DSDP Visualtext 7/86 ================================ = DEEP SEA DRILLING PROJECT = = VISUAL TEXT DATA BASE = ================================ I. INTRODUCTION A. BACKGROUND AND METHODS This Deep Sea Drilling Project (DSDP) data base contains the visual core descriptions written by participating shipboard scientists during each cruise. The descriptions were written onboard the Glomar Challenger as the cores were retrieved from the ocean floor. Although the data base allows a logical record for every sediment layer described by the shipboard party, it requires that there be a minimum of one logical record per section. This means that the data base views each layer as having a maximum thickness of a single section (1.5 meters). If in fact the geologic layer is greater than 1.5 meters, it is then represented by two or more logical records. Each logical record consists of a fixed-field lead record followed by one or more free-field text records. The structure of these two record types is covered later in this document. Every physical record is 52 characters long. B. LEGS IN DATA SET The data base contains data for legs 1-96. C. BIBLIOGRAPHY The SHIPBOARD HANDBOOK, issued by the Deep Sea Drilling Project, contains information on current methodology. The following reference gives the classification scheme used by the Project. Supko, Peter R., Perch-Nielsen, Katharina, and Carlson, Richard L., 1977. Introduction and Explanatory Notes, Leg 39. Deep Sea Drilling Project, Appendix A - Classification of Sediments. In Supko, P.R., Perch-Nielsen, K. et al., 1977. Initial Reports of the Deep Sea Drilling Project, Volume 39. Washington (U.S. Government Printing Office) pp. 19-24. Davies, Thomas A., Musich, Lillian F. and Woodbury, Peter B., 1977, Automated Classification of Deep-Sea Sediments: Journal of Sedimentary Petrology, Volume 47, No. 2, June 1977, pp. 650-656. II. FORMAT AND FIELD DESCRIPTIONS A. LEAD RECORD FORMAT Record length = 52 characters (fixed-field) 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 TOP OF LAYER DEPTH (meters) F8.2 36-43 BOTTOM OF LAYER DEPTH (meters) F8.2 44-45 NUMBER OF RECORDS I2 46-49 DESCRIBER A4 50-52 BLANK 3X B. LEAD RECORD FIELD DESCRIPTIONS 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. INTERVAL DEPTH: The depth, in centimeters, within a section marking the top or bottom of a layer. Values are encoded with an implicit decimal point, thus an encoded value of 805 represents 80.5 centimeters. CORE DEPTH: The subbottom depth in meters to the top of the core. LAYER DEPTH: The subbottom depth in meters to the top or bottom of the layer. NUMBER OF RECORDS: The number of records is equal to the number of free-field records plus one for the lead record. The number varies depending upon the number of free-field records which are needed to hold the entire core description text. DESCRIBER: The initials of the core describer. (NGDC NOTE: This field is blank for a large number of entries) C. FREE-FIELD RECORD FORMAT The free-field records consist of a series of descriptive phrases separated by semi-colons. A single code letter (listed below) precedes each descriptive phrase and characterizes the type of data within the phrase. If there is a compound descriptive term within a phrase (for example color), the items are separated by a dash. The entire description is terminated with a asterisk on the last record. CODE LETTER DATA TYPE =========== ========================= L Lithology C Color S Structures D Deformations due to drilling U Unusual occurrences M Minerals P Paleontology O Other observations H Hardness or induration Z Z-coding Below are a few examples of what a free field record may look like. L CLAY; (code letter "L" precedes a lithologic phrase) L SILT,CLAY;C -RED; (data types "L" and "C") L CLAY;C 5Y3/1-GREY; (data type "C" with compound terms) L CLAY;C 5Y3/1-GREY;H FIRM* (final record denoted by "*") D. FREE-FIELD DATA TYPE DESCRIPTIONS L = Lithology: There is a separate logical record for every core section or lithologic layer or section of core regardless of whether there is a lithologic change between sections. If the lithologies are mixed (i.e. clay lumps in sand), both lithologies are included on a single description. Pebbles of a unique lithology are not included within the lithology phrase (see data type U). C = Color: Colors are entered as a Munsell number and name when both are available (i.e. 5YR/1-GREY). If only the number is available, it is written alone. If only a name is available, it is written with a preceding dash (i.e. -GREY). S = Structures: This data type includes such items as burrows, laminations, faults, mottles, load casts, bedding of all types, etc. It does not include structures resulting from drilling (see data type D). D = Deformation: This refers to deformation resulting from drilling. U = Unusual occurrences: This category includes such items as pebbles, manganese nodules, manganese crust, pyrite nodules, oxidized layers and etc.. M = Minerals: List of any specific minerals mentioned in the description. P = Palentology: Macrofossil and microfossil occurrences mentioned in the visual core description. Categories M and P do not include information from smear slide or paleontology studies and therefore are incomplete. O = Other observations: This category allows for comments and observations which do not fit into any of other data types. H = Hardness or induration: Relative induration of the sediment. Z = Z-coding Z-codes are manually supplemented sediment codes that are used to create the DSDP SCREEN* file. They classify the sediment in areas where no smear slide data is available. Z-codes are used most often in areas of homogenous sediment type where smear slides may not have been taken as frequently. * The DSDP SCREEN file is a separate data base which contains computer generated lithologic classifications of DSDP sedimentary material (see Davies 1977). The file provides the user with a standardized lithologic data base. E. LOGICAL RECORD EXAMPLE Below is an example of a complete logical record taken from the visual text file for leg 71. 71511 7 4 5601500 52.50 57.56 58.50 5 BPB L NANNO DIATOM OOZE;H SOFT; C GRAY;M MANGANESE,VOLCANIC ASH, ZEOLITES; S ; U MANGANESE NODULES,VOLCANOGENIC DEPOSITS* The lead (fixed-field) record informs us that the data is indeed from leg 71, site 511, core 7, section 4. The described lithologic layer occurs within the section from 56.0 to 150.0 (implied decimal points) centimeters. The top of the core is at 52.50 (meters) and the layer is present from 57.56 to 58.50 meters subbottom. The logical record is made up of 5 physical records and the core was described by "BPB". The four free-field records which follow contain information on the layer's lithology (L), induration (H), color (C), minerals (M) and unusual occurrences (U). Data type "S" (structures) is present but is not followed by a phrase. The logical record is terminated by an asterix "*" on the last physical record. NGDC NOTES: (list of deviations from field descriptions) Description of deviation Record Number(s) ======================================= ================ Top interval depth exceeds bottom 1842,1847-1848,1930,1935-1936, 1938,1940,17487,36292 DSDP Visualtext 7/86