Exploration Geophysics

Talwani, Manik; Kessinger, Walter

doi:10.1016/b0-12-227410-5/00238-6

Cited by 7 publications

(4 citation statements)

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“…The depth to magnetic basement (DMB, discussed in Section 5.1) refers to the top of the magnetic layer. DMB may be regarded as a proxy for the thickness of sedimentary rocks if the underlying basement has magnetic minerals (Talwani & Kessinger, 2003). The approach, important in regions without seismic or borehole data on the thickness of sedimentary cover, assumes that highly magnetized rocks lie immediately below the sedimentary cover that does not host iron‐rich rocks (Figure 3a, Cases 3–4).…”

Section: Magnetic Anomaliesmentioning

confidence: 99%

“…Magnetic mapping provides an efficient tool for mapping hidden and buried magmatic structures and sutures (Blakely, 1995; Hinze et al., 2013; Lyngsie et al., 2006; Talwani & Kessinger, 2003). Here we use magnetic data, sensitive to the presence of iron‐rich rocks at temperatures below the Curie point, to map at depth the distribution of unknown ophiolites and basaltic rocks associated with paleo‐subduction systems and intraplate magmatism.…”

Section: Introductionmentioning

confidence: 99%

“…A strong magnetic susceptibility contrast between weakly magnetized sedimentary rocks and magnetized crystalline basement (Hunt et al., 1995) allows for calculating the depth to magnetic basement, which may be compared to the true basement depth determined from seismic or borehole data. In case the overlying sedimentary rocks do not include interbedded magnetic bodies (e.g., basaltic intrusions), the approach provides a proxy for the thickness of sedimentary sequences (Talwani & Kessinger, 2003) and is useful in regions with poor knowledge of the thickness of the sedimentary cover, such as in West Africa (Abdullahi et al., 2019) and Iran (Teknik & Ghods, 2017). The assumption that magnetic iron‐rich bodies are absent within the sedimentary cover is not expected to be satisfied in most of Anatolia.…”

Section: Introductionmentioning

confidence: 99%

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Geodynamics of the Central Tethyan Belt Revisited: Inferences From Crustal Magnetization in the Anatolia‐Caucasus‐Black Sea Region

2023

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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.

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Section: Magnetic Anomaliesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Geodynamics of the Central Tethyan Belt Revisited: Inferences From Crustal Magnetization in the Anatolia‐Caucasus‐Black Sea Region

2023

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“…Seismic exploration is the use of seismic imaging to investigate the subsurface structures of the Earth (Talwani and Kessinger, 2003). It plays a crucial role in the delineation of near surface geology for economic deposits of oil, gas, or minerals, but also for engineering purposes, archaeological, geophysical and geotechnical scientific studies.…”

Section: Introductionmentioning

confidence: 99%

Near-Surface Seismic Arrival Time Picking with Transfer and Semi-Supervised Learning

et al. 2023

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The understanding of subsurface information on the Earth is crucial in numerous fields such as economics of oil and gas, geophysical exploration, archaeology and hydro-geophysics, particularly in a context of climate change. The methodology consists in reconstructing the seismic velocity model of the near surface, that contains information about the basement structure, by solving the inverse problem and resolving the related complex nonlinear systems with the data collected from seismic experiments and measurements. In the last few years, many deep neural networks have been proposed to simplify the seismic inversion problem based for instance on automatic differentiation of the adjoint operator, or on automatic arrival time picking. However, such approaches require a large amount of labeled training data, which are hardly available in real applications. We present here a deep learning approach for arrival time picking, aimed to deal with unlabeled data. The main building blocks are transfer learning, as well as a semi-supervised learning strategy where the pseudo-labels are greedily computed with robust regression, and classification algorithms. The proposed model and methodology showcase a very high score when evaluating on synthetic data, and its application to a real dataset containing a limited amount of labeled data shows very accurate results.

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Integrated hydrogeological study of a tectonically controlled aquifer system: The Rohia–Sbiba graben, Central Tunisia

et al. 2021

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Exploration Geophysics

Cited by 7 publications

References 0 publications

Geodynamics of the Central Tethyan Belt Revisited: Inferences From Crustal Magnetization in the Anatolia‐Caucasus‐Black Sea Region

Geodynamics of the Central Tethyan Belt Revisited: Inferences From Crustal Magnetization in the Anatolia‐Caucasus‐Black Sea Region

Near-Surface Seismic Arrival Time Picking with Transfer and Semi-Supervised Learning

Integrated hydrogeological study of a tectonically controlled aquifer system: The Rohia–Sbiba graben, Central Tunisia

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