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Based on 43 Harvard CMT solutions in Yunnan region, GPS observations from 1999 to 2004 by China Crustal Movement Observatory Network, and results from SKS splitting and Pn fast wave anisotropy, we obtained the average directions of principle stress fields at different depths by average angle method. Then we further analyzed the coupling difference between geodynamic parameters in different tectonic blocks. Then we built five three-dimensional finite element models to simulate the crustal velocity field in Sichuan-Yunnan region and stratified stress–strain fields in different tectonic blocks. In order to implement the numerical simulation, we constrained the FEA model boundaries with GPS observations, and determined the possible flow patterns at the top of upper mantle by SKS anisotropic splitting data. Based on the simulated kinematic pattern and stress–strain fields, we analyzed the geodynamic environment in the deep part of the area, and found that the difference between lateral stress fields in different tectonic blocks is the main reason why the boundaries of tectonic blocks and their neighborhood are so active areas and capable of generating strong earthquakes. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The Lanping basin is a significant Pb–Zn–Cu–Ag mineralization belt in the Sanjiang Tethyan metallogenic province. A series of sediment-hosted Himalayan Cu–Ag–Pb–Zn polymetallic deposits have been discovered in the western part of the basin, controlled by a thrust–nappe system. In the thrust–nappe system, the Cu orebodies mainly occur in the western and relatively deep part of the mineralization system (the root zone), whereas the Pb–Zn–Ag (± Cu) orebodies occur in the eastern and relatively shallow part of the system (the front zone), both as vein-type mineralization. In this paper we present new data, combined with existing data on fluid inclusions, isotopes and geologic characteristics of representative deposits, to provide the first study that contrasts mineralizing fluids in the Cu–Ag (Mo) and Pb–Zn–Ag (Cu) polymetallic deposits. Fluid inclusion and isotope studies show that the Cu–Ag (Mo) mineralization in the root zone formed predominantly from deep crustal fluids, with the participation of basinal brines. The deep crustal fluids are marked by high CO 2 content, relatively high temperatures (280 to 340 °C) and low salinities (1 to 4 wt.% NaCl equivalent), whereas the basinal brine shows relatively low temperatures (160 °C to 220 °C) and high salinities (12 to 22 wt.% NaCl equivalent), containing almost no CO 2 . In comparison, hydrothermal activity associated with the Pb–Zn–Ag (± Cu) deposits in the front zone is characterized by basinal brine, with relatively low temperatures (130 °C to 180 °C), high salinities (9 to 24 wt.% NaCl equivalent), and low CO 2 concentrations. Although evolved meteoric waters have predominantly been proposed as the source for deep crustal fluids, magmatic and metamorphic components cannot be completely excluded. The basinal brine was predominantly derived from meteoric water. The δ 34 S values of sulfides from the Cu–Ag (Mo) deposits and Pb–Zn–Ag (± Cu) deposits range from − 17.9 to 16.3‰ and from 2.5 to 11.2‰, respectively. These ranges may relate to variations in physicochemical conditions or compositional variation of the sources. Lead isotope compositions indicate that the ore-forming metals were predominantly derived from sedimentary rocks of the Lanping basin. [ABSTRACT FROM AUTHOR]