IODP Expedition 325, Hole M0031A - Wireline Standard Data

IODP-MSP drilling and logging contractor: ESO

Hole: M0031A

Expedition: 325

Location: Great Barrier Reef (tropical SW Pacific Ocean)

Latitude: 19° 40.737' S

Longitude: 150 14.377° ' W

Logging date: February 16, 2010

Sea floor depth (driller's): 92 m DSL

Sea floor depth (logger's): 110.4 m WRF

Total core recovered: 5.68 m (13.21 % of cored section)

Lithologies: carbonate sand, corals, bioclastic sediments

Data

The logging data was recorded by the University of Montpellier (Laboratoire de Tectonophysique), which is part of the European Petrophysics Consortium (EPC) in .RD format (read by the log software package WellCAD). Data were processed by the European Petrophysics Consortium.

Logging Runs

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The depths in the table are for the processed logs (after applying a depth shift to the sea floor).

Processing

Depth shift: The original logs were corrected for tool zero (+0.07 m) and shifted to the sea floor (-110.4 m).

Environmental corrections: None were applied.

Quality Control

The ASGR log was acquired through the API pipe. In carbonate lithologies, where counts are normally very low, data were further attenuated by the presence of the drill pipe. Ideally, following logging through pipe the ASGR probe would be run in open hole and the signals compared and depth-matched for quality assurance/quality control. However, because of poor hole stability, this was not possible at this site. Total natural gamma radiation (TGR) is very low (~12.2 cps) despite logging speeds of 1 m/min. Although there is no clear differentiation between contributions of the different elements, changes in the concentration of uranium appear to coincide with the majority of variations in TGR. In order to identify statistically accurate results, negative component values (i.e., negative concentrations of potassium, uranium, and thorium) were removed from the dataset. When interpolated (assuming a gap between data points no greater than 10 m), both the original and edited datasets exhibit similar trends.

A Null value of -999.25 may replace invalid log values.

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 any question about the data or about the LogDB database, please contact LogDB support: logdb@ldeo.columbia.edu.