Tectonic Deformation in the Upper Crust and Sediments at the South Shetland Trench

2013 ◽  
pp. 157-166
Author(s):  
Y. Kim ◽  
H.-S. Kim ◽  
R. D. Larter ◽  
A. Camerlenghi ◽  
L. A. P. Gambôa ◽  
...  
Keyword(s):  
Tectonic Deformation ◽  
Upper Crust ◽  
The South ◽  
South Shetland Trench

Structure and tectonic evolution of the South Patagonian fold and thrust belt: Coupling between subduction dynamics, climate and tectonic deformation

2019 ◽  
pp. 675-697
Author(s):  
Matías C. Ghiglione ◽  
Gonzalo Ronda ◽  
Rodrigo J. Suárez ◽  
Inés Aramendía ◽  
Vanesa Barberón ◽  
...  
Keyword(s):  
Tectonic Evolution ◽  
Tectonic Deformation ◽  
Thrust Belt ◽  
The South ◽  
Fold And Thrust Belt

Chapter 3.2b Bransfield Strait and James Ross Island: petrology

2021 ◽  
pp. M55-2018-37 ◽  
Author(s):  
Karsten M. Haase ◽  
Christoph Beier
Keyword(s):  
Antarctic Peninsula ◽  
South Shetland Island ◽  
The South ◽  
Bransfield Strait ◽  
Geodynamic Processes ◽  
James Ross Island ◽  
South Shetland Trench ◽  
Low Degrees ◽  
Back Arc ◽  
The Antarctic

AbstractYoung volcanic centres of the Bransfield Strait and James Ross Island occur along back-arc extensional structures parallel to the South Shetland island arc. Back-arc extension was caused by slab rollback at the South Shetland Trench during the past 4 myr. The variability of lava compositions along the Bransfield Strait results from varying degrees of mantle depletion and input of a slab component. The mantle underneath the Bransfield Strait is heterogeneous on a scale of approximately tens of kilometres with portions in the mantle wedge not affected by slab fluids. Lavas from James Ross Island east of the Antarctic Peninsula differ in composition from those of the Bransfield Strait in that they are alkaline without evidence for a component from a subducted slab. Alkaline lavas from the volcanic centres east of the Antarctic Peninsula imply variably low degrees of partial melting in the presence of residual garnet, suggesting variable thinning of the lithosphere by extension. Magmas in the Bransfield Strait form by relatively high degrees of melting in the shallow mantle, whereas the magmas some 150 km further east form by low degrees of melting deeper in the mantle, reflecting the diversity of mantle geodynamic processes related to subduction along the South Shetland Trench.

scholarly journals Evaluation of crustal inhomogeneity parameters in the southern Longmenshan fault zone and adjacent regions

2020 ◽  
Vol 24 (6) ◽  
pp. 1175-1188
Author(s):  
Xiao-Ping Fan ◽  
Yi-Cheng He ◽  
Cong-Jie Yang ◽  
Jun-Fei Wang
Keyword(s):  
Fault Zone ◽  
Lower Crust ◽  
Tectonic Deformation ◽  
Upper Crust ◽  
Crust And Upper Mantle ◽  
Study Region ◽  
Waveform Data ◽  
Longmenshan Fault Zone ◽  
Deformation Features ◽  
Longmenshan Fault

AbstractBroadband teleseismic waveform data from 13 earthquakes recorded by 70 digital seismic stations were selected to evaluate the inhomogeneity parameters of the crustal medium in the southern Longmenshan fault zone and its adjacent regions using the teleseismic fluctuation wavefield method. Results show that a strong inhomogeneity exists beneath the study region, which can be divided into three blocks according to its structure and tectonic deformation features. These are known as the Sichuan-Qinghai Block, the Sichuan-Yunnan Block, and the Mid-Sichuan Block. The velocity fluctuation ratios of the three blocks are approximately 5.1%, 3.6%, and 5.1% in the upper crust and 5.1%, 3.8%, and 4.9% in the lower crust. The inhomogeneity correlation lengths of the three blocks are about 10.1 km, 14.0 km, and 10.7 km in the upper crust and 11.8 km, 17.0 km, and 11.8 km in the lower crust. The differences in the crustal medium inhomogeneity beneath the Sichuan-Yunnan Block, the Sichuan-Qinghai Block, and the Mid-Sichuan Block may be related to intensive tectonic movement and material flow in the crust and upper mantle.

On the depth of crater excavation and melting during the Sudbury impact: geochemical evidence from chilled impact melt dykes

2020 ◽  
Author(s):  
Alexander Kawohl ◽  
Hartwig E. Frimmel ◽  
Wesley E. Whymark ◽  
Andrejs Bite
Keyword(s):  
Continental Crust ◽  
Bulk Composition ◽  
Geochemical Data ◽  
Tectonic Deformation ◽  
Target Area ◽  
Upper Crust ◽  
Igneous Complex ◽  
Impact Melt ◽  
Sudbury Igneous Complex ◽  
The Impact

<p>The 1.85 Ga Sudbury Igneous Complex, Canada, is the remnant of a ~3 km thick impact-generated crustal melt sheet, caused by a 10-15 km large chondritic asteroid or comet that had left behind an impact structure of ~200 km prior to tectonic deformation und subsequent erosion. However, less is known about how deep the impactor penetrated the continental crust and where the source of the impact melt was. Mixing models including radioisotopes and trace elements on locally exposed country rocks have been used to evaluate their relative contribution to the impact melt. Based on this, Darling et al. (2010) have argued for shallow melting of the upper crust (UCC) only, either due to an oblique impact and/or a low-density bolide (comet). In contrast, the abundance of siderophile elements in impact melt-rocks was taken as evidence of a lower crustal source (Mungall et al. 2004), i.e. overlying rocks of the middle and upper crust must have been removed during the crater excavation stage. U-Pb age data on zircon xenocrysts also point to the involvement of rock types not exposed on surface (Petrus et al. 2016) in agreement with theoretical simulations, which have predicted a >20 km deep but unstable transient cavity (Ivanov & Deutsch 1999).</p><p>Large-scale (10s of km) and well-exposed impact melt dykes are a unique feature of Sudbury. The dykes are of granodioritic/quartz dioritic composition and are interpreted as clast-laden melt injections into the basement instantaneously after the impact (Pilles et al. 2018). Their vitric margins and distal extremities should therefore approximate the undifferentiated bulk composition of the Sudbury Igneous Complex prior to sulfide saturation. A compilation of published and new geochemical data of these dykes reveal a remarkably strong affinity (r<sup>2</sup> >0.989) to the average middle continental crust (MCC) as given by Rudnick & Gao (2014), especially in terms of major elements and fluid-immobile transition metals (Th, Zr, Hf, Nb, Ta, Ti, Sc, REE). The dykes are, however, significantly enriched in Ni, Cu and Cr, and to a lesser extent in V, Co and P relative to the typical UCC and MCC. A systematic loss of volatiles (Tl, Cd, Sn, Zn, Pb, Ag, Cs, Rb, Na, K, Ga, As) compared to either crustal model is not evident. These new observations favour a scenario in which the impactor and supracrustal rocks in the target area became vaporized and ejected. Shock melting affected predominantly the middle crust of the Canadian Shield. We also propose that the rocks that contributed to the impact melt were, on average, more mafic than the typical UCC and MCC. This is consistent with the report of exotic mafic-ultramafic xenoliths within the Sudbury Igneous Complex (Wang et al. 2018) and its anomalously high PGE concentrations (Mungall et al. 2004). (Ultra-)mafic rocks hidden at mid-crustal depth were a likely source of Ni-Cu-PGE-Co and gave rise to world class ore deposits presently mined at Sudbury. Such (ultra-)mafic intrabasement body might also explain the 1200 km<sup>2</sup> Temagami magnetic anomaly in the eastern vicinity of the Sudbury Complex.</p>

The transition from an active to a passive margin (SW end of the South Shetland Trench, Antarctic Peninsula)

2003 ◽  
Vol 366 (1-2) ◽  
pp. 55-81 ◽  
Author(s):  
Antonio Jabaloy ◽  
Juán-Carlos Balanyá ◽  
Antonio Barnolas ◽  
Jesús Galindo-Zaldı́var ◽  
F.Javier Hernández-Molina ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
Passive Margin ◽  
The South ◽  
South Shetland Trench

From rifting to drifting: tectonic evolution of the South-Alpine upper crust from the Triassic to the Early Cretaceous

1993 ◽  
Vol 86 (1-2) ◽  
pp. 53-76 ◽  
Author(s):  
Giovanni Bertotti ◽  
Vincenzo Picotti ◽  
Daniel Bernoulli ◽  
Alberto Castellarin
Keyword(s):  
Early Cretaceous ◽  
Tectonic Evolution ◽  
Upper Crust ◽  
The South

Research progress on the Zhongnan-Liyue Fault Zone in the South China Sea Basin

2020 ◽  
Author(s):  
Ziying Xu ◽  
Jun Wang ◽  
Hongfang Gao ◽  
Yongjian Yao
Keyword(s):  
Spatial Distribution ◽  
South China Sea ◽  
Fault Zone ◽  
South China ◽  
The South China Sea ◽  
Magnetic Data ◽  
Tectonic Deformation ◽  
The South ◽  
China Sea ◽  
The North

<p>We give a review of the up-to-date research situation about The Zhongnan-Liyue Fault Zone (ZLFZ), than analyze the spatial distribution and tectonic deformation feature of the ZLFZ based on the geophysical data including topographic, seismic, gravity and magnetic data. The results show that the ZLFZ has obvious north-south segmentation characteristics in in the South China Sea Basin. The north section, which is between northwest sub-basin and east sub-basin, is a narrow zone with the width of ~16 km, and is NNW trend from 18°N,115.5°E to 17.5°N,116°E. Meanwhile ,the south section, which is between southwest sub-basin and east sub-basin, is a wide zone with the width of 60-80 km, and is NNW trend from the east of ZhongshaBank to the west of LiyueBank. The main fault of the ZLFZ is NNW trend along the seamounts ridge of Zhongnan. the ZLFZ of transition region is NNE trend from the north section to the south section. According the sub-basin’s sedimentary thickness and oceanic crust thickness exist obvious difference, on both sides of the ZLFZ, we speculate that the ZLFZ play an important role on geological structure of sub-basin. According to the chang of crustal structure, We speculate that the ZLFZ is at least a crustal fracture zone.</p><p><strong>Key words: </strong>South China Sea Basin; Zhongnan-Liyue Fault Zone; Spatial distribution; Tectonic deformation<strong> </strong></p><p><strong>Foundation item:</strong> National Natural Science Foundation of China (41606080, 41576068); The China Geological Survey Program (GZH201400202, 1212011220117, DD20160138, 1212011220116).</p>

Fracture lineaments, fault mesh formation and seismicity

2009 ◽  
Vol 42 (1) ◽  
pp. 63-72 ◽  
Author(s):  
Tariq I.H. Rahiman ◽  
Jarg R. Pettinga
Keyword(s):  
Land Surface ◽  
Seismic Reflection ◽  
Late Quaternary ◽  
Statistical Tests ◽  
Tectonic Deformation ◽  
Upper Crust ◽  
Offshore Area ◽  
Seismic Reflection Data ◽  
Spatial Continuity ◽  
Regional Tectonic

Viti Levu, the main island of Fiji, is located in a seismically active area within the Fiji Platform, a remnant island arc that lies in a diffuse plate boundary zone between the Pacific and Australian tectonic plates in the SW Pacific. The upper crust of Viti Levu is dissected by numerous intersecting fault/lineament zones mapped from remote sensing imagery of the land surface (topography, radar and aerial photos) and basement (magnetic) and have been subject to rigorous statistical tests of reproducibility and verification with field mapped fault data. Lineaments on the various imagery correlate with faults mapped in the field, and show spatial continuity between and beyond mapped faults, thereby providing a fuller coverage of regional structural patterns than previously known. Some fault/lineaments zones extend beyond the coastline to the offshore area from the SE Viti Levu study area. Multibeam bathymetry and seismic reflection data show the fault zones occur along and exert control on the location of a number of submarine canyons on the SE slope of Viti Levu. Evidence for Late Quaternary fault activity is only rarely observed in onshore SE Viti Levu (e.g. by displaced shoreline features), and in seismic reflection profiles from offshore. The principal fault sets in Viti Levu represent generations of regional tectonic faulting that pervade the Fiji Platform during and after the disruption of the proto Fijian arc in the Middle to Late Miocene (~15Ma). These fault sets combine to form a complex network of interlocking faults creating a fault mesh that divides the upper crust into a number of fault blocks ranging from ~2-30 km wide. It is inferred that the fault mesh evolved throughout the Neogene as a response to the anticlockwise rotation of the Fiji Platform through progressive development of different fault sets and intervening crustal block rotations. Regional tectonic deformation is presently accommodated in a distributed manner through the entire fault mesh. Low magnitude earthquakes (<M4) occur regularly and may represent ruptures along short linking segments of the fault mesh, while infrequent larger earthquakes (>M4) may result from complex rupture propagation through several linking fault segments of the mesh that lie close to optimum stress orientations. The interpreted model of distributed deformation through the fault mesh for the study area in SE Viti Levu is inferred to be characteristic of the style of active deformation that occurs throughout the entire Fiji Platform.

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