Temperature measurements are important in the study of Earth's processes. Data collected during ODP have been used to study the transfer of heat from Earth's interior, ocean lithospheric evolution, continental margin formation, subduction zones, hotspot volcanism, fluid flow, and methane hydrate formation. Most measurements were made between 20 and 250 mbsf; however, a few measurements were taken below 500 mbsf.
Several tools have been used during ODP to collect borehole and formation temperature data and include the advanced piston corer temperature tool, water-sampling temperature probe, Uyeda Temperature Tool, and Davis-Villinger Temperature Probe.
The APCT tool was a temperature tool compatible with the APC system. This tool was first used during DSDP Leg 86. ODP purchased 10 von Herzen temperature tools, but all were unusable by Leg 117. The second generation APCT tool was often referred to as "Adara" after the company that built and interfaced the tools to a personal computer. The APCT tool resided in the APC cutting shoe and measured formation temperature while the APC core was being retrieved. These measurements were usually made to ~100–150 mbsf until the coring method switched because of the need to use a different drill bit.
The WSTP was a temperature tool compatible with the XCB and RCB coring systems and could be used in formations that were too stiff for the APC system. The WSTP was a hybrid of two other tools: the Uyeda Temperature Tool and the Barnes Fluid Sampler. The first generation WSTP was actually the Uyeda tool, used until Leg 116. The second generation WSTP was deployed during Leg 110. A third version of the WSTP was deployed on Leg 139. Coring was interrupted in order to take WSTP temperature measurements.
The DVTP was designed to take heat flow measurements in semiconsolidated sediments that were too stiff for APC coring. Coring was interrupted in order to take a temperature measurement with the DVTP. The DVTP could also be run on wireline and hung below the bit as a temperature logging tool for borehole fluids. The tool was officially deployed during Leg 168.
Several data reduction programs were used to determine in situ temperature during ODP. It wasn't practical to keep the temperature probe in contact with the sediment or rock for the extended period of time necessary to reach equilibrium. The data reduction programs determined the theoretical curve based on the observed data and inferred the equilibrium temperature. Factors that could affect estimates of temperature included frictional heating of the probe as a result of insertion, time interval of sampling, and in situ thermal conductivity.
Temperature measurements were logged on data sheets that were collected and sent to ODP/TAMU after the cruise for microfilming and archival. No interim database was found for these data. Digital files were created and stored starting with the APCT/Adara tool during Leg 144. After that time, all tools created digital files that have been archived on the ODP/TAMU servers.
The data model for downhole temperature data can be found in "Janus Downhole Temperature Data Model" in "Appendix P." Included are the relational diagram and the list of tables that contain data pertinent to temperature measurements, the column names, and the definition of each column attribute. The data model was designed for the APCT/Adara tool. An uploader was created and a couple Adara temperature runs were uploaded, but there was too much variability between data files. The format of the data files for the other tools varied significantly from the APCT/Adara files. The objective of uploading all the raw data was deferred and not completed during ODP.
As a result, only the final temperature determined by the Scientific Party was uploaded to Janus. Much of the temperature data were taken from the Initial Reports volumes; however, not all temperature data were analyzed and reported in the Initial Reports, so some temperature measurements are missing from the database.
Downhole temperatures can be retrieved from Janus Web using a predefined query. The downhole temperature query Web page allows the user to extract data using the following variables to restrict the amount of data retrieved: leg, site, hole, core, section, depth range, or latitude and longitude ranges. Table T34 contains the data fields retrieved from the Janus database using the query. The first column contains the data item, the second column indicates the Janus table or tables in which the data were stored, and the third column is the Janus column name or the calculations used to produce the value. "Description of Data Items from Downhole Temperature Query" in "Appendix P" contains additional information about the fields and data format for the archived ASCII files.
As described above, only the final temperature values determined by the Scientific Parties were uploaded to Janus. Because of time constraints, verification of these data was not completed. Any questions about downhole temperature data or requests for raw data should be directed to the IODP/TAMU Data Librarian.