Site 1195 penetrated a 521-m-thick lower Miocene to Pleistocene succession, overlying Eocene or lower Miocene carbonate buildup. The upper 130 m of sediments is unconsolidated, whereas the lower intervals are poorly to moderately lithified. The lithostratigraphy of Site 1195 comprises five units (Table T3; Fig. F4). Subdivisions are based upon sedimentary texture, glauconite content, color variations, noncarbonate constituents, and biotic associations. The sediments above the basal carbonates at Site 1195 consist of quartz-sandstone and grainstone with glauconite, representing a proximal periplatform environment (Unit IV), clay-rich carbonates deposited in a distal periplatform paleoenvironment (Unit III), and carbonates indicative of a hemipelagic environment (Units II and I).
Unit I consists of a 36.9-m-thick succession of skeletal packstone and grainstone (Fig. F4). It differs from underlying units by its high content of bioclasts and low content of carbonate mud. The sediment is usually well sorted, fine- to medium-grained, and pale yellow in color. Several 10- to 40-cm-thick layers of coarse and poorly sorted skeletal-rich floatstone or grainstone are present. Some of the layers show a sharp basal contact with the underlying finer-grained sediment. Fining-upward trends are observed in these layers. Skeletal components are dominantly planktonic foraminifers. Other bioclasts mostly appear within coarser layers and include benthic foraminifers, bivalves, gastropods, scaphopods, echinoids, arthropods, and rare bryozoans and solitary corals.
The contact with Unit II was positioned at the basal surface of the lowermost coarse layer, which is a skeletal floatstone at 34.5 mbsf (Fig. F5). This layer contains abundant light brown-stained phosphatized foraminifers and up to 5-mm-sized partly phosphatized lithoclasts.
Unit II consists of a 219-m-thick interval of skeletal wackestone and packstone (Fig. F4). It differs from Unit I in its reduced biotic diversity (dominantly planktonic foraminifers) and darker color (light greenish olive-gray). Unit II is topped by a 10-m-thick interval composed of medium sand-sized skeletal grainstone with glauconite. Glauconite is rare and mostly present within foraminifer chambers. Two 30-cm-thick layers at 36 mbsf and 38.3 mbsf have glauconite contents between 10% and 20% (Fig. F6). Unit II is divided into three subunits based on the occurrence of glauconite-rich intervals, textural variations, and pyrite content.
Subunit IIA consists of 57 m of very fine sand to fine sand-sized, poorly bioturbated foraminifer packstone and grainstone with clay. This subunit is defined by the absence of pyrite and textural alternations, which are abundant in Subunits IIB and IIC. Near the bottom of Subunit IIA at 90.4 mbsf, a 1.7-m-thick glauconite-rich layer occurs. The 20-cm-thick interval at its base has a glauconite content of ~10%.
Subunit IIB is a 30-m-thick silt-sized to very fine sand-sized skeletal packstone. It is characterized by a finer grain size than Subunit IIA and by common burrows that are stained black from finely disseminated pyrite. The boundary between Subunits IIA and IIB coincides with the first downcore appearance of silt-sized wackestone with a higher clay content, which is overlain by a fine sand-sized skeletal grainstone. This boundary occurs between Cores 194-1195B-10H and 11H and coincides with a marked downcore decrease of magnetic susceptibility values (see "Core Physical Properties").
In the upper part of Subunit IIC, the lithologies mainly consist of alternations between silt- and very fine sand-sized wackestone and very fine to fine sand-sized packstone. In the lower part, alternations of silt-to fine sand-sized packstone and fine to medium sand-sized grainstone occur. The grainstone layers frequently show a fining-upward trend. Scoured surfaces were observed at the bottom of some coarser layers (Fig. F7). Alternations of lithologies with different grain sizes occur every 0.2 to 1.5 m. The silt- to very fine sand-sized fraction is dominated by broken planktonic foraminifers. Compared to Subunit IIB, this subunit has a higher content of carbonate mud, a higher variability in grain size, and common Chondrites. Glauconite preferentially occurs in coarse layers within the uppermost 3 m and the lowermost 20 m of Subunit IIC.
Unit III, a 211.4-m-thick interval of skeletal mudstone to grainstone, differs from Unit II mainly in its higher benthic foraminifer content, lower planktonic foraminifer content, and finer grain size. An overall downhole decrease in color reflectance occurs at the transition between Unit II and Unit III, with the latter showing common dark olive-gray to greenish gray colors (Fig. F4) reflecting a higher noncarbonate fraction (mostly clay). This conclusion is supported by X-ray diffraction (XRD) data (see "Geochemistry"). Unit III is divided into two subunits based on clay and quartz content.
Subunit IIIA consists of 57.6 m of silt- to fine sand-sized wackestone to grainstone with glauconite occurring below 275 mbsf. Skeletal grains, particularly planktonic foraminifers, are mostly recrystallized. Benthic foraminifers are common. Alternations between wackestone and packstone occur but at a lower frequency than in Subunit IIC.
Subunit IIIB, a 153.8-m-thick interval of skeletal mudstone to grainstone, differs from Subunit IIIA in having a higher content of noncarbonate components and a higher content of total organic carbon (see "Geochemistry"). Within the 20-m-thick upper part of Subunit IIIB, quartz grains are common, coinciding with a noticeable peak in noncarbonate content (up to 50%) estimated from XRD measurements (Fig. F4). Downcore, alternations between mudstone, silt- to very fine sand-sized wackestone and very fine to fine sand-sized packstone occur. Toward the base of the subunit, alternations between silt- to very fine sand-sized packstone and fine to medium sand-sized grainstone are observed, similar in those of Subunit IIC. Mudstone and wackestone layers are always darker than packstone layers and show well-preserved Chondrites burrows (Fig. F8). As with Subunit IIC, a scoured surface overlies some of the finer layers. All layers are bioturbated. The lowermost 15 m of Subunit IIIB consists mainly of light gray grainstone with rare quartz grains. The color reflectance curve indicates a sharp decrease in lightness between this grainstone and a greenish gray wackestone with high glauconite content and quartz grains representing the top of Unit IV.
Unit IV consists of greenish gray, well-sorted, fine to medium sand-sized grainstone and quartz siltstone to sandstone (Figs. F4, F9, F10). Subordinate wackestone and packstone texture is also observed. Rounded glauconite and angular quartz grains are abundant. Pebble-sized sandstone and carbonate lithoclasts, as well as silt-sized foraminifer fragments are also present. Well-preserved Chondrites burrows are common (Fig. F9).
Unit V, the lowermost 20-cm core recovered at Site 1195, consists of a light yellowish brown skeletal grainstone with abundant nummulitids, mollusk fragments, coralline algae, and lithoclasts (Fig. F4). This dense limestone is capped along an irregular sharp surface by a centimeter-thick dark skeletal grainstone of Miocene age with lepidocyclinids (see "Biostratigraphy and Paleoenvironments").
Because Unit V is only 20 cm thick and heavily disturbed from drilling, an uncertainty remains about its origin. It could be the top of an Eocene platform, as bioclastic components and texture suggest a high-energy shelf. Alternatively, this nummulitid grainstone could also be a component of an early Miocene breccia.
Most sediment grains from Unit IV are reworked and generally well sorted. Rare Chondrites burrows, presence of planktonic foraminifers and calcareous nannofossils, and silt-sized reworked neritic foraminifers mixed with coarser sediment suggest a proximal periplatform setting (see "Biostratigraphy and Paleoenvironments"). Episodic periods of high terrigenous input are indicated by the occurrence of angular quartz sand. In addition, the well-sorted silt-sized to very fine sand-sized detrital material indicates significant sediment transport by bottom currents.
Unit III, with its higher content of planktonic foraminifers, represents a distal periplatform setting subject to the input of fine neritic carbonate components, especially benthic foraminifers. The higher abundance of coarse terrigenous layers in Subunit IIIB indicates a more proximal environment with respect to the platform, whereas Subunit IIIA with fewer benthic and more planktonic foraminifers, was deposited in a more distal setting.
Overall deepening continues upsection. As shown by its higher content of planktonic foraminifers and its low content of benthic foraminifers, Unit II reflects a deeper setting than Unit III. Larger benthic foraminifers (see "Biostratigraphy and Paleoenvironments") from Subunit IIC and the lower part of Subunit IIB record neritic input and were deposited in a periplatform setting. Above that interval, evidence of neritic input is minor, and a hemipelagic setting is indicated for the remainder of Unit II (see "Biostratigraphy and Paleoenvironments"). Textural evidence indicates an overall upsection decrease in energy through Subunits IIC and IIB, which could reflect further deepening. Within Subunit IIA, textures show a reverse trend with less mud and coarser material, which could indicate the onset of strong bottom currents during the Pliocene. The dominance of planktonic foraminifers and grainstone texture suggest that the sediments of Unit I were deposited by strong bottom currents in a high-energy hemipelagic setting.