A sandbox experiment model was designed to simulate how differences in rock strength and gravity between two blocks can influence the formation characteristics of thrusts. In the experiment the compression was from on...A sandbox experiment model was designed to simulate how differences in rock strength and gravity between two blocks can influence the formation characteristics of thrusts. In the experiment the compression was from one direction with basement shortening and the initial surfaces of the model were oblique. The results show that if the initial surface was horizontal or the slope angle was smaller than 7°, the compression induced two groups of thrusts with opposite dip orientations. If the slope angle of the initial surface was greater than 7°, the compression induced only one group of thrusts with a dip orientation contrary to the original compression direction. This result is similar to the actual section of a collision zone between two continental blocks. By applying stress analysis, rock strength is shown to be an important factor in deformation. As other boundary conditions are changeless, it is the change of gravitational potential energy that leads to different deformation styles.展开更多
The study aims to understand geometry and evolution of accommodation zones along restraining and releasing bends in strike slip systems which is often complex and characterized by sharp change in polarity,resulting in...The study aims to understand geometry and evolution of accommodation zones along restraining and releasing bends in strike slip systems which is often complex and characterized by sharp change in polarity,resulting in a difficult characterization of traps location.A batch of sandbox modelling experiments was performed using a layered scaled sand material.The setup parameters of the wooden baseplates used in the first two experiments(SS1 and SS2)are basement offset of 6.5 cm/3 cm,90/90stepovers in releasing and restraining bends of total 96 cm length and 25 cm width.The third experiment(SS3)was performed with basement offset of 6.5 cm/3 cm,156/126stepovers in releasing and restraining bends of total 96 cm length and 25 cm width.The experiments were performed with special attention to the role of syn-kinematic sedimentation and the pre-existing structure of the basement.A sequence of pop-up and pull-apart structures was produced.Along the main structures,complex fault trend was compatible with a sinistral riedel distribution and a counterclockwise rotation of pre-existent elements.Change of fault's polarity at depth and dip direction flipping of high angle faults in accommodation zones were clearly observed.Even more,progressive propagation of the pop-up structures produces a spectacular inversion of adjacent extensional structures.Comparing results of the model with the Seagap fault zone,it is possible to put in evidence similar fault orientation and distribution.Internal structures developed were strongly influenced by syn-kinematic sedimentation as observed by characteristic helicoidal shape of growth faults.The analogue models clearly describe how boundary faults of the pull-apart basin along a paired bend,initially characterized by a normal kinematic can be subsequently inverted in the later stages,which can potentially have a strong impact on the petroleum system.展开更多
基金This paper is supported by the project IGCP411(3-3-02-24) .
文摘A sandbox experiment model was designed to simulate how differences in rock strength and gravity between two blocks can influence the formation characteristics of thrusts. In the experiment the compression was from one direction with basement shortening and the initial surfaces of the model were oblique. The results show that if the initial surface was horizontal or the slope angle was smaller than 7°, the compression induced two groups of thrusts with opposite dip orientations. If the slope angle of the initial surface was greater than 7°, the compression induced only one group of thrusts with a dip orientation contrary to the original compression direction. This result is similar to the actual section of a collision zone between two continental blocks. By applying stress analysis, rock strength is shown to be an important factor in deformation. As other boundary conditions are changeless, it is the change of gravitational potential energy that leads to different deformation styles.
基金This research paper was prepared from the experimental data simulated with Sandbox analogy modelling machine in the Geomodel laboratory of College of Earth sciences,University of Dodoma.Our appreciation goes to senior LabEngineer Mr Audax Kiwango for his tireless technical support in operating the Sandbox machine and Statoil Tanzania(Equinor)for providing information of structural architecture of their play。
文摘The study aims to understand geometry and evolution of accommodation zones along restraining and releasing bends in strike slip systems which is often complex and characterized by sharp change in polarity,resulting in a difficult characterization of traps location.A batch of sandbox modelling experiments was performed using a layered scaled sand material.The setup parameters of the wooden baseplates used in the first two experiments(SS1 and SS2)are basement offset of 6.5 cm/3 cm,90/90stepovers in releasing and restraining bends of total 96 cm length and 25 cm width.The third experiment(SS3)was performed with basement offset of 6.5 cm/3 cm,156/126stepovers in releasing and restraining bends of total 96 cm length and 25 cm width.The experiments were performed with special attention to the role of syn-kinematic sedimentation and the pre-existing structure of the basement.A sequence of pop-up and pull-apart structures was produced.Along the main structures,complex fault trend was compatible with a sinistral riedel distribution and a counterclockwise rotation of pre-existent elements.Change of fault's polarity at depth and dip direction flipping of high angle faults in accommodation zones were clearly observed.Even more,progressive propagation of the pop-up structures produces a spectacular inversion of adjacent extensional structures.Comparing results of the model with the Seagap fault zone,it is possible to put in evidence similar fault orientation and distribution.Internal structures developed were strongly influenced by syn-kinematic sedimentation as observed by characteristic helicoidal shape of growth faults.The analogue models clearly describe how boundary faults of the pull-apart basin along a paired bend,initially characterized by a normal kinematic can be subsequently inverted in the later stages,which can potentially have a strong impact on the petroleum system.
