ISSN:
1440-1738
Quelle:
Blackwell Publishing Journal Backfiles 1879-2005
Thema:
Geologie und Paläontologie
Notizen:
Abstract Pseudotachylytes are present along the Dahezhen shear zone in the Qinling–Dabie Shan collisional orogenic belt, central China. Two types of pseudotachylyte vein are documented in the shear zone: cataclasite-related pseudotachylyte (C-Pt) and mylonite-related pseudotachylyte (M-Pt). M-Pt is associated with mylonite-development and is overprinted by C-Pt. All of the quartz and most of the feldspar porphyroclasts within the M-Pt are plastically deformed, but not in the C-Pt. Dynamically recrystallized fine-grained quartz and feldspar bands are oriented subparallel to the mylonite and M-Pt foliation, and partially surround the porphyroclasts. Our results suggest that the M-Pt formed cyclically in the ductile region at estimated conditions of 400–650°C and 400–800 MPa due to propagation of seismic fracturing associated with the thrusting-related rapid exhumation of the ultrahigh-pressure metamorphic complex in the brittle regime down to a greater depth than the base of the seismogenic zone. The M-Pt and mylonite formed in the Dahezhen shear zone at estimated conditions of 400–650°C and 400–800 MPa. The coexistence of C-Pt and M-Pt in the same shear zone suggests that repeated seismic slips occurred in both the brittle and ductile portions of the crust during the thrusting-related rapid exhumation of the ultrahigh-pressure metamorphic complex.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1046/j.1440-1738.2003.00407.x
