scholarly journals Crustal Density Model of the Sea of Marmara: Geophysical Data Integration and 3D Gravity Modelling

2018 ◽  
Author(s):  
Ershad Gholamrezaie ◽  
Magdalena Scheck-Wenderoth ◽  
Judith Sippel ◽  
Oliver Heidbach ◽  
Manfred R. Strecker
Keyword(s):  
Rheological Behaviour ◽  
Average Density ◽  
High Density ◽  
Density Model ◽  
Marmara Sea ◽  
Sea Of Marmara ◽  
Gravity Modelling ◽  
Crystalline Crust ◽  
3D Gravity ◽  
Crustal Density

Abstract. The Sea of Marmara, in Northwest Turkey, is a transition zone where the dextral North Anatolian Fault Zone (NAFZ) propagates westward from the Anatolian plate to the Aegean plate. The area is of interest in the context of seismic hazard in the vicinity of Istanbul, a metropolitan area with about 15 million inhabitants. Geophysical observations indicate that the crust is heterogeneous beneath the Marmara Basin, but a detailed characterization of the crustal heterogeneities is still missing. To assess if and how crustal heterogeneities are related to the NAFZ segmentation below the Marmara Sea, we develop a new crustal-scale 3D density model which integrates geological and seismological data and is additionally constrained by 3D gravity modelling. This model indicates that the observed gravitational anomalies originate from significant density heterogeneities within the crust. Two layers of sediments, one syn-kinematic and one pre-kinematic with respect to the Marmara Sea formation are underlain by a heterogeneous crystalline crust. A felsic upper crystalline crust (average density of 2720 kg m−3) and an intermediate to mafic lower crystalline crust (average density of 2890 kg m−3) appear to be crosscut by two large, dome-shaped mafic high-density bodies (average density of 3050 kg m−3) of considerable thickness above a rather uniform lithospheric mantle (3300 kg m−3). The spatial correlation between the bent segments of the fault and the location of the high-density bodies suggests that the distribution of lithological heterogeneities within the crust controls the rheological behaviour along the NAFZ, and consequently, influences fault segmentation and propagation dynamics.

scholarly journals 3-D crustal density model of the Sea of Marmara

Solid Earth ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 785-807 ◽  
Author(s):  
Ershad Gholamrezaie ◽  
Magdalena Scheck-Wenderoth ◽  
Judith Bott ◽  
Oliver Heidbach ◽  
Manfred R. Strecker
Keyword(s):  
Seismic Hazard ◽  
Seismic Hazard Assessment ◽  
Average Density ◽  
High Density ◽  
Gravity Modeling ◽  
Sea Of Marmara ◽  
Gravity Observation ◽  
Marine Gravity ◽  
Northwestern Turkey ◽  
Crystalline Crust

Abstract. The Sea of Marmara, in northwestern Turkey, is a transition zone where the dextral North Anatolian Fault zone (NAFZ) propagates westward from the Anatolian Plate to the Aegean Sea Plate. The area is of interest in the context of seismic hazard of Istanbul, a metropolitan area with about 15 million inhabitants. Geophysical observations indicate that the crust is heterogeneous beneath the Marmara basin, but a detailed characterization of the crustal heterogeneities is still missing. To assess if and how crustal heterogeneities are related to the NAFZ segmentation below the Sea of Marmara, we develop new crustal-scale 3-D density models which integrate geological and seismological data and that are additionally constrained by 3-D gravity modeling. For the latter, we use two different gravity datasets including global satellite data and local marine gravity observation. Considering the two different datasets and the general non-uniqueness in potential field modeling, we suggest three possible “end-member” solutions that are all consistent with the observed gravity field and illustrate the spectrum of possible solutions. These models indicate that the observed gravitational anomalies originate from significant density heterogeneities within the crust. Two layers of sediments, one syn-kinematic and one pre-kinematic with respect to the Sea of Marmara formation are underlain by a heterogeneous crystalline crust. A felsic upper crystalline crust (average density of 2720 kg m−3) and an intermediate to mafic lower crystalline crust (average density of 2890 kg m−3) appear to be cross-cut by two large, dome-shaped mafic high-density bodies (density of 2890 to 3150 kg m−3) of considerable thickness above a rather uniform lithospheric mantle (3300 kg m−3). The spatial correlation between two major bends of the main Marmara fault and the location of the high-density bodies suggests that the distribution of lithological heterogeneities within the crust controls the rheological behavior along the NAFZ and, consequently, maybe influences fault segmentation and thus the seismic hazard assessment in the region.

scholarly journals Density distribution across the Alpine lithosphere constrained by 3D gravity modelling and relation to seismicity and deformation

2019 ◽  
Author(s):  
Cameron Spooner ◽  
Magdalena Scheck-Wenderoth ◽  
Hans-Jürgen Götze ◽  
Jörg Ebbing ◽  
György Hetényi
Keyword(s):  
Open Access ◽  
Density Distribution ◽  
Gravity Field ◽  
Southern Alps ◽  
Density Model ◽  
Gravity Modelling ◽  
Tauern Window ◽  
History Of ◽  
The Alps ◽  
3D Gravity

Abstract. The Alpine Orogen formed as a result of the collision between the Adriatic and European plates. Significant crustal heterogeneity exists within the region due to the long history of interplay between these plates, other continental and oceanic blocks in the region, and inherited crustal features from earlier orogenys. Deformation relating to the collision continues to the present day. Here, a seismically constrained, 3D, structural and density model of the lithosphere of the Alps and their respective forelands, derived from integrating numerous geoscientific datasets, was adjusted to match the observed gravity field. It is shown that the distribution of seismicity and deformation within the region correlates strongly to thickness and density changes within the crust, and that the present day Adriatic crust is both thinner and denser (22.5 km, 2800 kg/m3) than the European crust (27.5 km, 2750 kg/m3). Alpine crust derived from each respective plate is found to show the same trend with zones of Adriatic provenance (Austro-Alpine and Southern Alps) found to be denser and those of European provenance (Helvetic Zone and Tauern Window) to be less dense suggesting the respective plates and related terrains had similar crustal properties to the present day prior to orogenesis. The model generated here is available for open access use to further discussions about the crust within the region.

3-D lithospheric-scale rheological model of the Sea of Marmara

2020 ◽  
Author(s):  
Ershad Gholamrezaie ◽  
Magdalena Scheck-Wenderoth ◽  
Judith Bott ◽  
Oliver Heidbach ◽  
Marco Bohnhoff ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Large Earthquake ◽  
High Density ◽  
Recurrence Time ◽  
Seismic Gap ◽  
Marmara Region ◽  
Sea Of Marmara ◽  
The North ◽  
Western Segment ◽  
Crystalline Crust

<p>The North Anatolian Fault (NAF) below the Sea of Marmara, also known as the Main Marmara Fault (MMF), has repeatedly produced major (M>7) earthquakes in the past. Currently, the MMF corresponds to a seismic gap between the locus of the most recent M>7 ruptures of the 1912 Ganos (M 7.3) and 1999 Izmit (M 7.4) earthquakes. This seismic gap has a recurrence time of approximately 250 years and has not ruptured since 1766. Consequently, it poses a major seismic hazard to the Marmara region, including the megacity Istanbul. The Marmara seismic gap is considered to be locked in the eastern and central segments of the MMF, while the western segment is partly creeping. In the context of seismic hazard and risk assessment, one of the main questions is, if either the Marmara seismic gap will rupture in a single large earthquake or in several ones due to segmentation along the MMF. In part this depends on the physical properties of the lithosphere below the Sea of Marmara as they are a key control of the contemporary stress state. To contribute to this discussion, we present 3‑D lithospheric-scale thermal and rheological models of the Sea of Marmara. These models are based on published 3‑D density models that indicate lateral and vertical crustal heterogeneities below the Sea of Marmara (Gholamrezaie et al., 2019). The density models consist of two layers of sediments, upper and lower crystalline crustal layers, and two crustal dome-shaped, high-density bodies that spatially correlate with major bends along the MMF. We show that these crustal heterogeneities may cause the lithospheric strength to vary significantly along the MMF, supporting the hypothesis that the fault is mechanically segmented. In addition, our results indicate a spatial correlation between observed aseismic fault patches (Wollin et al., 2018) and the location of the high-density bodies. These bodies are colder and stronger than the surrounding crystalline crust, and may thus represent the lateral bounds of the locked MMF segment.</p>

3D gravity modelling of the Chicxulub impact structure

2001 ◽  
Vol 49 (6) ◽  
pp. 599-609 ◽  
Author(s):  
Jörg Ebbing ◽  
Peter Janle ◽  
Jannis Koulouris ◽  
Bernd Milkereit
Keyword(s):  
Impact Structure ◽  
Gravity Modelling ◽  
3D Gravity ◽  
Chicxulub Impact

The Rheological Behaviour of Glass-Filled Low and High Density Polyethylenes

2008 ◽  
Author(s):  
J. Embery ◽  
M. Tassieri ◽  
P. J. Hine ◽  
Albert Co ◽  
Gary L. Leal ◽  
...  
Keyword(s):  
Rheological Behaviour ◽  
High Density

Finding new QTL for yield traits based on a high-density genetic map in the super hybrid rice Nei2You No.6

2019 ◽  
Author(s):  
Miao Zhang ◽  
Zhengping Zhou ◽  
Yuyu Chen ◽  
Yongrun Cao ◽  
Chenwei Deng ◽  
...  
Keyword(s):  
Complex Traits ◽  
Yield Components ◽  
Average Density ◽  
High Density ◽  
Yield Traits ◽  
Target Region ◽  
Effect On Yield ◽  
Positive Effect ◽  
High Density Linkage Map ◽  
1000 Grain Weight

Abstract Background Rice is one of the most important food crops in the world. To determine the genetic basis of yield components in super rice Nei2You No.6, 387 recombinant inbred sister lines (RISLs) were obtained for mapping quantitative trait loci (QTL) responsible for yield-associated traits, such as 1000-grain weight (TGW), grain number per plant (GNP), number of panicles per plant (NP), and grain yield per plant (GYP). Results Using whole genome re-sequencing, a high-density linkage map consisting of 3203 bin markers was constructed with total genetic coverage of 1951.1 cM and an average density of 0.61 cM. As a result of the multi-environment test, 43 yield-related QTL were mapped to all 12 chromosomes, among which 28 inherited from Nei2B showed a positive effect on yield traits. Nine QTL, qTGW-1a, qTGW-5, qTGW-7, qTGW-10b, qTGW-10c, qTGW-12, qNP-7, qGNP-6c, and qGYP-6b, showed stable effects across multiple environments. Five of the nine QTL were co-located with previously reported QTL, and four novel loci, qTGW-7, qTGW-12, qGNP-6c, and qNP-7, were identified in the present study. Subsequently, qNP-7, qTGW-12, and qTGW-7 were validated using corresponding paired lines which differed only in the target region. Conclusions the RISL population is an effective tool for mapping and validating QTL of complex traits, for instance, yield-associated traits, and newly detected QTL provide new genetic resources for research of yield components and molecular breeding in rice.

scholarly journals Crustal domains in the Western Barents Sea

2020 ◽  
Vol 221 (3) ◽  
pp. 2155-2169
Author(s):  
Alexey Shulgin ◽  
Jan Inge Faleide ◽  
Rolf Mjelde ◽  
Asbjørn Breivik ◽  
Ritske Huismans
Keyword(s):  
Seismic Reflection ◽  
Barents Sea ◽  
The Body ◽  
Gravity Modelling ◽  
Southern Boundary ◽  
Mafic Intrusions ◽  
Crustal Block ◽  
The Barents Sea ◽  
Crystalline Crust ◽  
Regional Gravity

SUMMARY The crustal architecture of the Barents Sea is still enigmatic due to complex evolution during the Timanian and Caledonian orogeny events, further complicated by several rifting episodes. In this study we present the new results on the crustal structure of the Caledonian–Timanian transition zone in the western Barents. We extend the work of Aarseth et al. (2017), by utilizing the seismic tomography approach to model Vp, Vs and Vp/Vs ratio, combined with the reprocessed seismic reflection line, and further complemented with gravity modelling. Based on our models we document in 3-D the position of the Caledonian nappes in the western Barents Sea. We find that the Caledonian domain is characterized by high crustal reflectivity, caused by strong deformation and/or emplacement of mafic intrusions within the crystalline crust. The Timanian domain shows semi-transparent crust with little internal reflectivity, suggesting less deformation. We find, that the eastern branch of the earlier proposed Caledonian suture, cannot be associated with the Caledonian event, but can rather be a relict from the Timanian terrane assemblance, marking one of the crustal microblocks. This crustal block may have an E–W striking southern boundary, along which the Caledonian nappes were offset. A high-velocity/density crustal body, adjacent to the Caledonian–Timanian contact zone, is interpreted as a zone of metamorphosed rocks based on the comparison with global compilations. The orientation of this body correlates with regional gravity maxima zone. Two scenarios for the origin of the body are proposed: mafic emplacement during the Timanian assembly, or massive mafic intrusions associated with the Devonian extension.

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