arabia plate boundary
expressed by a complex set of folds at the connection between the OFZ and the Dalrymple Trough.
The U-unconformity is not recognized at the Murray Ridge, whose uplift is recorded by an angular
unconformity dated at 8-10 Ma (Calvès, 2008). A Late Miocene compressive episode of deformation
is recognized throughout the Owen Basin (Rodriguez et al., 2014) and is linked to a Late Miocene
global plate reorganization event.
This study also shows the formation of a stepover area ~1.9 ± 0.9 Ma at the origin of both the
Dalrymple Trough and the second uplift of the Northern Murray Ridge. This age is significantly
younger than the Miocene age previously proposed (Gaedicke et al., 2002) and in better agreement
with the recent age of the OFZ, which shows no structure older than 3 Ma along strike (Rodriguez et
al., 2011; 2013). This younger age also implies that large stepover basins (150-km-long) can develop
with limited amount of strike-slip motion (5-10 km). Moreover, the M-unconformity is not coeval with
the structural reorganization that affected the Makran wedge during Tortonian (McCall, 1997; Burg et
al., 2008; Smit et al., 2010), and marks a younger episode of structural reorganization 1.9 ± 0.9 Ma.
The reassessment of the tectonic framework of the Dalrymple Trough and the Murray Ridge points out
interesting regional perspectives for the Indus turbiditic system and the Makran accretionary wedge.
The last structural reorganization marked by the M-unconformity is roughly coeval with the opening
of the Dead Sea Basin along the Levant Fault (TenBrink et al., 1989). Whether coeval deformation
events along both strike-slip boundaries of the Arabian plate reflect a poorly constrained Late
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Pliocene-Early Pleistocene kinematic change remains enigmatic (Allen et al., 2004; Smit et al., 2009,
Schattner, 2010). Considering the regional correlation with ODP Site 722, the last structural
reorganization marked by the M-unconformity is likely to be synchronous with a major monsoon
intensification over Asia around 2.4 Ma (Bloemendal and DeMenocal, 1989; An et al., 2001; Wang et
al., 2005; Huang et al., 2007), affecting the Makran and the Himalayan foreland. The critical Coulomb
wedge theory and geological studies (Berger et al., 2008; Whipple, 2009; Malavieille, 2010;
Iaffaldano et al., 2011) suggest that major climate changes can affect the wedge taper at a regional
scale, and induce widespread structural reorganization. Deep-sea drillings would be useful to decipher
the precise timing of the deformation in the area and confirms the link with monsoon intensity.
Second, the uplift of the northern Murray Ridge since ~1.9 ± 0.9 Ma might account for the Pleistocene
southwestward migration of the Indus canyon on the Indian Margin (Kolla and Coumes, 1987). A
precise dating of the episodes of migration of the canyon, together with reconstructions of the
evolution of the topography fossilized by channel-levee systems, would highlight the complex
interaction between tectonic and sedimentary processes (see similar examples in Mulder et al., 2012).
Acknowledgements
We thank the SHOM and GENAVIR team for their help in data acquisition. Processing of the OWEN-
2 dataset was carried out using the Geocluster 5000 software from CGGVeritas. We thank P. Dubernet
and N. Bacha for technical assistance, and L. Le Pourhiet for scientific discussions about horsetail
terminations. Tim Minshull and Lisa McNeill provided very detailed and constructive comments that
greatly helped us to improve this article. This study was supported by SHOM, IFREMER, INSU-
CNRS, and CEA (LRC Yves-Rocard).
Figure captions :
Figure 1 :a) Shaded-relief bathymetry of the Arabian sea and surrounding topography, from Becker et
al., 2009 and Fournier et al., 2011. LMR : Little Murray Ridge. Red stars: drill sites b) Simplified
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cross section of the Oman abyssal plain, modified from White and Klitgord (1976) (see a) for
location). c) and d) : topographic profiles running transverse to the northern and southern Murray
Ridge. Inset shows the simplified geodynamic framework of the Arabian Sea. AOC: Aden-Owen-
Carlsberg triple junction.
Figure 2 : Multibeam bathymetric map of the Dalrymple Trough (a), and interpretative morpho-
structural scheme (b), with local crustal seismicity since 1973 (focal depth < 50 km, magnitude
Mw > 2) from available databases. The small circle about the closure-enforced MORVEL Arabia–
India rotation pole (dark blue dashed line; DeMets et al., 2010) is parallel to the trend of the OFZ at
the entrance of the trough, whereas the small circle determined from the active trace of the OFZ (light
blue dashed line, Fournier et al., 2011) is parallel to the trace of the OFZ up to 21°30°N and to the en-
échelon fault system labeled “2”. Location of seismic profiles is indicated by black dashed lines. Insets
show close bathymetric views of the turbiditic channels observed in the area, labeled A and B
according to their age of activity (A : older channel, 5.8 ± 2.2 Ma, B : younger channel, 3.5 ± 1.4 Ma).
Yellow stars: drill sites.
Figure 3 : a-b) Line drawing of previously published seismic profiles and c) seismic line crossing in
the Dalrymple Trough-Murray Ridge area(see the inset in the upper right hand corner for location and
Fig. 2). a) Line drawing of a profile crossing the southern Murray Ridge, from Gaedicke et al., 2002b.
The U-unconformity is not recognized on the eastern side of the Dalrymple Trough and in the vicinity
of the Murray Ridge; b) Line drawing of a profile crossing the Dalrymple Trough and the southern
Murray Ridge, modified after Edwards et al., 2000. A potential fracture zone offset is identified on the
eastern flank of the Murray Ridge; c) Profile modified from Kolla and Coumes (1987) showing an
angular unconformity on the eastern side of the Murray Ridge. The angular unconformity was dated at
8-10 Ma by calibration with an industrial drilling located in the Indus deep-sea fan (Pak-G2-1; Calvès,
2008). CLS= Channel-Levee Systems.
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Figure 4 : Seismic profile from the Chamak cruise (Ellouz-Zimmerman et al., 2007; Mouchot, 2009)
crossing the Jinnah High, showing the M-unconformity (see figure 2 for location).a) close view of the
M-unconformity in the area of the Jinnah High; b) Seismic profile showing the M-unconformity and c)
its line drawing. CLS = channel-levee system.
Figure 5 : Synthesis of the seismic facies of the main sedimentary deposits observed in the study area.
Figure 6 : a) Bathymetry of the connection between the Owen Fracture Zone (OFZ) and the
Dalrymple Trough, showing en-échelon faults connecting transverse normal faults within the trough.
b) Seismic profile transverse to the Dalrymple Trough (see Fig. 2 and 6a for location) and c)
interpretation. MTD = mass transport deposits. CLS = channel-levee system.
Figure 7 : Close view of the seismic profile displayed in fig. 6, showing the stratigraphic correlation
of the last deformed layer within the trough with its western border. The last deformed layer within the
trough coincides with the M unconformity in the Oman Abyssal Plain. Close views of the profile
highlight the similar seismic sequence within and outside the Dalrymple Trough prior its opening.
Figure 8 : a) seismic profile crossing the transverse fault system and b) the interpretation.
Figure 9 : a) seismic profile crossing the Owen fracture Zone at the entrance of the Dalrymple Trough
(see Fig. 2 and 6 for location) and b) the interpretation.
Figure 10 : a)Seismic profile crossing the Owen Fracture Zone (OFZ) and the en-échelon fault system
2 (see Fig. 2 and 6 for location) and b) its interpretation. c) shows a bathymetric view of the en-
échelon fault system 2, with a particular emphasis over its relationship with fossil Indus turbiditic
channels.
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Figure 11 : Regional correlation of seismic facies at the edges of the Dalrymple Trough, the 20°N
Basin (Rodriguez et al., 2013) and the Owen Ridge (Shipboard Scientific Party, 1989; Rodriguez et
al., 2014).
Figure 12 : Simplified structural sketchmap of the Dalrymple Trough and comparison with results
from analog modeling experiments from Basile and Brun (1999).
Figure 13 : Sketches of the geological history of the Dalrymple Trough and the Murray Ridge. OFZ :
Owen Fracture Zone, PB : Plate-Boundary. Stage A : A Late Miocene episode (8-10 Ma) of
compression along the India-Arabia plate boundary triggered the main uplift of the Murray Ridge. The
plate boundary was probably located on the eastern side of the Murray Ridge according to sharp
offsets of the basement observed on previously collected seismic lines (see Fig. 3). Stage B : This
intermediate stage considers the alternative in which the opening of the Dalrymple Trough is not
coeval with the inception of the OFZ. Since the emplacement of the OFZ between 3-6 Ma, Late
Miocene folds were offset dextrally and progressively buried under Indus turbidites. Stage C: The
Dalrymple Trough opened (~2-3 Ma), and provoked a new episode of uplift of the northern Murray
Ridge. It is related to the formation of the M-unconformity in the Oman abyssal plain. At the same
time, the Indus canyon began its migration towards the south-east.
Table 1 : a) Range of sedimentation rates calculated at different drilling sites in the Arabian Sea (see
Fig. 1 for location). b) Age estimations of the different markers used in this study, from conversion of
pelagic sediment thicknesses into time. Different values of sedimentation rates calculated at the
different drilling/coring sites available, as well as different P-wave velocities, are used for the
conversion of the pelagic thickness into time.
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Sedimentation rates range along the Owen-Murray Ridge
Owen Ridge Murray Ridge
CORES ODP 722
(Shipboard Scientific
Party, 1989)
KS07
(Bourget et al.,
2013)
MD-2881
(Ziegker et al., 2007) S090-93KL
(Schultz et al., 1998)
Time sampled 15 Ma 160 ka 750 ka 110 ka
Average
sedimentation rates
(Plio-Pleistocene
rates)
30 m/Ma - 46 m/Ma
54 m/Ma
40 m/Ma
55 m/Ma
Table 1a
TWT (ms) Age estimates (Myr)
using P-wave velocities of 1530-1730 m.s
-1
Thickness of
pelagic
deposits
overlying the
last active
CLS -B
(OFZ-
Dalrymple
connection)
180 ± 10
3.5 ± 1.4
Thickness of
pelagic
deposits
overlying the
last active
CLS-A
(Top of
Murray Ridge)
300 ± 10
5.8 ± 2.2
Thickness of
pelagic
deposits
sealing the 'M'
unconformity
100 ± 10
1.9 ± 0.9
Table 1b
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Graphical abstract
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highlights
-A detailed structural framework of the Dalrymple horsetail termination of the Owen Fracture Zone
-Opening of the Dalrymple Trough around 2 Ma coeval with the regional M-unconformity
-Episode of compressive deformation along the India-Arabia plate boundary at 8-10 Ma
