The 286.1 m of sediment recovered at Site 1219 consists primarily of radiolarian and nannofossil ooze with varying clay contents in a sequence similar to Site 1218 and DSDP Site 162. Lithologic descriptions are primarily based on sediments from Hole 1219A. The Neogene is represented by 30 m of radiolarian clay and radiolarian ooze. About 120 m of nannofossil ooze, with variable radiolarian and clay content, comprises the lower Miocene and Oligocene sections at this site. A 95-m-thick Eocene section contains a diverse array of sediments including radiolarian and zeolitic clays, radiolarian and diatom oozes, and nannofossil oozes and chalks. Chert was encountered near the base of the Eocene section. Minor components throughout the sequence include diatoms, foraminifers, iron oxides, and zeolites. Other minor to trace components include fish teeth, sponge spicules, silicoflagellates, and volcanic glass.
The sequence is divided into five major lithologic units (Fig. F3). With the exception of the Unit I/II contact, all unit boundaries are sharp lithologic transitions (Figs. F4, F5, F6, F7). Physical properties data support our interpretation of lithologic units and subunits (see "Physical Properties"). Unit I extends from 0 to 30.0 mbsf (Hole 1219B: 21.0-29.2 mbsf) and consists primarily of radiolarian clay grading to radiolarian ooze that is late Miocene-Holocene in age. Alternations of nannofossil ooze with radiolarians and clay are present in the basal portion of Unit I. These variations are expressed as decimeter-scale, light-dark color cycles. Unit II, lower Oligocene-lower Miocene nannofossil oozes, begins at 30.0 mbsf and extends to 150.8 mbsf (Hole 1219B: 29.2-154.5 mbsf). The upper and basal portions of Unit II contain significant clay and radiolarian components, which are also expressed as decimeter- to meter-scale color cycles. Subunit IIIA (Hole 1219A: 150.8-224.5 mbsf; Hole 1219B: 154.5-158.0 mbsf) begins at the lithologic transition associated with the E/O boundary and grades from a radiolarian clay to a radiolarian ooze. Approximately 10 m of radiolarite and chert, underlain by a zeolitic clay, comprises Subunit IIIB (Hole 1219A: 224.5-234.2 mbsf). Core recovery in the cherty interval of Subunit IIIB was poor. Unit IV spans the interval from 234.2 to 244.8 mbsf and contains extensively recrystallized nannofossil chalk and calcareous chalk that is early Eocene in age. The basal portion of Unit IV contains 20-30 cm of extensively altered chalk and basalt. Unit V consists of a fine-grained phaneritic basalt.
The upper 14.6 m of Unit I consists of alternating radiolarian clay, clay with radiolarians, and clayey radiolarian ooze with the radiolarian fraction decreasing downhole. This is also expressed as a decrease in lightness (L*) and an increase in the red/blue (680 nm/420 nm; a*/b*) ratios in spectral reflectance (Fig. F8). Lithologic alternations are seen as half-meter to meter-scale, light-dark cycles. Clay layers range from dark yellowish brown (10YR 4/4) to very dark grayish brown (10YR 3/2) in color, whereas ooze intervals range from yellowish brown (10YR 5/4) to dark gray (7.5YR 3/2). Mottles are abundant in the clayey radiolarian ooze, common in the other lithologies, and tend to be light yellowish brown (10YR 6/4). Contacts between interbeds tend to be gradational and overprinted by bioturbation. Diatoms and iron oxides are minor components (up to 10%). Trace amounts (<5%) of silicoflagellates and volcanic glass are present throughout.
Below 14.6 mbsf, the biogenic fraction is dominant, and the principal lithology is radiolarian ooze. Color ranges from very dark brown (7.5YR 2.5/2) to dark brown (7/5YR 3/2) and lightens downcore, reflecting a relative decrease in the clay and an increase in the nannofossil component. Mottles are common in the radiolarian ooze. Contacts are gradational and heavily bioturbated. Diatoms, sponge spicules, and iron oxides are minor components, and foraminifers and volcanic glass are present in trace amounts.
Decimeter-scale alternations of nannofossil ooze with radiolarians and clay and nannofossil radiolarian ooze are present between 19 and 24 mbsf. These minor lithologies exhibit a marked increase in lightness and a decrease in the red/blue spectral ratio and range from yellowish brown (10YR 5/4) to dark brown (7.5YR 3/3) in color. Mottles are abundant and tend to be very pale brown (10YR 7/4) to yellowish brown (10YR 5/4).
The dominant lithology in Unit II is nannofossil ooze, with significant siliceous components in the upper (radiolarians) and basal (radiolarians and clay) portions. Clay and radiolarian contents (as estimated from smear slides) generally remain below 20% and 30%, respectively. From ~30.0 to 77.5 mbsf, this unit contains alternations of nannofossil radiolarian ooze, nannofossil ooze with radiolarians, and nannofossil ooze with the radiolarian fraction decreasing downhole. These variations are expressed as decimeter- to meter-scale, light-dark color cycles. A decrease in the amplitude of these color cycles is present below ~50.0 mbsf (Fig. F8). The layers of nannofossil radiolarian ooze range from brown (10YR 5/3) to yellowish brown (10YR 5/4) and contain abundant mottles. Intervals of nannofossil ooze with radiolarians range from light gray (10YR 7/2) to very pale brown (10YR 8/2, 10YR 8/3) and are slightly mottled. The nannofossil ooze layers range from very pale brown (10YR 7/3) to pale brown (10YR 6/3) and are homogeneous. Contacts between interbeds are gradational and overprinted by bioturbation. Iron oxides, diatoms, and siliceous sponge spicules are a minor component. Zeolites and silicoflagellates are present in trace amounts. Granule-sized concretions and burrow molds are common from 44.0 to 53.7 mbsf, and calcite needles are a minor component (up to 10%) from 53.5 to 63.0 mbsf. Black (N1) concretions, also granule sized, are present infrequently from 63 to 72.5 mbsf. X-ray diffraction results are inconclusive about the mineralogy of the concretions, burrow molds, and nodules but do indicate that these features are not pyrite or manganese oxides.
From 77.5 to 122.8 mbsf, Unit II consists of nannofossil ooze. Below ~123 mbsf, nannofossil ooze alternates with nannofossil ooze with clay and nannofossil ooze with radiolarians. Faint decimeter- to meter-scale color cycles are present throughout this lithology. Nannofossil ooze ranges from very pale brown (10YR 8/3, 10YR 8/2, and 10YR 8/4) to white (10YR 8/1) and pink (7.5YR 8/3, 7.5YR 8/4). Nannofossil ooze with clay ranges from pink (7.5YR 8/4) to reddish yellow (7.5YR 6/6) and light gray (10YR 7/2). Nannofossil ooze with radiolarians is light gray (10YR 7/2). Lithologic cycles are expressed in the lightness and red/blue spectral data and are of smaller amplitude than in the overlying lithologies (Fig. F8). Mottles are rare to common and range from pink (7.5YR 8/3) to very pale brown (10YR 8/3) in color. Zoophycos is the only recognizable trace fossil. Black (N1) spots containing iron and manganese oxides are also common. Radiolarians and foraminifers are minor components, and iron oxides, zeolites, volcanic glass, sponge spicules, and diatoms are present in trace amounts.
The base of Unit II represents the lithologic transition associated with the E/O boundary (Figs. F5, F9) and is marked by a 24-cm-thick interval of nannofossil ooze with clay and radiolarians that is distinguished by a yellowish brown (10YR 5/4) color (interval 199-1219A-17H-2, 63-87 cm). Coring disturbance obscured this transition in Hole 1219B. Several fish teeth fragments are found near the base of this layer (Hole 1219A interval).
The dominant lithology in Unit III is radiolarian ooze, with a significant clay component in the upper and basal portions (up to 50%).
Between 150.8 and 224.5 mbsf, the principal lithologies are radiolarian clay, clayey radiolarian ooze, and radiolarian ooze. Clay content gradually decreases and color lightens downhole, but below 188.6 mbsf, sediments are more clay rich and become darker in color. Sediments range from very dark brown (10YR 2/2) to dark yellowish brown (10YR 3/4, 10YR 4/4). Compositional variations are expressed in the lightness and red/blue spectral data and are similar in amplitude to cycles in the base of Unit II. Mottles are common and range from strong brown (7.5YR 5/6) to reddish yellow (7.5YR 6/6) to black (10YR 2/1) in color. Some mottles contain minor amounts of pyrite and radiolarian ooze with volcanic glass. Contacts are gradational and are obscured by bioturbation. Diatoms are a minor component, and nannofossils and sponge spicules are minor to trace components. Iron oxides, volcanic glass, foraminifers, and fish teeth are present in trace amounts. Aggregates of manganese oxide minerals are found occasionally, and porcellanite and pyrite concretions are present in the basal section of the radiolarian ooze.
Between 176.0 and 224.5 mbsf, decimeter- to meter-scale intervals of radiolarian ooze with nannofossils alternate with radiolarian ooze. Layers of this minor lithology range from pink (7.5YR 8/4) to light yellowish brown (10YR 6/4) and very pale brown (10YR 7/4). Contacts are gradational and are obscured by bioturbation.
Several minor lithologies are present between 188.2 and 196.0 mbsf (interval 199-1219A-21H-2, 25 cm, through 21H-CC, 24 cm). This interval contains 2.9 m of diatom ooze underlain by 2.7 m of nannofossil ooze, 20 cm of radiolarian ooze, 1.7 m of nannofossil ooze, and 30 cm of diatom ooze. Components of radiolarians, diatoms, nannofossils, and clay are present in each of these oozes (0%-20%). The diatom ooze grades from very pale brown (10YR 8/4) to light greenish gray (5GY 8/1). Nannofossil ooze ranges from light greenish gray (5GY 8/1) to bluish white (5B 9/1). Radiolarian ooze is light gray (5YR 7/2). The basal nannofossil ooze and diatom ooze are very pale brown (10YR 8/1 and 10YR 8/2). Interbeds are clearly demarcated in the lightness and red/blue spectral data (Fig. F8). Mottles are common throughout these lithologies.
Several normal faults with minor offsets (<10 cm) are present within the radiolarian ooze, between 173.0 and 181.0 mbsf (intervals 199-1219A-19H-4, 75-105 cm; 19H-6, 52-81 cm; and 20H-3, 67-102 cm). Faults are high angle (~70°) and ~30 cm in length. Along the fault plane, there is a 1-mm-thick layer that is slightly darker than surrounding sediment, which may represent microfault gouge or authigenic precipitates.
Sediments below 224.5 mbsf were cored with the XCB system. Radiolarite and chert are the dominant lithologies in Subunit IIIB between 224.5 and 234.2 mbsf. Radiolarite ranges from reddish yellow (7.5YR 8/6) to pink (7.5YR 8/4) and is homogeneous. Chert is present from 226.8 to 234.2 mbsf (interval 199-1219A-25X-CC, 26 cm, through 26X-1, 14 cm). The chert and surrounding sediments were poorly recovered. Chert is brown (7.5YR 4/3) to black (7.5YR 2/1). The base of Unit III is marked by a 14-cm-thick layer of black (10YR 2/1) zeolitic clay with iron oxides, chert fragments, and trace amounts of nannofossils (interval 199-1219A-26X-1, 0-14 cm).
The dominant lithologies in Unit IV are calcareous chalk and calcareous chalk with clay. A brown (10YR 3/3) nannofossil chalk with clay comprises the upper 34 cm of this unit (interval 199-1219A-26X-1, 14-48 cm). Recrystallized calcareous chalk grades from light gray (10YR 7/3) to pale yellow (2.5Y 8/2). Examination of the calcareous chalk in smear slides indicates that nannofossils were the likely source of carbonate. Horizontal streaks and layers are common throughout the chalk and probably represent collapsed burrows. Small low-angle (30°-60°) normal faults are present between 235.1 and 236.7 mbsf (Sections 199-1219A-26X-1, 97, 100, and 104 cm, and interval 26X-2, 97-106 cm). The chalk is biscuited and brecciated by XCB drilling disturbance.
Fragments of chloritized basalt and chalk comprise the basal 14 cm of Unit IV (interval 199-1219A-27X-CC, 13-27 cm), where the chalk dominating Unit IV overlies the basalt of Unit V. This lithology contains glassy, highly weathered basalt and is highly fragmented. Color ranges from grayish green (5GY 4/6) to brown (10YR 4/3).
The base of Core 199-1219A-27X contains weathered fine-grained phaneritic basalt. Millimeter-scale calcite veins are present within the basalt.
At Site 1219, early Eocene seafloor basalt is overlain by 245 m of biogenic sediments and pelagic clays. Four sedimentary units and a basal basalt unit are identified and can be correlated to lithologic Units I-V at Site 1218 (Fig. F10) (see "Lithostratigraphy" in the "Site 1218" chapter) and Units 162-1 to 162-8 at DSDP Site 162 (van Andel et al., 1973).
Sediments present in the basal few centimeters of Subunit IIIA and in Subunit IIIB and Unit IV have experienced compaction and lithification with depth as indicated by the presence of porcellanite, chert, radiolarite, and chalk. Strongly flattened burrows in the chalk recovered in Unit IV indicate considerable compaction prior to cementation. The green to gray colors in Core 199-1219A-21H and the presence of pyrite indicates that low redox conditions prevailed after deposition. A zeolitic clay bed marking the top of the basal carbonate chalk at this site and Site 162 probably represents an interval of rapid dissolution, a hiatus, and/or altered volcanic ash. Unlike Sites 1217 and 1218, dolomite was not found in the basal carbonate chalk.
Nannofossil and calcareous chalks dominate the lower Eocene section and are capped by a zeolitic clay at ODP Site 1219 and DSDP Site 162. A transition to radiolarian ooze deposition occurred at 52 Ma. Long-term deposition of radiolarian ooze during the middle and late Eocene was interrupted from 42 to 40 Ma, and nannofossil ooze was deposited at all three sites. Nannofossils and radiolarians dominate at Site 1218 and DSDP Site 162, whereas diatoms are more common at Site 1219. Whether this represents regional differences in sedimentation regimes associated with the position of the site relative to the paleoequatorial productivity zone or differences in preservation (or recovery) between sites resulting in lithologic "alias" remains to be seen. All sites may have experienced episodes of diatom ooze deposition from 42 to 40 Ma, but this may not be represented at DSDP Site 162 because of recrystallization of surrounding nannofossil ooze and formation of chalk.
Siliceous sediments dominate the Paleogene section until the E/O boundary. Unlike at Site 1218, the E/O boundary section at Site 1219 was recovered using ODP's APC technology (Figs. F5, F9) and a record of whole-core magnetostratigraphy was produced as a result (see "Paleomagnetism"). A concentration of fish teeth is present in the E/O boundary section in 1219A, probably as part of a large fecal pellet. The transition to nannofossil-rich sediments at Site 1219 is seen at other sites in the region and probably represents a deepening of the CCD (van Andel et al., 1975).
Nannofossil ooze was deposited throughout the region during the Oligocene and into the early Miocene. Variations in clay and radiolarian content are expressed as light-dark color cycles and are evident in color reflectance and physical properties data (Fig. F8). Amplitude of lightness (L*), red/blue spectral ratio (a*/b*), and gamma ray attenuation (GRA) bulk density data increases above ~50 mbsf, which corresponds to the O/M boundary. This change in amplitude is not seen in the MS data.
The O/M boundary section recovered at Site 1219, although similar to the record from Site 1218, is condensed. The Neogene section at this site, as at Site 1218 and DSDP Site 162, contains a transition from nannofossil ooze to noncarbonate deposition at ~18 Ma. However, Unit I at Site 1219 is dominated by a radiolarian biosiliceous component, whereas at Sites 1218 and 162 this interval is represented by an eolian component.