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The routine use of spectrophotometry on the sediment surfaces of archive halves of each section during the onboard sedimentological core description process is a great stride toward development of real-time noninvasive characterization of deep-sea sediments. Spectral reflectance data have been used so far for mineral composition studies as well as for lithostratigraphic correlation between sites (Balsam and Deaton, 1991; Balsam et al., 1997; Mix et al., 1995; Ortiz et al., 1999). Their results demonstrate that spectrophotometry can estimate CaCO3 content by using the 4.65-, 5.25-, and 5.55-μm wavelength spectrums. A detailed overview of various other noninvasive methods is given in Ortiz and Rack (1999). The purpose of this study is to test whether spectrophotometry in the visible band can be used as a tool to gather further information about grain-size variation, sorting, compaction, and porosity, which are directly linked to the sedimentation process. From remote sensing data analyses, it is known that diffuse spectral reflectance data in the visible band in the wavelength window of 7.0–6.5 μm are sensitive to grainsize variations. It appears that a relationship between grain size and signal absorption exists only in this wavelength window. (e.g., Clark, 1999; Gaffey, 1986; Gaffey et al., 1993). Variations in grain size during a sedimentation process are linked to depositional energy, which affects sorting, compaction, and porosity of sediment deposits. As an example, we study here the spectrophotometric data of the sedimentary sequence of Hole 1098C, which was deposited under widely varying environmental conditions. Alternating turbidite and finely laminated sediments were recovered from Hole 1098C. The turbidites are related to a high depositional energy environment; the finely laminated sediments are related to a low depositional energy environment. Data from Hole 1098C were therefore used to test whether the spectral reflectance data can provide a proxy for th

Site 1095 is the most distal of three continental rise sites drilled during Ocean Drilling Program Leg 178. A long (600 m), near-continuous section extends from the Holocene down to nearly 10-Ma sediments, comprising fine-grained turbidites, hemipelagites, and muddy contourites. Meter-scale lithologic cyclicity is seen in sediment facies, physical properties, composition, and grain size in the upper 300 m of the section, representing 0–7 Ma. The diatom content of the sediments suggests sea ice was a significant limitation on productivity only during the Pleistocene. Fine grain size implies that bottom currents were never significantly stronger that at present during the last 7 m.y. The presence of ice-rafted debris implies the Antarctic Peninsula was not deglaciated for any significant period during the “warm Pliocene” (3.2–4.5 Ma). Intermittent supply of fine terrigenous sediment to the rise is consistent with published depositional models showing the ice sheet grounded to the shelf edge during glacial periods. At some times, particularly during the late Miocene, processes related to submarine channel switching and lobe progradation may have masked climatic control on deposition at this site.

Strontium isotope ratios from multiple plates of two barnacle fragments from Site 1103 (Ocean Drilling Program Leg 178) provide maximum age estimates for the oldest glacial sedimentary package drilled. Three moderately preserved barnacle fragments from 262.63 meters below seafloor (mbsf) yielded a mean best-fit age of 7.4 Ma. A single, wellpreserved fragment from the same horizon yielded a best-fit age of 12.2 Ma. Two moderately preserved fragments from 262.98 mbsf yielded a mean best-fit age of 7.8 Ma. The calculated mean strontium ages of 7.8 and 7.4 Ma agree well with the diatom estimates of 8.68 to 5.89 Ma for the underlying sediments.

During Leg 178, multiple advanced piston corer holes were drilled at our sites (1095, 1096, 1098, and 1099). Cores from the holes were correlated on board to produce composite depths and optimal spliced sections, but the time limitations aboard ship caused these to be preliminary. Recomputed composite depths for Sites 1098 and 1099 in Palmer Deep are reported elsewhere in this volume. This paper reports recomputed composite depths and spliced sections for Sites 1095 and 1096, located on a sediment drift on the continental rise of the Pacific margin of the Antarctic Peninsula. Limits on the validity of the spliced sections arise from limited multiple coverage and possibly from the effects of ocean swell.

The area west of the Antarctic Peninsula is a key region for studying and understanding the history of glaciation in the southern high latitudes during the Neogene with respect to variations of the western Antarctic continental ice sheet, variable sea-ice cover, induced eustatic sea level change, as well as consequences for the global climatic system (Barker, Camerlenghi, Acton, et al., 1999). Sites 1095, 1096, and 1101 were drilled on sediment drifts forming the continental rise to examine the nature and composition of sediments deposited under the influence of the Antarctic Peninsula ice sheet, which has repeatedly advanced to the shelf edge and subsequently released glacially eroded material on the continental shelf and slope (Barker et al., 1999). Mass gravity processes on the slope are responsible for downslope sediment transport by turbidity currents within a channel system between the drifts. Furthermore, bottom currents redistribute the sediments, which leads to final build up of drift bodies (Rebesco et al., 1998). The high-resolution sedimentary sequences on the continental rise can be used to document the variability of continental glaciation and, therefore, allow us to assess the main factors that control the sediment transport and the deposi- tional processes during glaciation periods and their relationship to glacio-eustatic sea level changes. Site 1095 lies in 3840 m of water in a distal position on the northwestern lower flank of Drift 7, whereas Site 1096 lies in 3152 m of water in a more proximal position within Drift 7. Site 1101 is located at 3509m water depth on the northwestern flank of Drift 4. All three sites have high sedimentation rates. The oldest sediments were recovered at Site 1095 (late Miocene; 9.7 Ma), whereas sediments of Pliocene age were recovered at Site 1096 (4.7 Ma) and at Site 1101 (3.5 Ma). The purpose of this work is to provide a data set of bulk sediment parameters such as CaCO3, total organic carbon (TOC), and coarse-fract

The Pacific margin of the Antarctic Peninsula was drilled during Ocean Drilling Program (ODP) Leg 178 to understand the past 10 m.y. of its glacial history and to test a drilling strategy that might be applied in other regions of the Antarctic margin. This paper offers a mature view of the achievements of drilling, which succeeded in both aims, and focuses on the lessons for subsequent margin drilling and the results of postcruise studies on samples and data from the leg. One of two complementary depositional environments drilled was the topset component of the glacial prograded wedge of the outer continental shelf. Despite poor recovery, a Pliocene-Pleistocene age was found for the major glacial sedimentary sequence groups S1 and S2 previously defined using seismic reflection survey, and a glacial nature and late Miocene age was established for the sampled part of the underlying sequence group S3. Such broad, low-resolution conclusions are possible from shelf drilling using presently available techniques and are useful in terms of Antarctic glacial history, but may represent the limit of what can be achieved if core recovery is poor. The second depositional environment was the glacially derived fine-grained sediment drifts on the upper continental rise, which gave continuous recovery and a high-resolution record of the past 10 m.y. Biogenic opal concentrations showed that the southeast Pacific Ocean (through variations in temperature and sea-ice cover) behaved compatibly with global climate, with a cool late Miocene and warm early Pliocene, cooling to a cold Pleistocene. Nevertheless, ice-rafted detritus confirmed that the Antarctic Peninsula ice sheet was present throughout this period, and clay mineralogy showed that it remained sufficiently large for regular grounding-line migration to the shelf edge. Spectral analysis of sedimentary parameters at drift Sites 1095 and 1096 did not show the dominance of frequencies usually associated with orbital insolation varia

Protoperidiniacean dinoflagellate cysts were identified in 19 of 28 samples from two sites on the Antarctic Peninsula continental rise. Cysts are most common in the lower Pliocene and upper Miocene and include species of Brigantedinium, Lejeunecysta, and Selenopemphix. Autotrophic gonyaulacacean dinoflagellate cysts are very rare in the samples. The dominance of taxa derived from assumed heterotrophic dinoflagellate motile forms may indicate high nutrient content in the surface waters, which sustained a considerable diatom population.

Sites 1095, 1096, and 1101 were drilled on the continental rise west of the Antarctic Peninsula (Fig. F1) to recover a continuous high-resolution record of Antarctic glaciation. Site 1095 is the subject of a short paper in this volume (Pudsey, Chap. 25, this volume), whereas mass accumulation rates at the three sites are described by Wolf-Welling (Chap. 15, this volume) and ice-rafted debris at Site 1101 is discussed by Cowan (Chap. 10, this volume) This report documents grain-size data (sand and fine fraction) and the proportion of biogenic silica for the upper 300 m at Site 1095, the upper 250 m at Site 1096, and the whole 220 m at Site 1101.

Site 1095 is the most distal of three continental rise sites drilled during Ocean Drilling Program Leg 178. A long (600 m), near-continuous section extends from the Holocene down to nearly 10-Ma sediments, comprising fine-grained turbidites, hemipelagites, and muddy contourites. Meter-scale lithologic cyclicity is seen in sediment facies, physical properties, composition, and grain size in the upper 300 m of the section, representing 0–7 Ma. The diatom content of the sediments suggests sea ice was a significant limitation on productivity only during the Pleistocene. Fine grain size implies that bottom currents were never significantly stronger that at present during the last 7 m.y. The presence of ice-rafted debris implies the Antarctic Peninsula was not deglaciated for any significant period during the “warm Pliocene” (3.2–4.5 Ma). Intermittent supply of fine terrigenous sediment to the rise is consistent with published depositional models showing the ice sheet grounded to the shelf edge during glacial periods. At some times, particularly during the late Miocene, processes related to submarine channel switching and lobe progradation may have masked climatic control on deposition at this site.

Strontium isotope ratios from multiple plates of two barnacle fragments from Site 1103 (Ocean Drilling Program Leg 178) provide maximum age estimates for the oldest glacial sedimentary package drilled. Three moderately preserved barnacle fragments from 262.63 meters below seafloor (mbsf) yielded a mean best-fit age of 7.4 Ma. A single, wellpreserved fragment from the same horizon yielded a best-fit age of 12.2 Ma. Two moderately preserved fragments from 262.98 mbsf yielded a mean best-fit age of 7.8 Ma. The calculated mean strontium ages of 7.8 and 7.4 Ma agree well with the diatom estimates of 8.68 to 5.89 Ma for the underlying sediments.

Protoperidiniacean dinoflagellate cysts were identified in 19 of 28 samples from two sites on the Antarctic Peninsula continental rise. Cysts are most common in the lower Pliocene and upper Miocene and include species of Brigantedinium, Lejeunecysta, and Selenopemphix. Autotrophic gonyaulacacean dinoflagellate cysts are very rare in the samples. The dominance of taxa derived from assumed heterotrophic dinoflagellate motile forms may indicate high nutrient content in the surface waters, which sustained a considerable diatom population.

Sites 1095, 1096, and 1101 were drilled on the continental rise west of the Antarctic Peninsula (Fig. F1) to recover a continuous high-resolution record of Antarctic glaciation. Site 1095 is the subject of a short paper in this volume (Pudsey, Chap. 25, this volume), whereas mass accumulation rates at the three sites are described by Wolf-Welling (Chap. 15, this volume) and ice-rafted debris at Site 1101 is discussed by Cowan (Chap. 10, this volume) This report documents grain-size data (sand and fine fraction) and the proportion of biogenic silica for the upper 300 m at Site 1095, the upper 250 m at Site 1096, and the whole 220 m at Site 1101.

During Leg 178, multiple advanced piston corer holes were drilled at our sites (1095, 1096, 1098, and 1099). Cores from the holes were correlated on board to produce composite depths and optimal spliced sections, but the time limitations aboard ship caused these to be preliminary. Recomputed composite depths for Sites 1098 and 1099 in Palmer Deep are reported elsewhere in this volume. This paper reports recomputed composite depths and spliced sections for Sites 1095 and 1096, located on a sediment drift on the continental rise of the Pacific margin of the Antarctic Peninsula. Limits on the validity of the spliced sections arise from limited multiple coverage and possibly from the effects of ocean swell.

The Pacific margin of the Antarctic Peninsula was drilled during Ocean Drilling Program (ODP) Leg 178 to understand the past 10 m.y. of its glacial history and to test a drilling strategy that might be applied in other regions of the Antarctic margin. This paper offers a mature view of the achievements of drilling, which succeeded in both aims, and focuses on the lessons for subsequent margin drilling and the results of postcruise studies on samples and data from the leg. One of two complementary depositional environments drilled was the topset component of the glacial prograded wedge of the outer continental shelf. Despite poor recovery, a Pliocene-Pleistocene age was found for the major glacial sedimentary sequence groups S1 and S2 previously defined using seismic reflection survey, and a glacial nature and late Miocene age was established for the sampled part of the underlying sequence group S3. Such broad, low-resolution conclusions are possible from shelf drilling using presently available techniques and are useful in terms of Antarctic glacial history, but may represent the limit of what can be achieved if core recovery is poor. The second depositional environment was the glacially derived fine-grained sediment drifts on the upper continental rise, which gave continuous recovery and a high-resolution record of the past 10 m.y. Biogenic opal concentrations showed that the southeast Pacific Ocean (through variations in temperature and sea-ice cover) behaved compatibly with global climate, with a cool late Miocene and warm early Pliocene, cooling to a cold Pleistocene. Nevertheless, ice-rafted detritus confirmed that the Antarctic Peninsula ice sheet was present throughout this period, and clay mineralogy showed that it remained sufficiently large for regular grounding-line migration to the shelf edge. Spectral analysis of sedimentary parameters at drift Sites 1095 and 1096 did not show the dominance of frequencies usually associated with orbital insolation varia

The area west of the Antarctic Peninsula is a key region for studying and understanding the history of glaciation in the southern high latitudes during the Neogene with respect to variations of the western Antarctic continental ice sheet, variable sea-ice cover, induced eustatic sea level change, as well as consequences for the global climatic system (Barker, Camerlenghi, Acton, et al., 1999). Sites 1095, 1096, and 1101 were drilled on sediment drifts forming the continental rise to examine the nature and composition of sediments deposited under the influence of the Antarctic Peninsula ice sheet, which has repeatedly advanced to the shelf edge and subsequently released glacially eroded material on the continental shelf and slope (Barker et al., 1999). Mass gravity processes on the slope are responsible for downslope sediment transport by turbidity currents within a channel system between the drifts. Furthermore, bottom currents redistribute the sediments, which leads to final build up of drift bodies (Rebesco et al., 1998). The high-resolution sedimentary sequences on the continental rise can be used to document the variability of continental glaciation and, therefore, allow us to assess the main factors that control the sediment transport and the deposi- tional processes during glaciation periods and their relationship to glacio-eustatic sea level changes. Site 1095 lies in 3840 m of water in a distal position on the northwestern lower flank of Drift 7, whereas Site 1096 lies in 3152 m of water in a more proximal position within Drift 7. Site 1101 is located at 3509m water depth on the northwestern flank of Drift 4. All three sites have high sedimentation rates. The oldest sediments were recovered at Site 1095 (late Miocene; 9.7 Ma), whereas sediments of Pliocene age were recovered at Site 1096 (4.7 Ma) and at Site 1101 (3.5 Ma). The purpose of this work is to provide a data set of bulk sediment parameters such as CaCO3, total organic carbon (TOC), and coarse-fract