scholarly journals Feathery and network-like filamentous textures as indicators for the crystallization of quartz from a silica gel precursor at the Rusey Fault, Cornwall, UK

2016 ◽  
Author(s):  
Tim I. Yilmaz ◽  
Florian Duschl ◽  
Danilo Di Genova
Keyword(s):  
Raman Spectroscopy ◽  
Shear Zone ◽  
Fault Zone ◽  
Silica Gel ◽  
Blue Luminescence ◽  
Quartz Crystals ◽  
Violet Luminescence ◽  
Icp Ms ◽  
Weak Peak

Abstract. Quartz crystals from a hydrothermal shear-zone-hosted quartz deposit (Rusey Fault, Cornwall, UK) show feathery textures and network-like filamentous textures. Optical hot-cathodoluminescence (CL) analysis and LA-ICP-MS investigations on quartz samples revealed that positions exhibiting feathery textures (violet luminescence) incorporate higher amounts of Ca, As, Na, Mg, and K than quartz positions without feathery textures (blue luminescence). Raman spectroscopy investigations revealed the presence of a weak peak ("shoulder") at 507–509 cm−1 in quartz affected by feathery textures, which we attribute to the presence of moganite, a microcrystalline silica variety. The combined occurrence of feathery textures and network-like filamentous textures in quartz samples from the Rusey fault zone points to the presence of a silica gel precursor before or during the crystallization.

scholarly journals Feathery and network-like filamentous textures as indicators for the re-crystallization of quartz from a metastable silica precursor at the Rusey Fault Zone, Cornwall, UK

Solid Earth ◽  
2016 ◽  
Vol 7 (6) ◽  
pp. 1509-1519 ◽  
Author(s):  
Tim I. Yilmaz ◽  
Florian Duschl ◽  
Danilo Di Genova
Keyword(s):  
Fault Zone ◽  
Inductively Coupled Plasma ◽  
Quartz Crystals ◽  
Inductively Coupled ◽  
Hydrothermal Quartz ◽  
Violet Luminescence ◽  
Icp Ms ◽  
Plasma Mass Spectrometry ◽  
Silica Precursor ◽  
Weak Peak

Abstract. Hydrothermal quartz crystals, which occur in the Rusey Fault Zone (Cornwall, UK), show feathery textures and network-like filamentous textures. Optical hot-cathodoluminescence (CL) analysis and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) investigations on quartz samples revealed that positions exhibiting feathery textures (violet luminescence) contain higher amounts of Al and Li than quartz positions without feathery textures (blue luminescence), while concentrations of Al and Li are significantly lower in feathery textures. Both Al and Li correlate negatively with Si. Raman spectroscopy investigations revealed the presence of a weak peak at 507–509 cm−1 in quartz affected by feathery textures, which we attribute to the presence of  ≤  5 % moganite, a microcrystalline silica polymorph, intergrown with chalcedony. The combined occurrence of feathery textures and network-like filamentous textures in quartz samples from the Rusey Fault Zone points to the presence of a metastable silica precursor (i.e., amorphous silica or silica gel) before or during the crystallization.

Ten-million years of activity within the Eastern California Shear Zone from U–Pb dating of fault-zone opal

2019 ◽  
Vol 521 ◽  
pp. 37-45 ◽  
Author(s):  
Perach Nuriel ◽  
David M. Miller ◽  
Kevin M. Schmidt ◽  
Matthew A. Coble ◽  
Kate Maher
Keyword(s):  
Shear Zone ◽  
Fault Zone ◽  
Eastern California Shear Zone

Carbon ordering in an aseismic shear zone: implications for crustal weakening and Raman spectroscopy

2020 ◽  
Author(s):  
Lauren Kedar ◽  
Clare Bond ◽  
David Muirhead
Keyword(s):  
Raman Spectroscopy ◽  
Organic Carbon ◽  
Shear Zone ◽  
Experimental Studies ◽  
Carbonaceous Material ◽  
Shear Zones ◽  
Lower Limbs ◽  
Strain Partitioning ◽  
Increasing Temperature ◽  
Two Peaks

<p>Multi-layered stratigraphic sequences present ample opportunity for the study of strain localization and its complexities. By constraining mechanisms of crustal weakening, it is possible to gain a sounder understanding of the dynamic evolution of the Earth’s crust, especially when applied to realistic, field-based scenarios. One such mechanism is that of strain-related carbon ordering. This is the process whereby the amorphous nanostructure of fossilized organic matter contained within the rock is progressively organized towards a more sheet-like structure, similar to that of graphite. One common method of studying this process is through Raman spectroscopy. This is a non-destructive tool which makes use of the relative positions and intensities of two key spectral peaks, where one peak represents graphitic carbon and the other disordered (or amorphous) carbon. The intensity ratio between these two peaks suggests the degree to which the carbon has progressed from its original kerogen-like structure towards that of graphite. This progression can be due to increasing temperature or increasing strain, and until now, these two contributory factors have been difficult to separate, particularly in field examples.</p><p>Previous field-based studies have focused on carbon ordering on fault planes, while experimental studies have monitored the effects of strain-related ordering in organic carbon on both fault surfaces and more distributed shear zones. These studies confirmed the occurrence of strain-related ordering at seismic rates, particularly in the form of graphitization of carbon. However, these experiments showed the effects of strain-related ordering at aseismic rates to be limited when distributed shear zones were considered, in part due to the geological timescales required to emulate true conditions.</p><p>In this study, Raman spectroscopy is used to compare the relative nanostructural order of organic carbon within a recumbent isoclinal fold formed of interbedded limestones and marls. The central, overturned fold limb forms a 170m wide, 1km long aseismic shear zone, with evidence of increased strain recorded in calcite grains relative to the upper and lower limbs. Raman spectroscopy intensity ratios (I[d]/I[g]) are compared across the fold, showing a marked 23% decrease in the overturned limb. Such a decrease in I[d]/I[g] suggests increased carbon ordering within the overturned limb, which in combination with evidence for increased strain in calcite, suggests that the carbon ordering here is derived directly from strain-related ordering. This has important implications. We infer, from previous studies, that strain-related carbon ordering encourages further strain partitioning in carbonaceous material, and may enhance zones of weakness in the rock. This ordering in aseismic shear zones has so far been unreported in nature, and so our field-based results are significant in supporting previous experimental evidence for this phenomenon. Our results also have implications for understanding dynamic crustal evolution, and will play an important role in the development of Raman thermobarometry, especially since current methods do not distinguish between strain-related and temperature-related ordering.</p>

l-Cysteine Functionalized Silica Gel as an Efficient Adsorbent for the Determination of Heavy Metals in Foods by ICP-MS

2014 ◽  
Vol 8 (7) ◽  
pp. 1785-1793 ◽  
Author(s):  
Cuicui Liu ◽  
Shaoyuan He ◽  
Kun Shen ◽  
Xue Feng ◽  
Guozhen Fang ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Silica Gel ◽  
Functionalized Silica ◽  
Icp Ms ◽  
Efficient Adsorbent

scholarly journals Middle to Late Devonian–Carboniferous collapse basins on the Finnmark Platform and in the southwesternmost Nordkapp basin, SW Barents Sea

Solid Earth ◽  
2018 ◽  
Vol 9 (2) ◽  
pp. 341-372 ◽  
Author(s):  
Jean-Baptiste P. Koehl ◽  
Steffen G. Bergh ◽  
Tormod Henningsen ◽  
Jan Inge Faleide
Keyword(s):  
Shear Zone ◽  
Fault Zone ◽  
Large Scale ◽  
Barents Sea ◽  
Normal Fault ◽  
Early Carboniferous ◽  
Normal Displacement ◽  
Late Devonian ◽  
The North ◽  
Caledonian Orogeny

Abstract. The SW Barents Sea margin experienced a pulse of extensional deformation in the Middle–Late Devonian through the Carboniferous, after the Caledonian Orogeny terminated. These events marked the initial stages of formation of major offshore basins such as the Hammerfest and Nordkapp basins. We mapped and analyzed three major fault complexes, (i) the Måsøy Fault Complex, (ii) the Rolvsøya fault, and (iii) the Troms–Finnmark Fault Complex. We discuss the formation of the Måsøy Fault Complex as a possible extensional splay of an overall NE–SW-trending, NW-dipping, basement-seated Caledonian shear zone, the Sørøya–Ingøya shear zone, which was partly inverted during the collapse of the Caledonides and accommodated top–NW normal displacement in Middle to Late Devonian–Carboniferous times. The Troms–Finnmark Fault Complex displays a zigzag-shaped pattern of NNE–SSW- and ENE–WSW-trending extensional faults before it terminates to the north as a WNW–ESE-trending, NE-dipping normal fault that separates the southwesternmost Nordkapp basin in the northeast from the western Finnmark Platform and the Gjesvær Low in the southwest. The WNW–ESE-trending, margin-oblique segment of the Troms–Finnmark Fault Complex is considered to represent the offshore prolongation of a major Neoproterozoic fault complex, the Trollfjorden–Komagelva Fault Zone, which is made of WNW–ESE-trending, subvertical faults that crop out on the island of Magerøya in NW Finnmark. Our results suggest that the Trollfjorden–Komagelva Fault Zone dies out to the northwest before reaching the western Finnmark Platform. We propose an alternative model for the origin of the WNW–ESE-trending segment of the Troms–Finnmark Fault Complex as a possible hard-linked, accommodation cross fault that developed along the Sørøy–Ingøya shear zone. This brittle fault decoupled the western Finnmark Platform from the southwesternmost Nordkapp basin and merged with the Måsøy Fault Complex in Carboniferous times. Seismic data over the Gjesvær Low and southwesternmost Nordkapp basin show that the low-gravity anomaly observed in these areas may result from the presence of Middle to Upper Devonian sedimentary units resembling those in Middle Devonian, spoon-shaped, late- to post-orogenic collapse basins in western and mid-Norway. We propose a model for the formation of the southwesternmost Nordkapp basin and its counterpart Devonian basin in the Gjesvær Low by exhumation of narrow, ENE–WSW- to NE–SW-trending basement ridges along a bowed portion of the Sørøya-Ingøya shear zone in the Middle to Late Devonian–early Carboniferous. Exhumation may have involved part of a large-scale metamorphic core complex that potentially included the Lofoten Ridge, the West Troms Basement Complex and the Norsel High. Finally, we argue that the Sørøya–Ingøya shear zone truncated and decapitated the Trollfjorden–Komagelva Fault Zone during the Caledonian Orogeny and that the western continuation of the Trollfjorden–Komagelva Fault Zone was mostly eroded and potentially partly preserved in basement highs in the SW Barents Sea.

scholarly journals Results of the reinterpretation of materials of IV geotraverse of NHS (PK 295- 400) in the central part of the Holovanivsk suture zone

2021 ◽  
pp. 58-64
Author(s):  
O.A. Trypolsky ◽  
◽  
O.V. Topoliuk ◽  
O.O. Trypolska ◽  
O.B. Gintov ◽  
...  
Keyword(s):  
Shear Zone ◽  
Fault Zone ◽  
Deep Structure ◽  
Suture Zone ◽  
The Body ◽  
Intrusive Body ◽  
Seismic Section ◽  
Supply Channel ◽  
Host Rocks ◽  
The Given

This work provides the reinterpretation results of the research outcomes with the DSS method on geotraverse IV on section PK 295-400 in order to clarify a seismic section in the Holovanivsk area of high gravity. A number of points of diffraction and seismic sites have been identified in Earth’s crust (at a depth of 2-60 km), which gives an opportunity to considerably specify the data on the deep structure of the studied area. The position in a section of the Talnivska fault zone is clarified due to the identification of additional points of diffraction and a large number of short reflective elements at a depth of 2-8 km. In the central part of the section (PK 338-355), horizontal and inclined elements (at the depths of 2-9 km and 24-44 km) and a series of short steeply inclined reflective elements (at depths of 8-26 km) form the area of the medium which at the depth of 2-44 km differs in its characteristics from the host rocks. This allowed tracing the listriс shear zone that stretches continuously from a depth of 8 km on PK 355 to 44 km on PK 304. All this, as well as available seismotomographic data, allows us to suppose that the Talnivska fault zone is traced up to depths of 100-600 km as a boundary between blocks with different Vp velocities and degrees and gaps in the Golitsyn—Geiko layer. The listriс shear zone is connected to the main part of the Talnivska fault zone near the surface. According to the given re-interpretation of GSS data on geotraverse IV, the supply channel of the intrusive body of hyperbasites is rather narrow at depths of 60-33 km, and starting only from depth of 30 km and almost to the surface the body expands up to 15 km in width. Focusing on the area of increased Vp velocities at a depth of 2-33 km, one can assume that the main intrusive body that consists of hyperbasites and basite-Dunites, peridotites, pyroxenites, gabbro, and amphibolites, the density of which exceeds the density of rocks by 0.1-0.22 g/cm3, is located at these depths along the axis of the central part of the Holovanivsk suture zone.

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