(Table T1) Natural structures measured at ODP Hole 206-1256D with respect to the ODP reference frame and reorientation results

Brittle structures (open fractures and veins) from basaltic oceanic crust drilled at Ocean Drilling Program (ODP) Site 1256 (Guatemala Basin, Pacific Ocean) during Leg 206 were reoriented to the geographic coordinates by (1) correlating structures observed on the core with unoriented images of the exterior of the core and (2) correlating core structures and unoriented images with oriented borehole images. The images of the exterior of the core were obtained by scanning whole-core pieces with the Deutsche Montan Technologie Digital Color Core-Scan system. In the unrolled core images, nonhorizontal planar structures (e.g., veins, faults, or fractures) produce sinusoidal-shaped curves. These can be matched to similar-shaped features imaged along the borehole wall. The borehole images were obtained by the Formation MicroScanner (FMS)-sonic (Dipole Sonic Imager) tool string and the Ultrasonic Borehole Imager (UBI). The FMS provides high-resolution electrical resistivity-based images of borehole walls. FMS images are oriented to magnetic north using the General Purpose Inclinometer Tool. This allows the dip and azimuth of geological features intersecting the hole to be measured from the processed FMS image. The UBI features a high-resolution transducer that provides acoustic images of the borehole wall. The UBI was used in hard rocks for the first time in the history of the ODP during Leg 206.

本数据集针对大洋钻探计划（Ocean Drilling Program, ODP）第206航次于太平洋危地马拉盆地1256站位钻获的玄武洋壳中的脆性构造（张开裂隙与脉体）完成了地理坐标系定向处理，具体实现路径包含两项：其一，将岩芯上观测到的构造与岩芯外壁未定向图像进行关联比对；其二，将岩芯构造与未定向图像同定向井孔图像进行关联比对。岩芯外壁图像通过德国蒙坦技术（Deutsche Montan Technologie）数字彩色岩芯扫描系统对整根岩芯段扫描获取。在展开式岩芯图像中，非水平平面构造（如脉体、断层或裂隙）会形成正弦曲线状的形态特征，此类特征可与井壁成像得到的同类形态特征进行匹配。井孔图像由地层微扫描仪（Formation MicroScanner, FMS）-声波（偶极声波成像仪）测井串与超声井孔成像仪（Ultrasonic Borehole Imager, UBI）采集获取：其中FMS可基于电阻率生成井壁的高分辨率成像图像，并通过通用测斜仪（General Purpose Inclinometer Tool）将FMS图像定向至磁北方向，借此可通过处理后的FMS图像测算出与井眼相交的地质构造的倾角与方位角；UBI搭载高分辨率换能器，可生成井壁的声波成像图像，且在ODP第206航次中，UBI首次在硬岩地层中投入使用。