Zian Li

Numerical simulation of the effects of upward throughflow on the thermal structure and the thickness of the continental lithosphere

Based on the porosity-wave mass-transport and heat-transfer conceptual model in the continental lithosphere, the effects of upward throughflow on the continental lithosphere thermal structure are discussed. Previous theoretical works have proposed three thermal structure modes in the continental lithosphere, namely the heat-conductive-only lithosphere, the heat-conductive-and-advective lithosphere with a pore fluid of constant density, and the heat-conductive-and-advective lithosphere with a pore fluid of variable density (temperature-dependent density). The main purpose of this paper is to use the theoretical model to conduct parametric analysis and compare the numerical results produced with geological observation data. Two points are indicated. (1) The heat-conductive-only lithosphere may represent the thermal structure mode in the shield (or the stable platform), while the heat-conductive-and-advective lithosphere with a pore fluid of variable density often represents the lithospheric thermal structure mode in the continental active region or the orogenic belt. (2) The upward throughflow is the major factor to affect the stable lithospheric thickness of the Qinghai-Xizang plateau, North China, South China and the marginal sea region, demonstrating that the upward throughflow can have significant effects on the thermal structure mode of a continental lithosphere.

Continuous restoration of deformed shapes through the construction of a reverse displacement gradient and its application to granite emplacement in central North China

This paper presents a new technique to restore 2D/3D deformed shapes by minimization of the misfit between measured and theoretical reverse displacement gradients. Owing to its relatively direct and objective nature, the procedure ensures continuity of displacement across the boundaries between abutting elements. The procedure also minimizes the additional distortion of the elements that results from the compatibility of retro-deformation between abutting elements. We apply the technique to the Mesozoic Fangshan granodioritic pluton (FGP) in western Beijing, central North China. Based upon the measured strain of deformed enclaves, about 78% area of the present central zone can be restored by retro-deformation of the marginal and transitional zones. As a result of the emplacement of the central zone, deformation also occurred in both the outer zones and the wall rocks, predominantly by ductile flow. The associated deformation in the outer zones, with or without the involvement of the wall rocks, created space for the emplacement of the central zone. In addition, vertical expansion was effective in creating space for subsequent emplacement, producing approximately one third of the volume created by later expansion. Thus, ballooning is a viable mechanism for emplacement of the FGP.

Zircon U‐Pb Chronology and Hf Isotope From the Palawan‐Mindoro Block, Philippines: Implication to Provenance and Tectonic Evolution of the South China Sea

Yi Yan, Deng Yao, Zhixian Tian, Chiyue Huang, Wenhuang Chen, M. Santosh, Graciano P. Yumul Jr., Carla B. Dimalanta, Zian Li,

A numerical study of stress/strain response to oil development in reservoir rocks-a case study in Xingshugang area of Daqing Anticline

Formation pressure and the underground stress field will be disturbed by high pressure injection and production activities during oilfield development. Such disturbance will induce the deformation of formation rock, sometimes causing formation to slip. As a result, production wells and/or injection wells will encounter sanding, casing deformation, or even casing shear problems. This article introduced a simulation study on formation pressure and the underground stress field variation during injection and production activities in the Xingshugang area of the Daqing Anticline, Songliao Basin, China. The relationships of injection pressure to formation pressure, underground stress field variation, and strain variation were investigated in this paper.