The granites of northern Patagonia and the Gastre Fault System in relation to the break-up of Gondwana

The under-explored Carnarvon Terrace is situated offshore of the Cape Range area in the Carnarvon Basin near the boundary of the Gascoyne and Exmouth Sub-basins. The stratigraphy of the area is controlled by only two wells (Pendock-1, Yardie East-1), but several onshore wells aid interpretation of seismic data.Understanding of the structural evolution of the region is facilitated by interpretation of a high-resolution non-exclusive seismic survey acquired by Geco-Prakla in 1993 (GPCTR-93 Survey).Three major tectonic stages are responsible for the structural configuration of the region:Late Palaeozoic extension in the Gascoyne Sub-basin;continental break-up between Australia and Greater India which took place along a major fracture marked by the Flinders-Long Island-Learmonth fault system active in Late Triassic and Early Jurassic times; andthe collision between Australia and Asia that commenced in Miocene times and is continuing to the present day. This event, marked by wrench and compressional structures, and often reactivation of older structures, is one of the most economically important in Australian geological history.From a regional prospectivity viewpoint at least three plays are worthy of further investigation.

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Mechanisms of continental break-up : tectonic, stratigraphic and structural constraints from a preserved distal rifted margin (Agly massif, eastern Pyrenees)

10.5194/egusphere-egu2020-21580 ◽

2020 ◽

Author(s):

Martin Motus ◽

Yoann Denèle ◽

Frédéric Mouthereau ◽

Élise Nardin

Keyword(s):

Cross Sections ◽

Scale Space ◽

Depositional Environments ◽

Fault System ◽

Distal Margin ◽

Structural Constraints ◽

Strain Partitioning ◽

Tectonic Model ◽

Deep Crust ◽

Break Up

The Agly massif and its neighboring Mesozoic basins altogether form part of the Pyrenean Cretaceous rift preserved in the retro-wedge of the Pyrenean mountain belt. The relationships between the tectonic evolution of these syn-rift basins and the crustal-scale tectonic processes allows us to investigate the strain partitioning, the rheology and the sequence of deformation associated with the thinning of the deep crust leading to continental break-up.Based on structural, microstructural and thermochronological studies of the deep crust of the Agly massif and the revised stratigraphy and depositional environments of the pre- and syn-rift sedimentary rocks, we propose a tectonic reconstruction of the eastern segment of the Pyrenean rift at the time of continental break-up. Two parallel cross sections allow us to discuss about the mechanical behavior of the deep crust and the control by lateral rheological heterogeneities on the spatial and temporal evolution of rifting. We emphasize the role of low-angle (decollement) and high-angle (detachment) extensional structures in the deep crust that collectively accommodate thinning and exhumation, respectively. Structural relationships between the Variscan basement and the Mesozoic basins are highlighted, such as a major extensional detachment fault system exhuming the mantle at the contact between the Agly massif and the Boucheville basin in the south. We further discuss the origin of tectono-sedimentary breccias in the context of crustal-scale thinning/exhumation processes and basins evolution.Our different results are finally integrated in a 3D tectonic model of the distal margin, illustrating a crustal scale space-time vision of the mechanisms leading to continental break-up.

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SEM study of quartz grains from recent sediments: Western Iraq

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010017743x ◽

1990 ◽

Vol 48 (4) ◽

pp. 860-861

Author(s):

F. Al-Kufaishi

Keyword(s):

Factor Loading ◽

Fault System ◽

Clay Material ◽

Crustal Material ◽

Factor Analyses ◽

Five Factors ◽

Sem Study ◽

Recent Sediments ◽

Quartz Grains ◽

Positive Factor

Two localities (Al-Marij and Laik) were selected to investigate the type of Quartz Grains from crustal material formed by evaporation of waters discharged by springs in Hit area, western Iraq, Previous studies on the crustal material (1,2) showed that the water discharged by these springs are associated with Abu-Jir fault system which run parallel to the Euphrates river,Factor analyses of the crustal and soil materials (50 samples analysed for 16 variables)(2) showed five factors; the first factor includes SiO2, Al2O3 and TiO2 with positive factor loading, and CaO, L.O.I. with negative loading and hence lead to the conclusion that the distribution of these variables is a reflection of transported clay material.This study concentrates on the use of SEM to investigate the contribution of Quartz grains found in the crustal material on two selected sites.

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