During Leg 200, three general lithologies were described: sediments (at Sites 1223 and 1224), volcaniclastic rocks (at Site 1223), and basalts (at Site 1224). Separate forms were used to describe each lithology.
For sediments, detailed observations of each core were recorded initially by hand on standard ODP visual core description (VCD) forms. These forms provide a summary of the data obtained during shipboard analysis. The sediment VCDs were then entered into the computer using the AppleCORE software. Separate VCDs were custom designed in Adobe Illustrator for the volcaniclastic rocks (volcaniclastic VCDs [V-VCDs]) and the basalts (hard rock VCDs [HR-VCDs]). Both rock types were described on separate forms, and this description was added to the right column of the VCDs. The completed forms were then entered into the computer using Adobe Illustrator. The computerized versions of the visual core descriptions are renamed electronic visual core descriptions (eVCDs) (Fig. F2); V-VCD becomes eV-VCD (Figs. F3, F4), and HR-VCD becomes eHR-VCD (Figs. F5, F6).
The overall procedures used here are similar to those developed by the scientific parties during ODP Legs 183 (Shipboard Scientific Party, 2000a) and 197 (Shipboard Scientific Party, 2002).
Where appropriate, lithologic names according to the ODP sediment classification scheme (Mazzullo et al., 1988) were used. For volcaniclastics, however, we deviated from the standard ODP classification and we adopted a descriptive (nongenetic) terminology similar to that employed during ODP Legs 183 (Shipboard Scientific Party, 2000a) and 197 (Shipboard Scientific Party, 2002).
It is important to remember that the depths recorded for recovered cores may differ from true depths because of curation procedures. The top of the cored material is placed at the top of the cored interval even when recovery is <100%. This is ODP convention. The cored material may in fact have been recovered from deeper in the cored interval.
Sedimentary structures were described from observations of the split surface of the archive half. Lithologic names follow the ODP sediment classification scheme (Mazzullo et al., 1988). The naming conventions consist of a principal name based on composition, degree of lithification, and texture. For Leg 200, sediment names consist of a principal name (e.g., clay, sand, etc.) and a modifier that precedes the principal name. Minor components that represent between 10% and 25% of the sediment follow the principal name and the word "with" and are listed in order of increasing abundance. Granular sediments are subdivided on the basis of composition and abundance of different grain types estimated from visual examination of the core, smear slides, thin sections, and X-ray diffraction (XRD) analyses. For naming sediments, the Udden-Wentworth grain-size classification scheme (Wentworth, 1922) was used (Fig. F7).
The electronic descriptions for sediments were created using AppleCORE (version 8.1m) software, which generated a simplified, annotated graphic for each core (Fig. F2). Columns on the AppleCORE sheets include depth in core (meters), section number, graphic lithology, bioturbation, structure, disturbance, sample, color, and a description of the core. Features related to sedimentary structures and fossils are plotted on the graphic lithology near the interval in which they are present. The columns on the AppleCORE sheets are discussed below.
Sediment lithologies are represented by patterns in the "Graphic Lithology" column (Fig. F8). Limitations of the AppleCORE software result in an inadequate display of thin intervals of interbedded lithologies. These intervals are described in the "Description" column of the AppleCORE sheets.
Bioturbation is represented on the AppleCORE sheets by a symbol in the "Bioturbation" column. Intensity of bioturbation is not depicted by a symbol but is described in the "Description" column.
Sedimentary structures formed by natural processes (i.e., not a result of drilling disturbance) are represented on the AppleCORE sheets with symbols in the "Structure" column. These include varying degrees of grading. A symbol is positioned at the interval in the section where a particular feature is observed (Fig. F8). If the feature extends over an interval, the symbol appears on a vertical line bounded by arrows to denote the extent.
Deformation and disturbance of sediment that resulted from the coring process are illustrated in the "Disturbance" column. Intensity of disturbance may be denoted by lines of varying thickness and is described in the "Description" column. The degree of drilling disturbance is described using the following categories:
Sample material taken for shipboard sedimentological and chemical analyses consists of smear slide (SS), thin section (TS), XRD, microbiology (MBIO), and inductively coupled plasma (ICP) samples. Only the locations of smear slides are denoted in the "Sample" column.
Sediment color was determined visually by comparison with standard color charts (Munsell Color Company, 1994) and is reported in both the "Color" and "Description" columns. In addition to determining color visually, each core was scanned using a Minolta CM-2002 spectrophotometer mounted on the AMST. The spectrophotometer measures reflectance in thirty-one 10-nm-wide bands of the visible spectrum (400-700 nm) on the archive half of each core section. Spectrophotometer readings were taken after covering the surface of each core section with clear plastic film. Calibration for the color scanner did not include a correction for the plastic film because the effect is minor even with very brightly colored lithologies. The area measured is a circle 8 mm in diameter, and the spectrophotometer integrates the sensed color over this area. The AMST was not programmed to avoid taking measurements in intervals with a depressed core surface or in disturbed areas of core with drilling slurry or biscuits. The color data are a part of the ODP Janus database. Additional information about measurement and interpretation of spectral data with the Minolta spectrophotometer can be found in Balsam et al. (1997, 1998) and Balsam and Damuth (2000). Because of limitations in the AppleCORE software, small intervals of color variations are not shown in the "Color" column but are described in the "Description" column.
The written description for each core, located in the "Description" column on the AppleCORE sheets, contains a brief overview of both major and minor lithologies present, color and grain size gradation, location of sample in the section, and intensity of core disturbance.
Grain size, composition of sediments, and abundances were estimated using smear slides (Fig. F9). These were prepared according to the procedures described in the handbook for shipboard sedimentologists (Mazzullo and Graham, 1988). Identification in terms of general components was undertaken in accordance with Rothwell (1989). Estimates of the proportions of constituents were made using the Comparison Chart for Visual Percentage Estimation (Terry and Chilingar, 1955). In the case of smear slides, however, the percentage had to be corrected to compensate for the degree of dispersion of the grains in the smear slide. Quantitative estimate of grain size and composition are made to the nearest 5% in the tables located in the site chapters.
Smear slides provide only rough estimates of the relative abundances of detrital constituents. This is the result of some fundamental limits:
Thin sections from the core intervals noted on the VCD forms were examined to complement and refine the hand specimen and smear slide observations. The same terminology that was used for thin section descriptions was used for the VCDs. In sediments, the proportions of lithic, crystal, and vitric components, as well as the finer-grained matrix, were estimated. The textural terms that we used are defined in MacKenzie et al. (1982). Tables summarizing data from thin sections and smear slides are included in the site chapters. These tables include information about the locations of samples in the core and a quantitative estimate of the abundance and composition of different grain sizes and different grain types.
Unit textures and structures were described from observations of the split surface of both the working and archive cores. A combination of hand samples, smear slides, and thin sections were examined to categorize each unit. Volcaniclastic rocks were classified by designating a principal name with major and minor modifiers. The principal name defines its grain size class (e.g., sand, silt, or clay). Relative proportions of the vitric (glass), crystal (mineral), and lithic (rock fragment) components of the rocks are expressed as major (25%-40%) and minor (10%-25%) modifiers in the name. The major modifiers were placed before the principal name, whereas minor modifiers were placed after the principal name using "with." For example, a volcaniclastic rock composed of ~2-mm-sized particles, 45% glass, 25% crystals, and 10% lithic fragments, is named crystal vitric tuff with lithic fragments.
We used "volcaniclastic" as a nongenetic term for any fragmental aggregate of volcanic origin and containing >30% volcanic clasts and <70% other types of clastic and/or biogenic material. This definition is broader than that for a pyroclastic deposit. The term "pyroclastic" strictly applies to products of explosive volcanic activity and only includes hydrovolcanic deposits formed by explosive interaction between magma and water (i.e., hyaloclastite) and nonexplosive quenched fragmentation (i.e., peperite). The term "volcaniclastic" does not imply any active volcanism at the time of deposition; it also includes epiclastic sediments (the volcanic detritus produced by erosion of volcanic rocks).
Unless a pyroclastic origin for the rocks could be determined, we described deposits of volcanic provenance (volcaniclastic) according to the classification scheme for clastic sediments, noting the dominance of volcanic grains. We followed the clastic textural classification of Wentworth (1922) as shown by Boggs (1995) to separate the various volcanic sediments and sedimentary rocks into volcanic gravel (grain size 
2 mm), volcanic sand (2-0.0625 mm), volcanic silt (0.0625-0.0039 mm), and volcanic clay (<0.0039 mm) (Fig. F7). For volcaniclastic sediments, such as those produced by turbidity currents, we did not use the term volcanic ash. Instead we described them as volcaniclastic and named them based on grain size. Indurated units are called lithified, whereas units that are easily broken apart with a fingernail are termed weakly indurated.
The electronic descriptions for volcaniclastic rocks were recorded in Adobe Illustrator. The key to the symbols, colors, and other notations used on the eV-VCDs can be seen in Figure F3. The eV-VCD columns, from left to right, are Piece Number, Graphic Representation, Orientation, Shipboard Studies, Lithologic Unit, Contact/Boundary, Grain Size, Size Grading, Depositional Structure, and Disturbance (Fig. F4). These columns are described below.
The left column, "Piece Number," applies only to the volcaniclastic rocks that are well indurated (e.g., crystal vitric tuffs).
A graphic representation of the archive half of the core for the lithified units is shown as a pictorial representation, traced from the digital photo into Adobe Illustrator, in the "Graphic Representation" column. The units that were highly disturbed by drilling or are poorly indurated were not traced from the digital photos; a pattern was used to denote rock type instead.
When the orientation of individual pieces was possible, it was indicated on the form by an upward-pointing arrow in the column labeled "Orientation." A horizontal line across the width of this column denotes a plastic spacer and indicates an interval of no recovery.
Locations of samples selected for shipboard studies are indicated in the column headed "Shipboard Studies" with the following notation: XRD = X-ray diffraction analysis; ICP = inductively coupled plasma-atomic emission spectrometry analysis; TSB = thin section billet; PP = physical properties measurements; MBIO = microbiology sample; and PMAG = paleomagnetic measurements.
The core was subdivided into consecutively numbered lithologic units, under the "Lithologic Unit" column, on the basis of changes in grain size, mineral presence, and abundance.
The "Contact/Boundary" column refers to a relationship between two units that are in contact with one another within a core section. Two types of contacts were listed in this column, sharp and gradational (denoted with S and G, respectively).
The "Grain Size" column is used to describe the size of grains based on Wentworth's (1922) classification. The following notation is used:
cl = clay (<0.0039 mm). s = silt (0.0039-0.0625 mm). vfs = very fine sand (0.0625-0.125 mm). fs = fine sand (0.125-0.25 mm). m = medium sand (0.25-0.50 mm). c = coarse sand (0.50-1.00 mm). vc = very coarse sand (1.00-2.00 mm). g = granule (2.00-4.00 mm). p = pebble (4.00-16.00 mm). cl s = clayey silt (a unit of predominantly silt with some clay). s cl = silty clay (a unit of predominantly clay with some silt).
For the description of the crystal vitric tuff, we used the following scale for grain size:
vfg = very fine grained (<0.5 mm).
fg = fine grained (0.5-1 mm).
mg = medium grained (1-2 mm).
Size grading refers to the change in grain size within an individual unit. Normal grading refers to the grains becoming finer upward. Reverse grading refers to the grains becoming coarser upward. The word "NORMAL" or "REVERSE" was placed under the "Size Grading" column to denote the type of grading observed.
Depositional structure refers to large-scale patterns seen in the sediment and the rocks. It may include laminations, massive rip-up clasts, cross-bedding, cross-laminations, and erosional structures.
The "Disturbance" column is used to denote the amount of disturbance that has taken place in the unit since its deposition. The disturbance was described using the following criteria: no annotation = undisturbed; S = slightly disturbed; M = moderately disturbed; H = highly disturbed.
A written core description accompanies the schematic representation of the core sections. This includes leg, site, and hole information in addition to the headings "Unit," "Pieces," "Thin Section(s) #," "Contacts," "General Description," "Color," "Components," "Sedimentary Textures," "Sedimentary Structures," and "Comments." These are discussed below.
As with AppleCORE sheets, the leg, site, hole, core type, and section number (e.g., 200-1224D-3R-2), as well as the top and the bottom of the core section measured in meters below seafloor, are located at the top of the written description.
We assigned provisional rock names on the basis of hand specimen observation (hand lens and binocular microscope) and later checked these assignments by examining thin sections.
Samples that are lithified are given individual numbers for each piece and these pieces are listed under the "Pieces" heading.
The number(s) assigned by ODP to the thin section(s) for the lithologic unit described are given under the heading "Thin Section(s) #."
After describing the lithology, we defined unit boundaries. These unit boundaries are listed under "Contacts." The boundaries often reflect physical changes in the core intervals of the volcaniclastic rocks; changes in vesicularity, alteration, volume fraction, and type of matrix also define lithologic contacts. Where possible, whole-rock chemical analyses by inductively coupled plasma-atomic emission spectrometry analysis (ICP-AES) (see "Geochemistry") were used to investigate chemical differences between units.
The "General Description" section was used to give a brief overview of a unit, both macroscopically and microscopically.
"Color" provides a color name and code (for the dry rock surface) according to the Munsell rock color charts (Munsell Color Company, 1994).
The "Components" column includes a list of the principal constituents, their approximate percentages, and their average sizes—determined both petrographically, when thin sections were available, and macroscopically using a binocular microscope for units without thin sections.
The "Sedimentary Textures" section includes grain size, particle shape (roundness), and grain orientation.
The "Sedimentary Structures" section includes laminations, cross-bedding, erosion structures, and graded beds.
Any general descriptions of the unit that were not included under another heading were included under the "Comments" heading. Examples of this include drilling disturbance, freshness of glass shards, and how widespread a particular component is in a unit.
Basalts cored at Site 1224 are aphyric to sparsely phyric abyssal tholeiites (normal mid-ocean-ridge basalt [N-MORB]) based on chemistry. They include massive flows and holohyaline to hyalopilitic pillows. They were also classified as moderately or strongly differentiated based on chemistry.
Similar to the volcaniclastic rocks, the basalts were described first on paper, then this information was electronically transposed into Adobe Illustrator. The key to the symbols, colors, and other notations used on the eHR-VCDs can be seen in Figure F5. The first five columns of the eHR-VCD form ("Piece Number," "Graphic Representation," "Orientation," "Shipboard Studies," and "Lithologic Unit") are identical to the eV-VCD. For a description of these columns, see "Electronic Volcaniclastic Visual Core Descriptions".
The eHR-VCD columns that are different from the eV-VCD include "Phenocrysts (%)," "Groundmass/Grain Size," "Vesicularity (%)," "Vesicle Structure," and "Degree of Alteration." These are described below.
The column "Phenocrysts (%)" is used to represent a visual estimation of abundance and variation of phenocrysts throughout the core section using the following notations (Fig. F5):
The column "Groundmass/Grain Size" refers to the average size of the groundmass phases:
If groundmass phases are <0.5 mm in size (vfg), they cannot be seen with the naked eye and the rock is said to be aphanitic (Fig. F5).
The "Vesicularity (%)" column contains the following abbreviations (Fig. F5):
The "Vesicle Structure" column contains the following abbreviations (Fig. F5):
The "Degree of Alteration" column is used to denote the amount of alteration. The alteration was described using the following: no annotation = unaltered (alteration products form <2% of the rock); diagonal lines = slight (alteration products from 2%-10% of the rock); solid vertical lines = moderate (alteration products form 10% to 40% of the rock); wavy line = high (alteration products form 40% to 80% of the rock) (Fig. F5).
Similar to the eV-VCD, a written core description of the basalts accompanies the schematic representation of the basaltic core sections (eHR-VCD). The description includes the leg, site, and hole information, in addition to the headings "Unit," "Pieces," "Thin Sections," "Contacts," "Phenocrysts," "Groundmass," "Vesicles," "Color," "Structure," "Alteration," Veins/Fractures," and "Additional Comments." These are discussed below.
As with the AppleCORE sheets and the eV-VCDs, the leg, site, hole, core type, and section number (e.g., 200-1224D-3R-2), as well as the top of the core section measured in meters below seafloor are located at the top of the eHR-VCD description form.
The unit number (consecutive downhole) and the rock name are located next to "Unit." The provisional rock names were assigned on the basis of hand specimen observations (hand lens and binocular microscope) that were later cross-checked with thin sections and ICP data.
"Pieces" refers to the pieces shown in the "Graphic Representation" column with the numbers reported in the "Piece Number" column.
Where done, "Thin Section(s)#" indicates the number of the thin sections used for the petrographic description of the core.
The "Contacts" section includes contact relations and unit boundaries. The unit boundaries were defined based on lithology. The boundaries reflect physical changes in the core (e.g., sequential flows, pillows, or cooling units) that were also observed in the physical properties and downhole measurements. Intervals of sediment, hyaloclastite, and/or changes in vesicularity, chilled margins, alteration, and type of matrix also were used to define lithologic contacts.
The "Phenocrysts" entry describes the types of minerals visible with a hand lens or a binocular microscope and their distribution within the unit. The abundance (in volume percentage), range in size (in millimeters), shape, and degree of alteration were determined for each phase.
"Groundmass" includes texture and grain size such as glassy, very fine grained (<0.5 mm), fine grained (0.5-1 mm), medium grained (1-2 mm), or coarse grained (>2 mm) (Fig. F5).
The "Vesicles" section includes the abundance of vesicles (visual estimates of the volume fraction of vesicles were supplemented by observations using a binocular microscope), size, and shape (sphericity/angularity) (Fig. F6). The presence or absence of filling in the vesicles and the type of filling were also noted here.
"Color" includes a color name and code (for the dry rock surface) according to the Munsell rock color charts (Munsell Color Company, 1994).
"Structure" describes fractures and whether the unit is massive, pillowed, hyaloclastic, banded, or brecciated. The type of alteration mineral lining the fractures was noted. In addition, the presence of alteration adjacent to the fractures and alteration halos was described in this section. We sought to produce an integrated picture of the style of volcanism and environmental setting of each drill site by identifying features that are diagnostic of specific physical processes. Pillowed sequences were inferred using the presence of glassy margins and groundmass grain-size variations. A section was described as massive if there was no evidence for pillows, even though it may be part of a pillowed sequence.
"Alteration" describes the degree of alteration as unaltered (<2% of alteration products by volume), slight (2%-10%), moderate (>10%-40%), and high (>40%) (Fig. F5). Changes of alteration through a section or a unit were noted, in addition to the type of alteration material.
"Additional Comments" describes any general descriptions of the unit that were not included under another heading.
Thin sections of volcaniclastic rocks and basalts were examined in order to confirm the visual core descriptions and to better define the textures and relationships among the various constituents of the unit. Moreover, thin section descriptions helped to define the secondary alteration mineralogy and the state of alteration of minerals and glass (where present).
Percentages of individual mineral phases, glass, and alteration products were visually estimated to an accuracy of ±10%. A 1000-point mode was determined and was noted in the "Comments" for some thin sections.
Percentages of original paragenesis and of alteration products are given on the detailed thin section description sheets (Fig. F10).
Where possible, a detailed description of the minerals is given. Mineral identifications were made using standard optical mineralogical techniques. In particular, the main aspects considered to identify a mineral phase were shape (under crossed polars [XP] and in plane-polarized light [PP]), habit (XP and PP), color (PP), color (reflected light [RL]), relief (PP), Becke line (PP), interference color (XP), optical sign (conoscopic view with crossed polars [CXP]), determination of optical angle, 2V (CXP), and determination of the difference between crystallographic and optical directions (e.g., c
or a
; XP).
The information given in the thin section description sheets includes
All basalts cored at Site 1224 are aphyric to sparsely phyric.
Representative digital photomicrographs were obtained to better illustrate textures as well as primary and secondary mineralogy.
