What is the Evidence for and Against these Models of Continental Collision in Tibet? (Term Paper Sample)

Title
Name
 
 
Class
Professor
Institution
City and State
Date
Abstract
The evidence for or against the models of continental collision in Tibet has been debated in studies by various researchers. The two processes that the scholars continue to study to establish the true model that contributed to the observation at Tibet are the lateral extrusion and crustal thickening. According to research, since the collision took place between the Indian and the Asian plate, significant convergence was observed resulting in an internal deformation of the Asian lithosphere. Even though some researchers hold that crustal thickening around and inside the Tibetan plateau caused the collision, other scholar’s purport that lateral intrusion played a significant role in the process. This paper will examine different models presented in research such as active deformation, kinematic model, the thin viscous sheet model and the global positioning research on Tibet.
After the examination of different models, this paper revealed that the use of the Global Positioning System in Tibet contributed significantly in finding out the true model that caused the continent collision in the area. The GPS study revealed that the process of lateral extrusion caused the crustal shortening of the Tibetan plateau as opposed to crustal thickening. Even through the other models used to explain the phenomena contained credible information, the main limitation was the form of measurement of the findings. For instance, the findings from this paper revealed that the process of active deformation of continents was studied for many years, but the researchers encountered a challenge in quantifying the evidence accurately. The complexity of this model can be observed in the wide range of scales used to record evidence in the geologic maps.
Lateral extrusion versus crustal thickening: What is the evidence for and against these models of continental collision in Tibet?
Introduction
The crustal shortening that resulted from the collision of the Indo-Asian plate in over 40 to 70 million ago was investigated based on two processes that include the lateral extrusion and crustal thickening of the Tibetan Plateau in Himalaya. The evidence provided remains controversial as scholars continue to establish the true model that could be used as defend argument on the continental collision in the plateau. According to studies, since the start of the collision between Asia and India, there has been the significant convergence of approximately 2500 kilometers. In addition, the Indian plate has moved significantly as influenced by the internal deformation observed in the Asian Lithosphere (Yang & Liu, 2009, p.128).
Even though some scholars purport that the crustal thickening both around and inside Tibet caused the collision, debates continue to arise with assertions that the process of lateral extrusion played the key role in the colliding action. Many tests and research have been done to through rheological and geometrics structures of the lithosphere (Houseman & England, 1993, p.12233). This paper presents a discussion on the various studies regarding the topic including processes like active deformation, kinematics model, the thin viscous sheet model and the global positioning research about Tibet.
Active Deformation
The process of active deformation of the continents had been studying for many years even though researchers encountered a challenge in quantifying the evidence accurately. The complexity is observable in a wide range of scales that include the record of evidence from geologic maps with information about past plate tectonics and the distribution of the earthquake epicenters. Additionally, the process of quantifying recent deformation is problematic because scholars find no observational technique to measure the widely spread and complex trends and patterns of earth movements (England & Jackson, 1989, p.198). Despite the difficulties in the research about active deformation, methods such as space geodesy are applied to overcome the problem.
The process of active deformation has been used to explain the activity that was observed in Tibet and the adjacent regions. The measurements applied in the study played a significant role in identifying detailed information based on mapping of the past and current velocities across the field with the regions. The study helped reveal now knowledge about the process of continental deformation. According to studies, the current deformation measurements address the question of plate tectonics in the Eurasian and Indian collision zones (England & Jackson, 1989, p.198). The measurements reveal that Indian plate has converged onto the Eurasian plate to approximately 35 mm annually. Research holds that the process continues at the same rate even today. This evidence indicates that the globe experiences deformation through plate reconstructions. The importance of crustal thickening, shortening, eastward extrusion and block rotations in investigating the collision of the Tibetan plateau remain contentious.
The techniques of continental deformation today should provide better observational findings that lead to advanced systematic models. The process depends on the lithosphere strength and various driving forces. For instance, when the lithosphere experiences forces such as the boundary push, the plate resists the force that for many years has not been quantified or has been inadequately evidenced in various studies (England & Molnar, 1997, p.649). Other important factors in the process include the thickness, density and lateral gradient of the mantle and crust lithosphere. The variables result in a slope, which generates a gravitational pull or potential energy.
Additionally, the processes are coupled with internal buoyancy that creates a force, which can be derived from imaging and filed observations of seismic velocity structures. The guidelines that relate to the active forces of deformation such as rheology, assert that factors such as the distribution of strength inside the lithosphere are attributed by the behavior of rocks and characteristics like ductility and elasticity. Another factor that plays a significant role is the strength of the faults in the crust. Deformation is also presented as a product of instability of the continental lithosphere that is influenced by the speed of the relative field portions. For this reason, the seismic and geologic data constrains the observations made in space geodetics.
Kinematics model of deformation
Studies modeling the kinematics are seen as a prolog to the modeling of dynamics in explaining the process of lithosphere deformation. The two models assume that the surface contains a uniform and thin viscous expanse with no deep or lateral variations regarding rheological properties. The simplicity of the idea makes the model simple, which makes the process of quantifying the resisting motions and models traceable, particularly in a computational context. Consequently, the findings on the motions and forces can be applied to explain the process of surface deformation.
Studies revealed that forces such as internal buoyancy played a significant role in the process of continental deformation. Additionally, a balance in the forces enabled an analysis of the process and the calculation of resisting forces of the plate boundary and forces of internal buoyancy (Avouac & Tapponnier, 1993, p.897). However, some scholars assert that the conclusions are not specific because the balance in motion is not dependent on rheology for both isotropic and homogeneous material. The researchers add that the force balance has weakly depended on non-homogenous material in the lithosphere.
The key role of the plate kinematics model is to illustrate the sense and rate of slip across the major mountain belts, rotation rates and faults in the crustal blocks. The explanation is presented with the integration of knowledge about active tectonics. However, the block model is limited in its explanation of surface kinematics because of the omission of knowledge about the factors of ductility of the lithosphere that have not been used to relate the observation and the relative forces.
It is important to note that there is no contention regarding the assertion that continental deformation is greatly block-like. In this case, the reliability of the kinematics findings depends on the constraints experienced during the rotation of the single blocks and the presence of the internal block deformation. The distribution of data, which can be evaluated systematically, plays a critical role in understanding the procedure (Avouac & Tapponnier, 1993, p.898). The limiting factor to this model is that the choice of different block boundaries and the specific blocks are subject to doubt, which adds to the challenge of quantifying the results because of the doubt of reliability of the findings.
The patterns of misfit and residuals may be used to establish and remedy the problem, although the reliability of the approach largely depends on the density of available data. The challenges are discussed in detail in the link between the fault slip rate and the construction of a block model. The model that is most suited for understanding the process of surface deformation depends on the understanding of lithosphere rheology and the stresses that drive deformation. Additionally, reliable information should expound on the characteristics of the region such as the ductility of elasticity of the crust (Avouac & Tapponnier, 1993, p.898). The reason for this is because the strong element of the lithosphere of its ductility, which could result in a deformation because of the weaker motions that are more passive to control the kinematics in the process. In the case of high forces experienced in the upper crust, the b...