The sediment core description forms, or barrel sheets, summarize data obtained during shipboard analysis of each core (see the "Core Descriptions" contents list). The Ocean Drilling Program (ODP) conventions used for the compilation of each part of the core description forms and the exceptions to these procedures adopted by the Leg 182 Shipboard Scientific Party are described below.
A modified version of the lithologic classification of Mazzullo et al. (1988) was used during Leg 182. The classification adopted here is outlined in "Rock Classification and Principal Names". Sediment type is represented graphically on the core description forms using the symbols illustrated in Figure F1.
In the "Graphic Lithology" column a maximum of three different lithologies (for interbedded sediments) or three different components (for mixed sediments) can be represented within the same core interval. Percentages are rounded to the nearest 10%, and only lithologies that constitute at least 10% of each core are shown. Minor lithologies that are present as thin interbeds within the major lithology are shown by a dashed vertical line dividing the lithologies. Components that are present as minor fractions of the main lithology are shown by a continuous vertical line. Grain size of siliciclastic sediments or texture of neritic carbonates (see "Siliciclastic Sediments and Rocks" and "Neritic Calcareous Sediments and Rocks") is shown in the column to the left of the graphic lithology. However, note that only the mudstone and grainstone classes are displayed in Figure F1.
Five degrees of bioturbation were differentiated (Fig. F1), similar to that of Droser and Bottjer (1986). The relative degrees of bioturbation are illustrated in the color-banded bioturbation column of the barrel sheets.
The location and nature of sedimentary structures are shown in the "Structure" column of the core description form. The symbols used to designate structures found in Leg 182 cores are shown in Figure F1.
These columns indicate the occurrence of ichnofossil genera and major groups of macro- and microfossils. Bryozoans were classified using the growth-form scheme of Bone and James (1993). Symbols shown in this column are described in Figure F1.
This column indicates the position of secondary, diagenetic features such as ferruginous concretions or concretions in general. Symbols shown in this column are described in Figure F1.
Observations of drilling-related disturbance over an interval of 20 cm or more were recorded in the "Disturbance" column using the symbols shown in Figure F1. The degree of drilling disturbance in soft and firm sediments is as follows:
The degree of fracturing in indurated sediments and rocks is described using the following categories:
The positions of samples taken from each core for analysis are indicated in the "Sample" column of the core description form as follows: SS (smear slide), THS (thin section), PAL (micropaleontology), and IW (interstitial water).
After the core was split color was determined visually using the color chart of the Munsell Color Company (1994). In addition, color was measured with a Minolta CM-2002 spectrophotometer mounted on the archive multisensor track. These measurements were determined on the damp core surface, and Glad brand clear plastic film was used to cover the core. The Minolta CM-2002 measures reflected visible light in thirty-one 10-nm-wide bands ranging from 400 to 700 nm. Colors determined by this method correspond to those of the Munsell Color Company (1994). Routine measurements were made at evenly spaced intervals within each section, taking into account section length and the position of voids within the section.
Before and after obtaining measurements from each core, the spectrophotometer was calibrated for white color reflectance by attaching its white calibration cap. In addition, instrument calibration was checked using a white barium sulfate plate, which is the standard used for calibrating laboratory-grade spectrophotometers. These white color calibrations were made to avoid variation in color readings due to the laboratory environment (temperature, humidity, and background light) and instrument variations.
Note: After the cruise it was determined that a correction was applied erroneously to the color data by the recording software. The correction factors were not saved. Therefore, the absolute values of the raw data are incorrect. Calculation of color parameters such as L*, a*, and b* will contain large errors. However, relative variations with depth are probably consistent. Relative spectral analysis (e.g., reflectance ratios, first derivative) can probably be performed with insignificant errors.
Core description forms consist of a list of major lithologies followed by a more detailed description of the composition (as determined from smear slides), color, sedimentary structures, and other notable features. Descriptions and locations of thin, interbedded, or minor lithologies are also included in the text. The terminology for the thickness of sedimentary beds and laminae follows McKee and Weir (1953): very thick bedded (>100 cm), thick bedded (30-100 cm), medium bedded (10-30 cm), thin bedded (3-10 cm), thickly laminated (>0.3 cm), and thinly laminated (<0.3 cm). The term "wispy lamination" was used to describe laminae with undulatory and anastomosing shapes.
Tables summarizing data from smear-slide and thin-section analyses (see the "Core Descriptions" contents list) include information about the sample location, whether the sample represents a dominant (D) or a minor (M) lithology in the core, and an estimate of sand, silt, and clay, together with all identified components. The following categories were used: trace (<0.1%), rare (0.1%-1%), present (1%-5%), common (5%-20%), abundant (20%-50%), and dominant (>50%).
Grain types in granular sediments and rocks were classified according to mineralogy: (1) pelagic calcareous and siliceous, (2) neritic calcareous and siliceous, and (3) siliciclastic particles. Their definitions are as follows:
Pelagic carbonates contain more than 50% pelagic grains, whereas neritic carbonates contain more than 50% neritic grains. Siliciclastic sediments and rocks are composed of more than 50% siliciclastic grains.
Sediments and rocks were named on the basis of composition and texture using a principal name together with major and minor modifiers (Table T1). Principal names define the degree of consolidation (firmness) and granular sediment class. Composition is the most important classifier for pelagic and siliciclastic sediments and rocks, whereas texture is significant for the classification of neritic calcareous sediments and rocks (Table T2). Composition and texture of cored sediments and rocks were determined aboard ship by visual observation and visual estimates in smear slides, thin sections, and coarse fractions. Calcium carbonate content was qualitatively estimated in smear slides and quantitatively estimated by coulometric analysis (see "Organic Geochemistry").
Firmness of recovered materials was defined as in Gealy et al. (1971). Three classes of firmness were used to describe calcareous sediments and rocks:
Two classes of firmness were used to describe siliceous sediments and rocks:
For a better visualization of the different intensities of sediment lithification, degrees of firmness are also shown in the "Consolidation" column of the core descriptions (Fig. F1).
Principal names used to describe pelagic sediments and rocks during Leg 182 are as follows:
Neritic calcareous sediments and rocks were classified using a modification of the original Dunham (1962) classification, in conjunction with depositional textures described by Embry and Klovan (1971; Figure F2):
Texture, structure, and composition are the main criteria for the selection of a principal name for siliciclastic sediments and rocks. The Udden-Wentworth grain-size scale (Fig. F3; Wentworth, 1922) defines the grain-size ranges and the names of the textural groups (gravel, sand, silt, and clay) and subgroups (fine sand, coarse silt, etc.). This grain-size scale was also used in carbonate rocks. When two or more textural groups or subgroups are present, the principal names appear in order of increasing abundance. Eight major textural categories can be defined on the basis of the relative proportions of sand, silt, and clay (Fig. F4). Distinguishing between some size categories is difficult (e.g., silty clay and clayey silt) without accurate measurements of weight percentages. The terms conglomerate and breccia are the principal names of gravels with well-rounded and angular clasts, respectively.
To describe the lithology of the granular sediments and rocks in greater detail, the principal name of a granular sediment class is preceded by major modifiers and followed by minor modifiers (Table T1). Minor modifiers are preceded by the term "with." The most common uses of major and minor modifiers are to describe the composition and textures of grain types that are present in major (25%-40%) and minor (10%-25%) proportions. In addition, major modifiers can be used to describe grain fabric, grain shape, and sediment color.
The composition of pelagic grains can be described in greater detail with the major and minor modifiers "nannofossil," "foraminifer," "calcareous," and "siliceous." The terms calcareous and siliceous are used to describe sediments that are composed of calcareous or siliceous pelagic grains of uncertain origin.
The compositional terms for neritic calcareous grains include the following major and minor modifiers as skeletal and nonskeletal grains:
The textural designations for siliciclastic grains use standard major and minor modifiers such as gravel(-ly), sand(-y), silt(-y), and clay(-ey). The character of siliciclastic grains can be described further by mineralogy using modifiers such as "quartz," "feldspar," "glauconite," "mica," "lithic," or "calcareous." The fabric of a sediment can be described using major modifiers such as grain-supported, matrix-supported, and imbricated. Fabric terms are generally useful only when describing gravels, conglomerates, and breccias.