ABI40 Image Data Processing
IODP-MSP drilling and logging contractor: ESO
Hole: M0042A
Expedition: 325
Location:
Latitude: 19 50.63885° ' S
Longitude: 150° 26.8818' E
Logging
date:
Sea floor depth (driller's): 56.32 m DSL
Sea
floor depth (logger's): 73.78 m WRF on ASGR; 65 m WRF on all other tools
Total
core recovered:
10.94 m (23.58 % of cored section)
Lithologies:
ABI40: 7-43.2 m WMSF
OBI40: 8.2-39 m WMSF
The ABI40 acquired acoustic images at mm-scale resolution. The images show the acoustic hardness of the lithologies within the coral reef sequence with a pixel size of 1.1 mm horizontally by 4 mm vertically.
The images are displayed as an unwrapped
borehole cylinder and are provided in .BMP and .PDF format. A dipping plane in the
borehole will appear as a sinusoid on the image with the amplitude of this
sinusoid proportional to the dip of the plane. The images are oriented with
respect to north, hence the strike of dipping features can also be determined. Additional
processing on the accelerometer data of the image tools by a double integration
of the acceleration allowed, whenever needed, a detailed repositioning of the
recorded image data to its correct position with respect to the seafloor.
The optimal borehole diameter for both imaging tools is <15 cm, and therefore the images acquired in Hole M0042A, an API-sized hole were of low quality with very little detail recorded. Additionally, the hole, although flushed before logging, was very murky due to the use of 'mud' whilst drilling rather than just seawater - hence the images recorded by the optical imaging tool were negatively impacted.
Additional
information about the drilling and logging operations can be found in the
Operations section of the Site Chapter in IODP Proceedings of Expedition 325.
For further questions about the data, please contact:
Dr Louise Anderson
University of
Leicester
Phone:
011-44-116-252-3327
Fax:
011-44--116-252-3918
E-mail: IODP-UK
For any
web site-related problem please contact:
E-mail: Database Manager