scholarly journals Evolution of Sedimentary Basins as Recorded in Silica Concretions: An Example from the Ionian Zone, Western Greece

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 763
Author(s):  
Georgia Pe-Piper ◽  
David J. W. Piper ◽  
Nicolina Bourli ◽  
Avraam Zelilidis
Keyword(s):  
Sedimentary Basins ◽  
Black Shales ◽  
Fe Oxide ◽  
Basin Inversion ◽  
Clastic Rocks ◽  
Oxide Hydroxide ◽  
Novel Approach ◽  
Backscattered Electron ◽  
Diagenetic Minerals ◽  
Western Greece

Chert concretions in thick limestone successions preserve a more complete paragenetic sequence of diagenetic minerals than their host limestone and interbedded shale. The goal of this study was to test the possible presence of a high-temperature mineralising system in the Ionian basin of western Greece. Upper Cretaceous chert nodules were sampled at Araxos, where rocks are highly faulted and uplifted by salt diapirism, and on Kastos Island, on the flanks of a regional anticline. Chert concretions have microporosity produced by recrystallisation of opal to quartz and fractures produced in the brittle chert during basin inversion. Diagenetic mineral textures were interpreted from backscattered electron images, and minerals were identified from their chemistry. Diagenetic minerals in pores and veins include sedimentary apatite (francolite), dolomite, Fe-chlorite, Fe oxide-hydroxide mixtures, sphalerite, barite and calcite. Sphalerite is restricted to Araxos, suggesting that inferred basinal fluids were hotter and more saline than at Kastos. At Araxos, the Fe oxide-hydroxide also includes minor Cu, Zn, and Ni. Whether the transported metals were derived from sub-salt clastic rocks and basement, or from enriched Mesozoic black shales, is unclear. The effectiveness of this novel approach to understanding fluid flow history in thick limestone successions is validated.

scholarly journals Three-dimensional approach to understanding the relationship between the Plio-Quaternary stress field and tectonic inversion in the Triassic Cuyo Basin, Argentina

2015 ◽  
Vol 7 (1) ◽  
pp. 459-494
Author(s):  
L. Giambiagi ◽  
S. Spagnotto ◽  
S. M. Moreiras ◽  
G. Gómez ◽  
E. Stahlschmidt ◽  
...  
Keyword(s):  
Stress Field ◽  
Three Dimensional ◽  
Sedimentary Basins ◽  
Strike Slip ◽  
Stress Regime ◽  
Basin Inversion ◽  
Structural Style ◽  
Tectonic Inversion ◽  
The Impact ◽  
The Relationship

Abstract. The Cacheuta sub-basin of the Triassic Cuyo Basin is an example of rift basin inversion contemporaneous to the advance of the Andean thrust front, during the Plio-Quaternary. This basin is one of the most important sedimentary basins in a much larger Triassic NNW-trending depositional system along the southwestern margin of the Pangea supercontinent. The amount and structural style of inversion is provided in this paper by three-dimensional insights into the relationship between inversion of rift-related structures and spatial variations in late Cenozoic stress fields. The Plio-Quaternary stress field exhibits important N–S variations in the foreland area of the Southern Central Andes, between 33 and 34° S, with a southward gradually change from pure compression with σ1 and σ2 being horizontal, to a strike-slip type stress field with σ2 being vertical. We present a 3-D approach for studying the tectonic inversion of the sub-basin master fault associated with strike-slip/reverse to strike-slip faulting stress regimes. We suggest that the inversion of Triassic extensional structures, striking NNW to WNW, occurred during the Plio–Pleistocene in those areas with strike-slip/reverse to strike-slip faulting stress regime, while in the reverse faulting stress regime domain, they remain fossilized. Our example demonstrates the impact of the stress regime on the reactivation pattern along the faults.

Efficient gravity inversion of basement relief using a versatile modeling algorithm

Geophysics ◽  
2017 ◽  
Vol 82 (2) ◽  
pp. G23-G34 ◽  
Author(s):  
João B. C. Silva ◽  
Darcicléa F. Santos
Keyword(s):  
Gravity Anomaly ◽  
Region Of Interest ◽  
Sedimentary Basins ◽  
Density Contrast ◽  
Gravity Inversion ◽  
Deep Basin ◽  
Novel Approach ◽  
Green’S Operator ◽  
Translation Symmetry ◽  
Observation Position

We have developed a novel approach to compute, in an efficient and versatile way, the gravity anomaly produced by an arbitrary, discrete 3D distribution of density contrast. The method allows adjustable precision and is particularly suited for the interpretation of sedimentary basins. Because the gravity field decays with the square of the distance, we use a discrete Green’s operator that may be made much smaller than the whole study area. For irregularly positioned observations, this discrete Green’s operator must be computed just at the first iteration, and because each of its horizontal layers presents a center of symmetry, only one-eighth of its total elements need to be calculated. Furthermore, for gridded data on a plane, this operator develops translation symmetry for the whole region of interest and has to be computed just once for a single arbitrary observation position. The gravity anomaly is obtained as the product of this small operator by any arbitrary density contrast distribution in a convolution-like operation. We use the proposed modeling to estimate the basement relief of a [Formula: see text] basin with density contrast varying along [Formula: see text] only using a smaller Green’s operator at all iterations. The median of the absolute differences between relief estimates, using the small and a large operator (the latter covering the whole basin) has been approximately 9 m for a 3.6 km deep basin. We also successfully inverted the anomaly of a simulated basin with density contrast varying laterally and vertically, and a real anomaly produced by a steeply dipping basement. The proposed modeling is very fast. For 10,000 observations gridded on a plane, the inversion using the proposed approach for irregularly spaced data is two orders of magnitude faster than using an analytically derived fitting, and this ratio increases enormously with the number of observations.

scholarly journals Basin inversion and structural architecture as constraints on fluid flow and Pb-Zn mineralisation in the Paleo-Mesoproterozoic sedimentary sequences of northern Australia

2020 ◽  
Author(s):  
George M. Gibson ◽  
Sally Edwards
Keyword(s):  
Oil And Gas ◽  
Sedimentary Basins ◽  
Normal Faults ◽  
Northern Australia ◽  
Tectonic Event ◽  
Basin Inversion ◽  
Petroleum Systems ◽  
Sedimentary Sequences ◽  
Structural Architecture ◽  
Migration Pathways

Abstract. As host to several world-class sediment-hosted Pb-Zn deposits and unknown quantities of conventional and unconventional gas, the variably inverted 1730–1640 Ma Calvert and 1640–1580 Ma Isa superbasins of northern Australia have been the subject of numerous seismic reflection studies with a view to better understanding basin architecture and fluid migration pathways. Strikingly similar structural architecture has been reported from much younger inverted sedimentary basins considered prospective for oil and gas elsewhere in the world. Such similarities suggest that the mineral and petroleum systems in Paleo-Mesoproterozoic northern Australia may have spatially and temporally overlapped consistent with the observation that basinal sequences hosting Pb-Zn mineralisation in northern Australia are bituminous or abnormally enriched in hydrocarbons. This points to the possibility of a common tectonic driver and shared fluid pathways. Sediment-hosted Pb-Zn mineralisation coeval with basin inversion first occurred during the 1650–1640 Ma Riversleigh Tectonic Event towards the close of the Calvert Superbasin with further pulses accompanying the 1620–1580 Ma Isa Orogeny which brought about closure of the Isa Superbasin. Mineralisation in all cases is hosted by the syn-inversion fraction of basin fill, contrary to most existing interpretations of Pb-Zn ore genesis where the ore-forming fluids are introduced during the rifting or syn-extensional phase of basin development. Syn-extensional normal faults of Calvert and Isa age are mutually orthogonal, giving rise to a complex compartmentalisation of sub-basins with predominantly NNW and ENE strikes. Basin inversion subsequent to 1640 Ma occurred overall in a transpressive tectonic regime linked to continent-continent collision accompanied by orogen-parallel extensional collapse and right-stepping strike-slip faulting.

Visualizing Sub-Micron Burried Metal Line in VLSI Devices using a SEM

1997 ◽  
Vol 3 (S2) ◽  
pp. 499-500
Author(s):  
D. Drouin ◽  
P. Hovington ◽  
R. Gauvin ◽  
J. Beauvais
Keyword(s):  
Large Scale ◽  
Critical Dimension ◽  
Metal Line ◽  
Backscattered Electrons ◽  
Road Map ◽  
Novel Approach ◽  
Integrated Devices ◽  
Backscattered Electron ◽  
Microelectronics Industry ◽  
Year 2000

In recent years, the critical dimension in “Very Large Scale Integrated” devices has dramatically decreased. The microelectronics industry road map predicts that by the year 2000 the critical dimension will be below 250 nm. This reduction in scale will imply the development of new techniques to control the fabrication of such devices. This paper presents a novel approach to characterize VLSI devices based on Monte Carlo calculations. The principle of this technique is to use information from backscattered electrons (BE). The energies of those electrons are related to their maximum range within the structure. Thus it is possible to distinguish the layer from which they are backscattered. In order to collect this information an energy filtered backscattered electron detector must be used.Figure 1 shows a cross section of a structure produces using a typical VLSI process. The two metal layers are usually patterned to define small lines and contacts.

On the reactivation of extensional fault systems

1986 ◽  
Vol 317 (1539) ◽  
pp. 179-194 ◽  
Keyword(s):  
Large Fraction ◽  
Tectonic Setting ◽  
Sedimentary Basins ◽  
Shear Zones ◽  
Normal Faults ◽  
Basin Inversion ◽  
Fault Systems ◽  
Detachment Faults ◽  
Southeastern Australia ◽  
Transfer Faults

In terranes that have undergone substantial extension, three sets of faults dominate: ( a ) shallow- to steep-dipping, commonly rotational normal faults; ( b ) a really extensive, shallow-dipping, normal detachment faults; and ( c ) steep-dipping transfer faults that strike at high angles to the normal faults. These fault systems may extend through a large fraction of the crust. Reactivation of these fault systems will depend primarily on the relative strengths of the faults (shear zones) and their host rock, and their orientation in the prevailing stress field. It is concluded that reactivation is generally mechanically favoured, but that it will probably only take place when the fault-shear zones are in near-ideal orientations. Consideration of the tectonic setting of extended terranes and of the limited number of well described examples suggests that reverse (thrust) reactivation of the normal and detachment faults and wrench reactivation of transfer faults are the most likely styles. Examples of these styles are described from the Bass Strait Basins of southeastern Australia. Because extended terranes commonly underlie sedimentary basins (for example, on passive continental margins), reactivation of extensional faults may be a key control on the tectonic evolution of such basins (i.e. basin inversion).

Hydrocarbon‐generation‐induced microcracking of source rocks

Geophysics ◽  
1994 ◽  
Vol 59 (4) ◽  
pp. 555-563 ◽  
Author(s):  
Lev Vernik
Keyword(s):  
Pore Pressure ◽  
Principal Stress ◽  
Sedimentary Basins ◽  
Confining Pressure ◽  
Black Shales ◽  
Source Rocks ◽  
P Wave ◽  
Hydrocarbon Generation ◽  
S Wave

Laboratory measurements of ultrasonic velocity and anisotropy in kerogen‐rich black shales of varying maturity suggest that extensive, bedding‐parallel microcracks exist in situ in most mature source rocks undergoing the major stage of hydrocarbon generation and migration. Given the normal faulting regime with the vertical stress being the maximum principal stress typical of most sedimentary basins, this microcrack alignment cannot be accounted for using simplified fracture mechanics concepts. This subhorizontal microcrack alignment is consistent with (1) a model of local principal stress rotation and deviatoric stress reduction within an overpressured formation undergoing hydrocarbon generation, and with (2) a strong mechanical strength anisotropy of kerogen‐rich shales caused by bedding‐parallel alignment of kerogen microlayers. Microcracks originate within kerogen or at kerogen‐illite interfaces when pore pressure exceeds the bedding‐normal total stress by only a few MPa due to the extremely low‐fracture toughness of organic matter. P‐wave and, especially, S‐wave anisotropy of the most mature black shales, measured as a function of confining pressure, indicate the effective closure pressure of these microcracks in the range from 10 to 25 MPa. Estimates of pore pressure cycles in the matrix of the active hydrocarbon‐generating/expelling part of the source rock formation show that microcracks can be maintained open over the sequence of these cycles and hence be detectable via high‐resolution in‐situ sonic/seismic studies.

scholarly journals Comparison of the contribution of differently depth geological processes in the formation of a trace elements characteristic of caustobiolites

Georesursy ◽  
2019 ◽  
Vol 21 (3) ◽  
pp. 14-24 ◽  
Author(s):  
Svetlana A. Punanova ◽  
Mikhail V. Rodkin
Keyword(s):  
Trace Elements ◽  
Chemical Composition ◽  
Lower Crust ◽  
Oil And Gas ◽  
Sedimentary Basins ◽  
Black Shales ◽  
Average Chemical Composition ◽  
Gas Field ◽  
Geological Processes ◽  
Coal Fuel

The article analyzes the correlation dependences between the logarithms of the concentrations of trace elements (TE) in various geochemical environments (oil, coal, fuel and black shales, as well as in clays, organic matter (OM) of various types and biota) in comparison with the average chemical composition of the upper, middle and lower continental crust. At the same time, along with the TE content of oils of the main oil and gas basins (OGB) – the Volga-Ural and West Siberian ones, the data on the TE content in the so-called young oils were summarized; as such, data on the oil fields of the West Kamchatka oil and gas field and oil manifestations in the area of ​​the caldera of the Uzon volcano were used. Particular attention was also paid to the results of the analysis of the TE composition of the oils of the Romashkino group of fields, as it is possible that they are subject to the influence of deep-seated processes. The correlation coefficients between the studied parameters for the various studied oil- and gas-generating basins, including for the Romashkino group of fields, turned out to be close. For all oils, except for the young oils of Kamchatka and the caldera of the Uzon volcano, a closer connection of their TE composition with the TE composition of the lower crust was revealed. For young oils of the Uzon caldera in Kamchatka, this trend is absent, and a slightly closer relationship is revealed with the average composition of the upper but not lower crust, while for statistically more reliable data on the TE composition of the hydrothermal waters of the caldera of the Uzon volcano, a significantly closer relationship is observed with the average chemical composition of the middle and upper crust. Based on the identified correlations between the TE compositions of oil, caustobioliths and the crust of different levels, conclusions are made about the likely relationship between biogenic and deep processes in the formation of oil and gas fields. According to the authors, the obtained results support the crucially important role in the processes of naphthidogenesis of the upward flows of the low crustal fluids with the dominant source of hydrocarbons from the initial OM of sedimentary basins.

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