Skip to main content

IODP Expedition 371

Tasman Frontier Subduction Initiation and Paleogene Climate


Daily Science Report for 12 August 2017

Location: Hole U1507B (26°29.3158′S, 166°31.7155′E, water depth 3568.3 m)

Cores U1507B-10R through 19R penetrated from 452.5 m to 548.4 m DSF and recovered 62.1 m (65%).

Cores U1507B-5R through 14R consist of clayey nannofossil chalk with volcanic ash. Very thin to thin beds of clayey foraminiferal limestone and greenish-gray, heavily bioturbated nannofossil claystone with volcanic ash occur repeatedly throughout the cores. Soft-sediment deformation such as folds, tilted bedding, and small scale faults are common. Nannofossil and planktic foraminifera biostratigraphy indicate a late Oligocene age for Cores 9R to 16R. Radiolaria are present in these cores but are poorly preserved. They indicate an early Miocene age for Core 7R and late Oligocene to early Miocene for Core 9R. Ostracods are absent in this hole so far.​

Paleomagnetic measurements of archive section halves as well as discrete samples from Cores U1507B-4R to 14R yield a stable signal and a clear series of paleomagnetic reversals. Measurements of the anisotropy of magnetic susceptibility (AMS) were carried out for the first time on this expedition, on a total of 50 discrete samples from Site U1507. Petrophysical measurements show marked changes associated with the Oligocene–Miocene boundary, including a negative gradient in P-wave velocity.

Results from headspace gas analyses are all below detection limit. Interstitial water data are being generated for Hole U1507A. ​


Daily Science Report for 11 August 2017

Location: Hole U1507B (26°29.3158′S, 166°31.7155′E, water depth 3568.3 m)

Drilling without coring in Hole U1507B reached 376 m DSF by 0630 h. After pulling the center bit and dropping the RCB core barrel, coring began at 0730 h. Cores U1507B-2R through 9R penetrated to 452.5 m DSF and recovered 65.5 m (86%).

Cores U1507B-2R to 5R consist of clayey nannofossil chalk with volcanic ash, interbedded at the cm scale with foraminifer limestone and heavily bioturbated dark greenish grey nannofossil clay with volcanic ash. Slump structures, microfractures, and inclined lamination and bedding are common.​ Nannofossil and foraminifer biostratigraphy places Cores 2R to 7R in the early Miocene. Core 8H is of late Oligocene age. Rare, recrystallized radiolaria are present and possibly of Cretaceous age.​ Paleomagnetic measurements on Cores 2R and 3R show a coherent paleomagnetic pattern. Petrophysical core logging and other measurements caught up with Core U1507B-5R. Geochemical sampling of Hole U1507B cores began while analyses of pore water and sediment samples from Hole U1507A are still being completed.​


Daily Science Report for 10 August 2017

Location: Hole U1507B (26°29.3158′S, 166°31.7155′E, water depth 3568.4 m)​

The drill string was retrieved from Hole U1507A and cleared the rig floor at 0940 h. An RCB bottom-hole assembly was made up with a center bit that will allow us to drill without coring for the first 375 m. We also included a mechanical bit release (MBR) that will allow us to drop the bit at the bottom of the hole and then wireline log without retrieving the entire drill string. Drill pipe was deployed and by 1800 h the bit was just above the seafloor. After picking up the top drive we pulled the center bit and pumped a wiper “pig” through the drill string to clean out debris prior to drilling. The center bit was then dropped back in place and drilling in Hole U1507B began at 2015 h. By midnight we had reached 164 m DSF.

Cores U1507A-33X to 44X consist of nannofossil chalk with numerous ~1–10 cm layers of foraminifer sand and greenish-gray nannofossil clay with volcanic ash. Much of the nannofossil chalk shows evidence of soft-sediment deformation. From Core 38X downhole, the frequency and thickness of the foraminifer sand layers decrease, and the nannofossil chalk becomes more clayey and turns from white to pale yellow. Nannofossils and planktic foraminifers indicate an early Miocene to late Oligocene age for the bottom of the hole (Cores 43X–44X). Petrophysical core logging was completed for all sections from Hole U1507A, whereas final measurements and analyses on discrete petrophysics as well as geochemistry samples are still being completed.

Scientists submitted drafts of their Site U1506 site chapter and site summary to the science office.


Daily Science Report for 9 August 2017

Location: Hole U1507A (26°29.3158′S, 166°31.7039′E, water depth 3568.4 m)

Cores U1507A-32X through 46X penetrated from 291.4 to 425.4 m DSF and recovered 134.0 m (58%). Recovery in these XCB cores varied from 9% to 96%. Towards the end of the day, it took ~100–150 min to cut a core. At midnight we decided to terminate Hole U1507A and pull the drill string, make up an RCB bottom-hole assembly, start Hole U1507B by washing down to ~375 m DSF, and core to the target at ~700 m DSF.

Cores U1507A-17H to U1507A-32X consist predominantly of nannofossil ooze with numerous ~1–10 cm layers of foraminifer sand and greenish-gray volcanic ash-bearing clay. Much of the nannofossil ooze shows evidence of soft-sediment deformation. A ~100 cm layer of dark gray tuffaceous, matrix-supported, consolidated polymictic breccia-conglomerate was encountered in Core 32X. Cores 31X to 42X are late to early Miocene based on nannofossil and planktic foraminifers. Rare and recrystallized radiolarians are also present. ​Paleomagnetic directions are scattered as a result of soft sediment deformation. Petrophysical and geochemical sampling and measurements are complete or in progress to Core 44X.

The scientists held a meeting to review the results of Site U1506.​


Daily Science Report for 8 August 2017

Location: Hole U1507A (26°29.3158′S, 166°31.7039′E, water depth 3568.4 m)

Cores U1507A-12H through 31X penetrated from 101.2 to 291.4 m DSF and recovered 171.1 m (90%). Recovery of Cores 12H through 26H ranged from 99% to 106%. After we switched to the XCB system at 1815 h, recovery for Cores 27X through 30X varied from 12% to 78%. Additional temperature measurements were taken with Cores 13H, 16H, and 19H. Deployment of orientation and temperature tools was discontinued after Core 20H.

Cores U1507A-5H to 16H consist of white nannofossil ooze with foraminifers, with thin beds of light gray to white foraminifer ooze with nannofossils as well as greenish gray layers with bioturbation, both at meter scale intervals. Volcaniclastic grains and pyrite framboids occur sporadically throughout the cores. A meter scale slump structure was observed in Core 13H. Nannofossil and planktic foraminifer age control place Cores 3H to 19H in the early Pliocene and Cores 20H to 28H in the late Miocene. However, nannofossil and benthic foraminifers of Eocene age are also present in some cores, and radiolarian taxa of Miocene age were found in Core 4H. Radiolarians are barren from Cores 7H to 28H. Paleomagnetic results from Cores 2H to 12H are noisy as a result of the soft sediment deformation, except for a few short intervals. Petrophysical and geochemical sampling and measurements are complete or in progress to Core 30X. Hydrocarbon gas content is below detection limit for all cores.​


Daily Science Report for 7 August 2017

Location: Hole U1507A (26°29.3152′S, 166°31.7019′E, water depth 3568.4 m)

The rig crew completed the APC/XCB bottom-hole assembly by 0130 h, picked up drill pipe and the top drive, and deployed the bit just above the seafloor. The wiper “pig” was pumped through the drill string once more because of the added drill string here compared to Site U1506. The APC core barrel was prepared and deployed and Hole U1507A was initiated at 1040 h. After recovering a 6.2 m long mudline core, APC coring continued to Core U1507A-11H (101.2 m DSF) by midnight. Temperature measurements were taken with Cores 4H, 7H, and 10H. We plan to core to ~700 m.

The laboratory groups continued to process the final samples from Hole U1506A, including pore water samples and physical properties samples from the volcanic rocks. Later in the day, all laboratory groups began processing cores from Hole U1507A. Cores 1H through 4H consist of foraminifer nannofossil ooze. Core 1H is pale brown and contains clay, Cores 2H through 4H have cm to dm scale bands or layers in shades of white and gray, greenish gray intervals with clay and visible bioturbation, and foraminifer ooze layers, some appearing dark gray. Nannofossils and foraminifers from core catcher samples indicate a Pleistocene age for Cores 1H and 2H, and an early Pliocene age for Cores 3H through 11H. Radiolarians are present in Cores 1H through 6H. Paleomagnetic data appear noisy in these first cores from Hole U1507 except for a few short intervals. This is probably due to soft sediment deformation, mostly created by the coring process but in some cases also by depositional processes.


Daily Science Report for 6 August 2017

Location:
• Transit to Site U1507 (proposed site NCTN-8A)
• Hole U1507A (26°29.3152′S, 166°31.7019′E, water depth 3579.3 m)

We completed the final 245 nmi of the 286 nmi transit and arrived at Site U1507 at 2200 h. After lowering the thrusters and switching to dynamic positioning mode, the rig crew began assembling and deploying an APC/XCB bottom-hole assembly.

Description of the cores from Hole U1506A continued. In Core 28R (253.5–263.1 m CSF-A), the color of the nannofossil chalk with rare foraminifers and scattered micrometer-scale pyrite changes from white gray to pale yellow. In Core 29R, the nannofossil chalk has a basal interval containing dispersed glauconite (264.3–264.6 m), which is of middle Eocene age. Below the sharp sediment-rock contact at 264.65 m, all recovered material consists of slightly to severely altered volcanic rock with abundant veins, vesicles, and amygdules filled with secondary minerals. Thin section descriptions may allow us to define the rock type better in a few days.

Pore water analyses on samples from Hole U1506A continued, and 24 samples were prepared for carbonate analysis. We switched to igneous rock curation procedures for the volcanic section of Hole U1506A and began sampling for thin sections as well as petrophysical and paleomagnetic measurements on discrete samples.


Daily Science Report for 5 August 2017

Location:
• Hole U1506A (28°39.7180′S, 161°44.4240′E, water depth 1494.9 m)
• Transit to Site U1507 (26°29.3152′S, 166°31.7019′E; proposed Site NCTN-8A)

We completed coring at Hole U1506A at 1345 h. The drill string was pulled, disassembled, and inspected, and the rig floor was secured for transit, ending Hole U1506 at 1935 h. At 2000 h we were underway to Site U1507 (proposed Site NCTN-8A), and we completed 42 nmi of transit by midnight. We expect to arrive at Site U1507 at 2000 h on 6 August.

Cores U1506A-30R to 36R penetrated from 267.2 to 306.1 m with a recovery of 29.42 m (76%). Core 29R, the last core recovered on the previous day, penetrated the hard formation expected from the seismic data and representing the scientific objective for this site. Starting with Core 29R, we cut half intervals (~5 m) to maximize recovery. The lower part of Core 29R and all cores below consist of volcanic rock, with intervals of relatively fresh and fine grained rock and intervals of porphyritic, vesicular, and heavily altered rock. Several lava flow deposits can be differentiated. The age of the chalk immediately above the sediment-rock contact is middle Eocene, and the paleoenvironment is yet to be determined.

We continued to measure the physical properties of the cores, including magnetic susceptibility, natural gamma radiation, thermal conductivity, moisture and density, and P-wave velocity on all cores, and vane shear and penetrometer strength on the nannofossil ooze of the upper section (Cores 1R–22R). Several sections were run through both Whole-Round Multisensor Loggers (WRMSLs) available onboard to assess data reproducibility and to optimize data acquisition procedures in preparation for the next sites where stratigraphic correlation of multiple holes will require use of both loggers.

Paleomagnetic measurements are being carried out on section halves and discrete samples demagnetized up to 70 mT. The paleomagnetic signal appears to be seriously compromised by the rotary coring in the soft sediment above Core 27R, whereas the more lithified cores below yield reliable data.

Hydrocarbon concentrations from headspace samples from all cores are below detection limit. Pore water analysis is in progress, as is the preparation of samples for carbonate analysis.


Daily Science Report for 4 August 2017

Location: Hole U1506A (28°39.7180′S, 161°44.4240′E, water depth 1494.9 m)

The drill string assembly for the first hole of this expedition was assembled and lowered near the seafloor by 0330 h. After picking up the top drive, a “pig” was pumped through the drill string to remove some of the corrosion debris. An RCB core barrel was prepared and deployed, and coring at Hole U1506A began at 0600 h.

Cores U1506A-1R through 29R penetrated from the seafloor to 267.2 m with a recovery of 163.8 m (61%). The uppermost 97 m described by midnight consist of white to light grey nannofossil ooze with varying amounts of foraminifers. Micrometer-scale framboidal pyrite grains are dispersed throughout the core in centimeter-scale blebs. Nannofossils and planktic foraminifers indicate a Pleistocene to early Miocene or late Oligocene age. All cores are barren of radiolaria, and all ostracods are deep-water taxa.


Daily Science Report for 3 August 2017

Location:
• In transit to Site U1506 (proposed Site LHRN-3A)
• Hole U1506A (28°39.7183′S, 161°44.4433′E, water depth 1494.9 m)

We completed the last 198 nmi of the 1167 nmi transit to Site U1506, arriving at 1912 h. The dynamic positioning thrusters were lowered and the rig crew started to assemble the drill string for Hole U1506A. We plan to drill and core a single RCB hole with the objective of recovering, identifying, and dating the material beneath a high-amplitude reflector at ~310 m. While still in transit, the expedition scientists met to discuss the site survey and other science data available for the area. The rest of the day, the laboratory groups continued to prepare for the arrival of cores.


Daily Science Report for 2 August 2017

Location: In transit to Site U1506 (28°39.7183′S, 161°44.4433′E; proposed site LHRN-3A)

We completed 247 nmi of transit (991 nmi total to date). The expedition scientists received information and guidelines for writing shipboard reports and presentations of regional scientific research results. Drilling operations and science personnel held a meeting to establish the final operations plan for the first Site U1506, with a preview of operations at the subsequent sites. The Sample Allocation Committee finalized the sampling plan for the first site and made tentative plans for subsequent sites. Scientists and technicians working in the Geochemistry Laboratory received additional safety training. Estimated time of arrival at Site U1506 is 1800 h on 3 August 2017.


Daily Science Report for 1 August 2017

Location: In transit to Site U1506 (28°39.7183′S, 161°44.4433′E; proposed site LHRN-3A)

We completed 277 nmi of transit (714 nmi total to date). The expedition scientists presented their research plans to the full science contingent and received training on various data entry systems by IODP staff. Estimated time of arrival at Site U1506 is 1800 h on 3 August 2017.


Daily Science Report for 31 July 2017

Location: In transit to Site U1506 (28°39.7183′S, 161°44.4433′E; proposed site LHRN-3A)

We completed 268 nmi of transit (437 nmi total to date). The expedition scientists received presentations on drilling, coring, downhole measurements, curation, sampling procedures, depth computations, and the database and software applications environment. The laboratory teams also continued their work preparations. Estimated time of arrival at Site U1506 is 1800 h on 3 August 2017.


Daily Science Report for 30 July 2017

Location:
• Port of Townsville, Australia, Wharf 10
• In transit to Site U1506 (28°39.7183′S, 161°44.4433′E; proposed Site LHRN-3A)

The ship left Townsville with the last line released at 0712 h and is underway to Site U1506 (proposed Site LHRN-3A). The first fire and life boat safety drill was held for all aboard. The Co-Chief Scientists and Expedition Project Manager met with each laboratory team to discuss requirements, tasks, and issues, and the teams began to prepare for their work. Estimated time of arrival at Site U1506 is midday on 3 August 2017.


Daily Science Report for 29 July 2017

Location: Port of Townsville, Australia, Wharf 10 (19°15.0′S, 146°49.8′E)

Time Zone: UTC + 10 h (JOIDES Resolution is 15 h ahead of College Station, Texas)

The Expedition 371 scientists received several presentations, including an introduction of the project science from the Co-Chief Scientists, an overview of the Education and Outreach (E&O) plans from the two E&O Officers aboard, and an introduction to the expedition work plan from the Expedition Project Manager (EPM). The EPM then led the scientists on laboratory tours for an overview of scientific equipment, procedures, and work responsibilities. Loading of fuel was completed. The ship is scheduled to depart at 0700 h on 30 July.


Daily Science Report for 28 July 2017

Location: Port of Townsville, Australia, Wharf 10 (19°15.0′S, 146°49.8′E)

Time Zone: UTC + 10 h (JOIDES Resolution is 15 h ahead of College Station, Texas)

The Expedition 371 scientists boarded the ship in the morning and checked into their cabins. After a first visit to the galley, the scientists received a welcome presentation with introductory information. Next they were introduced to the technical support staff and received a presentation on life aboard the JOIDES Resolution, followed by a safety presentation as well as a safety tour of the shipboard laboratories. The scientist also received instructions on how to connect to the ship’s computing network and the email system. Technicians installed a new Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) in the Chemistry Laboratory and serviced the Scanning Electron Microscope (SEM). Catering and fuel were loaded onto the ship. Three public ship tours were held. The ship is scheduled to depart at 0700 h on 30 July.


Daily Science Report for 27 July 2017

Location: Port of Townsville, Australia, Wharf 10 (19°15.0′S, 146°49.8′E)

Time Zone: UTC + 10 h (JOIDES Resolution is 15 h ahead of College Station, Texas)

The Tasman Frontier Subduction Initiation and Paleogene Climate Expedition 371 started at 0812 h with the first line ashore at the Port of Townsville, Australia, Wharf 10. The Co-Chief Scientists and IODP staff moved onto the ship and began port call activities, including meetings with the offgoing staff and discharging and receiving cargo. One Co-Chief Scientist went to give a talk at James Cook University, Townsville, and returned to the vessel. Expedition scientists are scheduled to board the ship on 28 July. The vessel is scheduled to depart in the morning of 30 July.