Wyniki wyszukiwania - BazTech

1

Appraisal of lineaments patterns and crustal architectures around the Owen fracture zone, Arabian Sea, using global gravity model data

Narayan Satya, Kumar Ujjawal, Sahoo Soumyashree Debasis, Pal Sanjit Kumar

Acta Geophysica

|

2024

|

Vol. 72, no. 1

29--48

EN

This study evaluates the efficacy of GECO gravity data for geophysical studies, mapping structural and tectonic features and their impact on gravity signatures in the study area. Computed correlation coefficient (96-98%), root-mean-square error (5.1-5.3 mGal), and standard deviation (3.9-4.2 mGal) between the GECO model-derived and ship-borne free-air gravity reveal the efficacy of the GECO gravity data for the geophysical studies in the region. A total horizontal derivative approach was used in order to enhance the residual and regional responses of the Bouguer gravity anomaly. The shorter-wavelength lineaments originated from subsurface mass heterogeneities were found trending in the northwest direction, subsequently east, north-northeast and east-northeast directions. In contrast, the longer-wavelength lineaments originating from deep-seated mass heterogeneities dominated in the east-northeast direction, followed by north-northeast and northwest directions. Lineaments occurring at shallower depths are associated with sedimentary/basement columns and could be utilised in basin demarcation for hydrocarbon exploration. In contrast, deep-seated lineaments originated due to deformities at the crust-mantle boundary or in the mantle and could be used in the region’s seismicity analysis. Spectral analysis and 2D forward modelling results indicate sediment thickness of ~ 2.0-6.0 km, basement thickness of ~ 6-14 km, and Moho depth of ~ 10-18 km. Delineated lineaments and computed basement and Moho depths were further validated with existing data. Anomalously high and low gravity features were interpreted based on Moho depth, basement thickness, and sediment thickness. This study concludes that anomalous gravity anomalies are mainly controlled by Moho topography despite the relatively thicker crust in the northern region. The crustal thickness mainly controls the southern latitude’s gravity signatures.

2

Tektoniczne znaczenie strefy Teisseyre’a-Tornquista w świetle nowych badań

Mazur S., Krzywiec P., Malinowski M., Lewandowski M., Aleksandrowski P., Mikołajczak M.

Przegląd Geologiczny

|

2017

|

Vol. 65, nr 12

1511--1520

EN

The Teisseyre-Tornquist Zone (TTZ), a transcontinental feature evident from magnetic and gravity maps, runs obliquely across the territory of Poland from the NW to SE and for a century it has been considered a deep tectonic boundary between the Pre- cambrian East European Platform (EEP) in the NE and the so-called young Palaeozoic Platform in the SW. The results of quantitative interpretation of gravity and magnetic data, integrated with data from new reflection seismic profiles crossing the TTZ, indicate the continuation of the Precambrian basement of the EEP and its lower Palaeozoic cover toward the SW underneath the Palaeozoic Platform of southwestern Poland. They also suggest the occurrence of a crustal keel beneath the TTZ. In the broader context ofEuropean geology, these results imply the location of a hypothetical Caledonian tectonic suture, marking the site of the collision between Avalonia and Baltica, not along the TTZ, but farther SW, in northern Germany and southwest Poland. Another implication is that the extensive Permian-Mesozoic sedimentary basins of western Poland are established above the attenuated margin of the Baltica palaeocontinent.

3

O nowych rozwiązaniach tektonicznych w „Atlasie geologicznym Polski”

Aleksandrowski P., Mazur S.

Przegląd Geologiczny

|

2017

|

Vol. 65, nr 12

1499--1510

EN

Authorial comprehensive comments and explanations are given to some of the interpretations applied in the tectonic part of the newly published Geological Atlas of Poland (Nawrocki, Becker, 2017) that considerably change the hitherto generally accepted concepts. It should be, however, admitted that most of those "new’" solutions were already proposed in the past by other workers as hypotheses that could not have been tested in the then state of knowledge on Poland’s deep geology and scientific tools at hand. This has now changed with abundant new data obtained with modern seismic techniques and advanced methods of potential field modelling. Using those data, we justify the reasons for, among others, a significant eastward shifting the front of the Variscan Orogen in Poland andfor the accompanying change in position of the division line between the Precambrian and Palaeozoic platforms. We also show the rationale for accepting a far-reaching southwestward extent of the East European Craton’s crystalline basement below the Palaeozoic Platform and for reinterpretation of the Teisseyre-Tornquist Zone’s nature, together with the question of early Palaeozoic terranes in the TESZ and the situation of the Caledonian foredeep at the SW margin of the East-European Craton.