Site U1459

Gallagher, S.J.; Fulthorpe, C.S.; Bogus, K.; Auer, Gerald; Baranwal, Soma; Castañeda, Isla S.; Christensen, Beth A; Vleeschouwer, David De; Franco, Diogo; Groeneveld, Jeroen; Gurnis, Michael; Haller, Christian; He, Yuxin; Henderiks, Jorijntje; Himmler, Tobias; Ishiwa, Takeshige; Iwatani, Hokuto; Jatiningrum, R.S.; Kominz, Michelle A.; Korpanty, Chelsea; Lee, E.Y.; Levin, E.; Mamo, Briony; McGregor, Helen; McHugh, C. M.; Petrick, Benjamin; Potts, D. C.; Lari, A. Rastegar; Renema, Willem; Reuning, Lars; Takayanagi, Hideko; Zhang, W.

doi:10.14379/iodp.proc.356.104.2017

Cited by 4 publications

(8 citation statements)

References 15 publications

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“…Two holes yield Pliocene sediments ( Figure 2). A shipboard correlation between both holes was made using color reflectance data, resulting in composite depth scale (mcd) in which U1459A cores are shifted to fit with U1459B (Gallagher, Fulthorpe, Bogus, Auer, et al, 2017). A shipboard splice for Site U1459 was not constructed.…”

Section: Site Description and Geochronologymentioning

confidence: 99%

“…Superimposed on the long-term trend, significant meter-scale variability in Ca/Fe reflects fluctuations in carbonate content. We use the changes in Ca/Fe, in combination with geochronologic constraints from shipboard biostratigraphy (Gallagher, Fulthorpe, Bogus, Auer, et al, 2017), for astronomically tuning the U1459 stratigraphic column to the LR04 benthic oxygen isotope stack (Lisiecki & Raymo, 2005) and a southern hemisphere eccentricity-tilt-precession composite (Laskar et al, 2004; Figures 2 and S1 in the supporting information). Carbonate-rich intervals generally correspond to low TEX 86 temperatures, more positive δ 18 O G.sacculifer values and lower K/Al.…”

Section: Site Description and Geochronologymentioning

confidence: 99%

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Stepwise Weakening of the Pliocene Leeuwin Current

Vleeschouwer

Petrick

Martínez‐García

2019

Geophysical Research Letters

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The Indonesian Throughflow (ITF) operates as an important link in global thermohaline circulation, and ITF variability probably modulated Pliocene climate change. Yet, whether ITF variability accounted for oceanographic change south of Northwest Cape remains controversial. Here, we present a multiproxy oceanographic reconstruction from the Perth Basin and reconstruct the Pliocene history of the Leeuwin Current (LC). We show that the LC was active throughout the Pliocene, albeit with fluctuations in intensity and scope. Three main factors controlled LC strength. First, a tectonic ITF reorganization caused an abrupt and permanent LC reduction at 3.7 Ma. On shorter timescales, eustatic sea level and direct orbital forcing of wind patterns hampered or promoted the LC. At 3.3 Ma, for instance, LC intensity plunged in response to a eustatic ITF restriction. Site U1459 then fell outside the extent of a weakened LC, and the latitudinal sea surface temperature gradient along West Australia doubled its steepness.

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Section: Site Description and Geochronologymentioning

confidence: 99%

Section: Site Description and Geochronologymentioning

confidence: 99%

Stepwise Weakening of the Pliocene Leeuwin Current

Vleeschouwer

Petrick

Martínez‐García

2019

Geophysical Research Letters

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“…Although this stepwise behavior was also observed in the WRMSL data for this hole, the step in the SHMSL data occurred about 10 m higher than in the WRMSL data. As mentioned in Physical properties in the Site U1459 chapter (Gallagher et al, 2017b), the low-precision setting for the MSP measurements on the SHMSL (a single measurement per position) prevented a detailed comparison of MS data obtained by the WRMSL and the SHMSL. During shipboard measurements of Hole U1460B, different settings were used to run the SHMSL.…”

Section: Magnetic Susceptibilitymentioning

confidence: 99%

Site U1460

Gallagher¹,

Fulthorpe²,

Bogus³

et al. 2017

Proceedings of the International Ocean Discovery Program

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Site U1460 ended at 1945 h on 15 August. A total of 133 cores were recovered with the HLAPC system; of the 606.7 m cored, 592.2 m was recovered (recovery = 97%). Hole U1460A After arriving at Hole U1460A (27°22.4948′S, 112°55.4296′E), preparations for coring commenced. As a result of previous difficulty establishing the mudline core at Site U1459 (broken core barrel), the seafloor was tagged with the bit to determine its precise location and whether it was as hard as the previous site. A nonmagnetic HLAPC core barrel was dressed with a core liner, picked up, and run into the hole. Hole U1460A was started at 0115 h on 13 August. Based on the recovery of the mudline core, the seafloor depth was calculated to be 214.5 mbsl. Coring continued with the HLAPC system through Core 356-U1460A-64F to 298.2 m DSF. After the mudline core, each core was advanced 4.7 m despite partial strokes on Cores 2F, 9F, and 64F. Hole U1460A was cored to a final depth of 300.1 m DSF (Core 65F). During coring, a routine slip, cut, and retermination of the coring line was performed. At the conclusion of coring, the drill string was pulled back to 231.6 m DSF and the top drive was set back. The drill string was pulled back to just above the seafloor, clearing the seafloor at 0605 h on 14 August and ending Hole U1460A. Of 300.1 m cored, 291.39 m of material was recovered (recovery = 97.1%). The total time spent on Hole U1460A was 33.25 h. Hole U1460B After offsetting the vessel 20 m north of Hole U1460A, preparations were made to begin Hole U1460B (27°22.4867′S, 112°55.4265′E). A nonmagnetic HLAPC core barrel was dressed with a core liner, picked up, and run into the hole. Hole U1460B was started at 1920 h on 14 August. Based on the recovery of the mudline core, the seafloor depth was calculated to be 214.4 mbsl. Coring continued with the HLAPC system through Core 356-U1460B-68F to 306.6 m DSF. After the mudline core, each core was advanced by recovery in an attempt to cover any gaps from Hole U1460A. Of the 306.6 m cored, 800.81 m was recovered (recovery = 98%). Also in this hole, in situ temperature measurements were made with the APCT-3 before recovering Cores 12F, 20F, 28F, 33F, and 36F. During coring, a routine slip, cut, and retermination of the coring line was performed. At the conclusion of coring, the drill string was pulled back to 260.7 m DSF and the top drive was set back. The drill string was pulled from the hole and the advanced piston corer/extended core barrel bit cleared the rig floor at 1940 h. The thrusters and hydrophones were pulled and secured, and at 1945 h on 15 August, Site U1460 concluded. The total time spent on Hole U1460B was 37.75 h.

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“…However, this operations plan was not followed in some cases (see Operations in each site chapter for details) because the nature of the seafloor and the upper sediments precluded piston coring. This was particularly true for the southern sites (U1458 and U1459), where hard layers necessitated the use of the XCB system at the seafloor (see Operations in the Site U1458 chapter and Operations in the Site U1459 chapter [Gallagher et al, 2017b[Gallagher et al, , 2017c). Despite the challenges encountered during operations, excellent material was recovered to address the scientific objectives.…”

Section: Operations Strategymentioning

confidence: 99%

“…Gray bar = approximate depth of pipe in Hole U1459C; note the resulting dampened signal of gamma log in the upper 72 m WMSF. Age-depth model was produced from biostratigraphic datums based on calcareous nannofossils (black = Hole U1459B, blue = Hole U1459C) (see Biostratigraphy and micropaleontology in the Site U1459 chapter [Gallagher et al, 2017c]). Sedimentation rates are shown for Holes U1459A-U1459C.…”

Section: Paleomagnetismmentioning

confidence: 99%