tailieunhanh - .New Frontiers in Integrated Solid Earth Sciences Phần 3

Phương pháp tiếp cận gián tiếp là cần thiết để xác định phân bố nhiệt độ trong thạch quyển. Chụp cắt lớp vi địa chấn thường được sử dụng cho mục đích này. | 72 M. Tesauro et al. sedimentation and climatic changes which influence might be hardly removable beforehand. Furthermore in many areas affected by transient processes . mantle upwellings the steady state thermal conductivity equations cannot be applied while other approaches require a precise knowledge about thermal history which normally is not defined with sufficient accuracy. Therefore indirect approaches are needed to determine temperature distribution within the lithosphere. Seismic tomography is commonly used for this purpose . Sobolev et al. 1996 Goes et al. 2000 . The strong effect of temperature on the seismic velocity and elastic moduli has been known for a long time from laboratory studies . Birch 1943 Hughes and Cross 1951 . Therefore temperature changes in the mantle lithosphere can be derived from variations of seismic velocities. However seismic velocities also depend on many other factors . partial melt anisotropy and composition which strongly affect temperature estimations as discussed in the following section. In this paper an improved temperature model for the European lithosphere is presented. This model is obtained from inversion of a recent tomography model Koulakov et al. 2009 supplemented by the new reference model of the crust EuCRUST-07 Tesauro et al. this volume . EuCRUST-07 has a higher resolution 15 x15 and is more robust than previous compilations . Mooney et al. 1998 Bassin et al. 2000 primarily because of a significant number of recent seismic data assembled. Therefore EuCRUST-07 offers a starting point for various types of numerical modelling to remove a-priori the crustal effect and to exclude a trade-off with mantle heterogeneities. Previous studies . Waldhauser et al. 2002 Martin et al. 2006 demonstrated that the use of an a-priori crustal model may significantly improve determination of the seismic velocities in the uppermost mantle. Consequently employment of a more robust seismic .