OCEAN DRILLING PROGRAM revised DATA FILE DOCUMENTATION July 1990 PALEOMAGNETICS MEASUREMENTS INTENSITY AND DIRECTION I. INTRODUCTION The Paleomagnetics Intensity and Direction data file contains measurements taken onboard the JOIDES/Resolution. Two magnetometers are available on the ship for measuring the magnetization of samples: 1. A three-axis, pass through cryogenic (superconducting) magnetometer used primarily for whole core section continuous NRM or demagnetized measurements on the archive half of the core. This instrument can also be used for measurements on discrete samples. 2. A Molspin minispin spinner magnetometer used to measure both rock and sediment discrete samples up to 1 inch in diameter. Two other pieces of equipment are used to demagnetize discrete samples: 1. The Schonstedt GSD-1 Alternating Field Demagnetizer used for AF demagnetization of rock or sediment samples. 2. The Schonstedt TSD-1 Thermal Demagnetizer, available as of Leg 114, used for the thermal demagnetization of dry rock samples with a temperature range of 0 to 800 degrees C. The data are collected directly from the magnetometers onto the shipboard VAX computer and brought back to shore on magnetic tape. (Legs 101-107 discrete sample results were collected on paper forms and encoded on shore.) The data file contains measurements made on discrete samples and continuous whole core sections of the archive half, on hard rocks and sediments. Magnetic properties recorded in the data file include natural remanent magnetization (NRM) intensity, declination and inclination along with all intensity, declination and inclination values after demagnetization. If you have problems or questions concerning these data, please contact: Data Librarian, Data Base Group Ocean Drilling Program Texas A&M University Research Park 1000 Discovery Drive College Station, Texas 77845-9547 U.S.A. (979) 845-8495, 845-2673 Easylink (Telex) Number: 62760290 Email: database@odpemail.tamu.edu Fax Number: 979-845-4857 II. LEGS IN THE DATA FILE The data file contains data from Legs 101, 103-129. III. BIBLIOGRAPHY Shipboard Scientific Party, 1987. Explanatory Notes. in Srivastava, S. P., Arthur, M. A., Clement, B. M., et al., Proc., Init. Repts. (Pt A), ODP, 105. IV. DATA ITEM FORMATS The following table lists the data items and their formats. For data requests other than on paper (ie. on magnetic tape), an accompanying sheet will contain any more information needed to read the data. PALEOMAGNETIC DATA ITEMS FORMAT ======================== ======== SAMPLE_CODE TEXT 4 LEG INTEGER 3 SUBLEG TEXT 1 SITE INTEGER 4 HOLE TEXT 1 CORE INTEGER 3 CORETYPE TEXT 1 SECTION TEXT 2 TOP_INTERVAL INTEGER 3 BOTTOM_INTERVAL INTEGER 3 PIECE INTEGER 3 SUB_PIECE TEXT 1 VOLUME DECIMAL F5.1 A_OR_W TEXT 1 WC_OR_DS TEXT 2 METHOD TEXT 1 TREATMENT.TYPE TEXT 2 TREATMENT.LEVEL DECIMAL F6.1 DECLINATION DECIMAL F6.2 INCLINATION DECIMAL F6.2 INTENSITY DECIMAL F10.4 CSD DECIMAL F5.2 V. EXPLANATION OF THE PALEOMAGNETIC DATA ITEMS SAMPLE_CODE - An alpha code identifying the investigator or test for which the sample was taken. LEG - Number identifying the cruise. The Ocean Drilling Program started numbering the cruises of the JOIDES Resolution at Leg 101. SUBLEG - Letter identifying a subleg or transit. A subleg is the continuation of a Leg in the same area with the same objectives after a port call and crew change. SITE - Number identifying the site. A site is the position of a beacon around which holes are drilled. HOLE - Letter identifying the hole. CORE - Number identifying the core. Cores are numbered serially from the top of the hole downward. CORETYPE - A letter code identifying the drill bit/coring method used to retrieve the core. The coretype codes are: B - Drill Bit C - Center Bit D - Positive Displacement H - Hydraulic Piston Core M - Miscellaneous N - Downhole Mud Motor (Navidrill) P - Pressure Core Barrel R - Rotary S - Side Wall Core W - Wash Core X - Extended Core Barrel SECTION - A core is cut into 1.5 meter long sections that are numbered serially from the top of the core. A core with full recovery will have 7 sections and a core catcher and be approximately 9.8 meters long. TOP_INTERVAL - The location of the top of a sample within a section in centimeters. BOTTOM_INTERVAL - The location of the bottom of a sample within a section in centimeters. PIECE - Number identifying a rock piece within a section. A piece is one or a group of rock fragments that can be fitted together. SUB_PIECE - Letter identifying the individual rock fragments within a piece. VOLUME - The volume of the sample in cubic centimeters. For whole core cryogenic measurements volume is left blank. When whole cores are fed through the cryogenic it takes readings at predetermined intervals along the core. Since these readings are at "points", there is no volume. A_OR_W - Indicates whether the sample or reading was taken from the archive (A) or working (W) half of the core. WC_OR_DS - Indicates whether the reading was done on a discrete sample (DS) or the whole core (WC). METHOD - Method used to obtain the reading. S = Molspin Spinner Magnetometer C = Cryogenic Magnetometer TREATMENT.TYPE - AF = Alternating-field Demagnetization TH = Thermal Demagnetization NR = Natural Remnant Magnetization TREATMENT.LEVEL - The treatment level used for the measurement. AF is in mT TH in degrees C NRM is always 0. DECLINATION - Recorded in degrees from 0.00 - 359.99. INCLINATION - Recorded in degrees from -90.00 - 90.00. INTENSITY - The method used determines the units for the intensity value. Molspin Spinner Magnetometer is in mA/m Cryogenic Magnetometer is in cgs x10 -6 CSD - Circular Standard Deviation (Fisher, 1953) of three vectors measured during six spin measurements. Value indicates an internal consistency of the measurement. A value above 30 represents a random measurement. No CSD values for Cryogenic measurements. RECORD FORMAT ON TAPE FOR THE PALEOMAGNETICS MEASUREMENTS - INTENSITY AND DIRECTION DATA FILE COLUMN DATA ITEM ON TAPE ========= ======= SAMPLE_CODE 2-5 LEG 6-8 SUBLEG 9-9 SITE 10-13 HOLE 14-14 CORE 15-17 CORETYPE 18-18 SECTION 19-20 TOP_INTERVAL 21-23 BOTTOM_INTERVAL 24-26 PIECE 27-29 SUB_PIECE 30-30 VOLUME 31-35 A_OR_W 36-36 WC_OR_DS 37-38 METHOD 39-39 TREATMENT.TYPE 40-41 TREATMENT.LEVEL 42-47 DECLINATION 48-53 INCLINATION 54-59 INTENSITY 60-69 CSD 70-74