High-resolution shallow marine seismic surveys off Busan and Pohang, Korea, using a small-scale multichannel system

2004 ◽  
Vol 56 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Ho-Young Lee ◽  
Keun-Pil Park ◽  
Nam-Hyung Koo ◽  
Dong-Geun Yoo ◽  
Dong-Hyo Kang ◽  
...  
2014 ◽  
Vol 10 (2) ◽  
pp. 1223-1264 ◽  
Author(s):  
G. Auer ◽  
W. E. Piller ◽  
M. Harzhauser

Abstract. Within a 5.5 m-thick succession of Upper Burdigalian (Karpatian) sediments in the North Alpine Foreland Basin (NAFB; Austria), dated to CNP-zone NN4, a high-resolution section was logged continuously. 100 samples were taken with a resolution of ~10 mm per layer and analysed using an integrated multi-proxy approach. Earlier analyses of geochemistry and calcareous nannoplankton assemblages hint at small-scale, short-term variations in palaeoenvironmental conditions, such as water-column stratification, primary productivity, organic matter flux, bottom-water oxygenation, freshwater influx and changes in relative sea-level. The results indicate a highly dynamic shallow marine setting that was subject to high frequency environmental changes on a decadal to centennial scale. Time-series analyses on nine different proxy-datasets using REDFIT-analysis and Wavelet spectra were applied to resolve a possible cyclic nature of these variations. Analyses revealed that different proxies for precipitation, upwelling intensity, and over all productivity likely were controlled by different cyclicities. A best-fit adjustment of the likely sedimentation rates within the high-resolution section resulted in periodicities fitting well with the Lower (~65 yr) and Upper (~113 yr) Gleissberg cycle as well as the Suess/de Vries cycle (~211 yr). The section covers a timespan of ~1190 yr based on the correlation with solar cycles, which resulted in an estimated sedimentation rate of 575 mm kyr−1. For the first time, short-term climate variability on a decadal to centennial scale is resolved in Lower Miocene shallow marine laminated sediments in a land-based section. The results hint at a close relationship between climate variability and solar forcing during the Late Burdigalian. Moreover, accepting that these cyclicities are indeed of solar origin, this would indicate that precipitation was driven by the two Gleissberg cycles, while upwelling was driven by the Suess cycle. Furthermore, proxies for primary productivity were influenced by both cycles, although the Suess cycle exerts dominant control, reflecting a stronger influence of upwelling on primary productivity.


2015 ◽  
Vol 11 (2) ◽  
pp. 283-303 ◽  
Author(s):  
G. Auer ◽  
W. E. Piller ◽  
M. Harzhauser

Abstract. Within a 5.5 m thick succession of Upper Burdigalian (Karpatian) sediments in the North Alpine Foreland Basin (NAFB; Austria), dated to CNP-zone NN4, a high-resolution section was logged continuously. One hundred samples were taken with a resolution of ~10 mm (approximating ~17 years) per layer and analyzed using an integrated multi-proxy approach. Earlier analyses of geochemistry and calcareous nannoplankton assemblages hint at small-scale, short-term variations in paleoenvironmental conditions, such as water-column stratification, primary productivity, organic matter flux, bottom-water oxygenation, freshwater influx, and changes in relative sea level. The results indicate a highly dynamic shallow marine setting that was subject to high-frequency environmental changes on a decadal to centennial scale. Time-series analyses on nine different proxy data sets using REDFIT analysis and wavelet spectra were applied to resolve a possible cyclic nature of these variations. Analyses revealed that different proxies for precipitation, upwelling intensity, and overall productivity were likely controlled by different cyclicities. A best-fit adjustment of the likely sedimentation rates within the high-resolution section resulted in periodicities fitting well with the Lower (~65 years) and Upper (~113 years) Gleissberg cycle as well as the Suess/de Vries cycle (~211 years). The section covers a time span of ~1190 years based on the correlation with solar cycles, which resulted in an estimated sedimentation rate of 575 mm kyr−1. For the first time, short-term climate variability on a decadal to centennial scale is resolved in Lower Miocene shallow marine laminated sediments in a land-based section. The results hint at a close relationship between climate variability and solar forcing during the Late Burdigalian. Moreover, accepting that these cyclicities are indeed of solar origin, this would indicate that precipitation was driven by the two Gleissberg cycles, while upwelling was driven by the Suess cycle. Furthermore, proxies for primary productivity were influenced by both cycles, although the Suess cycle exerts dominant control, reflecting a stronger influence of upwelling on primary productivity.


2017 ◽  
Vol 15 (4) ◽  
pp. 347-358 ◽  
Author(s):  
Henrique Duarte ◽  
Nigel Wardell ◽  
Olivier Monrigal

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Ayobami Abegunrin ◽  
Daniel A. Hepp ◽  
Tobias Mörz

Abstract Variations in the physical properties of water column usually impede exact water column height correction on high-resolution seismic data, especially when the data are collected in shallow marine environments. Changes in water column properties can be attributed to variation in tides and currents, wind-generated swells, long and short amplitude wave-fronts, or variation in salinity and water temperature. Likewise, the proper motion of the vessel complicates the determinability of the water column height. This study provides a less time-consuming and precise differential Global Positioning System based methodology that can be applied to most types of high-resolution seismic data in order to significantly improve the tracking and quality of deduced geological interpretations on smaller depth scales. The methodology was tested on geophysical profiles obtained from the German sector of the North Sea. The focus here was to identify, distinguish and classify various sub-surface sedimentary structures in a stratigraphically highly complex shallow marine environment on decimeter small-scale. After applying the correction to the profiles, the sea floor, in general, occurs 1.1 to 3.4 m (mean of 2.2 m) deeper than the uncorrected profiles and is consistent with the sea floor from published tide corrected bathymetry data. The corrected seismic profiles were used in plotting the depth of the base of Holocene channel structures and to define their gradients. The applied correction methodology was also crucial in glacial and post-glacial valley features distinction, across profile correlation and establishing structural and stratigraphic framework of the study area.


2019 ◽  
Vol 15 (S359) ◽  
pp. 312-317
Author(s):  
Francoise Combes

AbstractGas fueling AGN (Active Galaxy Nuclei) is now traceable at high-resolution with ALMA (Atacama Large Millimeter Array) and NOEMA (NOrthern Extended Millimeter Array). Dynamical mechanisms are essential to exchange angular momentum and drive the gas to the super-massive black hole. While at 100pc scale, the gas is sometimes stalled in nuclear rings, recent observations reaching 10pc scale (50mas), may bring smoking gun evidence of fueling, within a randomly oriented nuclear gas disk. AGN feedback is also observed, in the form of narrow and collimated molecular outflows, which point towards the radio mode, or entrainment by a radio jet. Precession has been observed in a molecular outflow, indicating the precession of the radio jet. One of the best candidates for precession is the Bardeen-Petterson effect at small scale, which exerts a torque on the accreting material, and produces an extended disk warp. The misalignment between the inner and large-scale disk, enhances the coupling of the AGN feedback, since the jet sweeps a large part of the molecular disk.


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