scholarly journals Focusing of relative plate motion at a continental transform fault: Cenozoic dextral displacement >700 km on New Zealand's Alpine Fault, reversing >225 km of Late Cretaceous sinistral motion

2016 ◽  
Vol 17 (3) ◽  
pp. 1197-1213 ◽  
Author(s):  
Simon Lamb ◽  
Nick Mortimer ◽  
Euan Smith ◽  
Gillian Turner
Keyword(s):  
Late Cretaceous ◽  
Plate Motion ◽  
Transform Fault ◽  
Alpine Fault ◽  
Relative Plate Motion

Kinematic analysis of deformed structures in a tectonic mélange: a key unit for the manifestation of transpression along the Zagros Suture Zone, Iran

2012 ◽  
Vol 149 (6) ◽  
pp. 1107-1117 ◽  
Author(s):  
ALI FAGHIH ◽  
TIMOTHY KUSKY ◽  
BABAK SAMANI
Keyword(s):  
Late Cretaceous ◽  
Kinematic Analysis ◽  
Pillow Lava ◽  
Oceanic Lithosphere ◽  
Suture Zone ◽  
Plate Motion ◽  
Shear Sense ◽  
Tectonic Mélange ◽  
Relative Plate Motion ◽  
Parallel Extension

AbstractKinematic analysis of mélange fabrics provides critical information concerning tectonic processes and evaluation of the kinematics of ancient relative plate motion. Systematic kinematic analysis of deformed structures within a tectonic mélange exposed along the Zagros Suture Zone elucidates that this zone is an ancient transpressional boundary. The mélange is composed of a greywacke and mudstone matrix surrounding various lenses, blocks and ribbons of radiolarian chert, limestone, sandstone, pillow lava, tuff, serpentinite, shale and marl. The deformation fabrics of the mélange suggest that the mélange units were tectonically accreted at shallow levels within a subduction complex, resulting in layer-parallel extension and shearing along a NW–SE-trending suture that juxtaposes the Afro-Arabian continent to the south and the Central Iranian microcontinents to the north. The tectonic mélange is characterized by subhorizontal layer-parallel extension and subsequent heterogeneous non-coaxial shear resulting in alternating asymmetric and layer-parallel extensional fabrics such as P–Y fabrics and boudinaged layers. Kinematic data suggest that the mélange formed during oblique subduction of the Neo-Tethys oceanic lithosphere in Late Cretaceous time. Kinematic shear sense indicators reveal that the slip direction (N9°E to N14°E) during accretion-related deformations reflects the relative plate motion between the Afro-Arabian continent and Central Iranian microcontinents during Late Cretaceous to Miocene times.

A review of the tectonics of the northern Middle East region

1984 ◽  
Vol 121 (6) ◽  
pp. 577-587 ◽  
Author(s):  
P. E. R. Lovelock
Keyword(s):  
Late Cretaceous ◽  
Kinematic Model ◽  
Continental Collision ◽  
Dead Sea ◽  
Plate Motion ◽  
Arabian Plate ◽  
Southern Boundary ◽  
The North ◽  
The Dead ◽  
Two Stages

AbstractThe structure of the northern part of the Arabian platform is reviewed in the light of hitherto unpublished exploration data and the presently accepted kinematic model of plate motion in the region. The Palmyra and Sinjar zones share a common history of development involving two stages of rifting, one in the Triassic–Jurassic and the other during late Cretaceous to early Tertiary times. Deformation of the Palmyra zone during the Mio-Pliocene is attributed to north–south compression on the eastern block of the Dead Sea transcurrent system which occurred after continental collision in the north in southeast Turkey. The asymmetry of the Palmyra zone is believed to result from northward underthrusting along the southern boundary facilitated by the presence of shallow Triassic evaporites. An important NW-SE cross-plate shear zone has been identified, which can be traced for 600 km and which controls the course of the River Euphrates over long distances in Syria and Iraq. Transcurrent motion along this zone resulted in the formation of narrow grabens during the late Cretaceous which were compressed during the Mio-Pliocene. To a large extent, present day structures in the region result from compressional reactivation of old lineaments within the Arabian plate by the transcurrent motion of the Dead Sea fault zone and subsequent continental collision.

No signal of a plume push force in Indo-Atlantic plate speeds before, during, or after Deccan plume arrival

2021 ◽  
Author(s):  
Graeme Eagles ◽  
Lucía Pérez Díaz ◽  
Karin Sigloch
Keyword(s):  
Late Cretaceous ◽  
Upper Mantle ◽  
Plate Boundary ◽  
Plate Motion ◽  
Driving Mechanism ◽  
African Plate ◽  
Plate Motions ◽  
Driving Mechanisms ◽  
High Resolution Models ◽  
Spreading Rates

<p>Observations of the apparent links between plate speeds and the global distribution of plate boundary types have led to the suggestion that subduction may provide the largest component in the balance of torques maintaining plate motions. This would imply that plate speeds should not exceed the sinking rates of slabs into the upper mantle. Instances of this ‘speed limit’ having been broken may thus hint at the existence of driving mechanisms additional to those resulting from plate boundary forces. The arrival and emplacement of the Deccan-Réunion mantle plume beneath the Indian-African plate boundary in the 67-62 Ma period has been discussed in terms of one such additional driving mechanism, leading to the establishment of “plume-push” hypothesis, which in recent years has gained significant traction. We challenge the model-based observations that form the principal evidence in favour of plume-push: a late Cretaceous pulse of anticorrelating accelerations and decelerations in seafloor spreading rates around the African and Indian plates. Using existing and newly-calculated high-resolution models of plate motion, we instead document an increase in divergence rates at 67-64 Ma. Because of its ubiquity, we consider this increase to be the artefact of a timescale error affecting chrons 29-28. Corrected for this artefact, the evolution of plate speeds resembles a smooth continuation of pre-existing late Cretaceous trends, consistent with the idea that the arrival of the Réunion plume did not substantially affect the existing balance of plate boundary forces on the Indian and African plates. </p>

The petrogenesis and tectonic setting of lavas from the Baft Ophiolitic Mélange, southwest of Kerman, Iran

1994 ◽  
Vol 31 (5) ◽  
pp. 824-834 ◽  
Author(s):  
Mohsen Arvin ◽  
Paul T. Robinson
Keyword(s):  
Late Cretaceous ◽  
Tectonic Setting ◽  
Tholeiitic Basalt ◽  
Ocean Basin ◽  
Plate Motion ◽  
Geochemical Data ◽  
Ophiolite Complex ◽  
Ophiolitic Mélange ◽  
Lut Block ◽  
Mafic Lavas

A Late Cretaceous ophiolite complex in the Baft area, southwest of Kerman, Iran, is characteristic of the Central Iranian Ophiolitic Mélange Belt, which wraps around the Lut Block. Despite the extensive tectonic disruption of the Baft complex, most ophiolitic lithologies are present and many original igneous contacts are preserved. A lack of cumulate gabbros within the sequence suggests that a large and continuous magma chamber did not exist beneath the Baft spreading axis. Geochemical data confirm the presence of two distinct compositional groups in the mafic lavas: (1) tholeiitic basalt and (2) transitional tholeiitic basalt. The tholeiitic lavas are similar to typical mid-ocean-ridge basalt compositions, whereas the transitional tholeiites are similar to intraplate basalts. The available data suggest that the Baft ophiolite complex formed in a small ocean basin, possibly at or near a ridge–transform intersection. Emplacement may have occurred as a result of conversion of the transform fault to a subduction zone during a change in relative plate motion. A ridge–transform setting is compatible with the intraplate character of some of the transitional basalts, which probably represent off-axis (seamount) magmatism, marked by the absence of cumulate gabbros and the presence of a serpentinite mélange cut by basaltic dykes. The ridge–transform model suggests formation of the ophiolite in a narrow ocean basin separating the Sanandaj-Sirjan microcontinent from the Central Iran Block in Late Cretaceous time.

scholarly journals Interplate coupling and relative plate motion in the Tokai district, central Japan, deduced from geodetic data inversion using ABIC

1993 ◽  
Vol 113 (3) ◽  
pp. 607-621 ◽  
Author(s):  
Shoichi Yoshioka ◽  
Tetsuichiro Yabuki ◽  
Takeshi Sagiya ◽  
Takashi Tada ◽  
Mitsuhiro Matsu'ura
Keyword(s):  
Geodetic Data ◽  
Plate Motion ◽  
Central Japan ◽  
Data Inversion ◽  
Interplate Coupling ◽  
Relative Plate Motion

Continuous Deformation Versus Faulting Through the Continental Lithosphere of New Zealand

Science ◽  
1999 ◽  
Vol 286 (5439) ◽  
pp. 516-519 ◽  
Author(s):  
Peter Molnar ◽  
Helen J. Anderson ◽  
Etienne Audoine ◽  
Donna Eberhart-Phillips ◽  
Ken R. Gledhill ◽  
...  
Keyword(s):  
New Zealand ◽  
Seismic Anisotropy ◽  
Plate Motion ◽  
Plate Boundaries ◽  
Mantle Lithosphere ◽  
Continental Lithosphere ◽  
Continuous Deformation ◽  
Alpine Fault ◽  
Wave Splitting ◽  
Rule Out

Seismic anisotropy and P-wave delays in New Zealand imply widespread deformation in the underlying mantle, not slip on a narrow fault zone, which is characteristic of plate boundaries in oceanic regions. Large magnitudes of shear-wave splitting and orientations of fast polarization parallel to the Alpine fault show that pervasive simple shear of the mantle lithosphere has accommodated the cumulative strike-slip plate motion. Variations inP-wave residuals across the Southern Alps rule out underthrusting of one slab of mantle lithosphere beneath another but permit continuous deformation of lithosphere shortened by about 100 kilometers since 6 to 7 million years ago.

Reconciling seismic structures and Late Cretaceous kimberlite magmatism in northern Alberta, Canada

Geology ◽  
2020 ◽  
Vol 48 (9) ◽  
pp. 872-876
Author(s):  
Yunfeng Chen ◽  
Yu Jeffrey Gu ◽  
Larry M. Heaman ◽  
Lei Wu ◽  
Erdinc Saygin ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Source Region ◽  
Three Dimensional ◽  
Plate Motion ◽  
Mountain Lake ◽  
Low Velocity ◽  
Age Progression ◽  
Plate Reconstructions ◽  
Competing Models ◽  
Northern Alberta

Abstract The Late Cretaceous kimberlites in northern Alberta, Canada, intruded into the Paleoproterozoic crust and represent a nonconventional setting for the discovery of diamonds. Here, we examined the origin of kimberlite magmatism using a multidisciplinary approach. A new teleseismic survey reveals a low-velocity (−1%) corridor that connects two deep-rooted (>200 km) quasi-cylindrical anomalies underneath the Birch Mountains and Mountain Lake kimberlite fields. The radiometric data, including a new U-Pb perovskite age of 90.3 ± 2.6 Ma for the Mountain Lake intrusion, indicate a northeast-trending age progression in kimberlite magmatism, consistent with the (local) plate motion rate of North America constrained by global plate reconstructions. Taken together, these observations favor a deep stationary (relative to the lower mantle) source region for kimberlitic melt generation. Two competing models, mantle plume and slab subduction, can satisfy kinematic constraints and explain the exhumation of ultradeep diamonds. The plume hypothesis is less favorable due to the apparent age discrepancy between the oldest kimberlites (ca. 90 Ma) and the plume event (ca. 110 Ma). Alternatively, magma generation may have been facilitated by decompression of hydrous phases (e.g., wadsleyite and ringwoodite) within the mantle transition zone in response to thermal perturbations by a cold slab. The three-dimensional lithospheric structures largely controlled melt migration and intrusion processes during the Late Cretaceous kimberlite magmatism in northern Alberta.

scholarly journals Taking time to twist a continent—Multistage origin of the New Zealand orocline

Geology ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 56-60
Author(s):  
S. Lamb ◽  
N. Mortimer
Keyword(s):  
New Zealand ◽  
Large Scale ◽  
Plate Boundary ◽  
Plate Motion ◽  
West Antarctica ◽  
Alpine Fault ◽  
Plate Rotation ◽  
Dextral Shear ◽  
Plate Boundary Zone ◽  
Two Sides

Abstract In New Zealand, a giant coherent “Z” shape is defined by several curvilinear pre-Cenozoic basement terranes that extend across Zealandia for >1500 km along strike. It is widely assumed that this curvature was the result of bending during the Neogene, which together with ∼450 km of dextral displacement on the Alpine fault accommodated a total of ∼750 km of dextral shear through the New Zealand plate boundary zone between the Australian and Pacific plates. This would make it a very simple form of orocline. In fact, we show that its development was surprisingly complex and protracted, with a composite origin. Its western and southern parts were bent as much as 70° in the Mesozoic. In the Late Cretaceous, the already bent terranes were offset sinistrally by ∼250 km along the cross-cutting proto–Alpine fault, which acted as a transform to the rift between East and West Antarctica. Since the Eocene, and after Zealandia had completely separated from Antarctica, the two sides of the Alpine fault have undergone 45° of relative plate rotation, further bending the terranes. However, the eastern part of what appears today to be the same oroclinal structure has been created entirely since the Eocene, and mainly during the Neogene phase of dextral shear through the plate boundary, with large-scale internal bending and shortening. We suggest that multistage and composite evolutions may be typical features of oroclines, which would be difficult to unravel without a rich tectonic and plate motion database, such as that available for the New Zealand region.

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