Geology topics

Christian Teyssier

Publications and source records attributed to Christian Teyssier.

8 recordsLinked to original sources

USGS2024

Deep lithospheric controls on surface deformation and seismicity around the East Anatolian Fault Zone and A3 Triple Junction

The East Anatolian Fault Zone (EAFZ) is a plate-bounding strike-slip fault capable of hosting large earthquakes, as demonstrated by the extremely damaging February 2023 M w 7.8 and M w 7.7 mainshocks of the Kahramanmaraş earthquake sequence. Deformation related to this boundary, part of the Anatolia-Arabia-Africa (A 3 ) Triple Junction, is diffuse, as was shown by part of this earthquake sequence occurring on a northern splay of the EAFZ (the Sürgü-Çardak Fault Zone; SCFZ). Controls on surface deformation are commonly linked to stress in the brittle upper crust, but the complex deformation and seismicity patterns in this region may also reflect deeper processes, such as variations in the location and extent of the strong Arabian Plate lithospheric mantle. Seismic tomography indicates that the Arabian Plate underthrusts Anatolia as far north as the SCFZ and extends as far west as the central Adana Basin, coincident with a zone of relatively deep (>30 km) strike-slip seismogenesis that has produced M w >6 earthquakes. By investigating the relationship between deformation since the inception of the EAFZ (ca. 5 Ma), seismic structure, and seismicity, we infer that the SCFZ will become the future SE boundary of the Anatolian Plate as part of the evolving A 3 Triple Junction.

GSA Today↗

USGS2023

Breaking plates: Creation of the East Anatolian fault, the Anatolian plate, and a tectonic escape system

Lateral movement of lithospheric fragments along strike-slip faults in response to collision (escape tectonics) has characterized convergent settings since the onset of plate tectonics and is a mechanism for the formation of new plates. The Anatolian plate was created by the sequential connection of strike-slip faults following ≥10 m.y. of distributed deformation that ultimately localized into plate-bounding faults. Thermochronology data and seismic images of lithosphere structure near the East Anatolian fault zone (EAFZ) provide insights into the development of the new plate and escape system. Low-temperature thermochronology ages of rocks in and near the EAFZ are significantly younger than in other fault zones in the region, e.g., apatite (U-Th)/He: 11–1 Ma versus 27–13 Ma. Young apatite (U-Th)/He ages and thermal history modeling record thermal resetting along the EAFZ over the past ~5 m.y. and are interpreted to indicate thermal activity triggered by strike-slip faulting in the EAFZ as it formed as a through-going, lithosphere-scale structure. The mechanism for EAFZ formation may be discerned from S-wave velocity images from the Continental Dynamics–Central Anatolian Tectonics (CD-CAT) seismic experiment. These images indicate that thin but strong Arabian lithospheric mantle extends ~50–150 km north beneath Anatolian crust and would have been located near the present surficial location of the Bitlis-Zagros suture zone (co-located with the EAFZ in our study area) at ca. 5 Ma. Underthrusting of strong Arabian lithosphere facilitated localization of the EAFZ and thus was a fundamental control on the formation of the Anatolian plate and escape system.

East Anatolian Fault↗

USGS2021

Fast Pliocene integration of the Central Anatolian Plateau drainage: Evidence, processes, and driving forces

Continental sedimentation was widespread across the Central Anatolian Plateau in Miocene–Pliocene time, during the early stages of plateau uplift. Today, however, most sediment produced on the plateau is dispersed by a well-integrated drainage and released into surrounding marine depocenters. Residual long-term (10 6 –10 7 yr) sediment storage on the plateau is now restricted to a few closed catchments. Lacustrine sedimentation was widespread in the Miocene–Pliocene depocenters. Today, it is also restricted to the residual closed catchments. The present-day association of closed catchments, long-term sediment storage, and lacustrine sedimentation suggests that the Miocene–Pliocene sedimentation also occurred in closed catchments. The termination of sedimentation across the plateau would therefore mark the opening of these closed catchments, their integration, and the formation of the present-day drainage. By combining newly dated volcanic markers with previously dated sedimentary sequences, we show that this drainage integration occurred remarkably rapidly, within 1.5 m.y., at the turn of the Pliocene. The evolution of stream incision documented by these markers and newly obtained 10 Be erosion rates allow us to discriminate the respective contributions of three potential processes to drainage integration, namely, the capture of closed catchments by rivers draining the outer slopes of the plateau, the overflow of closed lakes, and the avulsion of closed catchments. Along the southern plateau margin, rivers draining the southern slope of the Central Anatolian Plateau expanded into the plateau interior; however, only a small amount of drainage integration was achieved by this process. Instead, avulsion and/or overflow between closed catchments achieved most of the integration, and these top-down processes left a distinctive sedimentary signal in the form of terminal lacustrine limestone sequences. In the absence of substantial regional climate wetting during the early Pliocene, we propose that two major tectonic events triggered drainage integration, separately or in tandem: the uplift of the Central Anatolian Plateau and the tectonic completion of the Anatolian microplate. Higher surface uplift of the eastern Central Anatolian Plateau relative to the western Central Anatolian Plateau promoted more positive water balances in the eastern catchments, higher water discharge, and larger sediment fluxes. Overflow/avulsion in some of the eastern catchments triggered a chain of avulsions and/or overflows, sparking sweeping integration across the plateau. Around 5 Ma, the inception of the full escape of the Anatolian microplate led to the disruption of the plateau surface by normal and strike-slip faults. Fault scarps partitioned large catchments fed by widely averaged sediment and water influxes into smaller catchments with more contrasted water balances and sediment fluxes. The evolution of the Central Anatolian Plateau shows that top-down processes of integration can outcompete erosion of outer plateau slopes to reintegrate plateau interior drainages, and this is overlooked in current models, in which drainage evolution is dominated by bottom-up integration. Top-down integration has the advantage that it can be driven by more subtle changes in climatic and tectonic boundary conditions than bottom-up integration.

Central Anatolian Plateau↗

USGS2020

Age and mantle sources of Quaternary basalts associated with “leaky” transform faults of the migrating Anatolia-Arabia-Africa triple junction

The Anatolia (Eurasia), Arabia, and Africa tectonic plates intersect in southeast Turkey, near the Gulf of İskenderun, forming a tectonically active and unstable triple junction (the A 3 triple junction). The plate boundaries are marked by broad zones of major, dominantly left-lateral transform faults including the East Anatolian fault zone (the Anatolia-Arabia boundary) and the Dead Sea fault zone (the Arabia-Africa boundary). Quaternary basalts occur locally within these “leaky” transform fault zones (similar to those observed within oceanic transform faults), providing evidence that mantle melting, basalt genesis, and eruption are linked to crustal deformation and faulting that extends into the upper mantle. We investigated samples of alkaline basalt (including basanite) from the Toprakkale and Karasu volcanic fields within a broad zone of transtension associated with these plate-boundary faults near the İskenderun and Amik Basins, respectively. Toprakkale basalts and basanites have 40 Ar/ 39 Ar plateau ages ranging from 810 ± 60 ka to 46 ± 13 ka, and Karasu volcanic field basalts have 40 Ar/ 39 Ar plateau ages ranging from 2.63 ± 0.17 Ma to 52 ± 16 ka. Two basanite samples within the Toprakkale volcanic field have isotopic characteristics of a depleted mantle source, with 87 Sr/ 86 Sr of 0.703070 and 0.703136, 143 Nd/ 144 Nd of 0.512931 and 0.512893, 176 Hf/ 177 Hf of 0.283019 and 0.282995, 206 Pb/ 204 Pb of 19.087 and 19.155, and 208 Pb/ 204 Pb of 38.861 and 38.915. The 176 Hf/ 177 Hf ratios of Toprakkale basalts (0.282966–0.283019) are more radiogenic than Karasu basalts (0.282837–0.282965), with some overlap in 143 Nd/ 144 Nd ratios (0.512781–0.512866 vs. 0.512648–0.512806). Toprakkale 206 Pb/ 204 Pb ratios (19.025 ± 0.001) exhibit less variation than that observed for Karasu basalts (18.800–19.324), and 208 Pb/ 204 Pb values for Toprakkale basalts (38.978– 39.103) are slightly lower than values for Karasu basalts (39.100–39.219). Melting depths estimated for the basalts from both volcanic fields generally cluster between 60 and 70 km, whereas the basanites record melting depths of ~90 km. Depth estimates for the basalts largely correspond to the base of a thin lithosphere (~60 km) observed by seismic imaging. We interpret the combined radiogenic isotope data (Sr, Nd, Hf, Pb) from all alkaline basalts to reflect partial melting at the base of the lithospheric mantle. In contrast, seismic imaging indicates a much thicker (>100 km) lithosphere beneath southern Anatolia, a substantial part of which is likely subducted African lithosphere. This thicker lithosphere is adjacent to the surface locations of the basanites. Thus, the greater melting depths inferred for the basanites may include partial melt contributions either from the lithospheric mantle of the attached and subducting African (Cyprean) slab, or from partial melting of detached blocks that foundered due to convective removal of the Anatolian lithosphere and that subsequently melted at ~90 km depth within the asthenosphere. The Quaternary basalts studied here are restricted to a broad zone of transtension formed in response to the development of the A 3 triple junction, with an earliest erupted age of 2.63 Ma. This indicates that the triple junction was well established by this time. While the current position of the A 3 triple junction is near the Amik Basin, faults and topographic expressions indicate that inception of the triple junction began as early as 5 Ma in a position farther to the northeast of the erupted basalts. Therefore, the position of the A 3 triple junction appears to have migrated to the southwest since the beginning of the Pliocene as the Anatolia-Africa plate boundary has adjusted to extrusion (tectonic escape) of the Anatolia plate. Establishment of the triple junction over the past 5 m.y. was synchronous with rollback of the African slab beneath Anatolia and associated trench retreat, consistent with Pliocene uplift in Cyprus and with the current positions of plate boundaries. The A 3 triple junction is considered to be unstable and likely to continue migrating to the southwest for the foreseeable geologic future.

Geosphere↗

USGS2020

Cenozoic tectonic evolution of the Ecemiş fault zone and adjacent basins, central Anatolia, Turkey during the transition from Arabia - Eurasia collision to escape tectonics

The effects of Arabia-Eurasia collision are recorded in faults, basins, and exhumed metamorphic massifs across eastern and central Anatolia. These faults and basins also preserve evidence of major changes in deformation and associated sedimentary processes along major suture zones including the Inner Tauride suture where it lies along the southern (Ecemiş) segment of the Central Anatolian fault zone. Stratigraphic and structural data from the Ecemiş fault zone, adjacent NE Ulukışla basin, and metamorphic dome (Niğde Massif) record two fundamentally different stages in the Cenozoic tectonic evolution of this part of central Anatolia. The Paleogene sedimentary and volcanic strata of the NE Ulukışla basin (Ecemiş corridor) were deposited in marginal marine to marine environments on the exhuming Niğde Massif and east of it. A late Eocene–Oligocene transpressional stage of deformation involved oblique northward thrusting of older Paleogene strata onto the eastern Niğde Massif and of the eastern massif onto the rest of the massif, reburying the entire massif to >10 km depth and accompanied by left-lateral motion on the Ecemiş fault zone. A profound change in the tectonic setting at the end of the Oligocene produced widespread transtensional deformation across the area west of the Ecemiş fault zone in the Miocene. In this stage, the Ecemiş fault zone had at least 25 km of left-lateral offset. Before and during this faulting episode, the central Tauride Mountains to the east became a source of sediments that were deposited in small Miocene transtensional basins formed on the Eocene–Oligocene thrust belt between the Ecemiş fault zone and the Niğde Massif. Normal faults compatible with SW-directed extension cut across the Niğde Massif and are associated with a second (Miocene) re-exhumation of the Massif. Geochronology and thermochronology indicate that the transtensional stage started at ca. 23–22 Ma, coeval with large and diverse geological and tectonic changes across Anatolia.

Geosphere↗

USGS2018

Rapid late Miocene surface uplift of the Central Anatolian Plateau margin

The Central Anatolian Plateau (CAP), Turkey, is bordered to its south by a steep mountain belt that emerged ∼8–7 Ma ago from the Mediterranean Sea. Knowledge of the onset, duration and rate of surface uplift and orographic barrier formation along the plateau margin is crucial for understanding the geodynamic drivers of plateau uplift. We present a new comprehensive data set that includes 12 40 Ar/ 39 Ar ages and lacustrine carbonate δ 18 "> δ18 O data ( n = 637 "> n=637 ) from 13 sections in upper Oligocene to Pliocene continental basins of the CAP interior. We aim at documenting the development of a rain shadow and therefore the surface uplift history of the CAP and its southern margin (Tauride Mts.). In the rain shadow of the Tauride Mts. we observe a gradual 3.9‰ decrease of δ 18 "> δ18 O values of lacustrine carbonate between ∼11 and 5 Ma that we interpret to originate from a similar change in δ 18 "> δ18 O values of precipitation owing to the late Miocene development of an orographic barrier. Our stable isotope paleoaltimetry data show that by 5 Ma the southern CAP margin had reached similar-to-present elevations of ∼2 km. Surface uplift was coeval with ignimbritic magmatism, forearc shortening and distributed compression. We suggest that the removal of lithospheric mantle below Anatolia led to surface uplift of the CAP interior, which was followed by surface uplift of the southern CAP margin due to crustal thickening as a result of northward subduction of the African plate below central Anatolia.

Earth and Planetary Science Letters↗

USGS2015

Eocene and Miocene extension, meteoric fluid infiltration, and core complex formation in the Great Basin (Raft River Mountains, Utah)

Metamorphic core complexes (MCCs) in the North American Cordillera reflect the effects of lithospheric extension and contribute to crustal adjustments both during and after a protracted subduction history along the Pacific plate margin. While the Miocene-to-recent history of most MCCs in the Great Basin, including the Raft River-Albion-Grouse Creek MCC, is well documented, early Cenozoic tectonic fabrics are commonly severely overprinted. We present stable isotope, geochronological ( 40 Ar/ 39 Ar), and microstructural data from the Raft River detachment shear zone. Hydrogen isotope ratios of syntectonic white mica ( δ 2 H ms ) from mylonitic quartzite within the shear zone are very low (−90‰ to −154‰, Vienna SMOW) and result from multiphase synkinematic interaction with surface-derived fluids. 40 Ar/ 39 Ar geochronology reveals Eocene (re)crystallization of white mica with δ 2 H ms ≥ −154‰ in quartzite mylonite of the western segment of the detachment system. These δ 2 H ms values are distinctively lower than in localities farther east ( δ 2 H ms ≥ −125‰), where 40 Ar/ 39 Ar geochronological data indicate Miocene (18–15 Ma) extensional shearing and mylonitic fabric formation. These data indicate that very low δ 2 H surface-derived fluids penetrated the brittle-ductile transition as early as the mid-Eocene during a first phase of exhumation along a detachment rooted to the east. In the eastern part of the core complex, prominent top-to-the-east ductile shearing, mid-Miocene 40 Ar/ 39 Ar ages, and higher δ 2 H values of recrystallized white mica, indicate Miocene structural and isotopic overprinting of Eocene fabrics.

Utah↗

USGS2015

Mid-Cretaceous oblique rifting of West Antarctica: Emplacement and rapid cooling of the Fosdick Mountains migmatite-cored gneiss dome

In Marie Byrd Land, West Antarctica, the Fosdick Mountains migmatite-cored gneiss dome was exhumed from mid- to lower middle crustal depths during the incipient stage of the West Antarctic Rift system in the mid-Cretaceous. Prior to and during exhumation, major crustal melting and deformation included transfer and emplacement of voluminous granitic material and numerous intrusions of mantle-derived diorite in dikes. A succession of melt- and magma-related structures formed at temperatures in excess of 665 ± 50 °C based on Ti-in-zircon thermometry. These record a transition from wrench to oblique extensional deformation that culminated in the development of the oblique South Fosdick Detachment zone. Solid-state fabrics within the detachment zone and overprinting brittle structures record translation of the detachment zone and dome to shallow levels. To determine the duration of exhumation and cooling, we sampled granite and gneisses at high spatial resolution for U–Pb zircon geochronology and 40 Ar/ 39 Ar hornblende and biotite thermochronology. U–Pb zircon crystallization ages for the youngest granites are 102 Ma. Three hornblende ages are 103 to 100 Ma and 12 biotite ages are 101 to 99 Ma. All overlap within uncertainty. The coincidence of zircon crystallization ages with 40 Ar/ 39 Ar cooling ages indicates cooling rates > 100 °C/m.y. that, when considered together with overprinting structures, indicates rapid exhumation of granite and migmatite from deep to shallow crustal levels within a transcurrent setting. Orientations of structures and age-constrained crosscutting relationships indicate counterclockwise rotation of stretching axes from oblique extension into nearly orthogonal extension with respect to the Marie Byrd Land margin. The rotation may be a result of localized extension arising from unroofing and arching of the Fosdick dome, extensional opening within a pull-apart zone, or changes in plate boundary configuration. The rapid tectonic and temperature evolution of the Fosdick Mountains dome lends support to recently developed numerical models of crustal flow and cooling in orogenic crust undergoing extension/transtension, and accords with numerous studies of migmatite-cored gneiss domes in transcurrent settings.

LITHOS↗