scholarly journals Seismic reflections from a lithospheric suture zone below the Archaean Yilgarn Craton

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Andrew J. Calvert ◽  
Michael P. Doublier ◽  
Samantha E. Sellars
Keyword(s):  
Seismic Reflection ◽  
Suture Zone ◽  
Plate Tectonic ◽  
Yilgarn Craton ◽  
Uppermost Mantle ◽  
Northern Edge ◽  
Greenstone Belts ◽  
Seismic Reflection Profiles ◽  
Seismic Reflections ◽  
Seismic Reflectors

AbstractSeismic reflectors in the uppermost mantle, which can indicate past plate tectonic subduction, are exceedingly rare below Archaean cratons, and restricted to the Neoarchaean. Here we present reprocessed seismic reflection profiles from the northwest Archaean Yilgarn Craton and the Palaeoproterozoic Capricorn Orogen of western Australia that reveal the existence of a ~4 km thick south-dipping band of seismic reflectors that extends from the base of the Archaean crust to at least 60 km depth. We interpret these reflectors, which lie south of a ~50 km deep crustal root, as a relict suture zone within the lithosphere. We suggest that the mantle reflectors were created either by subduction of an oceanic plate along the northern edge of the Yilgarn Craton, which started in the Mesoarchaean and produced the rocks in northern Yilgarn greenstone belts that formed in a supra-subduction zone setting, or, alternatively, by underthrusting of continental crust deep into the lithosphere during the Palaeoproterozoic.

Seismic Sedimentology Research on Sublacustrine Fan of the Oligocene Dongying Formation, Liaozhong Depression, Bohai Bay Basin, Northeast China

2013 ◽  
Vol 807-809 ◽  
pp. 2151-2154 ◽  
Author(s):  
Yan Yan Chang ◽  
Chang Song Lin ◽  
Xin Huai Zhou ◽  
Shi Qiang Xia
Keyword(s):  
Seismic Reflection ◽  
Gamma Ray ◽  
High Resistivity ◽  
Bohai Bay ◽  
Lateral Migration ◽  
Multi Stage ◽  
Seismic Reflection Profiles ◽  
Seismic Reflections ◽  
Stacking Patterns ◽  
Order Sequence

In Liaozhong Depression, five types of sublacustrine fans are developed in the relative lowstand systems tracts of the fourth-order sequence in Dongying Formation. In drilling cores, typical turbidites characteristics exist including bedding structures such as slump deformation structure, parallel bedding, grading laminations and multi-stage scoured basal surfaces. They also can be recognized in well logs with distinctive low gamma-ray and high-resistivity stacking patterns. Logging curves usually display serrated bell shape, cylinder shape and funnel shape respectively. On seismic reflection profiles, sublacustrine fan typically shows lateral downlap on its external geometry and continuous or discontinuous “vermicular” reflection characteristics in its inner seismic reflection texture. According to the calibration results of drilling data, continuous seismic reflection profiles are interpreted to be mud-rich deposits with cohesive, soft sediment-deformation. Discontinuous seismic reflections with lateral migration and apparent incised valleys are interpreted to be sand-rich deposits which probably host the most potential litho-stratigraphic traps.

Simultaneous extraction of stratigraphic sequences using iterative seismic DNA detection

2014 ◽  
Vol 2 (4) ◽  
pp. T167-T176 ◽  
Author(s):  
Oddgeir Gramstad ◽  
Jan Oystein Haavig Bakke ◽  
Lars Sonneland ◽  
Carlos Eduardo Abreu
Keyword(s):  
Base Pair ◽  
Seismic Reflection ◽  
Dna Detection ◽  
Dna Molecules ◽  
Simultaneous Extraction ◽  
Quality Metric ◽  
Main Components ◽  
Seismic Reflections ◽  
Seismic Reflectors ◽  
Stratigraphic Sequences

We developed a new stratigraphic interpretation methodology enabling extraction of stratigraphic sequences of surfaces. This methodology consisted of two main components. The first component was inspired by DNA search technology used in bioinformatics in which the goal was to detect base-pair sequences in DNA molecules. The base-pair sequences may be modified by mutations, so the search technology must be able to take such mutations into account. We have adapted this technology to search for seismic reflection sequences, acknowledging that seismic reflections were likely to vary laterally that were somewhat analogs to mutations in bioinformatics. One example of a seismic reflection sequence was a geologically sorted sequence of seismic reflectors. The second component of the workflow was how to connect the DNA hits into continuous surfaces. A quality metric was used to steer the connection process of the DNA hits in a sorted order. This workflow enabled the user to extract a sequence of surfaces simultaneously, which is crucial in seismic stratigraphic interpretation.

The geological structure and distribution of Paleozoic rocks on the Avalon Platform, offshore Newfoundland

1987 ◽  
Vol 24 (7) ◽  
pp. 1412-1420 ◽  
Author(s):  
P. W. Durling ◽  
J. S. Bell ◽  
G. B. J. Fader
Keyword(s):  
Seismic Reflection ◽  
Single Channel ◽  
Geological Structure ◽  
Structural Mapping ◽  
Grand Banks ◽  
Seismic Reflection Profiles ◽  
Paleozoic Rocks ◽  
Seismic Reflections ◽  
Avalon Peninsula ◽  
Overthrust Belt

Single-channel seismic reflection profiles obtained across the Avalon Platform, offshore Avalon Peninsula, Newfoundland, have been studied for seismic reflections and interpreted in conjunction with lithologic and biostratigraphic data. Formline structural mapping revealed a 4000 m thick Ordovician–Silurian marine shale sequence that is gently folded about north-northwest–south-southeast axes and is unconformably overlain by a synclinal outlier of Devonian(?) redbeds approximately 700 m thick.The Avalon Platform on the Grand Banks may represent a mildly deformed Acadian terrane, which is contiguous with onshore Avalonian sequences, or it may be part of a foreland zone adjacent to an overthrust belt, or both.

scholarly journals A regional Alpine graphite décollement level beneath the NW Pannonian Basin

2019 ◽  
Vol 149 (3) ◽  
pp. 279 ◽  
Author(s):  
Gábor Csaba Tari ◽  
Viktória Németh ◽  
Ferenc Horváth † ◽  
Viktor Wesztergom
Keyword(s):  
Seismic Reflection ◽  
Pannonian Basin ◽  
Eastern Alps ◽  
Conductivity Anomaly ◽  
Seismic Reflection Data ◽  
Reflection Seismic ◽  
Reflection Data ◽  
Seismic Reflection Profiles ◽  
Seismic Reflectors ◽  
First Time

The so-called Transdanubian Conductivity Anomaly (TCA) of the Hungarian part of the NW Pannonian Basin has been well known for more than five decades. The exceptionally low resistivity (i.e. 1–2 Ωm) zone has a very large areal extent (on the order a few thousand km2) and it is an entirely subsurface anomaly occurring at depth between circa 3–15 km, with no corresponding outcrops. Various geological explanations of this enigmatic crustal-scale geophysical anomaly range from invoking sub-horizontal Alpine nappe contacts to sub-vertical dikes with graphite and/or saline fluid content. Only one possible analogue outcrop area was considered for the high conductivity anomaly so far, namely the Drauzug/Gailtal area of the Eastern Alps in Austria, some 300 km to the West from the TCA area. Previous attempts to find correspondence between the TCA and prominent seismic reflectors seen on 2D seismic reflection profiles were based on data acquired by research institutions. This study systematically correlates, for the first time, the TCA with 2D industry seismic reflection data in the same area. Our new results show a very strong correlation between the subsurface extent and location of the TCA with various sub-horizontally oriented Cretaceous Alpine nappe surfaces. In addition, we draw on the latest structural correlation of the Alpine nappe stack of the Transdanubian Range with its proper tectonic counterpart in the Eastern Alps.At the southern edge of the Upper Austroalpine units in northern Styria, in the Veitsch Nappe of the Greywacke Zone, numerous graphite localities are known historically. These laterally extensive graphite units in NW Styria formed as the result of greenschist-grade metamorphism of a Carboniferous coal sequence during the Cretaceous. For the first time, we describe here one well penetration of possibly age-equivalent graphitic units in NW Hungary. Correlation of the magnetotelluric anomaly with the distinct reflection seismic signature suggests that the same Palaeozoic graphitebearing Upper Austroalpine units should be present at 3–15 km depth in our study area.Therefore we propose that the best explanation for the observed extent and geometry of the TCA is the presence of graphite in subhorizontal, tectonically thinned detachment surfaces at the base of the Upper Austroalpine nappe edifice of NW Hungary

Sign in / Sign up

Export Citation Format

Share Document