IODP Expedition 371
Tasman Frontier Subduction Initiation and Paleogene Climate
Daily Science Report for 31 August 2017
Location: Hole U1508C (34°26.8905′S, 171°20.5889′E, water depth 1609 m)
Cores U1508C-38R penetrated from 694.9 to 704.5 m and recovered 7.0 m (73%). Penetration rate had slowed down significantly and we decided to stop coring short of the desired target and conduct wireline logging. The rotary shifting tool (RST) was deployed to trigger the mechanical bit release (MBR) and drop the bit at the bottom of the hole (0325 h). Next the reverse RST was deployed to shift the MBR sleeve back into the circulation position (0430 h). The hole was displaced with 194 barrels of 11.0 ppg mud and the end of the drill string was set at 86.7 m. An additional 10 barrels of mud were pumped to ensure the entire hole was displaced with heavy mud.
At 0745 h assembly of the modified triple combo logging tool string began. This was the same tool configuration as used in Hole U1507B except that no source was installed this time. The logging tools were deployed at 0900 h and data were collected while we lowered the tool string to the bottom of the hole. After logging up 125 m for a calibration run, the tools were run back to the bottom of the hole, and the main logging pass began. At ~1230 h the tool string became stuck at ~270 m WSF (wireline depth below seafloor). The logging line was cut at the rig floor and terminated with connectors that would allow assembly of drill pipe over the logging line and washing down and over the logging tools with the open-ended bottom-hole assembly. The logging tools were free at 2105 h. After pulling the tool to 155 m WSF using the T-Bar procedure, the coring line was connected to pull the logging tools to the surface.
Cores U1508C-37R and 38R consist of light greenish grey nannofossil-rich limestone with decimeter-scale, darker greenish gray bands. The last core from this hole (Core U1508C-38R) is of early Eocene age based on nannofossil, planktic foraminifera, and radiolarian biostratigraphy.
Daily Science Report for 30 August 2017
Location: Hole U1508C (34°26.8905′S, 171°20.5889′E, water depth 1609 m)
Cores U1508C-31R to 37R penetrated from 647.1 to 694.9 m and recovered 32.2 m (67%).
The dominant lithology in Cores U1508C-26R through 36R is light greenish gray nannofossil chalk with foraminifers. Bioturbation is moderate and approximately millimeter-sized blebs of spherical iron sulfide occur throughout the cores. Shear veins were observed in Cores 29R and 30R. Cores 30R through 37R are early to middle Eocene in age based on calcareous nannofossil and planktic foraminifera biostratigraphy. P-wave velocities increase sharply, from 2600 to 3300 m/s, at 660 to 680 m, the interval where coring penetration rates slowed down significantly.
Daily Science Report for 29 August 2017
Location: Hole U1508C (34°26.8905′S, 171°20.5889′E, water depth 1609 m)
Cores U1508C-19R to 30R penetrated from 536.6 m to 647.1 m and recovered 95.0 m (86%).
Cores U1508C-14R to 25R consist of light greenish gray nannofossil chalk with foraminifers. Bioturbation varies from moderate to heavy. Blebs of approximately millimeter-sized pyrite occur throughout the cores. Green lamina appear in Core 17R (523 m) and remain present through Core 25R. Shear veins are observed starting with Core 20R.
Cores 20R to 29R are of middle Eocene age based on calcareous nannofossil and planktic foraminifera biostratigraphy.
Methane and ethane concentrations increase downhole from Core 17R (523 m) to 29R (629 m), to ~3000 ppmv and ~7 ppmv, respectively.
Daily Science Report for 28 August 2017
Location: Hole U1508C (34°26.8905′S, 171°20.5889′E, water depth 1609 m)
The day began while drilling without coring in Hole U1508C from 330.7 to 450.0 m. At 0730 h we retrieved the center bit and resumed RCB coring. Cores U1508C-9R to 18R advanced from 450.0 to 536.6 m and recovered 41.6 m (48%).
Cores U1508C-2R to 7R (278 to 330.7 m) are interbedded nannofossil chalk and foraminiferal sand. Cores U1508C-9R to 13R mostly consist of light greenish gray, moderately bioturbated nannofossil chalk with foraminifers, and nannofossil chalk. Centimeter-size calcareous porcellanite nodules and blebs of pyrite crystals were noted. Cores 9R to 17R are of middle to late Eocene age based on nannofossil and planktic foraminifera biostratigraphy. Methane concentrations increase from 0 ppmv in Core 13R (494 m) to 940 ppmv in Core 17R (532 m).
Daily Science Report for 27 August 2017
Location:
• Transit from Auckland, New Zealand, back to Site U1508
• Hole U1508C (34°26.8905′S, 171°20.5889′E, water depth 1609 m)
The ship completed the last 69 nmi of the 293 nmi transit from Auckland and arrived at Site U1508 at 0600 h. The drill floor was cleared for operations at 0715 h. The RCB bottom-hole assembly and drill pipe were assembled and deployed to the seafloor, the top drive was picked up, and Hole U1508C was spudded at 1150 h with a center bit installed in the core barrel.
The plan is to drill to ~480 m DSF, ~20 m above total depth of Hole U1508B, and resume coring. We also decided to spot core two intervals that had particularly low recovery in Hole U1508B and are of scientific interest. After drilling without coring to 278 m DSF, we pulled the center bit and cored from 278 to 292.6 m DSF (Cores U1508C-2R to 4R) with half cores. The center bit was deployed again to drill ahead from 292.6 to 316.4 m DSF, before cutting a half core and a full core (6R and 7R) from 316.4 to 330.7 m DSF. The center bit was deployed again and by midnight we had just resumed drilling without coring. Recovery for Cores 2R to 7R was 9.2 m (38%).
Cores 2R to 7R are early Miocene based on nannofossil and planktic foraminifera in core catcher samples. As in Hole U1508B, nannofossil Zones NN3 and NN2 (~15–18 Ma) were not identified.
Daily Science Report for 26 August 2017
Location:
• Auckland, New Zealand (medical evacuation)
• Transit from Auckland, New Zealand, to Site U1508
Preparations for departure from Auckland were completed and the ship left port at 0215 h. By the end of the day, we completed 214 nmi of the ~302 nmi transit. Expected time of arrival at Site U1508 is 0700 h on 27 August.
The scientists continued with data analysis and report writing and received a talk on subduction initiation.
Daily Science Report for 25 August 2017
Location:
• Transit to Auckland, New Zealand (medical evacuation)
• Auckland, New Zealand
The ship docked in Auckland at 2100 h after completing the 302 nmi transit from Site U1508. One medical evacuee and one crew member disembarked. Expected time of departure is 0200 h on 25 August.
The scientists continued with data analysis and report writing.
Daily Science Report for 24 August 2017
Location:
• Hole U1508B (34°26.8975′S, 171°20.5990′E, water depth 1609 m)
• Transit to Auckland, New Zealand (medical evacuation)
Cores U1508B-34R to 38R (455.5–503.4 m) recovered 36.6 m (76%). At 0700 h the Ship’s Doctor declared a medical emergency. The drill string was recovered and the rig floor was secured for transit. The seafloor positioning beacon was retrieved, the thrusters were raised, and at 1400 h we were underway to Auckland for a medical evacuation. We expect to arrive in Auckland at 2000 h on 25 August. Clocks were advanced by 1 h at 1400 h and will be advanced another hour at 0200 h tomorrow morning for the ship to be on Auckland local time.
Cores U1508B-23R to 38R consist of moderately bioturbated light greenish grey nannofossil chalk with foraminifers, with rare cm-size calcareous porcellanite layers and nodules, and blebs of mm-sized pyrite crystals in Core 37R. Cores 32R to 38R are middle to late Eocene in age. The porcellanite layers within Core 28R have P-wave velocities of 3300 m/s, ~1000 m/s faster than the host rock.
Daily Science Report for 23 August 2017
Location: Hole U1508B (34°26.8975′S, 171°20.5990′E, water depth 1609 m)
Cores U1508B-2R to 33R (186.7–455.5 m) recovered 96.8 m (36%). Cores 2R to 14R consist of alternating nannofossil chalk and foraminiferal chalk. Color ranges from white to greenish gray, reflecting the abundance and composition of lithic grains. Much of the foraminiferal chalk is bedded and normally graded. In Cores 15R to 22R, light greenish gray foraminiferal chalk is the main lithology. Pale green laminae and specks of a green mineral are common.
Nannofossil and planktic foraminifera biostratigraphy identified middle to early Miocene (Cores 2R to 19R), late Oligocene (Cores 20R and 21R), early Oligocene (Core 22R), and late Eocene (Cores 23R to 31R) biozones. All samples contain high amounts of reworked middle Eocene microfossils. Ostracods are abundant and show no change in paleowater depth. Despite the poor core recovery, paleomagnetic data show clear positive and negative magnetic inclinations—Core 20R is tentatively linked to Chron C7n (late Oligocene).
A total of 12 samples were processed for palynology: six from Hole U1507B, three from Hole U1508A, and three from Hole U1508B.
Hydrocarbon gas contents from headspace analysis are all below detection limit. Bulk sediment carbonate analysis was completed for Hole U1508A. Carbonate contents are all higher than 70%, with generally higher values in the upper 90 m of the hole.
Daily Science Report for 22 August 2017
Location:
• Hole U1508A (34°26.8902′S, 171°20.6073′E, water depth 1609 m)
• Hole U1508B (34°26.8975′S, 171°20.5990′E, water depth 1609 m)
Coring continued with Cores U1508A-17H to 23H (143.8–210.3 m) with a recovery of 68.3 m (103%). Core 23H had to be drilled over to release it from the formation. At 0600 h we started to retrieve the drill string and the bit cleared the rig floor at 1140 h, ending Hole U1508A. Total recovery for the 210.3 m cored in Hole U1508A was 201.1 m (96%).
The ship was offset by ~20 m. An RCB bottom-hole assembly was made up and deployed, and the drill pipe was assembled until the bit was just above the seafloor. The top drive was picked up and Hole U1508B was spudded at 1745 h, with the center bit installed. After drilling ahead without coring to 186.6 m (until 2245 h), the center bit was retrieved and an RCB core barrel was dropped to begin coring.
The dominant lithology in Cores U1508A-8H to 11H is foraminiferal ooze with bioclasts, including shell debris, sponge spicules, and bryozoans. In Section 11H-3 a sharp contact separates foraminiferal ooze and nannofossil ooze with foraminifers. The dominant lithology in Cores 12H–23H is nannofossil ooze, with varying amounts of foraminifers, biosilica (sponge spicules and diatoms), and clay. In Cores 19H and 20H, centimeter-scale volcanic ash beds were encountered. Nannofossil and planktic foraminifera biostratigraphy places Cores 15H to 23H in the late Miocene. Radiolaria are present throughout that interval. Paleomagnetic measurements on section halves and discrete samples from Cores 16H–23H reveal the presence of some magnetic reversals. The data are highly scattered, probably as a result of diagenesis, indicated by the presence of darkish layers often associated with magnetite dissolution. Physical properties profiles show changes that can be correlated with lithologic changes. Sampling for porewater and sediment elemental analyses was completed for Hole U1508A.
Daily Science Report for 21 August 2017
Location: Hole U1508A (34°26.8902′S, 171°20.6073′E, water depth 1609 m)
The drill string with an APC/XCB bottom-hole assembly was completed and run to the seafloor by 0700 h. After picking up the top drive and dressing and deploying the core barrel, Hole U1508A was spudded at 0900 h. After shooting Core U1508A-10H, the core line parted just above the sinker bar at 1520 h. An RCB core barrel was dressed with a fishing shoe and by 1800 h the sinker bars and core barrel with Core 10H had been recovered in two wireline trips. Coring continued to Core 16H (143.8 m) with a total recovery of 132.8 m (92%). Temperature measurements were taken on Cores 7H, 9H, 10H, 12H, 14H, and 17H. Orientation was measured on Cores 13H to 17H.
The dominant lithology in Cores U1508A-1H to 7H is color banded white, pale olive, and pale yellow foraminiferal ooze with bioclasts. Cores are severely disturbed by soupy drilling disturbance. Principal bioclasts observed are shell debris, sponge spicules, and bryozoans. Nannofossil and planktic foraminifera biostratigraphy places Cores 1H to 11H in the Pleistocene to Pliocene and Cores 12H to 14H in the late Miocene. Cores 1H through 21H are unsuitable for paleomagnetic investigation due to the drilling disturbance.
Physical properties measurements of the first two cores are unreliable due to the drilling disturbance and measurement from Cores 3H to 10H are partly compromised. Headspace gas results for Cores 1H–15H were below the detection limit. Pore water samples were collected for standard squeezing (16 samples from Cores 2H to 16H) and additional porewater was obtained by rhizon sampling (20 samples from Sections 2H-1 to 2H-6 and 13H-1 to 13H-6).
Daily Science Report for 20 August 2017
Location:
• In transit to Site U1508 (proposed Site REIS-2A)
• Hole U1508A (34°26.8902′S, 171°20.6058′E, water depth 1616 m)
We completed the final 255 nmi of the 546 nmi transit and arrived at Site U1508 at 2345 h. The thrusters were lowered for dynamic positioning and work on the APC/XCB bottom-hole assembly began.
Half of the science party participated in guided tours of the rig floor and engine room areas. All scientists worked to finalize the Site U1506 reports and to produce the first drafts for the Site U1507 reports.
Daily Science Report for 19 August 2017
Location: In transit to Site U1508 (34°26.8902′S, 171°20.6058′E, water depth 1585 m; proposed Site REIS-2A)
We completed 186 nmi, most of it at a reduced average speed of 7.75 kt due to rough weather. The total distance completed so far is 291 nmi. We expect to arrive at Site U1508 at 2200 h on 20 August.
Upon closer examination of the seismic profiles at proposed Site REIS-2A, we detected a possibly sandy channel deposit at depth. We requested and received permission to move the site location up to 500 m toward contingency Site REIS-1A along the common seismic line to avoid the channel feature.
Half of the science party participated in guided tours of the rig floor and engine room areas. All scientists worked to finalize the Site U1506 reports and to produce the first drafts of the Site U1507 reports.
Daily Science Report for 18 August 2017
Location:
• Hole U1507B (26°29.3158′S, 166°31.7155′E, water depth 3568 m)
• Transit to Site U1508 (34°26.7211′S, 171°20.8059′E, water depth 1581 m; proposed Site REIS-2A)
The main wireline logging pass with the modified triple combo tool string ended at 2400 h on the previous day, and the tools were back on the rig floor by 0200 h. Hole conditions were excellent with a hole diameter close to the bit diameter (~10 inch) all the way from the bottom of the hole (846.4 m WSF) to ~490 m WSF. Hole conditions were still good up to 234 m WSF, where a bridge with hole diameter of only 6 inch was encountered. Additional bridges were indicated in the caliper log further uphole and just below the base of the drill string. The tool string passed these obstructions successfully and acquired high quality measurements throughout the open hole, including hole size, natural gamma radiation, bulk density, resistivity, magnetic susceptibility, and P-wave and S-wave sonic velocity.
Several hours of remediation work (washing) would have been required before the Versatile Seismic Imager (VSI) tool could have been run as planned, with limited chance of success and significant daylight time restrictions. Given the quality of the standard logs, particularly the sonic log, the scientific objective of tying the cores to the seismic records had been achieved and we decided to cancel the VSI run.
The modified triple combo logging tool string was rigged down and logging operations ended at 0400 h. The drill string was pulled out of the hole and up to the rig floor, and the seafloor positioning beacon was released and recovered. The bottom-hole assembly was broken down and stored in preparation for rough weather on the transit, and the rig floor was secured by 1150 h. While raising the thrusters, a hydraulic malfunction occurred and was repaired, and the transit to Site U1508 (proposed Site REIS-2A) began at 1330 h. By midnight we had completed 105 nmi out of an estimated voyage of 546 nmi.
Daily Science Report for 17 August 2017
Location: Hole U1507B (26°29.3158′S, 166°31.7155′E, water depth 3568 m)
Cores U1507B-51R through 53R penetrated from 835.7 to 864.4 m and recovered 11.4 m (40%). This concluded coring in Hole U1507B at 1000 h. A 25-barrel mud sweep was pumped to clean the hole. The total cored interval in Hole U1507B is 376 to 864.4 m DSF, with a total recovery of 371.5 m (76%).
Preparations for wireline logging began with a wireline trip to activate the mechanical bit release (MBR) and drop the coring bit at the bottom of the hole. A second wireline trip was conducted to shift the MBR sleeve back into closed position. At 1230–1315 h the hole was displaced with 245 barrels of 11.0 ppg mud. The top drive was set back, the drill pipe was pulled to logging depth with the bit at 75.2 m DSF, and the rig floor was prepared for logging. Assembly of the modified triple combo logging tool string began at 1700 h. The string includes natural gamma ray, electrical resistivity, bulk density, magnetic susceptibility, and sonic tools. The neutron porosity and microresistivity imaging (FMS) tools will not be used in this hole. At 1815 h the tool string was lowered into Hole U1507B and reached the bottom of the hole (846.4 m WSF) at 2115 h. A calibration pass and the main logging pass up the entire open hole were completed by 2400 h.
Cores U1507B-48R to 50R consist mostly of light greenish grey bioturbated clayey nannofossil chalk, with Zoophycos, Nereites, and Spirophyton burrows. In Section 50R-7, the lithology changes to a greenish grey nannofossil claystone. Cores 51R–53R consist of clayey limestone. Cores 50R to 53R are of middle Eocene age. The Middle Eocene Climatic Optimum (MECO) interval can be placed in Cores 50R to 51R based on the occurrence of O. beckmanni (Zone E12). Despite the high noise level in the magnetic remanence data, integration with biostratigraphy identified the base of Chron C18n in Core 50R.
Daily Science Report for 16 August 2017
Location: Hole U1507B (26°29.3158′S, 166°31.7155′E, water depth 3568 m)
Cores U1507B-43R through 50R penetrated from 759.0 to 835.7 m and recovered 68.3 m (89%).
The dominant lithology in Cores U1507B-41R to 47R is light greenish grey bioturbated clayey nannofossil chalk, with Zoophycos, Nereites, and Spirophyton burrows. In Core 47R, a rare medium-bedded, planar laminated, sharp-based foraminiferal sandstone bed was observed. Biostratigraphic analyses of samples from Cores 43R to 49R yield a late to middle Eocene age. The paleomagnetic signal from Cores 41R through 46R is unstable and no clear reversals can be observed. The loss of volcaniclastic material with the downhole transition into Eocene sediment resulted in a decrease in magnetic remanence intensity, along with other physical properties—this includes relatively low and constant bulk density, magnetic susceptibility, and natural gamma radiation below a sharp drop of these properties in Core 34R.
Daily Science Report for 15 August 2017
Location: Hole U1507B (26°29.3158′S, 166°31.7155′E, water depth 3568 m)
Cores U1507B-37R through 42R penetrated from 701.5 to 759.0 m DSF and recovered 54.6 m (95%).
Cores U1507B-34R and 35R consist of clayey nannofossil chalk with volcanic ash, interbedded with medium to thin-bedded, sharp-based, normally graded, tuffaceous to clayey sandstone. Cores 36R to 40R are dominated by bioturbated clayey nannofossil chalk with color variations from light greenish grey to greenish grey that vary at an ~1 m scale in an apparently cyclic manner. The disappearance of the tuffaceous sandstone across Cores 34R and 35R is accompanied by an order of magnitude decrease in the magnetic susceptibility and natural gamma radiation signals.
Nannofossil and planktic foraminifera biostratigraphy places Cores 36R through 42R in the late to middle Eocene. Radiolaria biostratigraphy supports a late Eocene age for Cores 36R through 38R. Benthic foraminifera are sparse.
Carbonate and total carbon analysis was completed for the upper ~200 m of Hole U1507B (~400–600 m CSF-A). Carbonate content varies widely between lighter, calcareous sediments (~50%–85%) and the darker sandstone layers rich in volcaniclastics (~15%–30%), and generally decreases downhole within both lithologies. Total organic carbon (TOC) content is below 0.8% for all measured samples. Hydrocarbon concentrations are below detection limit in all cores.
Daily Science Report for 14 August 2017
Location: Hole U1507B (26°29.3158′S, 166°31.7155′E, water depth 3568 m)
Cores U1507B-29R through 36R penetrated from 634.5 to 701.5 m DSF and recovered 61.4 m (92%).
Cores U1507B-25R through 33R consist of alternating clayey nannofossil chalk with volcanic ash and thick to thin-bedded, normally graded tuffaceous calcareous sandstone. In the top of Core 25R, shallow water bioclasts were observed within the sandstone. The carbonate content decreases downhole from Core 25R, to <10% in Core 29R.
Nannofossil and planktic foraminifera biostratigraphy places core catcher samples of Cores 31R through 34R in the late Eocene. Benthic foraminifera indicate that the core catcher of Core 30R is also of late Eocene age. Correlation of the paleomagnetic record with the geomagnetic polarity timescale is now established back to Chron C15n, constraining the Eocene–Oligocene boundary within the base of Core 30R.
Daily Science Report for 13 August 2017
Location: Hole U1507B (26°29.3158′S, 166°31.7155′E, water depth 3568 m)
Cores U1507B-20R through 28R penetrated from 548.4 to 634.5 m DSF and recovered 48.3 m (56%). Core recovery ranged from 1% to 107%, with the lowest recovery rates resulting from coring jams that occurred twice. The jams were remedied by running the “deplugger” after Cores 22R and 28R to remove the jammed material from the core barrel.
Cores U1507B-15R through 24R consist of clayey nannofossil chalk interbedded with foraminiferal limestone, often with volcanic ash. Several decimeter-thick tuffaceous, clast-supported, polymictic conglomerate occurs in Sections 19R-3 and 24R-6. Core 24R has several decimeter-scale, dark gray, graded, and laminated tuffaceous sandstone intervals. Soft-sediment deformation was also observed. Nannofossil and planktic foraminifera biostratigraphy places Cores 24R to 27R in the early Oligocene. A first integration with biostratigraphic data allows an almost continuous correlation of the paleomagnetic reversals from Site U1507B with geomagnetic polarity Chrons C6n to C12n (early Miocene to late early Oligocene).
Carbonate content in Cores U1507A-1H to 36X is generally high (84–95 wt%). The more clay-rich intervals have lower carbonate contents (~50 wt%). Cores 37X through 46X have more variable carbonate content between lighter (65–90 wt%) and darker (20–45 wt%) intervals. For the entire hole, TOC ranges between 0.1–0.6 wt%.
Hydrocarbon gas is still below the detection limit for all samples.
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.