51 research outputs found
Crustal and Sedimentary Structures and Geodynamic Evolution of the West Antarctic Continental Margin and Pine Island Bay
No full textSince the last glacial maximum the West Antarctic Ice Sheet (WAIS) with a base mostly beneath the present-day sea-level has experienced dramatic volume changes within short periods of time. Studies are urgently required to show how these short-term variations are related to volume changes in the older geological past. Next to the ice drainage basins of the Weddell Sea and the Ross Embayment, Pine Island Bay forms the third-largest outflow area for the West Antarctic ice-shield. The main ice streams from the WAIS into Pine Island Bay flow through the Pine Island and Thwaites Glacier systems, through which most of the glacial-marine sediments onto the shelf of Pine Island Bay and across the continental slope into the deep sea have been transported. Geophysical surveys of the sedimentary sequences and the underlying basement of the shelf and slope of the southern Amundsen Sea, Pine Island Bay and its adjacent continental rise would allow reconstructions of the formation of the tectonic and older sedimentary processes as well as to find out about the history of large-scale glaciation in West Antarctica. Accurate models of the geodynamic- tectonic evolution contain some of the most important parameters for understanding and reconstruction of the palaeo-environment. The following objectives will be addressed during ANT XXflII4 as part of a cooperative project between the Vernadsky Institute in Moscow (Dr. Gleb Udintsev) and AWl:K. Gohl, G. Uenzelmann-Neben, G. Eagles, A. Fahl, T. Feigl, J. Grobys, J. Just, V. Leinweber, N. Lensch, C. Mayr, N. Parsiegla, N. Rackebrandt, P. Schloter, S. Suckro, K. Zimmermann, S. Gauger, H. Bohlmann, G. L. Netzeband, and P. Lemenkova. Crustal and Sedimentary Structures and Geodynamic Evolution of the West Antarctic Continental Margin and Pine Island Bay. Germany, Bremerhaven, 2006. doi: 10.13140/RG.2.2.16473.36961
When Tether says “JUMP!” Bitcoin asks “How low?”
No full textWhile stablecoins such as Tether closely track the peg, there is some evidence for recurring spikes in stablecoins’ intraday volatilities rendering stablecoin volatilities unstable (Grobys et al., 2021). Using the Barndorff-Nielsen and Shephard (2006a) methodology, the purpose of our study is to examine whether jumps in Tether have an impact on (subsequent) Bitcoin returns. We retrieve hourly data for Bitcoin and Tether from Bitfinex covering the November 2018 to June 2021 period and encode the binary choice (1 – ‘jump’ and 0 – ‘no jump’) using bi-power variation based on asymptotic distribution theory at 5% significance level for each trading day. Our results show that the joint effect of positive jumps in Tether in association with an 1% increase in Tether returns on the prior day significantly predict negative prices changes in Bitcoin ranging from -3.65% to -8.49% in daily terms. Our results remain robust even after controlling for various other variables.© 2021 The Author(s). Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).fi=vertaisarvioitu|en=peerReviewed
Neogene Reaktivierung des Bounty Trogs, östliches Neuseeland
No full textDer östliche Kontinentalrand Neuseelands wird durch den Bounty Trog unterbrochen, ein in der Kreide abgestorbenes Riftsystem. Die während der Sonne-Reise SO-169 gewonnenen reflexionsseismischen und magnetischen Daten wurden mit dem Ziel interpretiert, die Entwicklung dieser Struktur während des Känozoikums besser zu verstehen. Basement-Hochlagen, welche die sedimentären Lagen bis zum frühen/mittleren Miozän deformieren, konnten identifiziert werden. In Kombination mit einer Ausdünnung der Kruste, wie sie von Grobys et al. (in Vorbereitung) für den zentralen Bounty Trog beobachtet wird, interpretieren wir diese Basement-Hochlagen als das Ergebnis magmatisch-tektonischer Aktivitäten, die im Miozän begann. Diese magmatisch-tektonische Aktivitäten reaktivitierten lithospherische Schwächezonen, welche während der kretazischen Riftphase angelegt wurden. Als Ursache der magmatisch-tektonischen Aktivitäten lassen sich Änderungen in den Plattenbewegungen im Süd-Pazifik diskutieren, die vor ~10 Ma zu Kompressionen entlang der Alpine Fault in Neuseeland führten
Tectonic and Sedimentary Processes of the West Antarctic Margin of the Amundsen Sea Embayment and Pine Island Bay
No full textAccurate models of the geodynamic-tectonic evolution contain some of the most important parameters for understanding and reconstruction of the respective regional and global palaeo-environment. The region of the Amundsen Sea embayment and Pine Island Bay is of great importance for understanding both tectonic and sedimentary processes of West Antarctica. Tectonically, the Amundsen Sea embayment lies between the Palaeozoic crustal blocks of Marie Byrd Land, Ellsworth Land and Thurston Island. Its continental margin is conjugate to the passive margin of the eastern New Zealand submarine continental plateaux and Bounty Trough which underwent major extension during Cretaceous rifting between New Zealand and West Antarctica. Later, the embayment seemed to have played a role as a plate boundary when the Bellingshausen Plate acted independently as a microplate until the early Tertiary. It can be assumed that the tectonic architecture with the formation of deep basins and erosional troughs laid the foundation for major glacier outflow of the West Antarctic Ice-Sheet (WAIS) into Pine Island Bay and the South Pacific since early West Antarctic glaciation.During RV Polarstern expedition ANT-XXIII/4 (Feb-Apr 2006), and in cooperation with the RMS James Clark Ross cruise JR141 (Jan-Feb 2006), we intend to collect seismic, bathymetric, sub-bottom profiles as well as helicopter-magnetic data from the inner shelf, outer shelf, slope and deep sea of the Amundsen Sea embayment and Pine Island Bay to address tectonic as well as sedimentary objectives. We will present first results of both expeditions.info:eu-repo/semantics/publishe
Crustal evolution of the submarine plateaux of New Zealand and their tectonic reconstruction based on crustal balancing = Entwicklung der Kruste der submarinen Plateaus von Neuseeland und deren tektonische Rekonstruktion mit Hilfe von Krustenbilanzierungen
No full textCrustal evolution of the submarine plateaux of New Zealand and their tectonic reconstruction based on crustal balancing
No full textThe last supercontinent fell into pieces with the break-up of Gondwana. In this context, the separation of the microcontinent of New Zealand from Antarctica is a jigsaw puzzle of many pieces. Its parts lay at the convergent margin of East Gondwana, which changed into a divergent margin within a geologically short time. That is why the microcontinent of New Zealand experienced different tectonic regimes and phases of the Wilson cycle. Although it is a good object of investigation due to its changing history, remarkably little is known about the submerged parts of the microcontinent. Knowledge of the magmatic-tectonic development of the submarine plateaux such as Campbell Plateau and Chatham Rise will improve the understanding of the processes that led to the late Gondwana break-up, and, in turn, lead to better reconstructions of East Gondwana, as Zealandia is a key piece in plate-kinematic reconstructions of this part of Gondwana.The central part of this thesis deals with the separation process of Zealandia from Antarctica leading to an improved reconstruction of New Zealand with emphasis on the submarine plateaux. Bounty Trough separating Chatham Rise from Campbell Plateau, and the Great South Basin separating Campbell Plateau from the South Island are investigated with seismic refraction and reflection methods. They are interpreted jointly with magnetic and gravity data. The results of crustal thickness modelling based on satellite gravity data are combined with existing information about crustal thickness of Zealandia. With these data, a crustal thickness grid is calculated which creates the basis for a novel technique for plate-kinematic reconstructions in areas of crustal thinning and in the absence of magnetic seafloor anomalies. This reconstruction consists of crustal balancing to compensate for extension within basins and troughs.The seismic refraction and reflection survey across the Bounty Trough shows a strongly thinned crust in the trough. Zones of high P-and S-wave velocities were found in the lower crust shows. Comparison of the P-wave model and a Poisson's ratio model with rock type diagrams leads to a compositional model of the crust. The joint interpretation of all models suggests that extension in the Bounty Trough proceeded until seafloor spreading in the Middle Bounty Trough began. Geophysical data from the Great South Basin show underplating beneath the Central Campbell Plateau and crustal thinning in the basin, to a lesser extent than in Bounty Trough. Comparison of the seismic data with existing magnetic data across the Great South Basin (Stokes Magnetic Anomaly System - SMAS) and the Campbell Plateau (Campbell Magnetic Anomaly System - CMAS) resulted in the conclusion that these anomaly systems have different origins or histories. Contrary to the results of this thesis, previous investigations assumed a common origin of SMAS and CMAS. Plate-kinematic reconstruction on the base of observations and interpretations combined with existing and modelled crustal thickness shows that extension in Bounty Trough and Great South Basin as well as in New Caledonia Basin was significantly less than previously assumed. The novel technique for plate tectonic reconstructions in thinned continental crust presented in this thesis has the potential to improve plate-kinematic reconstructions for early break-up settings and failed rift systems with stretched continental crust worldwide
Untersuchung von Gas und Gashydratvorkommen im Yaquina-Becken durch 2D-Geschwindigkeitsbestimmung an OBH/s Registrierungen vor und nach einer Wellenfortsetzung
No full textDie krustale Entwicklung der submarinen Plateaus Neuseelands und ihre tektonische Rekonstruktion mit Hilfe von Krustenbilanzierungen
No full textThe last supercontinent fell into pieces with the break-up of Gondwana. In this context, the separation of the microcontinent of New Zealand from Antarctica is a jigsaw puzzle of many pieces. Its parts lay at the convergent margin of East Gondwana, which changed into a divergent margin within a geologically short time. That is why the microcontinent of New Zealand experienced different tectonic regimes and phases of the Wilson cycle. Although it is a good object of investigation due to its changing history, remarkably little is known about the submerged parts of the microcontinent. Knowledge of the magmatic-tectonic development of the submarine plateaux such as Campbell Plateau and Chatham Rise will improve the understanding of the processes that led to the late Gondwana break-up, and, in turn, lead to better reconstructions of East Gondwana, as Zealandia is a key piece in plate-kinematic reconstructions of this part of Gondwana.The central part of this thesis deals with the separation process of Zealandia from Antarctica leading to an improved reconstruction of New Zealand with emphasis on the submarine plateaux. Bounty Trough separating Chatham Rise from Campbell Plateau, and the Great South Basin separating Campbell Plateau from the South Island are investigated with seismic refraction and reflection methods. They are interpreted jointly with magnetic and gravity data. The results of crustal thickness modelling based on satellite gravity data are combined with existing information about crustal thickness of Zealandia. With these data, a crustal thickness grid is calculated which creates the basis for a novel technique for plate-kinematic reconstructions in areas of crustal thinning and in the absence of magnetic seafloor anomalies. This reconstruction consists of crustal balancing to compensate for extension within basins and troughs.The seismic refraction and reflection survey across the Bounty Trough shows a strongly thinned crust in the trough. Zones of high P-and S-wave velocities were found in the lower crust shows. Comparison of the P-wave model and a Poisson's ratio model with rock type diagrams leads to a compositional model of the crust. The joint interpretation of all models suggests that extension in the Bounty Trough proceeded until seafloor spreading in the Middle Bounty Trough began. Geophysical data from the Great South Basin show underplating beneath the Central Campbell Plateau and crustal thinning in the basin, to a lesser extent than in Bounty Trough. Comparison of the seismic data with existing magnetic data across the Great South Basin (Stokes Magnetic Anomaly System - SMAS) and the Campbell Plateau (Campbell Magnetic Anomaly System - CMAS) resulted in the conclusion that these anomaly systems have different origins or histories. Contrary to the results of this thesis, previous investigations assumed a common origin of SMAS and CMAS. Plate-kinematic reconstruction on the base of observations and interpretations combined with existing and modelled crustal thickness shows that extension in Bounty Trough and Great South Basin as well as in New Caledonia Basin was significantly less than previously assumed. The novel technique for plate tectonic reconstructions in thinned continental crust presented in this thesis has the potential to improve plate-kinematic reconstructions for early break-up settings and failed rift systems with stretched continental crust worldwide
Correlation versus co-fractality: Evidence from foreign-exchange-rate variances
No full textThe concept of correlation appears to be the cornerstone of modern finance as it is applied in almost all finance-related research studies. However, Fama (1963) argued that “if the [population] variance is infinite, other statistical tools (e.g., least-squares regression) which are based on the assumption of finite variance will, at best, be considerably weakened and may in fact give very misleading answers” (p. 421). This study shows variances of foreign exchange rates to be governed by power laws with a tail exponent of α < 3, suggesting infinite second moments. We derive a new concept to measure dependencies between power-law processes with this tail exponent, which we term co-fractality. We show that risk diversification based on the concept of correlation indeed gives misleading results. Notably, foreign-exchange-rate variances lacking co-fractality in our earlier subsample do not show evidence for co-fractality in our later subsample. We argue that co-fractality, as opposed to correlation, should be used to measure the dependency between processes governed by power laws.© 2023 The Author. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).fi=vertaisarvioitu|en=peerReviewed
P 500 Returns
No full textThe majority of previous studies used autocorrelation-based methodologies to explore the dependency structure for Bitcoin, but this paper follows Benoit Mandelbrot in taking a fractal point of view. This perspective showed that Bitcoin and S&P 500 returns exhibit fractal-like behavior. Additional evidence suggested that the infinite variance hypothesis cannot be rejected for either asset supporting Mandelbrot’s (1963) early study on cotton price changes. This result held across non-overlapping subsamples. Following Mandelbrot (2008), Hurst exponents were estimated using rescaled/range analysis. The key findings are that (a) Bitcoin returns exhibit a higher level of persistence than S&P 500 returns across various subsamples, (b) the level of persistence in Bitcoin returns did not change over time, (c) the S&P 500 moved from efficiency in the first subsample to inefficiency in the ex-post June 17, 2018, period, (d) even if it was assumed that the variance of S&P 500 returns was finite, the kurtosis remained statistically undefined. The study concluded that the correlation-based methods used to explore the S&P 500 universe result in misleading answers.© 2023 The Author. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).fi=vertaisarvioitu|en=peerReviewed
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