Vein structure and related small fractures in muddy sedimentary Oligocene to Miocene rocks of Sites 568 and 569 have been analyzed to study the deformation and tectonics of the Middle America Trench landward slope area off Guatemala. These veins are filled with fine, clayey materials and essentially developed as extensional fracture cleavages perpendicular to the minimum principal compressive stress axis. Three stages are recognized; early stage fractures parallel to bedding (probably caused by bedding parallel slip), abundant fractures highly oblique or perpendicular to bedding, and veins formed at various angles during tilting. Most of the veins show drag or rotation features, which mostly show downdip sliding and probably occurred during stages of large-scale folding related to faulting or draping of the middle Trench slope area. Veins are concentrated only in the middle part of the Trench landward slope of the late Oligocene to middle Miocene sections, where high sedimentation rates and possible normal faulting and folding caused by local uplift of the basement occurred. This may indicate that the veins required rapid sediment consolidation, which caused abnormal lithification

Sediment depth is given in mbsf. Empty cells indicate no data.

Supplement to: Ogawa, Yujiro; Miyata, Yuichiro (1985): Vein structure and its deformational history in the sedimentary rocks of the Middle America Trench Slope off Guatemala, Deep Sea Drilling Project Leg 84. In: von Heune, R; Aubouin, J; et al. (eds.), Initial Reports of the Deep Sea Drilling Project, Washington (U.S. Govt. Printing Office), 84, 811-829