Present-day Kinematics Research Articles

Present-day kinematics at the India-Asia collision zone: COMMENT and REPLY: COMMENT

The recent publication, “Present-day kinematics at the India-Asia collision zone” ([Meade, 2007][1]), attempts to address an ongoing controversy about the dynamics of the Tibetan Plateau by finding block models for the region that correctly reproduce the kinematics from many global positioning

Present-day kinematics at the India-Asia collision zone

Research Article| January 01, 2007 Present-day kinematics at the India-Asia collision zone Brendan J. Meade Brendan J. Meade 1Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, Massachusetts 02138, USA Search for other works by this author on: GSW Google Scholar Author and Article Information Brendan J. Meade 1Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, Massachusetts 02138, USA Publisher: Geological Society of America Received: 03 May 2006 Revision Received: 08 Aug 2006 Accepted: 28 Aug 2006 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (2007) 35 (1): 81–84. https://doi.org/10.1130/G22924A.1 Article history Received: 03 May 2006 Revision Received: 08 Aug 2006 Accepted: 28 Aug 2006 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Brendan J. Meade; Present-day kinematics at the India-Asia collision zone. Geology 2007;; 35 (1): 81–84. doi: https://doi.org/10.1130/G22924A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The collision of the Indian subcontinent with Asia drives the growth and evolution of the greater Tibetan Plateau region. Fault slip rates resulting from the relative motion between crustal blocks can provide a kinematic description of the distribution of present-day deformation. I construct a three-dimensional, regional-scale elastic block model of the India-Asia collision zone that is consistent with geodetic observations of interseismic deformation, mapped fault system geometry, historical seismicity, and the mechanics of the earthquake cycle. This mechanical model of the elastic upper crust yields a set of kinematically consistent fault slip rates and block motions that may serve to constrain dynamic models of continental crustal dynamics. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Present-day kinematics at the India-Asia collision zone: COMMENT and REPLY: REPLY

I welcome the Comment by Flesch and Bendick (2007) regarding my model and interpretation of global positioning system (GPS) velocities at the India-Asia collision zone ([Meade, 2007][1]), as well as the opportunity to further discuss the interpretation of GPS velocities in general. To be clear, it

Kinematics of the East African Rift from GPS and earthquake slip vector data

Abstract Although the East African Rift (EAR) System is often cited as the archetype for models of continental rifting and break-up, its present-day kinematics remains poorly constrained. We show that the currently available GPS and earthquake slip vector data are consistent with (1) a present-day Nubia-Somalia Euler pole located between the southern tip of Africa and the Southwest Indian ridge and (2) the existence of a distinct microplate (Victoria) between the Eastern and Western rifts, rotating counter-clockwise with respect to Nubia. Geodetic and geological data also suggest the existence of a (Rovuma) microplate between the Malawi rift and the Davie ridge, possibly rotating clockwise with respect to Nubia. The data indicate that the EAR comprises at least two rigid lithospheric blocks bounded by narrow belts of seismicity (<50 km wide) marking localized deformation rather than a wide zone of quasi-continuous, pervasive deformation. On the basis of this new kinematic model and mantle flow directions interpreted from seismic anisotropy measurements, we propose that regional asthenospheric upwelling and locally focused mantle flow may influence continental deformation in East Africa.

Tertiary to recent oblique convergence and wrenching of the Central Dinarides: Constraints from a palaeostress study

The late Eocene to Neogene tectonic evolution of the Dinarides is characterised by shortening and orogen-parallel wrenching superposed on the late Cretaceous and Eocene double-vergent orogenic system. The Central Dinarides exposes NW-trending tectonic units, which were transported towards the Adria/Apulian microcontinent during late Cretaceous–Palaeogene times. These units were also affected by subsequent processes of late Palaeogene to Neogene shortening, Neogene extension and subsidence of intramontane sedimentary basins and Pliocene–Quaternary surface uplift and denudation. The intramontane basins likely relate to formation of the Pannonian basin. Major dextral SE-trending strike-slip faults are mostly parallel to boundaries of major tectonic units and suggest dextral orogen-parallel wrenching of the whole Central Dinarides during the Neogene indentation of the Apulian microplate into the Alps and back-arc type extension in the Pannonian basin. These fault systems have been evaluated with the standard palaeostress techniques. We report four palaeostress tensor groups, which are tentatively ordered in a succession from oldest to youngest: (1) Palaeostress tensor group 1 (D 1) of likely late Eocene age indicates E–W shortening accommodated by reverse and strike-slip faults. (2) Palaeostress tensor group 2 (D 2) comprises N/NW-trending dextral and W/WSW-trending sinistral strike-slip faults, as well as WNW-striking reverse faults. These indicate NE–SW contraction and subordinate NW–SE extension related to Oligocene to early Miocene shortening of the Dinaric orogenic wedge. (3) Palaeostress tensor group 3a (D 3a) comprises mainly NW-trending normal faults, which indicate early/middle Miocene NE–SW extension related to syn-rift extension in the Pannonian basin. The subsequent palaeostress tensor group 3b (D 3b) includes NE-trending, SE-dipping normal faults indicating NW–SE extension, which is likely related to further extension in the Pannonian basin. (4) Palaeostress tensor group 4 (D 4) is characterised by mainly NW-trending dextral and NE-trending sinistral strike-slip faults. Together, with some E-trending reverse faults, they indicate roughly N–S shortening and dextral wrenching during late Miocene to Quaternary. This is partly consistent with the present-day kinematics, with motion of the Adriatic microplate constrained by GPS data and earthquake focal mechanisms. The north–north-westward motion and counterclockwise rotation of the Adriatic microplate significantly contribute the shortening and present-day wrenching in the Central Dinarides.

Prospect on present-day crustal kinematics and dynamics research in Sichuan-Yunnan area with geodetic data

Combining the dense GPS and gravity observation data in Sichuan-Yunnan area, where there are the relatively complete active tectonic zones and seismic data, this paper applies the geodesy and geophysical inversion technique and the advanced numerical simulation to the synthesis study of geodesy inversion to find the dynamic process of tectonic movement and deformation in the area and finally to investigate the kinematics characteristic of the geological structure of different layer and different scale. This paper discusses the kinematics, dynamics model about the crustal movement of active blocks in Sichuan-Yunnan area and its adjacent areas.

Geological and archaeological evidence of active faulting on the Martana Fault (Umbria–Marche Apennines, Italy) and its geodynamic implications

AbstractThis paper examines the morphotectonic and structural–geological characteristics of the Quaternary Martana Fault in the Umbria–Marche Apennines fold‐and‐thrust belt. This structure is more than 30 km long and comprises two segments: a N–NNW‐trending longer segment and a 100°N‐trending segment. After developing as a normal fault in Early Pleistocene times, the N–NNW Martana Fault segment experienced a phase of dextral faulting extending from the Early to Middle Pleistocene boundary until around 0.39 Ma, the absolute age of volcanics erupted in correspondence to releasing bends. The establishment of a stress field with a NE–ENE‐trending σ3 axis and NW–NNW σ1 axis in Late Pleistocene to Holocene times resulted in a strong component of sinistral faulting along N–NNW‐trending fault segments and almost pure normal faulting on newly formed NW–SE faults. Fresh fault scarps, the interaction of faulting with drainage systems and displacement of alluvial fan apexes provide evidence of the ongoing activity of this fault. The active left‐lateral kinematic along N–NNW‐trending fault segments is also revealed by the 1.8 m horizontal offset of the E–W‐trending Decumanus road, at the Roman town of Carsulae. We interpret the present‐day kinematics of the Martana Fault as consistent with a model connecting surface structures to the inferred north‐northwest trending lithospheric shear zone marking the western boundary of the Adria Plate. Copyright © 2003 John Wiley & Sons, Ltd.

GPS network monitors the Western Alps' deformation over a five-year period: 1993-1998

The Western Alps are among the best studied collisional belts with both detailed structural mapping and also crustal geophysical investigations such as the ECORS and EGT seismic profile. By contrast, the present-day kinematics of the belt is still largely unknown due to small relative motions and the insufficient accuracy of the triangulation data. As a consequence, several tectonic problems still remain to be solved, such as the amount of N–S convergence in the Occidental Alps, the repartition of the deformation between the Alpine tectonic units, and the relation between deformation and rotation across the Alpine arc. In order to address these problems, the GPS ALPES group, made up of French, Swiss and Italian research organizations, has achieved the first large-scale GPS surveys of the Western Alps. More than 60 sites were surveyed in 1993 and 1998 with a minimum observation of 3 days at each site. GPS data processing has been done by three independent teams using different software. The different solutions have horizontal repeatabilities (N–E) of 4–7 mm in 1993 and 2–3 mm in 1998 and compare at the 3–5-mm level in position and 2-mm/yr level in velocity. A comparison of 1993 and 1998 coordinates shows that residual velocities of the GPS marks are generally smaller than 2 mm/yr, precluding a detailed tectonic interpretation of the differential motions. However, these data seem to suggest that the N–S compression of the Western Alps is quite mild (less than 2 mm/yr) compared to the global convergence between the African and Eurasian plate (6 mm/yr). This implies that the shortening must be accomodated elsewhere by the deformation of the Maghrebids and/or by rotations of Mediterranean microplates. Also, E–W velocity components analysis supports the idea that E–W extension exists, as already suggested by recent structural and seismotectonic data interpretation.

Reappraisal of the Arabia–India–Somalia triple junction kinematics

We propose alternative kinematics for the Arabia–India–Somalia triple junction based on a re-interpretation of seismological and magnetic data. The new triple junction of the ridge–ridge–ridge type is located at the bend of the Sheba Ridge in the eastern gulf of Aden at 14.5°N and 56.4°E. The Owen fracture zone (Arabia–India boundary) is connected to the Sheba Ridge by an ultra-slow divergent boundary trending N80°E±10° marked by diffuse seismicity. The location of the Arabia–India rotation pole is constrained at 14.1°N and 71.2°E by fitting the active part of the Owen fracture zone with a small circle. The finite kinematics of the triple junction is inferred from the present-day kinematics. Since the inception of the accretion 15–18 Ma ago, the Sheba Ridge has probably receded ∼300 km at the expense of the Carlsberg Ridge which propagated northwestward in the gulf of Aden, while an ultra-slow divergent plate boundary developed between the Arabian and Indian plates. The overall geometry of the new triple junction is very similar to that of the Azores triple junction.

Review of the present-day geodynamics of the Pannonian basin: progress and problems

We present a comprehensive review on what we have learned during the last decade and what we need to know in the future about the present-day crustal deformation and geodynamics of the Pannonian basin and its surroundings. The recent tectonic activity of the region is controlled primarily by the counterclockwise rotation of the Adriatic microplate relative to Europe around a pole in the Western Alps. Due to the indentation of this crustal block against the Southern Alpine–Dinaric fold and thrust belt, intense shortening is effecting these orogens as evidenced by the general seismicity pattern and crustal deformation. The present-day kinematics of the Pannonian basin shows that the area is pushed from the south-southwest. As a result, strike-slip to compressive faulting is observed well inside the Pannonian basin and, furthermore, the nearly complete absence of normal faulting in the whole study area suggests that extension in the Pannonian basin has been finished and structural inversion is in progress. Due to an increase of intraplate compressional stress the Pannonian lithosphere exhibits large-scale bending manifested by the Quaternary subsidence and uplift history. The orientation of the modern tectonic stress field in and around the Pannonian basin shows a remarkable radial pattern of maximum horizontal stress around the Adriatic microplate. N–S directed compression observed at its northern tip in the Southern Alps gradually becomes NE–SW oriented along the Dinaric belt. This pattern is further traceable well inside the Pannonian basin, while in the Vrancea zone of the southeastern Carpathians E–W to ESE–WNW directed compression can be determined. Finite element stress modelling suggests that the stress regime in the Pannonian basin is governed by distinct tectonic factors in the overall convergent setting associated with the Africa–Europe collision. The most important stress source appears to be the active push of the Adriatic microplate. Additional boundary conditions, such as the deformation of crustal blocks with different geometry and rigidity at the margin of the Pannonian–Carpathian area and the effect of active compression in the Vrancea zone, significantly influence the stress regime and pattern. Finally, with a brief overview about the principal aims of the Central Europe Regional Geodynamic Project (CERGOP), we argue for the need of further investigations applying the latest techniques of space geodesy (GPS). This international cooperation can provide an excellent opportunity to further develop our understanding of the recent crustal deformation in Central Europe and to refine concepts and models about the tectonic inversion of sedimentary basins with back-arc origin.

Westward propagation of the North Anatolian fault into the northern Aegean: Timing and kinematics

We present new evidence for the propagation processes of the North Anatolian fault. Folding in the Dardanelles Straits region allows us to document the timing of the deformation preceding, and the finite displacement after, the passage of the propagating tip of the fault. The accuracy of the observations is due to interplay between deformation and the sea-level changes in the Mediterranean (the well-known Messinian regression followed by the Pliocene transgression). The long-term kinematics around the Sea of Marmara pull-apart (total displacement of about 85 km over the past 5 m.y.) is similar to the present-day kinematics deduced from space geodesy. At a larger scale, westward propagation of the North Anatolian fault over nearly 2000 km in the past 10 m.y. appears to be associated with strain recovery, suggesting that the continental lithosphere retains long-term elasticity.

Active tectonics in the central Apennines and possible implications for seismic hazard analysis in peninsular Italy

The central Apennines fault system (CAFS) of peninsular Italy, overprints earlier structures of a Neogene fold and thrust belt and includes segments characterized by diffuse seismicity distributed within a NNW-SSE-trending zone, 50–60 km wide. The system has been analysed by means of morphotectonic and structural analysis of exposed active fault segments. The resulting fault structure consists of an interconnecting network of roughly N-S-trending, left-lateral, strike-slip segments and mostly NW-SE-oriented, transtensional to normal faults. Evidence for recent activity of CAFS structures is provided by faulted Middle Pleistocene-Holocene deposits (including 30–40-ka-old pyroclastites and 40-ka-old palustrine sediments), fresh scarps in both bedrock and Late Quaternary continental deposits, and decametric lateral offsets locally affecting the post-Wurmian drainage pattern of the area. The regional stress field responsible for the development and evolution of the CAFS, as inferred from fault slip data, is characterized by a NW-SE compression and by a NE-SW extension. The CAFS pattern and its present-day kinematics have been related to left-lateral strike-slip motion on north-south-trending crustal faults. The existence of deep-seated strike-slip faults in the central Apennines has implications for seismic hazard analysis. Motion along these structures suggests, in fact, that coseismic surface faulting is distributed, and that cumulative displacements include normal, transtensional, and strike-slip components. The seismogenic potential of CAFS structures can therefore be best described by multiple-rupture models and be better analysed in terms of partial contributions of lower-rank features constituting congruent structural associations within the system.

The Somalia plate and the East African Rift System: present-day kinematics

The motion of the Somalia plate relative to the Nubia (Africa), Arabia and Antarctica plates is re-evaluated using a new inversion method based on a Monte Carlo technique and a least absolute value misfit criterion. A subset of the NUVEL 1 data set, with additional data along the Levant Fault and in the Red Sea is used. The results confirm that the motion of Arabia with respect to Africa is significantly different from the motion relative to Somalia. It is further shown that the data along the SW Indian Ridge are compatible with a pole of relative motion between Africa and Somalia located close to the hypothetical diffuse triple junction between the ridge and the East African Rift. The resulting Africa-Somalia motion is then compatible with the geological structures and seismological data along the East African Rift system. Assuming a separate Somalia plate thus solves kinematic and geological problems around the Afar triple junction and along the East African Rift.

Present-day kinematics of the plate boundary zone between Africa and Europe, from the Azores to the Aegean

Anticlockwise rotation of Africa relative to Europe around an Euler pole in the eastern Atlantic causes plate convergence in the central Mediterranean towards ∼ N20°W at rate considered a priori to be ∼ 5–10 mm yr −1. However, previous summaries of the present-day deformation sense in the central Mediterranean are inconsistent with observations in southern Italy. Recent investigations of Italy and adjacent parts of North Africa enable local deformation sense observed to be reconciled with sense predicted from relative plate motions. Suggested angular velocity of the African plate relative to Europe is ∼ 0.07° Myr −1, around a pole near 21°N, 21°W. This predicts ∼ 2.6 mm yr −1 maximum extension rate towards N64°E near the Azores, consistent with the minimum local accretion of new oceanic crust in the past few millions of years, and ∼ 4.3 mm yr −1 plate convergence towards N20°W in the central Mediterranean at 13°E. Further east, the northern margin of the African plate can be regarded as the Gargano seismic zone in the central Adriatic Sea. The northern Adriatic Sea is a microplate rotating anticlockwise relative to Europe at ∼ 0.3° Myr −1 around a pole in northwestern Italy, causing northeastward shortening in Yugoslavia and up to ∼ 4 mm yr −1 extension in central and northern Italy. The African plate is deforming internally in Tunisia and northern Libya, extending obliquely in direction ∼ E10°S at rate up to ∼ 5.5 mm yr −1. The resultant velocity relative to Europe in the Ionian and southern Adriatic Seas, ∼ 5 mm yr −1 towards ∼ N50°E, explains the observed relative velocity across southern Italy. Kinematic consistency requires present-day shortening rate east of Calabria associated with subduction on the Tyrrhenian Sea Benioff zone and Tyrrhenian Sea extension rate to be both zero or equal to within ∼ 1 mm yr −1.