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                                                            Page 1           =================================================          =           DEEP SEA DRILLING PROJECT           =          =          PALEOMAGNETICS MEASUREMENTS          =          =    IGNEOUS AND METAMORPHIC ROCKS DATA FILE    =          =================================================      I.  INTRODUCTION                                                                      A.  BACKGROUND                                                                          The file contains paleomagnetic and rock magnetic      measurements of igneous and metamorphic rocks and a few      sedimentary rocks composed of volcanic material.  Data were      encoded primarily from the "Initial Reports of the Deep Sea      Drilling Project".  The shipboard "Hole Summary Book" and      the DSDP data archives also were sources.  The file contains      both shipboard measurements and measurements made at onshore      laboratories.  Magnetic properties measured on the ship      include magnetic intensity, declination, inclination, and      initial susceptibility.  Shipboard paleomagnetic apparatus      included a Digico balanced fluxgate spinner magnetometer, a      Schonstedt alternating field GSD-1 demagnetizer and a Bison      magnetic susceptibility meter.  Shipboard measurements of      magnetic properties of igneous and metamorphic rocks were      made during DSDP Legs 34, 37, 45-46, 49, 51-55, 58-66,      68-73, 75-78, 81-85, 89, and 92.   B.  METHODS         Magnetic properties recorded in the file include natural      remanent magnetization (NRM) intensity, declination,      inclination, initial susceptibility, stable declination,      stable inclination, mean demagnetizing field, Curie      temperature, saturation intensity, saturation remanence,      coercive force, and remanent coercive force.  The      Koenigsberger ratio (Q) when calculated also is included.      In a few instances the paleomagnetist has indicated the      quality of orientation and a field is available for this      information.  There is also a field for the grain-size or      the grain-size range.       Each record includes an identifying code for the analyst's      or first author's name.  See Table 1 for the index to      analysts' codes.       Most records contain a code for data source (Table 3).  The      codes indicate whether the source was the "Initial Reports      of the Deep Sea Drilling Project", the Hole Summary Book, or      the prime data archives.  Each record has a code indicating                                 DSDP Hard Rocks Paleomagnetics 3/87                                                                  Page 2        whether the rock is igneous, sedimentary, or metamorphic.      Rock type can be further specified by the codes for tuff      (sedimentary), volcanic breccia (igneous), and brecciated      (igneous).  See Table 2 for rock type codes.       Codes indicate whether the measurements were done on board      ship or at a shore laboratory.       A blank field means not determined.       NRM intensities and initial susceptibilities are expressed      in scientific notation.  The symbol @ is used to represent      10.       Units for the magnetic parameters follow:        a)  Magnetic intensity             emu/cm\u3\d        b)  Mean demagnetizing field       oersteds        c)  Initial susceptibility         gauss/oersteds        d)  Saturation intensity           emu/cm\u3\d        e)  Saturation remanence           emu/cm\u3\d        f)  Coercive force                 oersteds        g)  Remanent coercive force        oersteds       In a few later DSDP reports data were expressed in SI units.      The DSDP encoders converted SI units to CGS units.  The      following conversions were used:         (A/m) / 79.6 = oersteds        (A/m) X 10\u-3\d = emu/cm\u3\d        mT X 10\u1\d = oersteds       As many as five comment records are present for information      about the analysis and the sample.  Lithological information      about the rock sample, including the rock name and a visual      estimate of the degree of alteration, is taken from the      Visual Core Description for Igneous Rocks forms, which are      completed by the shipboard scientists soon after core      recovery.       Each paleomagnetic measurements set includes a lead record      followed by one routine measurements record (R), and by one      comment record (C).  Since some comments are lengthy,      additional comment records may be employed as necessary.  An      optional extra measurements (X) record may follow the      routine measurements record.  The X record contains several      magnetic properties, including Curie temperature.  Several      temperatures may have been read from the thermomagnetic      curve.  The X record does not allow for repeating fields.      Therefore, additional X records to contain all the Curie      temperatures may be employed as necessary.   C.  LEGS IN DATA SET                                    DSDP Hard Rocks Paleomagnetics 3/87                                                                  Page 3        The data set contains data from Legs 14-16, 19, 23, 25-29,      32-34, 37-38, 41-43, 45-46, 49, 51-55, 58-66, 68-73, 75-78,      81-85, 89, 91-92.   D.  BIBLIOGRAPHY         Partial references to analytical methods for shipboard      measurements       Ade-Hall, J. M. and H. P. Johnson, 1976.  Paleomagnetism of      Basalts, Leg 34.  In Yeats, R. S., Hart, S. R., et al.,      Initial Reports of the Deep Sea Drilling Project, Volume 34:      Washington (U.S. Government Printing Office), pp.  513-532.       Hall, J. M. and P. J. C. Ryall, 1977.  Paleomagnetism of      Basement Rocks, Leg 37.  In Aumento, F., Melson, W. G. et      al., Initial Reports of the Deep Sea Drilling Project,      Volume 37:  Washington (U.S.  Government Printing Office),      pp.  425-448.       For methods used in a shore-based study, consult the paper      in the the Initial Reports.  The results and analytical      information of shipboard analyses similarly are published in      the Initial Reports.  See Table 1 for the index to analysts'      codes.                                                             DSDP Hard Rocks Paleomagnetics 3/87                                                                  Page 4    II.  FORMAT, FIELD DESCRIPTIONS, AND CODES      A.  RECORD FORMATS                            ===============                          = LEAD RECORD =                          ===============      Record length = 51 characters     (originally 60, blank fields removed by NGDC)      COLUMN   FIELD                                 FORMAT     ======   =====                                 ======        1-2    LEG                                     A2       3-5    SITE                                    A3       6      HOLE                                    A1       7-9    CORE                                    A3      10-11   SECTION                                 A2      12-15   TOP INTERVAL DEPTH (centimeters)        F4.1      16-19   BOTTOM INTERVAL DEPTH (centimeters)     F4.1      20-27   TOP OF CORE DEPTH (meters)              F8.2      28-35   SAMPLE MIDPOINT DEPTH (meters)          F8.2      36-39   ANALYST CODE                            A4      40-43   PIECE NUMBER                            A4      44      unused      45-46   NUMBER OF PHYSICAL RECORDS              I2      47      unused      48      LITHOLOGY CODE                          A1      49      SHIPBOARD OR ONSHORE MEASUREMENT CODE   A1      50      DATA SOURCE CODE                        A1          51      PHYSICAL RECORD NUMBER                  I1                    ===============================                  = ROUTINE MEASUREMENTS RECORD =                  ===============================      Record length = 51 characters      COLUMN   FIELD                                 FORMAT     ======   ===================================   ======        1      ROUTINE MEASUREMENTS CODE "R"           A1       2-9    NRM INTENSITY                           F8.0      10-14   NRM INCLINATION                         F5.0      15-19   NRM DECLINATION                         F5.0      20-24   STABLE INCLINATION                      F5.0      25-29   STABLE DECLINATION                      F5.0      30-31   QUALITY OF ORIENTATION                  A2      32-36   MEAN DEMAGNETIZING FIELD                A5                                 DSDP Hard Rocks Paleomagnetics 3/87                                                                  Page 5        37-44   INITIAL SUSCEPTIBILITY                  F8.0      45-49   KOENIGSBERGER RATIO                     A5      50      unused      51      PHYSICAL RECORD NUMBER                  I1                     ==============================                   = EXTRA MEASUREMENTS RECORD =                   ==============================      Record length = 51 characters      COLUMN   FIELD                                 FORMAT     ======   =====                                 ======        1      EXTRA MEASUREMENTS CODE "X"             A1       2      THERMOMAGNETIC CURVE                    A1       3-6    CURIE TEMPERATURE                       I4              Additional records are used if more than              one Curie temperature was read from the              thermomagnetic curve.       7-14   SATURATION INTENSITY                    F8.0      15-22   SATURATION REMANENCE                    F8.0      23-26   COERCIVE FORCE                          A4      27-30   REMANENT COERCIVE FORCE                 A4      31-40   GRAIN-SIZE                              A10      41-50   unused      51      PHYSICAL RECORD NUMBER                  I1                           =================                         = COMMENT RECORD=                         =================      Record length = 51 characters      COLUMN   FIELD                                 FORMAT     ======   ===================================   ======        1      COMMENT RECORD CODE "C"                 A1       2-50   COMMENT                                 A49                  Additional records are used if necessary.      51      PHYSICAL RECORD NUMBER                  I1      B.  FIELD DESCRIPTIONS AND CODES          The definition of leg, site, hole, core and section may be       found in the explanatory notes.  In addition, the special       core designations, as well as the methods of sample labeling       and calculating absolute sample depths are discussed.                                  DSDP Hard Rocks Paleomagnetics 3/87                                                                  Page 6       INTERVAL DEPTH:          Refers to the depth in centimeters within the section at       which the rock was sampled.  Values are encoded with an       implicit decimal point.     TOP OF CORE DEPTH:          The subbottom depth in meters to the top of the core.     SAMPLE MIDPOINT DEPTH:          The subbottom depth in meters to the level at which the       core was sampled.     ANALYST CODE:                    TABLE 1 - ANALYSTS'/AUTHORS' CODES      LEG  CODE  ANALYST/AUTHOR     ===  ====  ==============      14   LOW   Lowrie, W.     15   LOW   Lowrie, W.     16   HALL  Hall, J. M.     19   WHIT  Whitney, J.     23   HAM   Hamilton, N.     25   WOLE  Wolejszo, J.     26   PEIR  Peirce, J. W.     27   MCEL  McElhinny, M. W.     28   LOW   Lowrie, W.     29   LOW   Lowrie, W.     32   LARS  Larson, R.     33   CKM   Cockerham, R. S.     34   HALL  Hall, J. M.          TARA  Tarasiewicz, G.          GROM  Gromme, S.          ELL   Ellwood, B.          DEN   Denham, C.          LOW   Lowrie, W.     37   HALL  Hall, J. M.          BLEI  Bleil, U.          ELL   Ellwood, B.          KENT  Kent, D.          BREC  Brecher, A.                                 DSDP Hard Rocks Paleomagnetics 3/87                                                                  Page 7            DEUT  Deutsch, E.          SCHW  Schwartz, E.          CARM  Carmichael, C.     38   KENT  Kent, D.     41   KENT  Kent, D.     42   PET   Petersen, N.     43   PET   Petersen, N.     45   JOH   Johnson, P.     46   PET   Petersen, N.     49   DAY   Day, R.     51   BLEI  Bleil, U.          LEVI  Levi, S.          HAMY  Hamano, Y.     52   LEVI  Levi, S.          BLEI  Bleil, U.          HAMY  Hamano, Y.          RIG   Rigotti, P.     53   RIG   Rigotti, P.          HAMY  Hamano, Y.          LEVI  Levi, S.     54   PET   Petersen, N.     55   KONO  Kono, M.     58   KNS   Kinoshita, H.     59   KEA   Keating, B.     60   BLEI  Bleil, U.     61   STR   Steiner, M.          SYR   Sayre, W.     62   SYR   Sayre, W.     63   DEN   Denham, C.          SUR   Pal Verma, S.     64   VAC   Vacquier, V.          SUR   Pal Verma, S.     65   DAY   Day, R.          PECH  Pechersky, D. M.     66   NM    Niitsuma, N.     68         unknown     69   PECH  Pechersky, D. M.          FUR   Furuta, T.          ODON  O'Donovan, J. B.     70   FUR   Furuta, T.          PECH  Pechersky, D. M.          LEVI  Levi, S.     71   SAL   Salloway, J.     72   HAM   Hamilton, N.     73   PET   Petersen, N.          HOUS  Housden, J.     75   KEA   Keating, B.     76   TEST  Testarmata, M.     77   KNS   Kinoshita, H.          TEST  Testarmata, M.     78   WIL   Wilson, D.     81   KRMK  Krumsiek, K.     82   SMIT  Smith, G. M.     83   SMIT  Smith, G. M.                                 DSDP Hard Rocks Paleomagnetics 3/87                                                                  Page 8            KNS   Kinoshita, H.          NEW   Newmark, R.          FACY  Facey, D.     84   LIE   Lienert, B.     85   WEIN  Weinreich, N.     89   OGG   Ogg, J.     91   MONT  Montgomery, A. F.     92   NISH  Nishitani, T.     PIECE NUMBER:          The sample number assigned to the rock is included when       available.     NUMBER OF PHYSICAL RECORDS:          The total number of physical records which together       comprise a complete set of paleomagnetic measurements for a       sample.  Since there is always a lead record, a routine       measurements record (R), and a comment record (C), the       number of records is never less than 3.     LITHOLOGY CODE:                       TABLE 2 - LITHOLOGY CODES          I = Igneous         S = Sedimentary         M = Metamorphic         T = Tuff (sedimentary)         V = Volcanic breccia (igneous)         B = Brecciated (igneous)     SHIPBOARD OR ONSHORE MEASUREMENTS CODE:          C = Shipboard       S = Onshore     DATA SOURCE CODE:                       TABLE 3 - DATA SOURCE CODES      R = Initial Reports (IR)     S = Hole Summary Book (HSB)     A = Prime data archives                                 DSDP Hard Rocks Paleomagnetics 3/87                                                                  Page 9       PHYSICAL RECORD NUMBER:          Each physical record in a paleomagnetics measurements set       is numbered sequentially in column 51.  The physical record       number will always be "1" for the lead record and "2" for       the routine measurements (R) record.     NATURAL REMANENT MAGNETIZATION INTENSITY:          NRM intensity is encoded in gauss or emu/cc units.  It is       always represented in scientific notation.     NATURAL REMANENT MAGNETIZATION INCLINATION:          Information about the polarity is contained in the sign       preceding the inclination.  Units are degrees.  No absolute       value should exceed 90\uo\d.     NATURAL REMANENT MAGNETIZATION DECLINATION:          Values range from 0 to 360\uo\d and are always positive.     STABLE INCLINATION:          The value after alternating field demagnetization.     STABLE DECLINATION:          The value after alternating field demagnetization.     QUALITY OF ORIENTATION:                  TABLE 4 - QUALITY OF ORIENTATION CODES           G  = good          MG = medium good          P  = poor          VP = very poor          U  = unstable                                 DSDP Hard Rocks Paleomagnetics 3/87                                                                Page 10            M  = medium          R  = reversed          N  = none          F  = fair          PC = polarity corrected          UC = unoriented  **(Believed to be 'UO' by NGDC.  Found in data                              file as 'UO')**          SI = shallow orientation     MEAN DEMAGNETIZING FIELD:          Symbols for greater than ">" and less than "<" may appear       in the MDF field.     INITIAL SUSCEPTIBILITY:          Always represented in scientific notation.     KOENIGSBERGER RATIO:          Obtained by the formula:  NRM intensity/(initial       susceptibility X H), where H is the Earth's magnetic field       at the sampling location.     THERMOMAGNETIC CURVE:          A "C" is encoded in this field if the Curie temperature is       from the cooling curve, an "H" if it is from the heating       curve.     CURIE TEMPERATURE:          Multiple Curie temperature records:  Because of the sorting       routine used, the Curie temperature records may not be in       the correct order, particularly in data processed after Leg       66.     SATURATION INTENSITY:          Entered as a decimal.     SATURATION REMANENCE:                                  DSDP Hard Rocks Paleomagnetics 3/87                                                                Page 11          Entered as a decimal.     COERCIVE FORCE:          Symbols for greater than ">" and less than "<" may appear       in this field.     REMANENT COERCIVE FORCE:          Symbols for greater than ">" and less than "<" may appear       in this field.     GRAIN-SIZE:          Grain-size may have been determined by a visual estimate.       Units are microns.  Often a range is given.     COMMENT RECORD:          The rock name, degree of alteration and comments about the       results belong here.  Lithological information about the       rock sample, including the rock name and a visual estimate       of the degree of alteration, is taken from the Visual Core       Descriptions for Igneous Rocks forms, which are completed       by the shipboard scientists soon after core recovery.                      TABLE 5 - ALTERATION CODES           ALT FRESH    =          ROCK IS FRESH          ALT MOD      =          MODERATELY ALTERED          ALT EXT      =          EXTENSIVELY ALTERED          ALT INTENSE  =          INTENSELY ALTERED          ALT SLIGHT   =          SLIGHTLY ALTERED                                             DSDP Hard Rocks Paleomagnetics 3/87                                                                  Page 12    NGDC NOTES: (list of deviations from field descriptions)     Descriptions of deviation                   Record Number(s) ======================================      ================ Bottom interval depth is 0, top is not      occurs throughout the file  Unknown quality of orientation - the        1342,1373,1375,1375,1377,4332,    UO is believed to stand for              4343,4344,4357,4358,5116,5121,    'unorientated' but it was flagged        5123,5128,5133,5138,5143    as an error just in case 'UO' is    incorrect                                                                       DSDP Hard Rocks Paleomagnetics 3/87 

paleomagnetics measurements : igneous and metamorphic rocks data file - background and methods

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