ALBERT

Description: Sea surface temperature data based on the tetraether index based on glycerol dialkyl glycerol tetraethers consisting of 86 carbon atoms (TEX86) and unsaturated ketone index (UK'37) paleothermometers as well as methane index (MI) and branched and isoprenoid tetraether index (BIT) values of the past 1 Ma at Site U1437.

Description: Concentrations of plant wax lipids (long-chain n-alkanes, n-alcohols, and nonacosan-10-ol), the carbon preference index of n-alkanes, the branched and isoprenoid tetraether index (BIT), and mass accumulation rates of total organic carbon (TOC) and C37 alkenones.

Description: The dataset comprises fractional abundances of individual isoprenoid and branched glycerol dialkyl glycerol tetraethers (GDGTs) and C37 alkenones of samples from the past 1 Ma at Site 350-U1437 relevant for the calculation of the TEX86 (tetraether index based on glycerol dialkyl glycerol tetraethers consisting of 86 carbon atoms), methane index (MI), branched and isoprenoid tetraether index (BIT), and the unsaturated ketone index (UK'37), respectively. The ketone-bearing fractions were measured on an Agilent 7980 GC coupled to an Agilent 5975 MS (Agilent, Germany). The polar fractions were analyzed by high performance liquid chromatography coupled to mass spectrometry (HPLC/MS) using an Alliance 2690 HPLC (Waters, UK) and a Quattro LC triple quadrupole MS (Micromass, UK) to measure glycerol dialkyl glycerol tetraethers (GDGTs).

Description: Selected elemental ratios (Ba/Al and Al/Ca*1000) calculated from individual element abundances in counts per second (cps) as measured via X-ray fluorescence (XRF)-scanning of the uppermost 120 meters below seafloor of Site U1437.

Description: Sediment core U1437B was drilled during International Ocean Discovery Program Expedition 350 in 2014. The aim of this study was to infer information on the paleoclimatic and paleoceanographic evolution of the Northwest Pacific Ocean and adjacent East Asian continent over the past 1 Ma. For this, 174 freeze-dried and homogenized sediment samples from Site U1437 Hole B were extracted using a solvent mixture of dichloromethane:methanol (93:7, v:v) at elevated temperature (75° ) and pressure (50 bar) using a Büchi Speed Extractor (Büchi, Switzerland). Total lipid extracts were desulfurized and an aliquot with an added standard mixture was measured on an Agilent 7980 gas chromatograph (GC) coupled to an Agilent 5975 mass spectrometer (MS) to quantify long- chain n-alkanes, n-alcohols, and nonacosan-10-ol. Another aliquot of the total lipid extracts was separated into apolar, ketone and polar fractions using column chromatography. The ketone-bearing fractions were subsequently measured on an Agilent 7980 GC coupled to an Agilent 5975 MS (Agilent, Germany). The polar fractions were analyzed by high performance liquid chromatography coupled to mass spectrometry (HPLC/MS) using an Alliance 2690 HPLC (Waters, UK) and a Quattro LC triple quadrupole MS (Micromass, UK) to measure glycerol dialkyl glycerol tetraethers (GDGTs). Total organic carbon contents were determined on 200 mg decarbonized sediment powder using an ELTRA CS- 580A elemental analyzer. Additionally, sections 350-U1437B-1H-1A to 17F-4A, comprising the uppermost 120 m of Hole B and corresponding to the past 1 Ma, were scanned using an ITRAX micro-X-ray fluorescence (XRF) core scanner at Kochi Core Center, Japan. XRF spectra were generated every 2 cm with an exposure time of 60 sec. The X-ray beam was generated with a 3 kW Mo tube run at 30 kV and 55 mA. Sea surface temperature estimates calculated from the unsaturated ketone index (UK'37) and GDGT- based tetraether index (TEX86) as well as GDGT-based methane index (MI) and branched and isoprenoid tetraether index (BIT) values are reported in Dataset S1. Dataset S2 contains summed concentrations of long-chain n-alkanes, n-alcohols and nonacosan-10- ol, as well as mass accumulation rates of TOC and C37 alkenones, which were calculated using linear sedimentation rates, alkenone or TOC contents, and dry bulk densities from shipboard measurements (Tamura et al., 2015). Fractional abundances of individual GDGTs and C37 ketones are reported in Dataset S3. Dataset S4 comprises ratios of selected elements calculated from XRF scanning measurements on core sections of the uppermost 120 meters below seafloor of Site U1437 Hole B.

Description: Magnetic mineral diagenesis is an important process in sediments that is responsible for the partial or total destruction of records of Earth's magnetic field variations and also plays an important part in iron and sulfur cycling. A rock magnetic study has been carried out at International Ocean Discovery Program Expedition 350 Site U1437 in the Izu Bonin rear arc to investigate magnetic mineral diagenesis in deeply buried sediments from ~775 to ~1,002 m below sea floor (mbsf) with burial temperatures ranging from ~67 to 85 °C. Nonsteady state geochemical environments occur within an unusual deep methanic zone (below 850 mbsf) because of a release of sulfate below the shallow sulfate reduction zone. A drastic decline in magnetic susceptibility and remanence is observed at ~850 mbsf due to a decrease in ferrimagnetic iron oxide contents. Reduction of (titano)-magnetite and pyritization occur at this inferred deep sulfate-methane transition zone. Below ~850 mbsf, lower magnetic mineral contents coincide with further methane release. Geochemical analyses support a change in redox conditions and secondary precipitation of iron sulfides and carbonates in the methane-rich zone. Magnetic mineral alteration is enhanced in zones where methane accumulates underneath low porosity intervals that act as seals. Although geochemical processes due to methane occurrence are likely dominant, more than one mechanism, possibly involving microbial activity, is probably responsible for the observed magnetic mineral assemblage changes. ©2018. American Geophysical Union. All Rights Reserved.

Description: IODP Expedition 350 was the first to be drilled in the rear part of the Izu-Bonin, although several sites had been drilled in the arc axis to fore-arc region; the scientific objective was to understand the evolution of the Izu rear arc, by drilling a deep-water volcaniclastic section with a long temporal record (Site U1437). The Izu rear arc is dominated by a series of basaltic to dacitic seamount chains up to ~100-km long roughly perpendicular to the arc front. Dredge samples from these are geochemically distinct from arc front rocks, and drilling was undertaken to understand this arc asymmetry. Site U1437 lies in an ~20-km-wide basin between two rear arc seamount chains, ~90-km west of the arc front, and was drilled to 1804 m below the sea floor (mbsf) with excellent recovery. We expected to drill a volcaniclastic apron, but the section is much more mud-rich than expected (~60%), and the remaining fraction of the section is much finer-grained than predicted from its position within the Izu arc, composed half of ashes/tuffs, and half of lapilli tuffs of fine grain size (clasts 〈3 cm). Volcanic blocks (〉6.4 cm) are only sparsely scattered through the lowermost 25% of the section, and only one igneous unit was encountered, a rhyolite peperite intrusion at ~1390 mbsf. The lowest biostratigaphic datum is at 867 mbsf (~6.5 Ma), the lowest palaeomagnetic datum is at ~1300 mbsf (~9 Ma), and the rhyolite peperite at ~1390 mbsf has yielded a U–Pb zircon concordia intercept age of (13.6 + 1.6/−1.7) Ma. Both arc front and rear arc sources contributed to the fine-grained (distal) tephras of the upper 1320 m, but the coarse-grained (proximal) volcaniclastics in the lowest 25% of the section are geochemically similar to the arc front, suggesting arc asymmetry is not recorded in rocks older than ~13 Ma.