Site 1134 is located at a water depth of 701 m. It provides a 397.1-m-thick record of Eocene-Pleistocene sedimentation in a middle to upper slope depositional setting. The sedimentary succession is similar in a general way to the succession at Site 1126 and comprises two sedimentary packages.
The lower package is a sandstone unit of uncertain, probable middle Eocene age (see "Seismic Stratigraphy") (Fig. F3). The presence of bioclasts and planktonic foraminifers points to a marine origin for these sediments. The upper package at Site 1134 consists of upper? Eocene-Pleistocene pelagic marine carbonates, wackestone to floatstone, and minor chert and porcellanite. Some of these deposits are slumped (Fig. F3).
Based on major sediment types, compositional changes, and sediment deformation structures, six lithostratigraphic units are differentiated. Because core recovery at Site 1134 was good within the uppermost 180 m, the level of confidence for the placement of the boundaries in this part of the succession is high. Core recovery was low below Cores 182-1134A-17X and 182-1134B-20X; therefore information from the downhole logs (see "Downhole Measurements") was used to refine depth assignments of individual boundaries.
Unit I consists of calcareous nannofossil ooze with varying amounts of planktonic foraminifers. The base of the unit is placed between Cores 4H and 5H in Hole 1134A at the contact between an unlithified wackestone and a calcareous nannofossil ooze. In general, whitish matrix-supported intervals alternate with darker, light gray intervals that are grainier and have a wackestone to packstone texture. In the light intervals, the major sedimentary components in the >63-µm fraction are planktonic foraminifers, sponge spicules, bioclasts, benthic foraminifers, radiolarians, and minor tunicate spicules. The darker sediments also contain echinoid spines as well as rare glauconite, pyrite, and black grains. The glauconite and pyrite content of the sediments is highest in light gray layers in the lower part of the Unit (Core 182-1134A-4H) (Fig. F3).
In general, the boundaries between lighter and darker sediments are gradual because of intense bioturbation, but some of the contacts are sharp. These sharp contacts occur at the base of the grainier layers. Bioturbation of the deposits appears as faint white to gray mottling but also as well-defined burrows which are conspicuously present at the transition between light and dark sediments.
Unit II is characterized by soft-sediment deformation that is inter-preted as slumping. Two slump intervals occur (Fig. F3): the upper one in Core 182-1134A-5H and the lower one in Cores 182-1134A-6H through 8H. The base of the lower slump interval defines the lower boundary of Unit II.
Unit II contains calcareous nannofossil ooze, calcareous nannofossil foraminifer ooze, as well as unlithified wackestones, packstones, floatstones, and rudstones. The ooze is white to light gray. Components in the >63-µm fraction are planktonic foraminifers, echinoid spines, bioclasts, sponge spicules, and minor bryozoans. In the lower part of the unit (Core 182-1134A-8H), some of the planktonic foraminifers are infilled with glauconite; glauconite also occurs as isolated grains. The light gray wackestones to rudstones contain a wide variety of coarse components such as different types of bryozoans (robust and delicate branching, arborescent, and fenestrate growth forms), bioclasts, sponge and tunicate spicules, as well as pellets. Pebble-sized lumps of calcareous nannofossil ooze, which are interpreted to be reworked clasts, are present in packstones and floatstones of Sections 182-1134A-5H-3 through 5H-CC and 6H-5 through 6H-CC. Soft-sediment deformation affects both the ooze and the deposits dominated by neritic components. Sediment between the slump packages is calcareous nannofossil ooze and calcareous nannofossil foraminifer ooze rich in glauconite.
Unit III consists of calcareous nannofossil ooze and calcareous nannofossil foraminifer ooze. The lower limit of the unit is indicated by a change from dominantly pelagic sediments of this unit to partially lithified wackestones in Unit IV. At this point, carbonate content drops from values of ~90% in Unit III to values <80% in Unit IV (see "Inorganic Geochemistry"). The boundary between the units was not recovered in Hole 1134A, but was observed between Sections 17X-2 and 17X-3 in Hole 1134B. The gamma-ray log shows a downhole increase at 152 mbsf (see "Downhole Measurements") that probably reflects the corresponding lithologic change. Although the deposits of Unit III are not uniform throughout, it was decided not to subdivide them further because such lithologic changes are minor.
In general, the matrix of the ooze in Unit III is clearly dominated by calcareous nannofossils with only minor amounts of clay (see "Site 1134 Smear Slides"). In addition to the planktonic foraminifers, the >63-µm fraction contains benthic foraminifers, bioclasts, sponge spicules, minor silicoflagellates, and traces of glauconite. The first lithologic variation in Unit III occurs in Core 182-1134A-12H, where the matrix of the deposit contains minor amounts of silt-sized rock fragments and clay (see "Site 1134 Smear Slides"). This interval correlates well with a minor hiatus as detected in the same core by the calcareous nannofossil associations (see "Biostratigraphy").
The second lithologic variation is in Cores 182-1134A-14H through 16X, where the degree of lithification alternates between unlithified and lithified over short intervals. These short-term variations imply processes other than simple depth-related sediment compaction. This lower limit of the interval with alternating lithification corresponds to the base of Sequence 3 (see "Seismic Stratigraphy"); therefore, the lithification pattern may reflect condensed sedimentation related to this sequence boundary.
Unit IV consists of unlithified to partially lithified wackestone/packstone, foraminifer chalk, and very minor packstone. The lower boundary of the unit is at the top of a white foraminifer chalk in Core 182-1134A-25X and also occurs in Section 182-1134B-24X-2. This boundary is also well defined on the sonic velocity log, where an abrupt downhole increase of the sonic velocity occurs at 217 mbsf (see "Downhole Measurements").
The style of deposition is uniform throughout the unit and characterized by a metric alternation of light gray foraminifer chalk and light gray to gray wackestone/packstone. The chalk contains planktonic foraminifers, bioclasts, and sponge spicules, as well as minor quartz grains, glauconite, benthic foraminifers, and echinoid spines. The unlithified to partially lithified wackestone/packstone—although richer in glauconite and having more abundant bioclasts—contains the same components. Some of these layers (e.g., in Core 182-1134A-17X) have a sharp base and are normally graded. Such beds may represent turbidites.
Composition of the packstones can be seen in the "Site 1134 Thin Sections". The components are very fine sand sized and rich in glauconite and quartz. Biogenic components are planktonic and benthic foraminifers, bryozoans and ostracode fragments. Dolomite makes up ~10% of the sediment. Deposits of Unit IV are intensely bioturbated; thus, in general, boundaries between the different lithologies are transitional. Centimeter-scale dark green reduction laminae are scattered throughout the succession.
Two main lithologies were recovered between 214.3 and 368.2 mbsf: (1) calcareous nannofossil chalk and (2) fragments of porcellanite and chert. The matrix of the white chalk is dominated by calcareous nannofossils, with common sponge spicules as well as trace amounts of bioclasts and dolomite. The coarse fraction consists of planktonic and benthic foraminifers. The chalks are strongly bioturbated. Burrows appear as faint color mottling (gray-white) but also as well-defined traces, such as Zoophycos. (e.g., Core 182-1134A-39X). Green and dark gray to black reduction laminae are present throughout the unit. The gray and green porcellanite lithologies are silicified chalk.
Although the core recovery was very poor in the interval corresponding to Unit V and no subunits were defined, there appears to be a division into three major sedimentary packages. This differentiation relies on textural trends of the deposits. The uppermost package, which is dominated by a wackestone texture, is from Cores 182-1134A-25X through 28X (214.3-252.9 mbsf). The lower limit of this interval matches with a strong excursion of the gamma-ray log to higher values at 252 mbsf (see "Downhole Measurements"). The base of the middle package is at the top of Core 182-1134A-34X at a depth of 300.8 mbsf. This limit probably corresponds to a peak of the gamma-ray log, followed by a general decrease of the values at 305 mbsf (see "Downhole Measurements"). This middle package shows an uphole change from a packstone to a mudstone texture. The lower sedimentary package of Unit V is dominated by a mudstone texture with wackestone and packstone texture intervals.
Only 30 cm of the lowermost deposits at Site 1134 were recovered. The sediments are brown limonitic sandstone with quartz, limonite, glauconite, mica, and abundant skeletal grains, as well as minor planktonic foraminifers. Siliciclastic components are as large as coarse sand sized.
The basal sandstones at Site 1134 (Unit VI) were so poorly recovered that no information can be provided as to the development of the succession. The deposits are probably marine, as indicated by the occurrence of planktonic foraminifers and bioclasts. The seismic tie with the succession drilled in the borehole Jerboa-1 (see "Seismic Stratigraphy") indicates that the sandstones form a ~40- to 50-m-thick cap of probable Eocene age that overlies Cretaceous sandstone.
The nature of the contact between the basal siliciclastics and the chalks could not be assessed at Site 1134 because of poor core recovery. The overlying sediments of Unit V roughly coincide with the seismically defined Sequence 6A (see "Seismic Stratigraphy"). These sediments are pelagic carbonates that formed under well-oxygenated bottom-water conditions, as indicated by the intense burrowing. The limits of the sedimentary bundles within this unit correspond roughly to the Eocene/Oligocene and the Oligocene/Miocene boundaries, respectively.
In contrast to Site 1126, where pelagic sedimentation was uniform throughout the early Miocene, Site 1134 records a subtle early Miocene change of the sedimentary regime toward an increased input of shelf and shallower water particles at the base of Unit IV. This turnover roughly corresponds to the base of the outer slope part of the "Little Barrier Reef" Sequence 6B as defined by Feary and James (1998, reprinted as Chap. 2) (see "Seismic Stratigraphy"). The discrepancy between the record at Site 1126 and 1134 is best explained by the lateral variability of Sequence 6B, which is characterized by a lobate geometry north of Site 1134 (fig. 10 in Feary and James, 1998, reprinted as Chap. 2). Site 1134 records the most distal part of this lobe, whereas Site 1126 records the pure pelagic equivalent, as the limit of the distal part of Sequence 6B at this locality is situated further to the north.
Pure pelagic conditions at Site 1134 returned during middle Miocene time with the formation of calcareous ooze. An interruption in uniform pelagic sedimentation is represented by the slumps of Unit II. In contrast to Site 1126, where slumping occurs in an equivalent stratigraphic position, slumps at Site 1134 contain a mixture of pelagic and neritic sediments. Porcellanite fragments in the slumped deposits at Site 1134 show that sediment as old as middle Miocene age may have been affected by the slumping, as the first in situ porcellanite occurrence at Site 1134 is in the middle Miocene sequence. Relatively monotonous pelagic sedimentation at Site 1134 resumed during the Pliocene (Unit I) and persisted throughout the Pleistocene. Similar to Site 1126, sediments of Unit I alternate between layers rich in planktonic foraminifers and layers dominated by calcareous nannofossils. How this alternation correlates with the Pleistocene depositional cycles recorded in the Leg 182 shallower water drill sites will be addressed during additional postcruise research.