IODP Expedition 356
Indonesian Throughflow
Daily Science Report for 31 August 2015
Location: Hole U1462A (19°49.2857′S, 115°42.5984′E; 87.1 mbsl)
Science Update: We recovered Cores U1462A-14X to 50X to 475.5 mbsf. Core recovery continued to be <5% until ~300 mbsf (Core U1462A-33X) where we penetrated into a different lithology and the overall recovery increased to 46%. The material above 300 mbsf consists of lithified creamy gray to light greenish gray non-skeletal coarse sand-sized packstone with abundant peloids, ooids, and macrofossils. Below 300 mbsf, Cores U1462A-33X to 39X were described and consist of lithified light grayish green to olive gray packstone with fine to very fine sand-sized grains, small benthic foraminifers, macrofossil (bivalves and scaphopods) fragments, and slight to moderate bioturbation. Preliminary biostratigraphy indicates the material at the base of Core U1462A-50X is ~2 Ma.
The science party also participated in a review meeting for Site U1461.
Daily Science Report for 30 August 2015
Location:
• Transit to Site U1462 (proposed site NWS-3A)
• Hole U1462A (19°49.2857′S, 115°42.5984′E; 87.1 mbsl)
Science Update: We arrived at Site U1462 and deployed the seafloor positioning beacon at 0340 h. Preparations for coring were then made and we tagged the seafloor with the bit (87.1 mbsl). The vessel was offset 20 m and we then attempted to start Hole U1462A with the HLAPC system at 0530 h. However, while attempting to take the mudline core, the core barrel became stuck in the bottom-hole assembly; we pulled the drill string back up to the rig floor and removed the bent core barrel by 1200 h. We then began coring Hole U1462A with the XCB system at 1525 h. We recovered Cores 1X to 6X with very poor recovery (0.3 m recovered from 58.2 m cored). We then switched to the HLAPC system and recovered Core U1462A-7F with 0.25 m of material. We switched back the XCB system and cut Cores U1462A-8X to 13X to 116.6 mbsf with no significant increase in recovery (average 3%).
All of the recovered material was contained in the core catchers and has been described (Cores U1462A-1X to 13X). The lithology ranges from partially lithified cream pelloid-rich packstone to unlithified creamy gray grainstone with gravel to coarse sand grains, abundant macrofossils, and lithic fragments. Core U1462A-13X contains lithified, cream, skeletal packstone with gravel-size macrofossils and few lithic fragments and suggests that we penetrated a reef. Biostratigraphy (nannofossils) suggests the material in Sample U1462A-11X-CC is >0.44 Ma.
Final analyses from Site U1461 were completed and the scientists are finalizing those site reports.
Daily Science Report for 29 August 2015
Location: Hole U1461D (20°12.8325′S, 115°03.9389′E; 127.3 mbsl) and in transit to Site U1462 (proposed site NWS-3A)
Science Update: We continued preparations for downhole logging and then raised the end of the drill string to 78.3 mbsf. The triple combination tool string was deployed at 0445 h and reached 1030 mbsf. While logging upward, the tool string encountered hole problems between 450 and 375 mbsf, which corresponded to the interval of cores with greatest gas-induced expansion. The Formation MicroScanner and sonic imager (FMS-sonic) was then deployed but was unable to pass below 192.7 mbsf, and log data was collected from there up to just below the end of the drill pipe. All logging operations were completed at 1645 h, and the vessel was underway to Site U1462 at 2048 h.
The remaining cores from Hole U1461D (Cores U1461D-60R and 61R) were described and consist of interbedded greenish gray and creamy gray packstone with fine sand, and thin sand beds and mud beds. Preliminary biostratigraphy suggests the material at the base of Hole U1461D (Sample U1461D-61R-CC) is middle Miocene in age (<13.36 Ma). Final analyses from Site U1461 from all laboratory groups are winding down and the science party is working on the site report.
Daily Science Report for 28 August 2015
Location: Hole U1461D (20°12.8325′S, 115°03.9389′E; 127.3 mbsl)
Science Update: We completed RCB coring with the recovery of Cores U1461D-44R to 61R to 1095.3 mbsf, which ended coring operations at Site U1461. We recovered 325.51 m of 559.4 m cored (58%) in Hole U1461D. After releasing the bit at the bottom of the hole, we raised the bit up to 500.1 mbsf and prepared to circulate heavy mud to condition the hole for logging. The logging plan is to run three different tool strings: the triple combination, the FMS-sonic, and the Versatile Seismic Imager (VSI).
Cores U1461D-41R to 59R were described. The material down to Core U1461D-50R (982.3 mbsf) continued to consist of lithified greenish gray wackestone. However, beginning with Core U1461D-51R, there was an increase in coarser, sand-sized grains interbedded with the mud-rich beds. Core U1461D-52R is transitional and contains interbedding between greenish gray packstone and creamy gray packstone with coarse sand, sand beds with sharp contacts, and fewer mud beds. Cores U1461D-53R to 57R (1011.2–1054.27 mbsf) consist of creamy gray packstone with coarse sand and 3–5 cm thick sand beds. Cores U1461D-58R and 59R transition back to interbedded greenish gray and creamy gray packstone with fine sand, sand beds (1–2 cm thick), and mud beds (1–2 cm thick). Preliminary biostratigraphy (calcareous nannofossils) suggests the material at the base of Core U1461D-54R (1023.83 mbsf) is late Miocene (~9 Ma) in age.
Daily Science Report for 27 August 2015
Location: Hole U1461D (20°12.8325′S, 115°03.9389′E; 127.3 mbsl)
Science Update: We continued RCB coring and recovered Cores U1461D-25R to 43R to 923.9 mbsf. Core recovery has been exceedingly variable. Cores U1461D-20R to 40R were described. The lithology continues to parallel cores recovered with the XCB system in Hole U1461B, and consists of lithified greenish gray wackestone with different degrees of bioturbation and varying amounts of foraminifera, disseminated pyrite, and pyrite nodules. The material at the base of Core U1461D-40R (885.45 mbsf) is Pliocene in age.
Daily Science Report for 26 August 2015
Location: Hole U1461D (20°12.8325′S, 115°03.9389′E; 127.3 mbsl)
Science Update: We drilled from 512.7 to 565 mbsf and recovered Cores U1461D-7R to 24R to 739.6 mbsf. Cores U1461D-2R to 19R were described. The lithology continues to parallel cores recovered in other holes, in this case cores recovered with the XCB system in Hole U1461B, and consists of lithified olive gray packstone and light olive gray wackestone with intervals of varying grain size (sand-size and mud-size), color (light and dark), degree of bioturbation, and macrofossil content. The material is earliest Pleistocene to latest Pliocene in age.
At 1345 h, a boat transfer from Dampier, WA, was initiated. Four oncoming passengers and two offgoing were exchanged, along with luggage and cargo. The transfer was complete at 1400 h.
Daily Science Report for 25 August 2015
Location: Hole U1461D (20°12.8325′S, 115°03.9389′E; 127.3 mbsl)
Science Update: We recovered Cores U1461C-71F to 73F to 443.9 mbsf, completing Hole U1461C at 0510 h. Overall, we recovered 448.53 m from 440.0 m cored (102%). The rest of the cores were described (Cores U1461C-29F to 73F) and consist of unlithified olive gray wackestone. There is one unlithified cream mudstone interval from Sections U1461C-51F-1 to 54F-1 (339.0–353.1 mbsf), below which the lithology is again olive gray wackestone. Additionally, Hole U1461C extended the depth of piston coring beyond Hole U1461B (375.61 mbsf) and successfully recovered the material that was not well represented with the XCB system. This is represented in Cores U1461C-64F to 73F (400.1–443.88 mbsf) and, in addition to the olive gray wackestone, contains intervals of soupy, light gray wackestone with coarse sand-size grains and common glauconite interspersed with thin lithified intervals. Biostratigraphy indicates the base of the hole is Pleistocene in age. This hole completes the triple piston coring strategy and the stratigraphic correlators are currently working on the splice for Site U1461.
After ending Hole U1461C, we offset the vessel 20 m north and began Hole U1461D at 0940 h. We drilled down to 455 mbsf and then cut Cores U1461D-2R and 3R to 474.4 mbsf. These spot cores will be used also to fill in recovery gaps from Hole U1461B cored using the XCB system. We then drilled to 503.0 mbsf and began continuous coring. Cores U1461D-4R and 5R were recovered to 512.7 mbsf.
Daily Science Report for 24 August 2015
Location: Hole U1461C (20°12.8427′S, 115°03.9369′E; 127.3 mbsl)
Science Update: We recovered Cores U1461C-10H to 23H to 215.5 mbsf. We then switched to the HLAPC system and recovered Cores U1461C-24F to 39F to 289.0 mbsf. Formation temperature measurements were made with the APCT-3 tool on Cores U1461C-10H, 16H, and 24F. We then drilled 3 m without coring to 292.0 mbsf for correlation purposes and resumed coring; Cores U1461C-41F to 73F penetrated to 433.0 mbsf.
Cores U1461C-1H to 28F were described and the lithologies are very similar to those in Holes U1461A and U1461B. The upper cores (U1461C-1H to 11H; 0–94.82 mbsf) consist of unlithified packstone with glauconite and rare macrofossils, and mudstone. Cores U1461C-11H to 13H-5 (94.82–117.29 mbsf) contain an unlithified cream to white mudstone, underlain by a cemented dark greenish gray glauconite-rich packstone with macrofossils and bioturbation. Below this (Cores U1461C-13H-6 to 28F; 117.29–239.39 mbsf) the material is unlithified light olive gray wackestone. Biostratigraphic datums indicate the material is Pleistocene in age.
Daily Science Report for 23 August 2015
Location: Hole U1461C (20°12.8427′S, 115°03.9369′E; 127.3 mbsl)
Science Update: We cut Cores U1461B-124X to 129X to a total depth of 879.2 mbsf. Hole U1461B ended at 1640 h. Overall, we recovered 743.24 m from 879.2 m cored (85%). We then offset the vessel 20 m north of Hole U1461B and began Hole U1461C at 1915 h. We recovered Cores U1461C-1H to 9H to 82.5 mbsf. The plan is to continue coring to HLAPC refusal, and then begin our RCB hole (Hole U1461D), which will go no deeper than 1155 mbsf.
The remaining cores from Hole U1461B were described (Cores U1461B-113X to 129X). The lithology consists of lithified olive gray wackestone with varying amounts of small benthic foraminifers and sand-sized grains. Slight to moderate burrowing (Chondrites isp. and Zoophycus isp.) was also found with pyrite infilling the burrows. Preliminary biostratigraphy (planktic foraminifers) indicates the material at the base of Hole U1461B is mid to early Pliocene in age (~4 Ma). Additionally, the Plio–Pleistocene boundary was tentatively identified at 677.47 mbsf (Sample U1461B-100X-CC) and will be targeted for RCB coring in Hole U1461D.
Daily Science Report for 22 August 2015
Location: Hole U1461B (20°12.8522′S, 115°03.9396′E; 128 mbsl)
Science Update: We continued XCB coring in Hole U1461B from 728.0 to 827.1 mbsf (109X–123X). We plan to continue coring to XCB refusal.
Cores U1461B-88X to 112X have been described. The lithology consists of lithified olive gray wackestone with different degrees of bioturbation and varying amounts of glauconite, and foraminifers. From Cores U1461B-109X to 112X, there are also numerous ~5 cm thick intervals of lithified greenish gray packstone with sand that are normally graded and exhibit sharp and/or scoured bottom contacts. These intervals are almost always accompanied by moderate bioturbation above. Preliminary biostratigraphy (planktic foraminifers) indicates the material in Sample U1461B-112X-CC is middle to late Pliocene in age (3.35 Ma).
Daily Science Report for 21 August 2015
Location: Hole U1461B (20°12.8522′S, 115°03.9396′E; 128 mbsl)
Science Update: We cut Cores U1461B-92X to 108X to 728.0 mbsf with extremely variable recovery. So far, we have recovered 651.19 m of 776.1 m cored (84%). We plan to continue coring to XCB refusal.
Cores U1461B-50F to 87X have been described. The lithology consists of olive gray wackestone with different degrees of bioturbation and varying amounts of clay, fine sand, glauconite, and foraminifers. From Core U1461B-76X (476.45 mbsf), the material is lithified. Preliminary biostratigraphy (planktic foraminifers) indicates the material in Sample U1461B-60X-CC (384.9 mbsf) is middle to early Pleistocene in age (>1.64 Ma).
Daily Science Report for 20 August 2015
Location: Hole U1461B (20°12.8522′S, 115°03.9396′E; 128 mbsl)
Science Update: We cut Cores U1461B-68X to 91X to 598.6 mbsf with variable recovery. We plan to continue coring to XCB refusal.
Cores U1461B-20H to 49F were described. Cores U1461B-20H to 36F have similar lithololgies to the material in the upper part of the hole and consist of unlithified dark greenish gray packstone. Core U1461B-37F (273–277.7 mbsf) contains a bioturbated, glauconite-rich interval with gravel size concretions and macrofossils (gastropods and bivalves) characteristic of shallow water. Below that interval is a cemented packstone underlain by unlithified, strongly bioturbated mudstone. This mudstone continued to Core U1461B-40X (292 mbsf) where another cemented and strongly bioturbated interval of glauconite-rich packstone was found. Cores U1461B-41F to 49F are unlithified dark olive gray packstone and partially lithified light olive gray wackestone. Preliminary biostratigraphy indicates the material is still Pleistocene in age.
Daily Science Report for 19 August 2015
Location: Hole U1461B (20°12.8522′S, 115°03.9396′E; 128 mbsl)
Science Update: We continued coring with the APC system and recovered Cores U1461B-16H to 25H to 221.3 mbsf. A formation temperature measurement was made with the APCT-3 tool while taking Core U1461B-16H. After recovering Core U1461B-25H, we switched to the HLAPC and recovered Cores 26F to 39F to 284.2 mbsf. We anticipated a hard layer, based on the previous hole, so we switched to the XCB system and cut Core U1461B-40X. We switched back to the HLAPC and recovered Cores U1461B-41F to 58F to 375.2 mbsf where piston coring refusal was reached. We then cut Cores U1461B-59X to 67X to 432.8 mbsf. We plan to continue coring to XCB refusal.
The lithologic description of Hole U1461A was completed and Hole U1461B begun. The lithology in Hole U1461B is very similar to Hole U1461A, particularly in the upper 60 m, and consists of unlithified packstone with glauconite and rare macrofossils, and mudstone. Below this depth, Cores U1461B-11H to 15H (87–121 mbsf) contain a strikingly light gray to white clay-rich mudstone underlain by a cemented interval before returning to unlithified packstone and wackestone (Cores U1461B-16H to 19H). Preliminary biostratigraphy (nannofossils) indicate the material is Pleistocene (<0.9 Ma) in age.
Daily Science Report for 18 August 2015
Location: Hole U1461A (20°12.8634′S, 115°03.9495′E; 127 mbsl) and Hole U1461B (20°12.8522′S, 115°03.9396′E; 128 mbsl)
Science Update: We continued coring with the APC system and recovered Cores U1461A-13H to 28H. While recovering Core U1461A-29H at 228.1 mbsf, the core barrel could not be pulled out of the formation and we drilled over it to release it. As a result, we switched to the HLAPC and recovered Cores U1461A-30F to 42F to 284.7 mbsf, where piston coring refusal was reached. Hole U1461A ended at 1430 h. Overall, core recovery was excellent (287.55 m recovered from 284.7 m cored, excess is a result of core expansion). Cores U1461A-1F to 31F (to 237.65 mbsf) have been described and alternate between unlithified, olive gray to dark greenish gray, homogeneous packstone with glauconite and rare macrofossils, and unlithified, off white to more commonly light olive gray, homogeneous mudstone. Smear slides revealed dolomite becoming more abundant in the deeper cores (Cores U1461A-27H to 31F; ~200–240 mbsf). Preliminary biostratigraphy (nannofossils) indicate the material is Pleistocene (<0.9 Ma) in age.
After finishing coring at Hole U1461A, we offset 20 m to the north and started coring Hole U1461B at 1600 h. We recovered Cores U1461B-1H to 7H to 55.1 mbsf; in anticipation of a hard layer encountered in the previous hole, we switched to the HLAPC for a single core (U1461B-8F). We then returned to full length APC coring, and Cores U1461B-9H to 15H penetrated to 126.3 mbsf. Core recovery thus far in Hole U1461B is also in excess of 100% due to core expansion. Formation temperature measurements were made while taking Cores U1461B-4H, 9H, and 13H.
Daily Science Report for 17 August 2015
Location: Hole U1461A (20°12.8634′S, 115°03.9495′E; 127.2 mbsl)
Science Update: We completed our transit to Site U1461 (proposed site NWS-4A) at ~1400 h when we switched to dynamic positioning control and deployed the seafloor positioning beacon. We offset 50 m west of the beacon and began preparations for coring. Because the seismic data suggested a hard bottom, we tagged the seafloor with the bit and then offset an additional 20 m to the west. Hole U1461A was started at 1825 h with the HLAPC. Cores U1461A-1F to 3F were recovered to 11 mbsf. As we encountered only soft sediment, we switched to the APC system and recovered Core U1461A-4H to 8H (97% recovery). While advancing Core U1461A-8H (54.3 mbsf), we encountered a hard layer, so we switched to the HLAPC and recovered Core U1461A-9F (0.37 m recovered). We then changed to the XCB system to get through the hard layer, advanced 2.5 m, and cut Core U1461A-10X (0% recovery). We changed back to HLAPC and recovered Cores U1461A-11F and 12F to 66.6 mbsf.
The science party participated in a Site U1460 review meeting and are finalizing their site reports.
Daily Science Report for 16 August 2015
Location: In transit to Site U1461 (proposed site NWS-4A)
Science Update: We are currently underway Site U1461 with an expected arrival ~1500 h on 17 August. The operating plan at this site is triple APC/double XCB to refusal with a fourth RCB hole to reach our total depth (~1100 m).
The sedimentology group completed describing all Hole U1460B cores. The lithology remained very similar to that in Hole U1460A, consisting of unlithified, beige or light greenish gray packstone. However, there is a series of thicker intervals from 252 to 275 mbsf in Hole U1460B that may be at the base or toes of prograding clinoforms. This 23 m thick zone, which was only ~2 m in Hole U1460A, consists of wackestone with recumbent and isoclinal folds, fluidized structures, inclined layers, and floating clasts up to cm-scale. The structures are noted due to color variations ranging from creamy gray to dark brown to light greenish gray. Sharp and inclined contacts separate the deposits, which are tentatively interpreted as debris flows. These intervals are being used to correlate Holes U1460B and U1460A.
All personal sampling of Site U1460 was completed.
Daily Science Report for 15 August 2015
Location: Hole U1460B (27°22.4867′S, 112°55.4265′E; 214 mbsl) and in transit to Site U1461 (proposed site NWS-4A)
Science Update: We recovered Cores U1460B-42F to 68F to 306.6 mbsf. At this depth, HLAPC refusal was reached. Hole U1460B was completed at 1505 h; overall, recovery was very good with 296.41 m recovered from 306.6 m cored (97%). Preparations then began for our ~2 d transit to the more northern sites of our latitudinal transect. The drill string was recovered and the bit was back on the rig floor at 1940 h. We started the transit to Site U1461 at 1945 h.
Core description was completed through Core U1460B-28F (124.8 mbsf). The lithology is very similar to that in Hole U1460B. The sediment is mainly composed of unlithified, beige or light greenish gray packstone with glauconite in the upper part of the hole (to ~50 mbsf) and sponge spicules from ~50 to ~120 mbsf. Preliminary biostratigraphy (planktic foraminifers) for the entire hole indicates the material at the base is latest Pliocene in age.
Daily Science Report for 14 August 2015
Location: Hole U1460A (27°22.4948′S, 112°55.4396′E; 215 mbsl) and Hole U1460B (27°22.4867′S, 112°55.4265′E; 214 mbsl)
Science Update: We recovered Cores U1460A-57F to 65F, at which point we reached piston coring refusal (300 mbsf). Core recovery for this hole was excellent (300 m cored, 291.4 m recovered, 97% recovery). We cleared the seafloor at 0605 h and offset 20 m north. Hole U1460B was spudded at 0745 h with the half-length advanced piston corer (HLAPC). We then recovered Cores U1460B-1F to 41F to 186 mbsf. In situ temperature measurements of the formation were obtained while taking Cores U1460B-12F, 20F, 28F, 33F, and 36F.
The remaining cores from Hole U1460A were described (23F to 65F) and are composed of unlithified to partially lithified light gray to cream homogenous packstone. In Core U1460A-58F, a transported sand bed noted by a sharp scoured basal contact was noted. The sand is dark gray and glauconite rich. Just below this sand bed, there is a second transported deposit that contains gravel to pebble size lithic clasts contained in a dark gray packstone matrix. Biostratigraphy (nannofossils and planktic foraminifers) indicates the material at the base of the hole is late Pliocene in age.
Daily Science Report for 13 August 2015
Location: Hole U1460A (27°22.4948′S, 112°55.4396′E)
Science Update: We tagged bottom at Site U1460 at 0015 h and then offset 20 m west. Hole U1460A was spudded at 0115 h with the half-length advanced piston corer (HLAPC). We recovered Cores U1460A-1F to 56F to 255.9 mbsf. After recovering Core U1460A-56F, we slipped and cut 150 m of core winch line, after which we expect to continue coring with the HLAPC to refusal. Cores U1460A-1F to 22F were described and are composed of unlithified light green to gray homogenous packstone. The upper 60 m (to Core U1460A-14F) contain glauconite and abundant sponge spicules, small benthic and planktic forams, which gradually diminish (to ~100 mbsf) and dolomite rhombs appear. Biostratigraphy (nannofossils) indicates the material is late to middle Pleistocene in age.
Daily Science Report for 12 August 2015
Location: Hole U1459C (28°40.2398′S, 113°33.5365′E) and Hole U1460A (27°22.4948′S, 112°55.4396′E)
Science Update: The early part of the day was spent preparing for downhole logging operations. The end of the drill pipe was pulled up to 72.2 mbsf and the logging tool strings were readied. Planned operations included runs with the triple-combo, measuring natural gamma ray, density (without the source), resistivity and magnetic susceptibility, and the Formation MicroScanner and sonic imager (FMS-sonic). The triple-combo run reached 390 mbsf, which is 10 m above the bottom of the hole. The FMS-sonic was then deployed twice to 300 and 292 mbsf. Logging operations concluded at 0915 h. We then recovered the drill string and the seafloor positioning beacon, and were underway to Site U1460 (proposed site NWS-5A) by 1300 h. At 2050 h, we reached Site U1460 and then prepared for coring operations. The coring plan at this site is two holes to piston coring refusal depth.
The core description team finalized the lithologic units for Site U1459; in total, there are seven units at this site. The two deepest were described from Hole U1459C: Unit VI (light greenish gray to brown dolostone with glauconite) and Unit VII (light greenish gray chert-rich packstone and microcrystalline chert). Further refinement of the biostratigraphy with planktonic foraminifers confirms that the base of Hole U1459C is middle Eocene in age (~50 Ma).
Finally, all personal sampling at Site U1459 was completed.
Daily Science Report for 11 August 2015
Location: Hole U1459C (28°40.2398′S, 113°33.5365′E)
Science Update: We cut and recovered Cores U1459C-19R to 42R to 400 m. This was our final approved penetration depth for this site. Recovery from these cores was fairly poor overall (<20%), likely as a result of alternating softer and harder (chert) intervals. All of the cores were described. Cores 19R and 20R consist of glauconite-rich dolostone or dolostone with glauconite and quartz. There is a lithologic unit boundary between Cores 20R and 21R. Cores 21R to 42R (base of the hole) consist of chert-rich grainstone with glauconite. The grainstone contain lenticular bedding and wavy laminations of brown mud while the cherts are banded with veins and cavities filled with grainstone or carbonate. Microfossils are again present from Core 20R. Preliminary biostratigraphy (nannofossils) indicates the material is middle Eocene in age.
Daily Science Report for 10 August 2015
Location: Hole U1459C (28°40.2398′S, 113°33.5365′E)
Science Update: We continued waiting for the heave to diminish (3.8 m at 0830 h) before resuming RCB coring at 1215 h. All RCB cores from this hole have been half-cores; we are only advancing 4.8 m with each recovery. We cut Cores U1459C-5R to 10R (all <0.25 m of recovered material) by 1530 h. The drill string became stuck while cutting Core 10R. After working the stuck pipe free for over an hour, we resumed RCB coring at 1645 h. We cut and retrieved Cores U1459C-11R to 18R (<30% recovery) to 287 m below sea floor. Cores U1459C-5R to 13R consist of intervals of grayish green glauconite-rich grainstone and creamy brown grainstone with dolomite. Preliminary biostratigraphy up to Core U1459C-10R indicates that the material is likely early Oligocene in age. Cores U1459C-11R and deeper have been barren of microfossils.
Daily Science Report for 9 August 2015
Location: Hole U1459C (28°40.2398′S, 113°33.5365′E)
Science Update: We continued drilling down in Hole U1459C to 205.8 m and then began coring with the rotary core barrel (RCB) system. We cut Cores U1459C-2R to 4R, which all recovered <1 m of material. We dropped the core barrel to cut Core U1459C-5R but experienced excessive heave. Due to shallow water safety protocols, we ceased operations, pulled the bit off bottom, and continued to rotate and circulate while we waited for the heave to diminish. At 1510 h we experienced increased torque and loss of rotation; the stuck pipe was freed at 1600 h. We raised the bit from 200 to 115.5 m and continued to wait for the heave to diminish. At 1800 h, the heave was 5.8 m, but slowly decreasing. By 2300 h it had reduced to 4 m. All cores recovered from this hole were described and are composed of lithified, light greenish gray and grayish green glauconite rich grainstone, and dark greenish gray dolostone with sand. Material recovered while drilling from 0 to 205 m (Core 1-1; 2.65 m of sediment) consists of unlithified, light gray to creamy gray fine grained, very well sorted sand and gravel size grainstone containing glauconite, benthic foraminifers, echinoderm tests, bryozoans, and hematite-stained grains. A sharp contact separates the grainstone from unlithified cream to beige wackestone and gravel size grainstone.
Daily Science Report for 8 August 2015
Location: Hole U1459B (28°40.2519′S, 113°33.5375′E) and Hole U1459C (28°40.2398′S, 113°33.5365′E)
Science Update: We continued coring with the half-length advanced piston corer (HLAPC), recovering Cores U1459B-40F to 46F to 217 m below sea floor (mbsf), which was APC refusal. We switched to the extended core barrel (XCB) system and cut Cores 47X to 49X, which all had <0.4 m recovery. While cutting Core 50X (0.12 m recovered), we encountered an extremely hard layer and were only able to advance 0.1 m after nearly an hour—during which we also destroyed the XCB cutting shoe. We thus decided to end Hole U1459B (233 mbsf total depth). The drill string cleared the seafloor at 1345 h and Hole U1459B officially ended at 1640 h. We offset the vessel 20 m north and spudded Hole U1459C at 2225 h. By midnight, we had just started to drill down to just above the APC refusal depth in Hole U1459B (210 mbsf); once we reach this depth, we will begin coring with the rotary core barrel (RCB) system. All remaining cores from Hole U1459B (21F to 50X) were described and the sedimentology group tentatively identified five lithologic units. Unit I is grainstone and sand intervals with macrofossils; Unit II is mud without macrofossils; Unit III is glauconite-rich grainstone; Unit IV is glauconite-rich grainstone without macrofossils; and Unit V is dolomitic packstone. Biostratigraphy (nannofossils) indicates that the base of Hole U1459B is middle Miocene in age.
Daily Science Report for 7 August 2015
Location: Hole U1459B (28°40.2519′S, 113°33.5375′E)
Science Update: We spudded Hole U1459B at 0025 h and drilled down to 13.5 m below sea floor (mbsf). This was done because we had a difficult time establishing Hole U1459A due to a hard seafloor. We also anticipated alternating hard and soft layers in this hole based on Hole U1459A, so we switched between the extended core barrel (XCB) system and the half length advanced piston corer (HLAPC) to optimize recovery. We cut Core U1459B-2X (0.24 m recovered) to 22.5 mbsf. We then used the HLAPC to recover cores 3F to 5F (98% recovery) to 34.8 mbsf. We switched back to XCB to cut Core 6X (0.04 m recovered) to 40 mbsf. We recovered Cores 7F to 9F (95% recovery) before changing to the XCB for the last time in the upper part of the hole; Core 10X (0.07 m recovered) extended to 55 mbsf. By midnight, we had recovered Cores 11F to 39F with excellent recovery. Cores 2X to 20F contain carbonates with abundant glauconite alternating between lithified and unlithified intervals. The lithified intervals also contain abundant microfossils, such as small and large benthic foraminifers, bryozoa, bivalves, and gastropods. The unlithified intervals contain alternating darker and lighter grays, possibly indicating variations in glauconite content. Biostratigraphy indicates that the base of Core 19F is <3.92 Ma (nannofossils).
Daily Science Report for 6 August 2015
Location: Holes U1459A (28°40.2606′S, 113°33.5376′E) and U1459B (28°40.2519′S, 113°33.5375′E)
Science Update: We cut Cores U1459A-3X to 5X from 9.7 to 32 m below sea floor (mbsf), however we only recovered 0.56 and 0.1 m of sediment in Cores 4X and 5X, respectively. Coring rates indicated that the sediments had softened significantly, so we switched to the half-length APC (HLAPC) system and recovered Cores 6F (2.89 m) and 7F (0.46 m) to ~40 mbsf. Biostratigraphic datums indicate that the age at the base of Core 6F is <1.73 Ma. We encountered another significantly hard layer after Core 7F, so we switched back to the extended core barrel (XCB) system and cut Core 8X to 42 mbsf, but recovered no material. We returned to the HLAPC system and recovered Cores 9F to 14F with excellent recovery (92%). However, while retrieving Core U1459A-14F at 70 mbsf, the core barrel became stuck in the bottom-hole assembly. We were unable to work it free and had to pull out of the hole, abandoning Hole U1459A at 2135 h. The core description team described all of the cores from Hole U1459A, which consist of grainstone with abundant glauconite and foraminifers and intervals of more gravelly material with fragments of echinoids, bryozoans, and bivalves. By 2315 h, we had offset 20 m north and begun preparing to spud Hole U1459B. The science party also finalized their reports on Site U1458.
Daily Science Report for 5 August 2015
Location: Site U1458 (28°39.8475′S, 113°34.6676′E) and Site U1459 (28°40.2606′S, 113°33.5376′E)
Science Update: We finished repairing the parted coring line at 0215 h. We spudded Hole U1458A at 0300 h. Two advanced piston corer (APC) cores (U1458A-1H and 2H) only penetrated to 3.1 m below sea floor (mbsf). We then switched to the extended core barrel (XCB) system and penetrated to 9.4 mbsf (Core U1458A-3X), but without any recovery. We then attempted to use the half-length APC system and recovered Core U1458A-4F (0.6 m) to a total depth of 10 mbsf. Biostratigraphic datums indicate that the age at the base of Core U1458A-2H is ~0.61 Ma (planktic foraminifers) and the base of the site (Sample U1458A-4F-CC) is <1.73 Ma (nannofossils).
After discussion with the science party, we decided to abandon Site U1458 in favor of a slightly deeper alternate site (U1459; proposed site NWS-13A). Based on the small amount of material recovered from Site U1458, which consists of unconsolidated skeletal limestone containing bryozoans, small benthic foraminifers, rhodoliths, coralline algae, gastropods and bivalves, we hoped that moving more distal to the Houtman-Abrolhos reef complex would reduce the amount of coarse-grained material at the seafloor. We left Site U1458 at 1415 h and arrived at Site U1459 at 1550 h where we began preparations for coring. The coring plan at this site is the same as for Site U1458. On the second attempt to recover the mudline core with the APC, we broke the core barrel, indicating a very hard bottom. We switched to the half-length APC, spudded Hole U1459A at 1920 h, and recovered Core U1459A-1F (0.1 m). We then switched to XCB at 2000 h and began to cut Core U1459A-2X. In the meantime, the science party began writing up their results for Site U1458.
Daily Science Report for 4 August 2015
Location: Site U1458 (28°39.8475′S, 113°34.6676′E)
Science Update: We arrived at Site U1458 (NWS-6A) at 1400 h and began preparations for coring the first hole; the coring plan at this site is to triple core with the advanced piston corer (APC) to refusal and double core with the extended core barrel (XCB) to total depth (330 mbsf). Both coring systems and bottom-hole assembly (BHA) were made up, along with the drill string, and the bit was spaced out by 2000 h. However, the core line parted at 2015 h before recovering any core, and required several hours to restring it. Therefore, we tentatively expect the first cores tomorrow. In the meantime, the onboard Education/Outreach Officers gave an introduction to the science party, and the Sample Allocation Committee finalized the shipboard sampling plan and continued meeting with small groups and individuals as necessary.
Daily Science Report for 3 August 2015
Location: Victoria Quay, Berth C (Fremantle, Australia) and in transit to Site U1458 (NWS-6A)
Science Update: The science party received an introduction to our coring systems and planned operations for the expedition from the Operations Superintendent, which was followed by core flow information and tours given by the Curator and Staff Scientist. Final laboratory preparations in anticipation for the first cores of the expedition were also made. The loading of all freight was completed in the morning and final port call activities came to a close. We departed the dock at 1615 h and began the transit to our first site (U1458; proposed site NWS-6A). Our expected time of arrival is 1330 h on 4 August.
Daily Science Report for 2 August 2015
Location: Victoria Quay, Berth C, Fremantle, Australia
Science Update: The Co-Chief Scientists gave an introduction to the expedition science, which was followed by a practical presentation by the Staff Scientist about expedition reports and tasks. The science party discussed their personal research interests with the result of some important collaborations forming. They then broke into their laboratory groups for the rest of the day. During this time, the Sample Allocation Committee met with several laboratory groups to discuss shipboard sampling. We are scheduled to leave port at 1600 h on 4 August.
Daily Science Report for 1 August 2015
Location: Victoria Quay, Berth C, Fremantle, Australia
Science Update: All members of the science party arrived and settled into their cabins, after which we began orientation activities and expedition preparation. This included getting set up on the network, tips for living at sea, and laboratory safety tours. The science party also began work in their laboratory groups with the respective laboratory specialists. We also continued our port call activities, including the ship’s crew change and loading of freight. We are tentatively scheduled to leave Fremantle the afternoon of 3 August.
Daily Science Report for 31 July 2015
Location: Victoria Quay, Berth C, Fremantle, Australia
Science Update: IODP Indonesian Throughflow Expedition 356 officially began at 0800 h. The technical staff, EPM, and Co-Chief Scientists boarded the vessel and began port call activities, including IODP JRSO crew change and crossover. Scientists are scheduled to board the ship on 1 August.