scholarly journals Understanding the Relationship between Large-Scale Fold Structures and Small-Scale Fracture Patterns: A Case Study from the Oman Mountains

Geosciences ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 490
Author(s):  
Mohammed H. N. Al-Kindi
Keyword(s):  
Late Cretaceous ◽  
Large Scale ◽  
Small Scale ◽  
Oman Mountains ◽  
Fracture Patterns ◽  
Late Cretaceous Period ◽  
Late Neogene ◽  
Cretaceous Period ◽  
Longitudinal Strains ◽  
The Relationship

Considering the foreland fold belt of the Salakh Arch in the northern Oman Mountains, predictions made from two-dimensional (2D) restorations and geometrical analyses are tested here to assess the relationship between large-scale folds and small-scale fractures. The Salakh Arch is composed of six anticlines that are interpreted as faulted detachment folds. They have an overall stratigraphy of a 2-km-thick carbonate platform underlain by more than 1.5 km of interbedded sandstone and shale sequences. These sequences are most likely detached on a regionally extensive evaporite horizon. The folding of the Salakh Arch structures most likely occurred during the Neogene Period, and perhaps partly in the early Quaternary Period. This is evident from the thrusting of the Late Neogene Barzaman Formation which was deposited during the Late Neogene Period. Robust outcrop and subsurface fracture data are used to test these predictions. The results from the study indicate that most fractures are related to the orientation of the local structure, with some sets parallel and some sets perpendicular to local hinge lines. Prefolding regional fractures are also widely distributed, and these were mostly formed during the Late Cretaceous Period. Many pre-existing fractures are associated with faults that formed during the Late Cretaceous Period under a NW–SE compression. The local fractures generally have orientations that are consistent with being formed by the flexural slip/flexural flow of fold limbs and tangential longitudinal strains on fold hinges. These structures can be predicted from finite stratal dips, simple curvatures, and three-dimensional (3D) folding restoration maps. The Gaussian curvatures and 3D faulting restoration maps can be used as proxies for fault-related fractures. Local hinge-related fractures may reflect local tangential longitudinal strain during large-scale fold tightening. Fold structures that have formed at an oblique orientation to the regional shortening direction show additional fracture arrays perpendicular to the hinge, indicating weak axial extension. This is presumed to develop as the arcuate thrust belt of Salakh Arch was amplified. The analysis here illustrates the importance of taking a 3D approach, especially for noncylindrical folds. The protocols developed in this study and their results may have general applicability to investigations of fracture patterns in other folds.

scholarly journals Challenges Posed on The New Mining Act and Its Regulations in Tanzania

2015 ◽  
Vol 8 (4) ◽  
pp. 185 ◽  
Author(s):  
Charles W. Marwa ◽  
Isabela Warioba
Keyword(s):  
Law Enforcement ◽  
Large Scale ◽  
Good Governance ◽  
Land Ownership ◽  
Local Communities ◽  
Small Scale ◽  
Mining Sector ◽  
Mining Companies ◽  
Mining Law ◽  
The Relationship

<p>This paper assesses the challenges that are posed to the new mining law and other Regulations that govern the mining sector in Tanzania. The main issues discussed in this paper include the conflicts between the local people and the mining companies regarding land ownership, compensation and forced eviction, conflicts between Small Scale Mining (SSM) and Large Scale Mining (LSM).</p><p>The findings obtained by the authors, intimates that the major problems in the mining sector are due to lack of law enforcement and good governance in the sector as well as lack of awareness of the laws governing the sector by the local communities.</p>Lastly, the authors concludes and recommend that, until and unless the laws are adhered to and kept into practice, the problems in the mining sector will not be easily resolved. Hence in order for the mining sector to benefit the indigenous and the investors, there should be enhancement of sustainable development;, people should be educated on the laws and the effects of mining on the environment and the relationship between SSM and LSM be improved.

The pterosaurian remains from the Grünbach Formation (Campanian, Gosau Group) of Austria: a reappraisal of ‘Ornithocheirus buenzeli’

2010 ◽  
Vol 148 (2) ◽  
pp. 334-339 ◽  
Author(s):  
ERIC BUFFETAUT ◽  
ATTILA ŐSI ◽  
EDINA PRONDVAI
Keyword(s):  
Late Cretaceous ◽  
Proximal Part ◽  
Great Accuracy ◽  
Distinctive Features ◽  
Lower Jaw ◽  
Nomen Dubium ◽  
Late Cretaceous Period ◽  
The Family ◽  
Gosau Group ◽  
Cretaceous Period

AbstractThe fragmentary pterosaur material from the Campanian Grünbach Formation (Gosau Group) of Muthmannsdorf (Austria), previously identified as Ornithocheirus buenzeli Bunzel, 1871, is revised. A lower jaw fragment shows a helical type of articulation, which is known in several families of pterosaurs, and cannot be identified with great accuracy. The proximal part of a humerus shows distinctive features that allow it to be referred to as a member of the family Azhdarchidae, which is widespread in the Late Cretaceous Period of Europe. Ornithocheirus buenzeli is considered a nomen dubium. The pterosaur material from the Grünbach Formation cannot be used as evidence for the presence of ornithocheirids in the Late Cretaceous of Europe.

scholarly journals The Kilen Expedition 1985

1993 ◽  
Vol 40 ◽  
pp. 9-32
Author(s):  
E. Håkansson ◽  
C. Heinberg ◽  
C. Hjort ◽  
P. Mølgaard ◽  
S. A. S. Pedersen
Keyword(s):  
Late Cretaceous ◽  
Late Jurassic ◽  
Higher Plants ◽  
Mobile Belt ◽  
Pull Apart Basin ◽  
Late Cretaceous Period ◽  
History Of ◽  
Entire Sequence ◽  
Cretaceous Period ◽  
Inland Ice

The 1985 expedition constitutes the first comprehensive investigation of the isolated, hyperarctic semi­nunatak Kilen in eastern North Greenland. Well over 3 km of generally marine, elastic sediments are preserved from the Late Jurassic to Late Cretaceous period. While half this amount accumulated in ·a comparatively stable tectonic regime prevailing during Late Jurassic and Early Cretaceous time, the Late Cretaceous (Turonian-Coniacian) sediments are characterized by their deposition in a local pull-apart basin developed in the regional Wandel Hav Strike-Slip Mobile Belt. Subsequent, localized compression along this belt has deformed the entire sequence rather severely in a complex series of en echelon domal folding and thrusting, most likely during the later part of the Cretaceous. Quaternary marine sediments of probable interglacial origin (> 100.000 years old) have been found to contain a mollusc fauna requiring temperatures above the present level. Flade lsblink, the largest local icecap in Greenland, is composed of several semi-independant ice domes, and there is evidence that the history of this icecap deviates significantly from that of the Inland Ice. A total of 34 species of higher plants, 29 species of birds, and 11 species of mammals have been recorded from Kilen; vegetation studies indicate a July mean temperature of around 2.5°C.

scholarly journals Late Cretaceous to Paleogene post-obduction extension and subsequent Neogene compression in the Oman Mountains

GeoArabia ◽  
2006 ◽  
Vol 11 (4) ◽  
pp. 17-40 ◽  
Author(s):  
Marc Fournier ◽  
Claude Lepvrier ◽  
Philippe Razin ◽  
Laurent Jolivet
Keyword(s):  
Late Cretaceous ◽  
Large Scale ◽  
Early Miocene ◽  
Normal Faults ◽  
Zagros Mountains ◽  
Lower Eocene ◽  
Oman Mountains ◽  
Tectonic History ◽  
History Of ◽  
Arabian Platform

ABSTRACT After the obduction of the Semail ophiolitic nappe onto the Arabian Platform in the Late Cretaceous, north Oman underwent several phases of extension before being affected by compression in the framework of the Arabia-Eurasia convergence. A tectonic survey, based on structural analysis of fault-slip data in the post-nappe units of the Oman Mountains, allowed us to identify major events of the Late Cretaceous and Cenozoic tectonic history of northern Oman. An early ENE-WSW extensional phase is indicated by synsedimentary normal faults in the Upper Cretaceous to lower Eocene formations. This extensional phase, which immediately followed ductile extension and exhumation of high-pressure rocks in the Saih Hatat region of the Oman Mountains, is associated with large-scale normal faulting in the northeast Oman margin and the development of the Abat Basin. A second extensional phase, recorded in lower Oligocene formations and only documented by minor structures, is characterized by NNE (N20°E) and NW (N150°E) oriented extensions. It is interpreted as the far-field effect of the Oligocene-Miocene rifting in the Gulf of Aden. A late E-W to NE-SW directed compressional phase started in the late Oligocene or early Miocene, shortly after the collision in the Zagros Mountains. It is attested by folding, and strike-slip and reverse faulting in the Cenozoic series. The direction of compression changed from ENE-WSW in the Early Miocene to almost N-S in the Pliocene.

Determination of formation paleo-pressure and evolution process using gaseous hydrocarbon inclusions

2020 ◽  
Author(s):  
Cunjian Zhang ◽  
Jingdong Liu ◽  
Youlu Jiang
Keyword(s):  
Late Cretaceous ◽  
Middle Jurassic ◽  
Formation Mechanisms ◽  
Formation Pressure ◽  
Gas Reservoirs ◽  
Gaseous Hydrocarbon ◽  
Late Cretaceous Period ◽  
Cretaceous Period ◽  
Early Late ◽  
Vapor Liquid

&lt;p&gt;Research on overpressure evolution and its formation mechanisms is of great significance for revealing reservoir formation mechanisms and predicting formation pressures in oil and gas reservoirs before drilling. However, research methods addressing overpressure evolution are not without issues. The fluid inclusion PVT simulation and basin simulation can be used to investigate the paleo-pressure.&lt;/p&gt; &lt;p&gt;The homogenization temperatures of inclusions were tested. The accuracy of the microscopic laser Raman spectroscopy analysis is too limited to fully test the components of gaseous hydrocarbon inclusions so that the organic components of the natural gas in the present-day gas reservoirs represented the gaseous hydrocarbon inclusions. In addition, the vapor-liquid ratio of gaseous hydrocarbon inclusions cannot be measured by CLSM. Firstly, A series of images at different slice depths was obtained by adjusting the focal length of a high-resolution microscope. Secondly, CorelDRAW software was used to calculate the areas of inclusions and bubbles; fitting functions were established between the inclusion areas and slice depths, and between the bubble areas and slice depths. Finally, the inclusion and bubble volumes were integrated to obtain the vapor-liquid ratios of the inclusions. PVTsim software can calculate the trapping pressures of inclusions. Combined with basin simulation, the evolution of paleo-pressure can be determined.&lt;/p&gt; &lt;p&gt;The above methods were used to investigate the paleo-pressure of the Upper Triassic Xujiahe Formation in the northeast portion of the Sichuan Basin. Overpressure began to develop in the Middle Jurassic period. Due to hydrocarbon generation taking place, the formation pressure increased rapidly from the Middle Jurassic period to the early Late Cretaceous period. Since the early Late Cretaceous period, the formation pressure has gradually decreased due to tectonic uplift and erosion. From the Oligocene period to the present, the formation pressure have increased again in local areas due to tectonic compression.&lt;/p&gt;

Fracture of Monoliths Fabricated by Stacking Water Processed Green Ceramic Tapes

2005 ◽  
Vol 290 ◽  
pp. 203-207 ◽  
Author(s):  
Jonas Gurauskis ◽  
Javier Pascual ◽  
Tanja Lube ◽  
Antonio Javier Sanchez-Herencia ◽  
Carmen Baudín
Keyword(s):  
Fracture Behavior ◽  
Large Scale ◽  
Room Temperature ◽  
Tape Casting ◽  
Casting Process ◽  
Small Scale ◽  
Interface Defects ◽  
Fracture Patterns ◽  
Zro2 System

A lamination technique for joining ceramic green tapes fabricated from aqueous ceramic slurries via tape casting process is investigated. Monolithic pieces with varying compositions within the Al2O3 / t-ZrO2 system were fabricated by gluing the constituent tapes and pressing at room temperature. The quality of the interfaces between the different tapes in sintered specimens was evaluated by means of the fracture behavior of the pieces during the ball on three balls test. Different fracture patterns were found as a function of pressure and the characteristics of the tapes. Large scale interface defects led to delamination during fracture whereas no critical defects could be observed in the smooth fracture surfaces. Small scale interface defects were revealed by fracture.

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