Probing tectonic processes with space geodesy in the south Carpathians: insights from archive SAR data

Satellite-based multi-sensor data coupled with field and microscopic investigations are used to unravel the setting and controls of gold mineralization in the Wadi Beitan–Wadi Rahaba area in the South Eastern Desert of Egypt. The satellite-based multispectral and Synthetic Aperture Radar (SAR) data promoted a vibrant litho-tectonic understanding and abetted in assessing the regional structural control of the scattered gold occurrences in the study area. The herein detailed approach includes band rationing, principal component and independent component analyses, directional filtering, and automated and semi-automated lineament extraction techniques to Landsat 8- Operational Land Imager (OLI), Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), Phased Array L-band Synthetic Aperture Radar (PALSAR), and Sentinel-1B data. Results of optical and SAR data processed as grayscale raster images of band ratios, Relative Absorption Band Depth (RBD), and (mafic–carbonate–hydrous) mineralogical indices are used to extract the representative pixels (regions of interest). The extracted pixels are then converted to vector shape files and are finally imported into the ArcMap environment. Similarly, manually and automatically extracted lineaments are merged with the band ratios and mineralogical indices vector layers. The data fusion approach used herein reveals no particular spatial association between gold occurrences and certain lithological units, but shows a preferential distribution of gold–quartz veins in zones of chlorite–epidote alteration overlapping with high-density intersections of lineaments. Structural features including en-echelon arrays of quartz veins and intense recrystallization and sub-grain development textures are consistent with vein formation and gold deposition syn-kinematic with the host shear zones. The mineralized, central-shear quartz veins, and the associated strong stretching lineation affirm vein formation amid stress build-up and stress relaxation of an enduring oblique convergence (assigned as Najd-related sinistral transpression; ~640–610 Ma). As the main outcome of this research, we present a priority map with zones defined as high potential targets for undiscovered gold resources.

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Southern Chile crustal structure from teleseismic receiver functions: Responses to ridge subduction and terrane assembly of Patagonia

Geosphere ◽

10.1130/ges01692.1 ◽

2019 ◽

Vol 16 (1) ◽

pp. 378-391 ◽

Cited By ~ 1

Author(s):

E.E. Rodriguez ◽

R.M. Russo

Keyword(s):

Crustal Structure ◽

Triple Junction ◽

Oceanic Lithosphere ◽

Receiver Functions ◽

Moho Depth ◽

The South ◽

Ridge Subduction ◽

The North ◽

Tectonic Processes ◽

Chile Triple Junction

Abstract Continental crustal structure is the product of those processes that operate typically during a long tectonic history. For the Patagonia composite terrane, these tectonic processes include its early Paleozoic accretion to the South America portion of Gondwana, Triassic rifting of Gondwana, and overriding of Pacific Basin oceanic lithosphere since the Mesozoic. To assess the crustal structure and glean insight into how these tectonic processes affected Patagonia, we combined data from two temporary seismic networks situated inboard of the Chile triple junction, with a combined total of 80 broadband seismic stations. Events suitable for analysis yielded 995 teleseismic receiver functions. We estimated crustal thicknesses using two methods, the H-k stacking method and common conversion point stacking. Crustal thicknesses vary between 30 and 55 km. The South American Moho lies at 28–35 km depth in forearc regions that have experienced ridge subduction, in contrast to crustal thicknesses ranging from 34 to 55 km beneath regions north of the Chile triple junction. Inboard, the prevailing Moho depth of ∼35 km shallows to ∼30 km along an E-W trend between 46.5°S and 47°S; we relate this structure to Paleozoic thrust emplacement of the Proterozoic Deseado Massif terrane above the thicker crust of the North Patagonian/Somún Cura terrane along a major south-dipping fault.

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Structure, tectonic processes and deformation of the South Aegean Sea

10.12681/eadd/50584 ◽

2021 ◽

Author(s):

Κωνσταντίνα Τσαμπουράκη-Κραουνάκη

Keyword(s):

Aegean Sea ◽

The South ◽

Tectonic Processes ◽

Back Arc

Η παρούσα διατριβή διερευνά τη μακροχρόνια παραμόρφωση και τους ενεργούς τεκτονικούς μηχανισμούς που συνέβαλαν στην εξέλιξη και στο σχηματισμό του πολύπλοκου ανάγλυφου του Νοτίου Αιγαίου. Παρά τις γεωλογικές έρευνες που έχουν διεξαχθεί στο Αιγαίο, μέχρι και σήμερα γνωρίζουμε πολύ λίγα για τη γεωδυναμική εξέλιξη του. Αν και είναι ευρέως αποδεκτό ότι στη γεωτεκτονική εξέλιξη της μικρο-πλάκας του Αιγαίου κυριαρχούν κυρίως οι εφελκυστικές διεργασίες παραμόρφωσης που συναντώνται σε ένα back-arc περιβάλλον (οπισθοτόξο), πρόσφατες γεωλογικές, σεισμολογικές και γεωδαιτικές μελέτες έχουν δείξει ότι η συνολικός εφελκυσμός δύναται να περιλαμβάνει και πλαγιό-συμπιεστικές και πλαγιό- εφελκυστικές διεργασίες. Η παρούσα διπλωματική εργασία συνοψίζει την προϋπάρχουσα βιβλιογραφία και τα κύρια μοντέλα παραμόρφωσης που έχουν προταθεί για το Αιγαίο και μέσω της παρουσίασης νέων βαθυμετρικών και σεισμικών δεδομένων στοχεύει στη βελτίωση της κατανόησης των τεκτονικών διεργασιών και των παραμορφώσεων που επικρατούν στο Νότιο Αιγαίο. Προκειμένου να αναπτυχθεί ένα γεωδυναμικό μοντέλο που θα εξηγεί τις κινηματικές διεργασίες και τους μηχανισμούς παραμόρφωσης που έλαβαν χώρα στην περιοχή, ο κύριος άξονας της διατριβής δομείται από τρεις κύριες ερευνητικές εργασίες, τα αποτελέσματα των οποίων παρέχουν νεότερες πληροφορίες για τη γεωδυναμική εξέλιξη του Νοτίου Αιγαίου.

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Linking collision, slab break-off and subduction polarity reversal in the evolution of the Central Indian Tectonic Zone

Geological Magazine ◽

10.1017/s0016756819001419 ◽

2020 ◽

Vol 157 (2) ◽

pp. 340-350

Author(s):

Tanzil Deshmukh ◽

N. Prabhakar

Keyword(s):

Polarity Reversal ◽

The South ◽

Tectonic Zone ◽

The North ◽

Tectonic Processes ◽

South Indian ◽

Indian Craton ◽

Directed System ◽

Central Indian Tectonic Zone ◽

Collisional Regime

AbstractThe Central Indian Tectonic Zone demarcates the zone of amalgamation between the North Indian Craton and the South Indian Craton. Presently, the major controversies in the existing tectonic models of the Central Indian Tectonic Zone revolve around the direction of subduction and the precise timing of accretion between the North Indian Craton and the South Indian Craton. A new model for the tectonic evolution of the Central Indian Tectonic Zone is postulated in this contribution, based on recent geological and geophysical evidence, combined with previously documented tectonic configurations. The present study employs the slab break-off hypothesis and subsequent polarity reversal to explain the tectonic processes involved in the evolution of the Central Indian Tectonic Zone. We propose that the subduction initiated (c. 2.5 Ga) in a S-directed system producing island-arc sequences on the South Indian Craton. The southward subduction regime culminated with slab break-off underneath the South Indian Craton between c. 1.65 Ga and 1.55 Ga, which subsequently induced subduction polarity reversal and set the course for N-directed subduction (<1.55 Ga). The final closure along the Central Indian Tectonic Zone is governed by the collisional regime during the Sausar Orogeny (1.0–0.9 Ga).

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Observations sur la bordure occidentale de la Bresse, region de Pont-de-Vaux (Ain)

BSGF - Earth Sciences Bulletin ◽

10.2113/gssgfbull.s6-i.4-6.265 ◽

1951 ◽

Vol S6-I (4-6) ◽

pp. 265-275

Author(s):

Philibert Russo

Keyword(s):

The South ◽

The West ◽

Quaternary Deposits ◽

Crustal Movements ◽

Tectonic Processes ◽

West Central

Abstract Presents data on the distribution of the Pliocene and Quaternary in the western part of the Bresse region, France, obtained from 40 well borings, ranging from 7 to 17 meters in depth, in the vicinity of Pont-de-Vaux. Valleys cut in the Plaisancian (lower Pliocene) blue clays during later Pliocene times are filled with Quaternary deposits. The changes in level causing dissection and filling seem to have been produced by tectonic processes associated with the Alpine crustal movements, which caused subsidence in the west-central part of the region and uplift in the south, rather than by eustaticmovements.

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Sequence architecture and depositional evolution of the northern continental slope of the South China Sea: responses to tectonic processes and changes in sea level

Basin Research ◽

10.1111/bre.12238 ◽

2017 ◽

Vol 30 ◽

pp. 568-595 ◽

Cited By ~ 15

Author(s):

Changsong Lin ◽

Jing Jiang ◽

Hesheng Shi ◽

Zhongtao Zhang ◽

Jingyan Liu ◽

...

Keyword(s):

South China Sea ◽

Sea Level ◽

Continental Slope ◽

South China ◽

The South China Sea ◽

The South ◽

Sequence Architecture ◽

China Sea ◽

Tectonic Processes ◽

Depositional Evolution

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The 2011-2020 long-term sustained inflation at Long Valley Caldera: investigation of the interaction of magmatic and tectonic processes

10.5194/egusphere-egu21-5394 ◽

2021 ◽

Author(s):

Erica De Paolo ◽

Elisa Trasatti ◽

Cristiano Tolomei ◽

Emily K. Montgomery-Brown

Keyword(s):

Ground Deformation ◽

Deformation Source ◽

Deformation Pattern ◽

Seismic Zone ◽

The South ◽

Long Valley Caldera ◽

Tectonic Processes ◽

Sustained Inflation ◽

Long Valley

<p>The Long Valley Caldera, California (USA), has been restless over the past few decades, experiencing seismic swarms and ground deformation episodes. The last inflation began in late 2011, when a radially symmetric tumescence was detected coinciding with a large resurgent dome within the caldera. Since then, a continuous inflation with quasi-steady rate of ~1.5 cm/yr has been observed.<span>&#160; </span>Earthquakes mostly occur within the caldera along the South Moat Seismic Zone, to the south of the maximum deformation area. Although the area is tectonically active, increased seismic activity has been documented during periods of renewed inflation since the onset of this tumescence in 1978. In this study, we aim to investigate the nature and dynamics of the long-term unrest at Long Valley Caldera, as well as to provide new insights into the interaction between magmatic and tectonic processes. For this purpose, we consider a variety of datasets including geodetic and seismic records over the period spanning from late 2011 to the end of 2020. A complete seismic catalog supports our study, with more than 200 M2.5-4.5 earthquakes recorded since 2011, most with epicenters located within the caldera. Measurements from a dense network of continuous GPS stations collected in the last 10 years are analyzed in combination with high resolution Interferometric Synthetic Aperture Radar (InSAR) data. For full temporal coverage, we integrate InSAR velocities obtained from the acquisition of different satellite missions. We use, in particular, data from SAR systems operating with X and C-bands such as TerraSAR-X, COSMO-SkyMed and Sentinel-1. The multi-sensor dataset (i.e., GPS and multi-mission InSAR data) compensate the limitations of each technique, with reliable mapping of the deformation pattern evolving over several years. Data analysis highlights uplift velocities with peaks of ~2 cm/yr within the caldera and beyond its southern rim. Moreover, compared to the first half of the period of analysis (2011-2014), the area affected by high deformation rates is broader in the last several years (2017-2020). Models based on the geodetic data are developed to constrain the deformation source and to better interpret the observed signals. This study is motivated as a contribution to the understanding of this long-lived caldera unrest, for a more reliable hazard assessment.</p>

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