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Geological records from the Antarctic margin offer direct evidence of environmental variability at high southern latitudes and provide insight regarding ice sheet sensitivity to past climate change. The early to mid-Miocene (23–14 Mya) is a compelling interval to study as global temperatures and atmospheric CO2 concentrations were similar to those projected for coming centuries. Importantly, this time interval includes the Miocene Climatic Optimum, a period of global warmth during which average surface temperatures were 3–4 °C higher than today. Miocene sediments in the ANDRILL-2A drill core from the Western Ross Sea, Antarctica, indicate that the Antarctic ice sheet (AIS) was highly variable through this key time interval. A multiproxy dataset derived from the core identifies four distinct environmental motifs based on changes in sedimentary facies, fossil assemblages, geochemistry, and paleotemperature. Four major disconformities in the drill core coincide with regional seismic discontinuities and reflect transient expansion of grounded ice across the Ross Sea. They correlate with major positive shifts in benthic oxygen isotope records and generally coincide with intervals when atmospheric CO2 concentrations were at or below preindustrial levels (∼280 ppm). Five intervals reflect ice sheet minima and air temperatures warm enough for substantial ice mass loss during episodes of high (∼500 ppm) atmospheric CO2. These new drill core data and associated ice sheet modeling experiments indicate that polar climate and the AIS were highly sensitive to relatively small changes in atmospheric CO2 during the early to mid-Miocene.

BACKGROUND: Safe and effective treatments are urgently needed for patients with relapsed or refractory acute myeloid leukaemia. We investigated the efficacy and safety of vosaroxin, a first-in-class anticancer quinolone derivative, plus cytarabine in patients with relapsed or refractory acute myeloid leukaemia. METHODS: This phase 3, double-blind, placebo-controlled trial was undertaken at 101 international sites. Eligible patients with acute myeloid leukaemia were aged 18 years of age or older and had refractory disease or were in first relapse after one or two cycles of previous induction chemotherapy, including at least one cycle of anthracycline (or anthracenedione) plus cytarabine. Patients were randomly assigned 1:1 to vosaroxin (90 mg/m(2) intravenously on days 1 and 4 in a first cycle; 70 mg/m(2) in subsequent cycles) plus cytarabine (1 g/m(2) intravenously on days 1-5) or placebo plus cytarabine through a central interactive voice system with a permuted block procedure stratified by disease status, age, and geographical location. All participants were masked to treatment assignment. The primary efficacy endpoint was overall survival and the primary safety endpoint was 30-day and 60-day all-cause mortality. Efficacy analyses were done by intention to treat; safety analyses included all treated patients. This study is registered with ClinicalTrials.gov, number NCT01191801. FINDINGS: Between Dec 17, 2010, and Sept 25, 2013, 711 patients were randomly assigned to vosaroxin plus cytarabine (n=356) or placebo plus cytarabine (n=355). At the final analysis, median overall survival was 7·5 months (95% CI 6·4-8·5) in the vosaroxin plus cytarabine group and 6·1 months (5·2-7·1) in the placebo plus cytarabine group (hazard ratio 0·87, 95% CI 0·73-1·02; unstratified log-rank p=0·061; stratified p=0·024). A higher proportion of patients achieved complete remission in the vosaroxin plus cytarabine group than in the placebo plus cytarabine group (107 [30%] of 356 patients

We analyze magnetic properties from Ocean Drilling Program (ODP)/Integrated ODP (IODP) Hole 1256D (6°44.1' N, 91°56.1' W) on the Cocos Plate in ∼15.2 Ma oceanic crust generated by superfast seafloor spreading, the only drill hole that has sampled all

Atmospheric carbon dioxide concentrations and climate are regulated on geological timescales by the balance between carbon input from volcanic and metamorphic outgassing and its removal by weathering feedbacks; these feedbacks involve the erosion of silicate rocks and organic-carbon-bearing rocks. The integrated effect of these processes is reflected in the calcium carbonate compensation depth, which is the oceanic depth at which calcium carbonate is dissolved. Here we present a carbonate accumulation record that covers the past 53 million years from a depth transect in the equatorial Pacific Ocean. The carbonate compensation depth tracks long-term ocean cooling, deepening from 3.0-3.5 kilometres during the early Cenozoic (approximately 55 million years ago) to 4.6 kilometres at present, consistent with an overall Cenozoic increase in weathering. We find large superimposed fluctuations in carbonate compensation depth during the middle and late Eocene. Using Earth system models, we identify changes in weathering and the mode of organic-carbon delivery as two key processes to explain these large-scale Eocene fluctuations of the carbonate compensation depth., AuthorCount:65

During Integrated Ocean Drilling Program Expedition 339, five sites were drilled in the Gulf of Cadiz and two sites were drilled off the West Iberian margin from November 2011 to January 2012. Total length of recovered core is 5447 m, with an average recovery of 86.4%. The Gulf of Cadiz was targeted for drilling as a key location for the investigation of Mediterranean Outflow Water (MOW) through the Strait of Gibraltar gateway and its influence on global circulation and climate. The gulf is also a prime area for understanding the effects of tectonic activity on evolution of the Strait of Gibraltar gateway and margin sedimentation.

Here we present orbitally-resolved records of terrestrial higher plant leaf wax input to the North Atlantic over the last 3.5 Ma, based on the accumulation of long-chain n-alkanes and n-alkanl-1-ols at IODP Site U1313. These lipids are a major component of dust, even in remote ocean areas, and have a predominantly aeolian origin in distal marine sediments. Our results demonstrate that around 2.7 million years ago (Ma), coinciding with the intensification of the Northern Hemisphere glaciation (NHG), the aeolian input of terrestrial material to the North Atlantic increased drastically. Since then, during every glacial the aeolian input of higher plant material was up to 30 times higher than during interglacials. The close correspondence between aeolian input to the North Atlantic and other dust records indicates a globally uniform response of dust sources to Quaternary climate variability, although the amplitude of variation differs among areas. We argue that the increased aeolian input at Site U1313 during glacials is predominantly related to the episodic appearance of continental ice sheets in North America and the associated strengthening of glaciogenic dust sources. Evolutional spectral analyses of the n-alkane records were therefore used to determine the dominant astronomical forcing in North American ice sheet advances. These results demonstrate that during the early Pleistocene North American ice sheet dynamics responded predominantly to variations in obliquity (41 ka), which argues against previous suggestions of precession-related variations in Northern Hemisphere ice sheets during the early Pleistocene.

Sediments from the paleoequatorial Pacific record the paleomagnetic field with high-fidelity and contain cyclic variations in chemical and physical properties that can be astronomically tuned, as has been shown from past Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) cruises, e.g., Legs 85, 138, 198, and 199. In an effort to fill gaps from past coring and to construct complete stratigraphic sections spanning the Cenozoic, Integrated Ocean Drilling Program (IODP) Expeditions 320 and 321 cored sediments along a Pacific Equatorial Age Transect (PEAT) earlier this year. A total of 23 holes at 8 Sites (Sites U1331 through U1338) were cored, recovering 6,141 m of sediment (Preliminary Reports are available at http://iodp.tamu.edu/publications/PR.html). Initial paleomagnetic results from Expedition 320 include measurements at 56,222 intervals along ~2000 split-core sections, as well as detailed progressive alternating field (AF) and thermal demagnetization of over 400 discrete samples (7 cm3 cubes). The cleaned paleomagnetic data were characterized by shallow inclinations, consistent with the sites being near the paleoequator, and by 180° alternations in declination downhole, reflecting magnetic polarity zones. The resulting magnetostratigraphies, which are used to develop initial age models for the drill sites, yield 803 dates ranging from 51.743 Ma (the base of Chron 23n.2n at Site 1331) to the present (Chron C1n; 0 to 0.783 Ma at Site U1335). In addition, 83 short polarity intervals were observed that might correspond to cryptochrons or geomagnetic excursions. We will discuss initial efforts to further resolve the PEAT magnetostratigraphies and to integrate them with bio-, chemo-, and cyclo- stratigraphies from the equatorial Pacific and elsewhere in order to improve and extend astronomical calibration of the geologic timescale.

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.