Videos by Irina M. Artemieva
The European Geosciences Union (EGU) Augustus Love Medal lecture of 2021 presented by the awardee... more The European Geosciences Union (EGU) Augustus Love Medal lecture of 2021 presented by the awardee Prof. Dr. Irina M. Artemieva. Title of the Medal Lecture: "Heterogeneous lithosphere mantle".
Recorded by EGU, April 29, 2021.
Duration: lecture ca. 35 min with foreword and medal citation by EGU-GD president Prof. Jeroen van Hunen.
Level: from MS students to professional. 13 views
The video is an invited 45 min lecture by Professor Irina M. Artemieva at the on-line conference ... more The video is an invited 45 min lecture by Professor Irina M. Artemieva at the on-line conference organized by the Geological Society of South Africa on Geoheritage (September 2020).
The lecture focuses on the lithosphere structure of the cratons worldwide with special focus on the cratons of southern Africa. Geophysical models on mantle temperatures and densities are presented in comparison with geochemical data.
Level: from MS students to professional.
Duration: 45 min + 10 min discussion
https://www.youtube.com/watch?v=O9kUEVnh7bw 124 views
This invited 35 min long lecture (at MS level in natural sciences) provides an overview of academ... more This invited 35 min long lecture (at MS level in natural sciences) provides an overview of academic Solid Earth Geophysics with applications to climate changes and mineral exploration.
Presented at the first international online conference "WOW Physics! (Women Of the World in Physics!)", Nov 9 to 11, 2022, hosted by Goethe University Frankfurt, Germany. https://indico.cern.ch/event/1108414/ 10 views
All papers by Irina M. Artemieva
Nature Communications, 2025
Plate tectonics predicts that mountain ranges form by tectono-magmatic processes at plate boundar... more Plate tectonics predicts that mountain ranges form by tectono-magmatic processes at plate boundaries, but high topography is often observed along passive margins far from any plate boundary. The high topography of the Scandes range at the Atlantic coast of Fennoscandia is traditionally assumed isostatically supported by variation in crustal density and thickness. Here we demonstrate, by our Silverroad seismic profile, that the constantly ~44 km
thick crust instead is homogenous above the Moho, and Pn-velocity abruptly change from 7.6 kms−1 below the Scandes to >8.2 kms−1 below the Proterozoic shield. By modelling gravity anomalies and topography, based on the seismic model, we demonstrate that this change corresponds to an increase in metamorphic eclogitic grade from 35% below the high-topography Scandes to 70% below the low-topography shield. The sharp contrast between the low-grade,
reduced-density and the high-grade, high-density eclogitic bodies below the uniform seismological Moho explains the enigmatic topography of the mountain range without a crustal root.
Earth and Planetary Science Letters, 2024
Ocean age-dependent cooling subsidence with seafloor deepening is traditionally described by mode... more Ocean age-dependent cooling subsidence with seafloor deepening is traditionally described by models of thermochemical buoyancy of oceanic plates with globally constant parameters, that specify a linear correlation between square-root of seafloor age, sqrt(age), and bathymetry. Here I present a worldwide analysis of the ocean floor split into 94 segments, delineated by wide-offset transform faults and mid-ocean ridges, to demonstrate a strong heterogeneity of sediment-corrected isostatic cooling subsidence both between and within normal oceans. Anomalous oceans are identified from bathymetry deviation from age-dependent predictions during data processing. Subsidence parameters for individual ocean segments significantly deviate from global constants in conventional models and show a large variability of subsidence rate (270-535 m/Ma 1/2) and zero-age depth (− 1.30 to − 3.03 km) with plate thickness estimated between 50 and 160 km for cooling models with constant mantle properties. Statistically strong correlations (R 2 =0.80-0.94) between major characteristics of cooling subsidence and spreading rate indicate that ocean evolution is essentially controlled by spreading rate, despite this factor is not included in conventional models of ocean subsidence. Normal oceans with slower spreading rate have, statistically, higher subsidence rate which implies faster gravitational collapse caused by faster plate cooling with moderate-to-low mantle temperatures at mid-ocean ridges. Fast-spreading oceans have the opposite characteristics. The ultraslow SW Indian and the fast-spreading Central Pacific Oceans are the end-members in ocean cooling subsidence trends, with the Atlantic/NW Indian Oceans tending towards the ultraslow end, and the Pacific/SE Indian Oceans being closer to the fast-spreading end. The Arctic Ocean and the Atlantics north of the Charlie-Gibbs Fracture Zone with an atypical subsidence behavior often deviate from the global trends. Strong correlation between spreading rate, ocean half-width and the type of ocean margins implies that ridge-push dominates tectonic forces in slower-spreading, narrower oceans with passive margins, while slab-pull at active margins is a dominant tectonic force in faster-spreading oceans with half-width exceeding 4250 km. The age of bathymetry departure from cooling subsidence, controlled by distribution of hotspots on ocean floor, correlates (R 2 =0.76) with spreading rate, and thus is not fully random. Slower-spreading oceans follow normal cooling subsidence to older ages (7.5-9.5 Ma 1/2) than faster-spreading oceans (5-7 Ma 1/2). Recognition that spreading rate controls ocean evolution with formation of active or passive ocean margins dominated by slab-pull or ridge-push contributes to advances in understanding driving forces in geodynamics.
Nature Communications, 2024
The thick crust of the southern Tibetan and central Andean plateaus includes high-conductivity, l... more The thick crust of the southern Tibetan and central Andean plateaus includes high-conductivity, low-velocity zones ascribed to partial melt. The melt origin and effect on plateau uplift remain speculative, in particular if plateau uplift happens before continental collision. The East Anatolian Plateau (EAP) has experienced similar, more recent uplift but its structure is largely unknown. Here we present an 80 km deep geophysical model across EAP, constrained by seismic receiver functions integrated with interpretation of gravity data and seismic tomographic, magnetotelluric, geothermal, and geochemical models. The results indicate a 20 km thick lower crustal layer and a 10 km thick midcrustal layer, which both contain pockets of partial melt. We explain plateau uplift by isostatic equilibration following magmatism associated with roll-back and break-off of the Neo-Tethys slab. Our results suggest that crustal thickening by felsic melt and mafic underplate are important for plateau uplift in the EAP, Andes and Tibet.
Geology, 2025
Post-Archean secular changes in continental crust composition, which provide key evidence for the... more Post-Archean secular changes in continental crust composition, which provide key evidence for the evolution of plate tectonics, remain uncertain, particularly regarding the lower crust. Here, by digitizing 18,000 km of seismic profiles, we demonstrate a change in bulk crustal composition at the Proterozoic-Phanerozoic transition. We document that a mafic crustal layer is preserved in Proterozoic orogens but generally absent in Phanerozoic orogens. We explain this fundamental shift by a change in the global subduction style, where continental collision became important in the Phanerozoic. Densification of the lower crust by widespread eclogitization, triggered by continental collision and subduction, led to massive recycling of mafic lower crust into the mantle, leaving behind buoyant felsic crust and promoting the rise of continents, which led to the emergence of large continental areas above sea level and the related Neoproterozoic oxidation event, followed by the explosion of life in the Phanerozoic.
Earth and Planetary Science Letters, 2024
Subduction processes usually involve extensive seismicity and create voluminous magmatic arcs by ... more Subduction processes usually involve extensive seismicity and create voluminous magmatic arcs by mantle
wedge melting caused by dehydration of the subducting slab, but the Makran subduction zone has anomalously
low seismicity and magmatism. Here we explain these anomalous features by 60–65% serpentinization in the
peridotitic shallow mantle wedge based on our new integrated seismic, magnetic, gravity and isostatic model
across the Makran subduction zone. The low-angle, slow Makran subduction provides ample time for the slab to
release sufficient amounts of fluids for creating a large volume of rheologically weak serpentinite. This reduces
seismicity by lowering the friction between the slab and surrounding rocks. Further, very little fluid is left in the
slab when it reaches the melting depth, which explains the limited arc magmatism. Around 100 km depth, the
subduction switches from low-angle to almost vertical. Our model demonstrates the combined effects of subduction
rate and dip on mantle serpentinization with implication for assessment of seismic and volcanic hazards
in subduction systems.
Earth-Science Reviews, 2023
This global study of 31 off-shore back-arc basins and subbasins (BABs) identifies their principal... more This global study of 31 off-shore back-arc basins and subbasins (BABs) identifies their principal characteristics
based on a broad spectrum of geophysical and subduction-related parameters. My synthesis is used to identify
trends in the evolution of back-arc basins for improving our understanding of subduction systems in general. The
analysis, based on the present plate configuration, demonstrates that geophysical characteristics and fate of the
back-arc basins are essentially controlled by the tectonic type of the overriding plate, which controls the lithosphere
thermo-compositional structure and rheology. The type of the plate governs the length of the extensional
zone in back-arc settings along the trench, the efficiency of lithosphere stretching, and the crustal structure,
buoyancy and bathymetry of the BABs. Subduction dip angle apparently controls the location of the slab melting
zone and the efficiency of slab roll-back with feedback links to other parameters. By the tectonic nature of the
overriding plate (the downgoing plate is always oceanic) the back-arc basins are split into active BABs formed by
ocean-ocean, arc-ocean, and continent-ocean convergence, and extinct back-arc basins. By geophysical characteristics,
BABs formed on continental plates are subdivided into active BABs with and without seafloor spreading,
and extinct BABs are subdivided into the Pacific BABs, possibly formed on oceanic plates, and the non-Pacific
BABs with reworked continental or arc fragments.
Six types of BABs are distinctly different. Extension of the overriding oceanic plate above a steeply dipping old
oceanic plate, preferentially subducting nearly westwards, forms large deep back-arc basins with a thin oceanictype
crust. In contrast, BABs on the overriding continental or arc plates form at small opening rates and often by
shallow subduction of younger oceanic plates with a random subduction orientation; these BABs have small sizes,
shallow bathymetry, and hyperextended or transitional ~20 km thick arc- or continental-type crust typical of
passive margins. The presence of a 2–5 km thick high-Vp lowermost crustal layer, characteristic of BABs in all
settings, indicates the importance of magmatic underplating in the crustal growth.
Conditions required for the initiation of a back-arc basin and transition from stretching to seafloor opening
depend on the nature of the overriding plate. BABs formed on oceanic plates always evolve to seafloor spreading.
BABs formed on continental or arc plates require long spreading duration with large (>8 cm/y) opening rates and
a large crustal thinning factor of 2.8–5.0 to progress from crustal extension to seafloor spreading. On the present
Earth such transition does not happen in the back-arc basins formed behind a shallow subduction (<45o) of a
young (<40 My) oceanic plate.
The nature of the overriding plate also determines the fate of back-arc basins after termination of lithosphere
extension: the extinct Pacific back-arc basins with oceanic-type crust evolve towards deep old “normal” oceans,
while the shallow non-Pacific BABs with low heat flow and thick crust are likely to preserve their continental or
arc affinity. BABs do not follow the oceanic cooling plate model predictions. Distinctly different geophysical
signatures for mid-ocean ridge spreading and for back-arc seafloor spreading are caused by principally different
dynamics.
Tectonics, 2023
We calculate the depth to magnetic basement and the average crustal magnetic susceptibility,
whic... more We calculate the depth to magnetic basement and the average crustal magnetic susceptibility,
which is sensitive to the presence of iron-rich minerals, to interpret the present structure and the tecto-magmatic
evolution in the Central Tethyan belt. Our results demonstrate exceptional variability of crustal magnetization
with smooth, small-amplitude anomalies in the Gondwana realm and short-wavelength high-amplitude
variations in the Laurentia realm. Poor correlation between known ophiolites and magnetization anomalies
indicates that Tethyan ophiolites are relatively poorly magnetized, which we explain by demagnetization during
recent magmatism. We analyze regional magnetic characteristics for mapping previously unknown oceanic
fragments and mafic intrusions, hidden beneath sedimentary sequences or overprinted by tectono-magmatic
events. By the style of crustal magnetization, we distinguish three types of basins and demonstrate that many
small-size basins host large volumes of magmatic rocks within or below the sedimentary cover. We map the
width of magmatic arcs to estimate paleo-subduction dip angle and find no systematic variation between the
Neo-Tethys and Paleo-Tethys subduction systems, while the Pontides magmatic arc has shallow (∼15°) dip
in the east and steep (∼50°–55°) dip in the west. We recognize an unknown, buried 450 km-long magmatic
arc along the western margin of the Kırşehir massif formed above steep (55°) subduction. We propose that
lithosphere fragmentation associated with Neo-Tethys subduction systems may explain high-amplitude,
high-gradient crustal magnetization in the Caucasus Large Igneous Province. Our results challenge conventional
regional geological models, such as Neo-Tethyan subduction below the Greater Caucasus, and call for
reevaluation of the regional paleotectonics.
Geophysical Journal International, 2023
(by Zhou Z., Thybo H., Tang C-C., Artemieva I.M., et al.)
The seismic receiver function (RF) tec... more (by Zhou Z., Thybo H., Tang C-C., Artemieva I.M., et al.)
The seismic receiver function (RF) technique is widely used as an economic method to image earth’s deep interior in a large number of seismic experiments. P-wave receiver functions (RFs) constrain crustal thickness and average Vp/Vs in the crust by analysis of the Ps phase and multiples (reflected/converted waves) from the Moho. Regional studies often show significant differences between the Moho depth constrained by RF and by reflection/refraction methods.
We compare the results from RF and controlled source seismology for the Baikal Rift Zone by calculating 1480 synthetic RFs for a seismic refraction/reflection velocity model and processing them with two common RF techniques [H–κ and Common Conversion Point (CCP) stacking]. We compare the resulting synthetic RF structure with the velocity model, a density model (derived from gravity and the velocity model), and with observed RFs.
Our results demonstrate that the use of different frequency filters, the presence of complex phases from sediments and gradual changes in the properties of crustal layers can lead to erroneous interpretation of RFs and incorrect geological interpretations. We suggest that the interpretation of RFs should be combined with other geophysical methods, in particular in complex tectonic regions and that the long-wavelength Bouguer gravity anomaly signal may provide effective calibration for the determination of the correct Moho depth from RF results. We propose and validate a new automated, efficient method for this calibration.
Journal of Geodynamics, 2022
(by Huang S.H., Thybo H., Dong S.W., Artemieva I.M., et al.)
The Ordos Block in the western part... more (by Huang S.H., Thybo H., Dong S.W., Artemieva I.M., et al.)
The Ordos Block in the western part of the North China Craton is enigmatic in having contrasting topographic structure in the northern and southern parts, while previous geophysical studies show little difference in crustal and upper mantle structure across the region. Here we present a new model of upper mantle structure in the Ordos Block region in order to test the importance of mantle heterogeneity for topographic differences. Our model is based on P-and S-wave seismic receiver functions calculated for data from 171 stations. It documents the presence of an uppermost mantle low-velocity zone between the Mid Lithospheric Discontinuity (MLD) and the Lehmann discontinuity. Clear converters at the 410 and 660 km discontinuities show constant Mantle Transition Zone (MTZ) thickness within the Ordos Block region, which indicates that no deep mantle thermal anomaly affects its present dynamics. However, the amplitude of the MTZ-converters is higher in the southern than the northern Ordos Block. In contrast, the conversions from MLD and the Lehmann discontinuity are strongest in Northern Ordos, which we interpret as a block with essentially preserved cratonic lithospheric mantle. We speculate that smaller amplitudes of the MLD and Lehmann converters in Southern than Northern Ordos may be related to either rheological weakening of cratonic lithosphere during the Mesozoic convergence between the North and South (Yangtze) China Cratons, or northeast extrusion of Tibetan lower crust and upper mantle in the Cenozoic caused by the India-Asia collision.
Encyclopedia of Solid Earth Geophysics (Gupta H., ed.) Springer, 2020
The Trans-European Suture Zone (TESZ) is the transition zone from the Precambrian East European C... more The Trans-European Suture Zone (TESZ) is the transition zone from the Precambrian East European Craton in the north and east to the younger Phanerozoic mobile belts to the south and west. It is the most prominent lithospheric tectonic feature of Europe. The term Trans-European Suture Zone was only adapted around year 2000 during the Pan-European EUROPROBE program of the European Science Foundation. Until then, parts of the zone were termed Teisseyre-Tornquist Zone, Sorgenfrei-Tornquist Zone, Trans-European Fault, and Tornquist Fan.
Seismological Research Letters, 2021
The ScanArray international collaborative program acquired broadband seismological data at 192 lo... more The ScanArray international collaborative program acquired broadband seismological data at 192 locations in the Baltic Shield during the period between 2012 and 2017. The main objective of the program is to provide seismological constraints on the structure of the lithospheric crust and mantle as well as the sublithospheric upper mantle. The new information will be applied to studies of how the lithospheric and deep structure affect observed fast topographic change and geological-tectonic evolution of the region. The program also provides new information on local seismicity, focal mechanisms, and seismic noise. The recordings are generally of very high quality and are used for analysis by various seismological methods, including Pand S-wave receiver functions for the crust and upper mantle, surface wave and ambient noise inversion for seismic velocity, body-wave Pand S-wave tomography for upper mantle velocity structure using ray and finite frequency methods, and shear-wave splitting measurements for obtaining bulk anisotropy of the upper and lowermost mantle. Here, we provide a short overview of the data acquisition and initial analysis of the new data, together with an example of integrated seismological results obtained by the project group along a representative ∼ 1800 km long profile across most of the tectonic provinces in the Baltic Shield between Denmark and the North Cape. The first models support a subdivision of the Paleoproterozoic Svecofennian province into three domains, where the highest topography of the Scandes mountain range in Norway along the Atlantic Coast has developed solely in the southern and northern domains, whereas the topography is more subdued in the central domain.
Earth-Science Reviews, 2022
Formation of new oceans by continental break-up is understood as a continuous evolution from rift... more Formation of new oceans by continental break-up is understood as a continuous evolution from rifting to ocean spreading. The Red Sea is one of few locations on Earth where a new plate boundary presently forms. Its evolution provides key information on how the plate tectonics operates and how the plate boundaries form and evolve in time. While the new plate boundary has already been formed in the southern Red Sea where ocean spreading is active, the north-central segment still experiences continental rifting. The region also has west-east asymmetry: in the north-central Red Sea the rift-related magmatism is not located beneath the rift axis, as conventional models predict, but instead is offset by ca 300 km into Arabia.
We propose a new geodynamic model which explains the enigmatic asymmetry of the Red Sea region and is fully consistent with various types of geological and geophysical observations. We demonstrate that the north-central rift is a transient feature that will not develop into coincident ocean spreading. Instead, the new plate boundary forms across Arabia. Our numerical experiments, supported by geological, seismic and gravity observations, predict that in 1-5 Myr the north-central extensional axis will jump ~300 km eastward into Arabia. The Ad Damm strike-slip fault, normal to the central Red Sea rift axis, will evolve into a transform fault between the ongoing ocean spreading in the southern Red Sea and the future spreading in north-central Arabia.
We demonstrate that crustal-scale weakness zones control lithosphere extension and lead to long-distance jumps of extensional axes in continental lithosphere not affected by hotspots. Therefore, our model also provides theoretical basis for understanding dynamics and mechanisms of the transition from rifting to continental break-up at passive continental margins not affected by hotspots.
Earth-Science Reviews, 2022
Antarctica is losing ice mass by basal melting associated with processes in deep Earth and reflec... more Antarctica is losing ice mass by basal melting associated with processes in deep Earth and reflected in geothermal heat flux. The latter is poorly known and existing models based on disputed assumptions are controversial. Here I present a new geophysical model for lithospheric thickness and mantle heat flux for the entire Antarctica and demonstrate that significant parts of the East Antarctica craton have lost the cratonic lithosphere signature and the entire West Antarctica has a highly extended lithosphere, consistent with its origin as a system of back-arc basins. I conclude that the rate of Antarctica ice basal melting is significantly underestimated: (i) the area with high heat flux is double in size and (ii) the amplitude of the high heat flux anomalies is 20-30% higher than in previous results. Extremely high heat flux (>100 mW/m2) in almost all of West Antarctica, continuing to the South Pole region, and beneath the Lake Vostok region in East Antarctica requires a thin (<70 km) lithosphere and shallow mantle melting, caused by recent geodynamic activity. This high heat flux may promote sliding lubrication and result in dramatic reduction of ice mass, such as in Heinrich events. The results form basis for reevaluation of the Antarctica ice-sheet dynamics models with consequences for global environmental changes.
Nature Communications , 2021
(Authors: Buntin S., Artemieva I.M., Malehmir A., Thybo H., et al.)
The nature of the lower cr... more (Authors: Buntin S., Artemieva I.M., Malehmir A., Thybo H., et al.)
The nature of the lower crust and the crust-mantle transition is fundamental to Earth sciences. Transformation of lower crustal rocks into eclogite facies is usually expected to result in lower crustal delamination. Here we provide compelling evidence for long-lasting presence of lower crustal eclogite below the seismic Moho. Our new wide-angle seismic data from the Paleoproterozoic Fennoscandian Shield identify a 6-8 km thick body with extremely high velocity (Vp~8.5-8.6 km/s) and high density (>3.4 g/cm 3) immediately beneath equally thinned high-velocity (Vp~7.3-7.4 km/s) lowermost crust, which extends over >350 km distance. We relate this observed structure to partial (50-70%) transformation of part of the mafic lowermost crustal layer into eclogite facies during Paleoproterozoic orogeny without later delamination. Our findings challenge conventional models for the role of lower crustal eclogitization and delamination in lithosphere evolution and for the long-term stability of cratonic crust.
Nature Communications, 2021
(by Wang G., Thybo H., Artemieva I.M.) All models of the magmatic and plate tectonic processes th... more (by Wang G., Thybo H., Artemieva I.M.) All models of the magmatic and plate tectonic processes that create continental crust predict the presence of a mafic lower crust. Earlier proposed crustal doubling in Tibet and the Himalayas by underthrusting of the Indian plate requires the presence of a mafic layer with high seismic P-wave velocity (V p > 7.0 km/s) above the Moho. Our new seismic data demonstrates that some of the thickest crust on Earth in the middle Lhasa Terrane has exceptionally low velocity (V p < 6.7 km/s) throughout the whole 80 km thick crust. Observed deep crustal earthquakes throughout the crustal column and thick lithosphere from seismic tomography imply low temperature crust. Therefore, the whole crust must consist of felsic rocks as any mafic layer would have high velocity unless the temperature of the crust were high. Our results form basis for alternative models for the formation of extremely thick juvenile crust with predominantly felsic composition in continental collision zones.
Earth-Science Reviews, 2020
(by I.M.Artemieva and H.Thybo)
Antarctica has traditionally been considered continental insi... more (by I.M.Artemieva and H.Thybo)
Antarctica has traditionally been considered continental inside the coastline of ice and bedrock since Press and Dewart (1959). Sixty years later, we reconsider the conventional extent of this sixth continent. Geochemical observations show that subduction was active along the whole western coast of West Antarctica until the mid-Cretaceous after which it gradually ceased towards the tip of the Antarctic Peninsula. We propose that the entire West Antarctica formed as a back-arc basin system flanked by a volcanic arc, similar to e.g. the Japan Sea, instead of a continental rift system as conventionally interpreted. Globally, the fundamental difference between oceanic and continental lithosphere is reflected in hypsometry, largely controlled by lithosphere buoyancy. The equivalent hypsometry in West Antarctica (−580 ± 335 m on average, extending down to −1.6 km) is much deeper than in any continent, but corresponds to back-arc basins and oceans proper. This first order observation questions the conventional interpretation of West Antarctica as continental, since even continental shelves do not extend deeper than −200 m in equivalent hypsometry.
We present a suite of geophysical observations that supports our geodynamic interpretation: a linear belt of seismicity sub-parallel to the volcanic arc along the Pacific margin of West Antarctica; a pattern of free air gravity anomalies typical of subduction systems; and extremely thin crystalline crust typical of back-arc basins. We calculate residual mantle gravity anomalies and demonstrate that they require the presence of (1) a thick sedimentary sequence of up to ca. 50% of the total crustal thickness or (2) extremely low density mantle below the deep basins of West Antarctica and, possibly, the Wilkes Basin in East Antarctica. Case (2) requires the presence of anomalously hot mantle below the entire West Antarctica with a size much larger than around continental rifts. We propose, by analogy with back-arc basins in the Western Pacific, the existence of rotated back-arc basins caused by differential slab roll-back during subduction of the Phoenix plate under the West Antarctica margin. Our finding reduces the continental lithosphere in Antarctica to 2/3 of its traditional area. It has significant implications for global models of lithosphere-mantle dynamics and models of the ice sheet evolution.
Journal of Geophysical Research: Solid Earth, 2020
(by B. Xia, H. Thybo, I.M. Artemieva) We constrain the lithospheric mantle density of the North C... more (by B. Xia, H. Thybo, I.M. Artemieva) We constrain the lithospheric mantle density of the North China Craton (NCC) at both in situ and standard temperature-pressure (STP) conditions from gravity data. The lithosphere-asthenosphere boundary (LAB) depth is constrained by our new thermal model, which is based on a new regional heat flow data set and a recent regional crustal model NCcrust. The new thermal model shows that the thermal lithosphere thickness is <120 km in most of the NCC, except for the northern and southern parts with the maximum depth of 170 km. The gravity calculations reveal a highly heterogeneous density structure of the lithospheric mantle with in situ and STP values of 3.22-3.29 and 3.32-3.40 g/cm 3 , respectively. Thick and reduced-density cratonic-type lithosphere is preserved mostly in the southern NCC. Most of the Eastern Block has a thin (90-140 km) and high-density lithospheric mantle. Most of the Western Block has a high-density lithospheric mantle and a thin (80-110 km) lithosphere typical of Phanerozoic regions, which suggests that the Archean lithosphere is no longer present there. We conclude that in almost the entire NCC the lithosphere has lost its cratonic characteristics by geodynamic processes that include, but are not limited to, the Paleozoic closure of the Paleo-Asian Ocean in the north, the Mesozoic Yangtze Craton flat subduction in the south, the Mesozoic Pacific subduction in the east, the Cenozoic remote response to the Indian-Eurasian collision in the west, and the Cenozoic extensional tectonics (possibly associated with the slab roll-back) in the center.
Tectonophysics, 2020
(by V. Teknik, H. Thybo, I.M. Artemieva, A. Ghods)
The Iranian plateau is one of the most com... more (by V. Teknik, H. Thybo, I.M. Artemieva, A. Ghods)
The Iranian plateau is one of the most complex geodynamic settings within the Alpine-Himalayan belt. The Paleo-Tethys and Neo-Tethys ocean subduction is responsible for the formation of several magmatic arcs and sedimentary basins within the plateau. These zones mostly are separated by thrust faults related to paleo-suture zones, which are highlighted by ophiolites. Sediment cover and overprint of a different magmatic phase from late Triassic to the Quaternary impede identification of some magmatic arcs and ophiolite belts. We track the known magmatic arcs, such as the Urmia-Dokhtar Magmatic Arc (UDMA), and unknown, sediment covered magmatic arcs by aeromagnetic data. We present a new map of average susceptibility calculated by the radially averaged power spectrum method. High average susceptibility values indicate the presence of a number of lineaments that correlate with known occurrences of Magmatic-Ophiolite Arcs (MOA), and low average susceptibility coincides with known sedimentary basins like Zagros, Makran, Kopeh-Dagh, and Tabas. In analogy to Zagros, low average susceptibility values indicate sedimentary basins to the south of the Darouneh fault and in the northern part of the Lut, Tabas and Yazd blocks. We interpret the Tabas basin as a pull-apart or back-arc basin. We identify hitherto unknown parallel MOAs in eastern Iran and the SE part of UDMA which both indicate steeply dipping (> 60°dip) paleo-subduction zones. In contrast, we interpret shallow subduction (< 20°dip) of Neo-Tethys in the NW part of UDMA as well as in the Sabzevar-Kavir MOA.
![Research paper thumbnail of Isopycnicity of cratonic mantle restricted to kimberlite provinces [by Artemieva I.M., Thybo H., Cherepanova Y.]](https://attachments.academia-assets.com/58217855/thumbnails/1.jpg)
Earth and Planeary Science Letters, 2019
[By Artemieva I.M., Thybo H., Cherepanova Y.]
The isopycnicity hypothesis states that the lith... more [By Artemieva I.M., Thybo H., Cherepanova Y.]
The isopycnicity hypothesis states that the lithospheric mantle of ancient platforms has a unique composition such that high density due to low lithosphere temperature is nearly compensated by low-density composition of old cratonic mantle. This hypothesis is supported by petrological studies of mantle xenoliths hosted in kimberlite magmas. However, the representativeness of the kimberlite sampling may be questioned, given that any type of magmatism is atypical for stable regions. We use EGM2008 gravity data to examine the density structure of the Siberian lithospheric mantle, which we compare with independent constraints based on free-board analysis. We find that in the Siberian craton, geochemically studied kimberlite-hosted xenoliths sample exclusively those parts of the mantle where the isopycnic condition is satisfied, while the pristine lithospheric mantle, which has not been affected by magmatism, has a significantly lower density than required by isopycnicity. This discovery allows us to conclude that our knowledge on the composition of cratonic mantle is incomplete and that it is biased by kimberlite sampling which provides a deceptive basis for the isopycnicity hypothesis
J. Geophysical Research: Solid Earth, 2019
(By Shulgin A. and Artemieva I.M.) [open access]
We present a new model, EUNA-rho, for the den... more (By Shulgin A. and Artemieva I.M.) [open access]
We present a new model, EUNA-rho, for the density structure of the continental and oceanic upper mantle based on 3-D tesseroid gravity modeling. On continent, there is no clear difference in lithospheric mantle (LM) density between the cratonic and Phanerozoic Europe, yet an ~300-km-wide zone of a high-density LM along the Trans-European Suture Zone may image a paleosubduction. Kimberlite provinces of the Baltica and Greenland cratons have a low-density (3.32 g/cm 3) mantle where all non-diamondiferous kimberlites tend to a higher-density (3.34 g/cm 3) anomalies. LM density correlates with the depth of sedimentary basins implying that mantle densification plays an important role in basin subsidence. A very dense (3.40-3.45 g/cm 3) mantle beneath the superdeep platform basins and the East Barents shelf requires the presence of 10-20% of eclogite, while the West Barents Basin has LM density of 3.35 g/cm 3 similar to the Variscan massifs of western Europe. In the North Atlantics, south of the Charlie Gibbs fracture zone (CGFZ) mantle density follows half-space cooling model with significant deviations at volcanic provinces. North of the CGFZ, the entire North Atlantics is anomalous. Strong low-density LM anomalies (< −3%) beneath the Azores and north of the CGFZ correlate with geochemical anomalies and indicate the presence of continental fragments and heterogeneous melting sources. Thermal anomalies in the upper mantle averaged down to the transition zone are 100-150 °C at the Azores and can be detected seismically, while a <50 °C anomaly around Iceland is at the limit of seismic resolution.
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Videos by Irina M. Artemieva
Recorded by EGU, April 29, 2021.
Duration: lecture ca. 35 min with foreword and medal citation by EGU-GD president Prof. Jeroen van Hunen.
Level: from MS students to professional.
The lecture focuses on the lithosphere structure of the cratons worldwide with special focus on the cratons of southern Africa. Geophysical models on mantle temperatures and densities are presented in comparison with geochemical data.
Level: from MS students to professional.
Duration: 45 min + 10 min discussion
https://www.youtube.com/watch?v=O9kUEVnh7bw
Presented at the first international online conference "WOW Physics! (Women Of the World in Physics!)", Nov 9 to 11, 2022, hosted by Goethe University Frankfurt, Germany. https://indico.cern.ch/event/1108414/
All papers by Irina M. Artemieva
thick crust instead is homogenous above the Moho, and Pn-velocity abruptly change from 7.6 kms−1 below the Scandes to >8.2 kms−1 below the Proterozoic shield. By modelling gravity anomalies and topography, based on the seismic model, we demonstrate that this change corresponds to an increase in metamorphic eclogitic grade from 35% below the high-topography Scandes to 70% below the low-topography shield. The sharp contrast between the low-grade,
reduced-density and the high-grade, high-density eclogitic bodies below the uniform seismological Moho explains the enigmatic topography of the mountain range without a crustal root.
wedge melting caused by dehydration of the subducting slab, but the Makran subduction zone has anomalously
low seismicity and magmatism. Here we explain these anomalous features by 60–65% serpentinization in the
peridotitic shallow mantle wedge based on our new integrated seismic, magnetic, gravity and isostatic model
across the Makran subduction zone. The low-angle, slow Makran subduction provides ample time for the slab to
release sufficient amounts of fluids for creating a large volume of rheologically weak serpentinite. This reduces
seismicity by lowering the friction between the slab and surrounding rocks. Further, very little fluid is left in the
slab when it reaches the melting depth, which explains the limited arc magmatism. Around 100 km depth, the
subduction switches from low-angle to almost vertical. Our model demonstrates the combined effects of subduction
rate and dip on mantle serpentinization with implication for assessment of seismic and volcanic hazards
in subduction systems.
based on a broad spectrum of geophysical and subduction-related parameters. My synthesis is used to identify
trends in the evolution of back-arc basins for improving our understanding of subduction systems in general. The
analysis, based on the present plate configuration, demonstrates that geophysical characteristics and fate of the
back-arc basins are essentially controlled by the tectonic type of the overriding plate, which controls the lithosphere
thermo-compositional structure and rheology. The type of the plate governs the length of the extensional
zone in back-arc settings along the trench, the efficiency of lithosphere stretching, and the crustal structure,
buoyancy and bathymetry of the BABs. Subduction dip angle apparently controls the location of the slab melting
zone and the efficiency of slab roll-back with feedback links to other parameters. By the tectonic nature of the
overriding plate (the downgoing plate is always oceanic) the back-arc basins are split into active BABs formed by
ocean-ocean, arc-ocean, and continent-ocean convergence, and extinct back-arc basins. By geophysical characteristics,
BABs formed on continental plates are subdivided into active BABs with and without seafloor spreading,
and extinct BABs are subdivided into the Pacific BABs, possibly formed on oceanic plates, and the non-Pacific
BABs with reworked continental or arc fragments.
Six types of BABs are distinctly different. Extension of the overriding oceanic plate above a steeply dipping old
oceanic plate, preferentially subducting nearly westwards, forms large deep back-arc basins with a thin oceanictype
crust. In contrast, BABs on the overriding continental or arc plates form at small opening rates and often by
shallow subduction of younger oceanic plates with a random subduction orientation; these BABs have small sizes,
shallow bathymetry, and hyperextended or transitional ~20 km thick arc- or continental-type crust typical of
passive margins. The presence of a 2–5 km thick high-Vp lowermost crustal layer, characteristic of BABs in all
settings, indicates the importance of magmatic underplating in the crustal growth.
Conditions required for the initiation of a back-arc basin and transition from stretching to seafloor opening
depend on the nature of the overriding plate. BABs formed on oceanic plates always evolve to seafloor spreading.
BABs formed on continental or arc plates require long spreading duration with large (>8 cm/y) opening rates and
a large crustal thinning factor of 2.8–5.0 to progress from crustal extension to seafloor spreading. On the present
Earth such transition does not happen in the back-arc basins formed behind a shallow subduction (<45o) of a
young (<40 My) oceanic plate.
The nature of the overriding plate also determines the fate of back-arc basins after termination of lithosphere
extension: the extinct Pacific back-arc basins with oceanic-type crust evolve towards deep old “normal” oceans,
while the shallow non-Pacific BABs with low heat flow and thick crust are likely to preserve their continental or
arc affinity. BABs do not follow the oceanic cooling plate model predictions. Distinctly different geophysical
signatures for mid-ocean ridge spreading and for back-arc seafloor spreading are caused by principally different
dynamics.
which is sensitive to the presence of iron-rich minerals, to interpret the present structure and the tecto-magmatic
evolution in the Central Tethyan belt. Our results demonstrate exceptional variability of crustal magnetization
with smooth, small-amplitude anomalies in the Gondwana realm and short-wavelength high-amplitude
variations in the Laurentia realm. Poor correlation between known ophiolites and magnetization anomalies
indicates that Tethyan ophiolites are relatively poorly magnetized, which we explain by demagnetization during
recent magmatism. We analyze regional magnetic characteristics for mapping previously unknown oceanic
fragments and mafic intrusions, hidden beneath sedimentary sequences or overprinted by tectono-magmatic
events. By the style of crustal magnetization, we distinguish three types of basins and demonstrate that many
small-size basins host large volumes of magmatic rocks within or below the sedimentary cover. We map the
width of magmatic arcs to estimate paleo-subduction dip angle and find no systematic variation between the
Neo-Tethys and Paleo-Tethys subduction systems, while the Pontides magmatic arc has shallow (∼15°) dip
in the east and steep (∼50°–55°) dip in the west. We recognize an unknown, buried 450 km-long magmatic
arc along the western margin of the Kırşehir massif formed above steep (55°) subduction. We propose that
lithosphere fragmentation associated with Neo-Tethys subduction systems may explain high-amplitude,
high-gradient crustal magnetization in the Caucasus Large Igneous Province. Our results challenge conventional
regional geological models, such as Neo-Tethyan subduction below the Greater Caucasus, and call for
reevaluation of the regional paleotectonics.
The seismic receiver function (RF) technique is widely used as an economic method to image earth’s deep interior in a large number of seismic experiments. P-wave receiver functions (RFs) constrain crustal thickness and average Vp/Vs in the crust by analysis of the Ps phase and multiples (reflected/converted waves) from the Moho. Regional studies often show significant differences between the Moho depth constrained by RF and by reflection/refraction methods.
We compare the results from RF and controlled source seismology for the Baikal Rift Zone by calculating 1480 synthetic RFs for a seismic refraction/reflection velocity model and processing them with two common RF techniques [H–κ and Common Conversion Point (CCP) stacking]. We compare the resulting synthetic RF structure with the velocity model, a density model (derived from gravity and the velocity model), and with observed RFs.
Our results demonstrate that the use of different frequency filters, the presence of complex phases from sediments and gradual changes in the properties of crustal layers can lead to erroneous interpretation of RFs and incorrect geological interpretations. We suggest that the interpretation of RFs should be combined with other geophysical methods, in particular in complex tectonic regions and that the long-wavelength Bouguer gravity anomaly signal may provide effective calibration for the determination of the correct Moho depth from RF results. We propose and validate a new automated, efficient method for this calibration.
The Ordos Block in the western part of the North China Craton is enigmatic in having contrasting topographic structure in the northern and southern parts, while previous geophysical studies show little difference in crustal and upper mantle structure across the region. Here we present a new model of upper mantle structure in the Ordos Block region in order to test the importance of mantle heterogeneity for topographic differences. Our model is based on P-and S-wave seismic receiver functions calculated for data from 171 stations. It documents the presence of an uppermost mantle low-velocity zone between the Mid Lithospheric Discontinuity (MLD) and the Lehmann discontinuity. Clear converters at the 410 and 660 km discontinuities show constant Mantle Transition Zone (MTZ) thickness within the Ordos Block region, which indicates that no deep mantle thermal anomaly affects its present dynamics. However, the amplitude of the MTZ-converters is higher in the southern than the northern Ordos Block. In contrast, the conversions from MLD and the Lehmann discontinuity are strongest in Northern Ordos, which we interpret as a block with essentially preserved cratonic lithospheric mantle. We speculate that smaller amplitudes of the MLD and Lehmann converters in Southern than Northern Ordos may be related to either rheological weakening of cratonic lithosphere during the Mesozoic convergence between the North and South (Yangtze) China Cratons, or northeast extrusion of Tibetan lower crust and upper mantle in the Cenozoic caused by the India-Asia collision.
We propose a new geodynamic model which explains the enigmatic asymmetry of the Red Sea region and is fully consistent with various types of geological and geophysical observations. We demonstrate that the north-central rift is a transient feature that will not develop into coincident ocean spreading. Instead, the new plate boundary forms across Arabia. Our numerical experiments, supported by geological, seismic and gravity observations, predict that in 1-5 Myr the north-central extensional axis will jump ~300 km eastward into Arabia. The Ad Damm strike-slip fault, normal to the central Red Sea rift axis, will evolve into a transform fault between the ongoing ocean spreading in the southern Red Sea and the future spreading in north-central Arabia.
We demonstrate that crustal-scale weakness zones control lithosphere extension and lead to long-distance jumps of extensional axes in continental lithosphere not affected by hotspots. Therefore, our model also provides theoretical basis for understanding dynamics and mechanisms of the transition from rifting to continental break-up at passive continental margins not affected by hotspots.
The nature of the lower crust and the crust-mantle transition is fundamental to Earth sciences. Transformation of lower crustal rocks into eclogite facies is usually expected to result in lower crustal delamination. Here we provide compelling evidence for long-lasting presence of lower crustal eclogite below the seismic Moho. Our new wide-angle seismic data from the Paleoproterozoic Fennoscandian Shield identify a 6-8 km thick body with extremely high velocity (Vp~8.5-8.6 km/s) and high density (>3.4 g/cm 3) immediately beneath equally thinned high-velocity (Vp~7.3-7.4 km/s) lowermost crust, which extends over >350 km distance. We relate this observed structure to partial (50-70%) transformation of part of the mafic lowermost crustal layer into eclogite facies during Paleoproterozoic orogeny without later delamination. Our findings challenge conventional models for the role of lower crustal eclogitization and delamination in lithosphere evolution and for the long-term stability of cratonic crust.
Antarctica has traditionally been considered continental inside the coastline of ice and bedrock since Press and Dewart (1959). Sixty years later, we reconsider the conventional extent of this sixth continent. Geochemical observations show that subduction was active along the whole western coast of West Antarctica until the mid-Cretaceous after which it gradually ceased towards the tip of the Antarctic Peninsula. We propose that the entire West Antarctica formed as a back-arc basin system flanked by a volcanic arc, similar to e.g. the Japan Sea, instead of a continental rift system as conventionally interpreted. Globally, the fundamental difference between oceanic and continental lithosphere is reflected in hypsometry, largely controlled by lithosphere buoyancy. The equivalent hypsometry in West Antarctica (−580 ± 335 m on average, extending down to −1.6 km) is much deeper than in any continent, but corresponds to back-arc basins and oceans proper. This first order observation questions the conventional interpretation of West Antarctica as continental, since even continental shelves do not extend deeper than −200 m in equivalent hypsometry.
We present a suite of geophysical observations that supports our geodynamic interpretation: a linear belt of seismicity sub-parallel to the volcanic arc along the Pacific margin of West Antarctica; a pattern of free air gravity anomalies typical of subduction systems; and extremely thin crystalline crust typical of back-arc basins. We calculate residual mantle gravity anomalies and demonstrate that they require the presence of (1) a thick sedimentary sequence of up to ca. 50% of the total crustal thickness or (2) extremely low density mantle below the deep basins of West Antarctica and, possibly, the Wilkes Basin in East Antarctica. Case (2) requires the presence of anomalously hot mantle below the entire West Antarctica with a size much larger than around continental rifts. We propose, by analogy with back-arc basins in the Western Pacific, the existence of rotated back-arc basins caused by differential slab roll-back during subduction of the Phoenix plate under the West Antarctica margin. Our finding reduces the continental lithosphere in Antarctica to 2/3 of its traditional area. It has significant implications for global models of lithosphere-mantle dynamics and models of the ice sheet evolution.
The Iranian plateau is one of the most complex geodynamic settings within the Alpine-Himalayan belt. The Paleo-Tethys and Neo-Tethys ocean subduction is responsible for the formation of several magmatic arcs and sedimentary basins within the plateau. These zones mostly are separated by thrust faults related to paleo-suture zones, which are highlighted by ophiolites. Sediment cover and overprint of a different magmatic phase from late Triassic to the Quaternary impede identification of some magmatic arcs and ophiolite belts. We track the known magmatic arcs, such as the Urmia-Dokhtar Magmatic Arc (UDMA), and unknown, sediment covered magmatic arcs by aeromagnetic data. We present a new map of average susceptibility calculated by the radially averaged power spectrum method. High average susceptibility values indicate the presence of a number of lineaments that correlate with known occurrences of Magmatic-Ophiolite Arcs (MOA), and low average susceptibility coincides with known sedimentary basins like Zagros, Makran, Kopeh-Dagh, and Tabas. In analogy to Zagros, low average susceptibility values indicate sedimentary basins to the south of the Darouneh fault and in the northern part of the Lut, Tabas and Yazd blocks. We interpret the Tabas basin as a pull-apart or back-arc basin. We identify hitherto unknown parallel MOAs in eastern Iran and the SE part of UDMA which both indicate steeply dipping (> 60°dip) paleo-subduction zones. In contrast, we interpret shallow subduction (< 20°dip) of Neo-Tethys in the NW part of UDMA as well as in the Sabzevar-Kavir MOA.
The isopycnicity hypothesis states that the lithospheric mantle of ancient platforms has a unique composition such that high density due to low lithosphere temperature is nearly compensated by low-density composition of old cratonic mantle. This hypothesis is supported by petrological studies of mantle xenoliths hosted in kimberlite magmas. However, the representativeness of the kimberlite sampling may be questioned, given that any type of magmatism is atypical for stable regions. We use EGM2008 gravity data to examine the density structure of the Siberian lithospheric mantle, which we compare with independent constraints based on free-board analysis. We find that in the Siberian craton, geochemically studied kimberlite-hosted xenoliths sample exclusively those parts of the mantle where the isopycnic condition is satisfied, while the pristine lithospheric mantle, which has not been affected by magmatism, has a significantly lower density than required by isopycnicity. This discovery allows us to conclude that our knowledge on the composition of cratonic mantle is incomplete and that it is biased by kimberlite sampling which provides a deceptive basis for the isopycnicity hypothesis
We present a new model, EUNA-rho, for the density structure of the continental and oceanic upper mantle based on 3-D tesseroid gravity modeling. On continent, there is no clear difference in lithospheric mantle (LM) density between the cratonic and Phanerozoic Europe, yet an ~300-km-wide zone of a high-density LM along the Trans-European Suture Zone may image a paleosubduction. Kimberlite provinces of the Baltica and Greenland cratons have a low-density (3.32 g/cm 3) mantle where all non-diamondiferous kimberlites tend to a higher-density (3.34 g/cm 3) anomalies. LM density correlates with the depth of sedimentary basins implying that mantle densification plays an important role in basin subsidence. A very dense (3.40-3.45 g/cm 3) mantle beneath the superdeep platform basins and the East Barents shelf requires the presence of 10-20% of eclogite, while the West Barents Basin has LM density of 3.35 g/cm 3 similar to the Variscan massifs of western Europe. In the North Atlantics, south of the Charlie Gibbs fracture zone (CGFZ) mantle density follows half-space cooling model with significant deviations at volcanic provinces. North of the CGFZ, the entire North Atlantics is anomalous. Strong low-density LM anomalies (< −3%) beneath the Azores and north of the CGFZ correlate with geochemical anomalies and indicate the presence of continental fragments and heterogeneous melting sources. Thermal anomalies in the upper mantle averaged down to the transition zone are 100-150 °C at the Azores and can be detected seismically, while a <50 °C anomaly around Iceland is at the limit of seismic resolution.