IODP Expedition 356
Indonesian Throughflow
Daily Science Report for 29 September 2015
Location: In transit to Darwin, NT, Australia
Science Update: We are currently underway to Darwin, Australia. We still expect to arrive at 0900 h on 30 September.
Science meetings to discuss the expedition findings and postcruise research are ongoing.
Daily Science Report for 28 September 2015
Location: In transit to Darwin, NT, Australia
Science Update: We are currently underway to Darwin, Australia. Our estimated time of arrival is 0900 h on 30 September.
The science party completed all of the Site U1464 reports. Science meetings to discuss the expedition findings and postcruise research are ongoing.
Daily Science Report for 27 September 2015
Location: In transit to Darwin, NT, Australia
Science Update: We are currently underway to Darwin, Australia. Our estimated time of arrival is 0700 h on 30 September.
The science party are finalizing the Site U1464 reports. Science meetings are planned over the next two days to discuss the expedition findings and plan postcruise research.
Daily Science Report for 26 September 2015
Location: In transit to Darwin, NT, Australia
Science Update: We recovered Cores U1464D-47X to 58X to 529.6 mbsf, which completed coring at Site U1464. Overall recovery in Hole U1464D was 57% (529.6 m cored and 300.74 m recovered). The final core of Expedition 356 was on deck at 1410 h, after which we began recovering the drill pipe and preparing the rig floor for transit. At 2100 h, we were underway to Darwin.
The remaining cores from Hole U1464D were described. Cores U1464D-43X to 54X consist of lithified light gray and light brown skeletal packstone and mudstone. Macrofossils, when identifiable, consist of bivalve fragments, bryozoan, echinoderms, foraminifers, and branching corals. There is a single interval (Section U1464D-44X-CC) of anhydrite rock (8 cm long).
Cores U1464D-55X to 58X consist of lithified light brown, brown, and beige dolomitic grainstone, packstone, wackestone, and mudstone with complete to moderate bioturbation. Small (mm-scale) burrows are generally filled with gypsum, while larger burrows often contain coarser sand-sized grains of glauconite and pyrite. The amount of shell fragment varies from sparse to abundant and varied. For example, Interval U1464D-55X-1A, 0–132 cm contains abundant bivalves (up to 5 cm long), gastropods, bryozoans (up to 2 cm long), a sand dollar (3 cm), corals (Acropora, Fungiid), and small and large benthic foraminifers, including Cycloclypeus. Most macrofossil shells have been replaced by gypsum and, in some cases, gypsum and anhydrite nodules occur in the same shell. Anhydrite nodules occur sporadically throughout the lithology. An interval of dolomitic wackestone (Interval U1464D-57X-1A, 0–60 cm) contains abundant anhydrite with chicken wire structures and nodules as large as 10 × 5 cm.
Daily Science Report for 25 September 2015
Location: Hole U1464D (18°03.9230′S, 118°37.8836′E; 264.7 mbsl)
Science Update: We recovered Cores U1464D-20H to 32H to 293.5 mbsf. Formation temperature measurements were made while taking Cores U1464D-22H and 28H. After recovering Core U1464D-32H, we switched to the XCB system and recovered Cores U1464D-33X to 46X to 425.4 mbsf. Recovery with the XCB system has been very low (<10%). Our plan is to continue coring with the XCB system until we need to end operations for Expedition 356 (1300 h tomorrow).
Cores U1464D-7H to 42X were described and the dominant lithologies continue to mirror Hole U1464B. The lithology down to Core U1464D-34X is unlithified, light greenish gray and olive gray homogenous mudstone with slight to moderate bioturbation and very sparse shell fragments. Disseminated pyrite is mainly found in burrows. Pyrite nodules and celestite concretions are common. Towards the base of Section U1464D-34X-6A, small benthic foraminifers become common to abundant. Sections U1464D-34X-7A to 35X-CC are composed of lithified, dark greenish gray packstone with sand and coarse sand-sized grains of glauconite, pyrite, and carbonate. Macrofossils are common and include abundant benthic foraminifers, such as Cycloclypeus (a very shallow water benthic foraminifer), bivalves, bryozoan (full colonies and fragments), and echinoderm spines. Cores U1464D-36X to 42X consist of lithified, foraminifer-rich, creamy gray grainstone with glauconite. Macrofossils include bivalves (up to 5 cm long), Cycloclypeus, other benthic foraminifers, and bryozoan fragments.
Daily Science Report for 24 September 2015
Location: Hole U1464D (18°03.9230′S, 118°37.8836′E; 264.7 mbsl)
Science Update: We successfully recovered both the triple combination tool string (that had been stuck in the hole) and the drill pipe from Hole U1464C by 0645 h. Hole U1464C ended at 0830 h, after which we moved to Hole U1464D and began preparations for coring. We started Hole U1464D at 1300 h and recovered Cores U1464D-1H to 19H to 173.2 mbsf. All APC cores from U1464D-2H are oriented and formation temperature measurements were made while taking Cores U1464D-5H, 8H, 12H, and 16H.
Cores U1464D-1H to 6H were described and the overall lithology is similar to Hole U1464B. Cores U1464D-1H and 2H consist of unlithified, light brownish gray grainstone, packstone, and wackestone with coarse sand, sand, and fine sand-sized grains. Macrofossils include pterapods, bivalves, gastropods, a crustacean fragment, echinoderm spines, a solitary coral, and benthic foraminfers. Core U1464D-3H to Section U1464D-6H-1A is unlithified, creamy gray, homogeneous mudstone. There is an unlithified dark greenish gray packstone with abundant glauconite in Sections U1464D-6H-2A to 4A that has a sharp subvertical contact at its base, suggesting it is a transported deposit. The rest of Core U1464D-6H is wackestone and packstone with common glauconite and benthic foraminifers.
Daily Science Report for 23 September 2015
Location: Hole U1464C (18°03.9244′S, 118°37.8942′E; 264.3 mbsl)
Science Update: We deployed the triple combination tool string at 0115 h. The tool string successfully completed a downlog from the bottom of the drill string at 71.6 mbsf to 794.7 mbsf. We began the uplog from that depth, but the tool string became stuck at 619.1 mbsf. Several attempts to free the tool were unsuccessful so we prepared to lower the open end of the drill pipe down to free the tool (the bit had previously been dropped in the bottom of the hole for logging). The end of the drill pipe was lowered from 71.6 to 625.6 mbsf, washing through any obstructions that were encountered, over the logging wireline, and finally over the triple combo tool string. We began to recover the triple combo tool string by the end of the day.
The science party finalized all reports from Site U1463 and began work on Site U1464.
Daily Science Report for 22 September 2015
Location: Hole U1464C (18°03.9244′S, 118°37.8942′E; 264.3 mbsl)
Science Update: We recovered Cores U1464C-40R to 56R to 840 mbsf with continued low (<20%) recovery. Coring was completed in Hole U1464C by 1430 h. Overall for this hole, we recovered 94.03 m of 532.0 m cored (18%). We then began preparations for logging operations, which included dropping the bit in the bottom of the hole, displacing the upper 360 m of the hole with heavy mud, and setting the end of the drill pipe to logging depth (86.9 mbsf). By midnight, we were assembling the first of three planned logging deployments, the triple combination tool string.
The remaining cores from Hole U1464C (25R to 56R) were described. The lithology consisted of dolomitic-limestone (‑mudstone, ‑wackestone, ‑packstone, ‑grainstone). In the upper cores (U1464C-25R to 44R), the lithology is mainly dolomitic packstone with skeletal carbonate (small and large benthic foraminifers, solitary corals, bryozoan, echinoderms, and bivalves), which transitions to an interval of mudstone, wackestone, and dolostone intercalated with packstone, anhydrite nodules, and crystals. Cores U1464C- 45R to 49R are dolomitic grainstone with gypsum and anhydrite nodules, while Cores U1464C-50R to 56R are characterized by alternating wackestone, packstone, and grainstone with anhydrite and gypsum nodules. Preliminary biostratigraphy (calcareous nannofossils) suggests the material at the base of Core U1464C-30R is ~12 Ma.
Daily Science Report for 21 September 2015
Location: Hole U1464C (18°03.9244′S, 118°37.8942′E; 264.3 mbsl)
Science Update: We recovered Cores U1464C-13R to 39R to 676.6 mbsf. The recovery has been low, in the upper 450 m, averaging <10%; however, it began to improve after Core U1464C-17R (453.92 mbsf) with an average of 32%.
The remaining cores from Hole U1464B (27H to 35F) were described. They consist of unlithified, light greenish gray mudstone with slight to moderate bioturbation infilled with pyrite. Celestite crystals and concretions are common. Preliminary biostratigraphy (planktic foraminifers) indicates the material in Section U1464B-30H-5 (272.57 mbsf) is 4.53 Ma.
In addition, Cores U1464C-2R to 24R were also described. Most of the lithology consisted of dolomitic, skeletal grainstone or packstone with abundant macrofossils including Cycloclypeus, a very shallow water benthic foraminifer, bivalves, gastropods, bryozoan, sea urchin spines, and coralline algae. Additionally, coral fragments and molds of corals are common and include branching corals and solitary corals (possibly Acropora and Porites). Karstic cavities and moldic porosity are common structures with gypsum infilling the spaces. Gypsum is also found as nodules, shell replacement, and burrow infill. Anhydrite nodules with chicken-wire texture are large (up to 20 cm long) are abundant in Cores U1464C-22R to 24R. Cores U1464C-23R and 24R have intertidal and supratidal sedimentary structures (birds eye, ball and pillow, intraclasts, moldic porosity). The base of Core U1464C-24R has a 2 cm thick bed of black organic-rich material with greenish gray clay beneath it, suggestive of subaerial exposure.
Daily Science Report for 20 September 2015
Location: Hole U1464C (18°03.9244′S, 118°37.8942′E; 264.3 mbsl)
Science Update: We recovered Cores U1464B-34H and 35F to 316.9 mbsf, at which depth piston coring refusal was reached. We pulled the drill string clear of the seafloor and set the bottom-hole assembly back in the derrick. Hole U1464B ended at 0615 h. In Hole U1464B, we cored a total of 316.9 m and recovered 292.27 m (92%). We offset the vessel 20 m and started Hole U1464C at 0940 h. After drilling without coring to 308 mbsf we began coring at 1600 h. Cores U1464C-2R to 12R penetrated to 414.7 mbsf.
Cores U1464B-8H to 26H were described. They consist of unlithified, light greenish gray mudstone with slight to moderate bioturbation. The burrows are usually filled with pyrite and small benthic foraminifers. Sand-sized shell fragments (bivalves, echinoderm spines, bryozoan) occur occasionally. Celestite crystals and concretions up to 3 cm long commonly occur. A large pebble-sized pyrite concretion is present in Section U1464B-26H-4A. Preliminary biostratigraphy (planktic foraminifers) indicates the material at the base of Core U1464B-20H is 3.58 Ma.
Daily Science Report for 19 September 2015
Location: Hole U1464B (18°03.9115′S, 118°37.8935′E; 264.3 mbsl)
Science Update: We arrived at Site U1464 at 0345 h and began preparations for coring. We verified the seafloor depth by tagging the seafloor with the bit and then started XCB coring in Hole U1464A at 0655 h. Cores U1464A-1X and 2X extended from the seafloor to 19.4 mbsf. Since neither core recovered any material and drilling indications suggested the sediment was soft enough for piston coring, we terminated Hole U1464A, offset the vessel 20 m to the east, and started APC coring in Hole U1464B at 0915 h. Cores U1464B-1H to 33H penetrated to 303.7 mbsf with good recovery (92%).
The remaining cores from our previous site (Cores U1463D-19H to 47F) were described and consist of partially lithified, olive gray homogeneous mudstone with intervals of fine sand-sized grains, and slight to moderate bioturbation.
Additionally, the first cores from Hole U1464B (1H to 7H) were described. Cores U1464B-1H to 6H consist of two alternating lithologies: 1) unlithified, light brown, skeletal grainstone and packstone with fine to coarse sand-sized grains (mainly glauconite), peloids, foraminifers, and a great diversity of unidentifiable macrofossils; and 2) unlithified creamy gray, homogeneous mudstone and wackestone with very fine sand, foraminifers, and glauconite. At the top of Core U1464B-7H (49.75 mbsf), the lithology changed to unlithified, greenish gray, homogeneous wackestone and packstone with small benthic foraminifers. This is consistent with information from the biostratigraphy group that suggests reworking of microfossils in this core. Preliminary biostratigraphy indicates the base of Core U1464B-6H is early Pleistocene.
Daily Science Report for 18 September 2015
Location:
• Hole U1463D (18°57.9285′S, 117°37.4216′E; 144.5 mbsl)
• In transit to Site U1464 (proposed site NWS-7A)
Science Update: We recovered Cores U1463D-19H to 47F to 352.8 mbsf, which completed coring for Site U1463. Hole U1463D cored 352.8 m and recovered 346.61 m (98%) of high-quality core. After we finished coring, the drill pipe was pulled out of the seafloor. Once the bit was recovered back on the rig floor (2025 h), we started the transit to Site U1464.
The remaining cores from Hole U1463C (57F to 61F) were described and are similar to previous cores from this hole, consisting of partially lithified, olive gray homogeneous mudstone with intervals of fine sand-sized grains, and slight to moderate bioturbation. Additionally, the first cores from Hole U1463D (1H to 18H) were described. Cores U1463D-1H to 13H consist of unlithified greenish gray mudstone and wackestone alternating with creamy gray packstone and beige mudstone with coarse sand-sized grains. Macrofossils are generally sparse in the mudstone and wackestone lithologies. The packstone contains very coarse sand-sized and up to pebble-sized grains of mostly carbonate material. Macrofossil fragments are common and consist mainly of bivalves (<3 cm long). There is a 20 cm interval in Section U1463D-10H-1 with sharp lower and upper contacts containing almost entirely well-preserved large benthic foraminifers. Cores U1463D-14H to 18H contain unlithified, greenish gray homogenous mudstones with occasional sand-sized macrofossil fragments (bivalves, tubes, benthic foraminifers).
Daily Science Report for 17 September 2015
Location:
• Hole U1463C (18°57.9295′S, 117°37.4336′E; 144.7 mbsl)
• Hole U1463D (18°57.9285′S, 117°37.4216′E; 144.5 mbsl)
Science Update: We recovered Cores U1463C-38F to 61F to 392.2 mbsf, ending Hole U1463C at 1640 h. Core recovery and quality were excellent throughout Hole U1463C (392.2 m cored, 397.34 m recovered; 101%). After the drill string was pulled out of the hole, we offset 20 m west, and started Hole U1463D at 1730 h with the recovery of a 1.4 m long mudline core. Piston coring continued, recovering Cores U1463D-2H to 18H to 160.9 mbsf by the end of the day.
Cores U1463C-18H to 56F (153.6–369.77 mbsf) were described. They consist of partially lithified, olive gray homogeneous mudstone with intervals of fine sand-sized grains, and slight to moderate bioturbation. Pyrite is disseminated through the matrix and concentrated in burrows. Pyrite nodules (1–2 mm) and macrofossils (bivalve fragments, gastropods, benthic foraminifers) are sparse. There was one interval of particular interest in Section U1463C-34F-1, a 5 cm thick lithified packstone that is linked to a sharp peak in magnetic susceptibility. Below this interval, magnetic susceptibility remains relatively high overall.
Daily Science Report for 16 September 2015
Location: Hole U1463C (18°57.9295′S, 117°37.4336′E; 144.7 mbsl)
Science Update: Hole U1463C began at 0115 h with the recovery of a 4.1 m mudline core (U1463C-1H). After this core, we installed the orientation tool and recovered Cores U1463C-2H to 31H to 280.7 mbsf. Formation temperature measurements were made while taking Cores U1463C-4H, 7H, 10H, 13H, 16H, and 20H. After recovering Core U1463C-31H, we switched to the HLAPC system and recovered Cores U1463C-32F to 37F to 301.7 mbsf.
Cores U1463C-1H to 17H (0–153.94 mbsf) were described. Cores U1463C-1H to 13H consist of alternating unlithified creamy gray, light greenish gray wackestone and mudstone. Macrofossils are common and consist of bivalves, small benthic foraminifers, gastropods, bryozoan, pterapods, and echinoderms. Intervals (several meters thick) of unlithified, light olive gray and creamy gray packstone with sand, coarse sand, and pebble-sized grains with very poorly preserved macrofossils, abundant large benthic foraminifers, and mineralized grains were found in Sections U1463C-7H-2A and -3A, 9H-4A-CC, and 10H-1A and -2A. Cores U1463C-13H to 17H consist of unlithified, light olive gray and olive gray homogeneous mudstone with sparse macrofossils (tubes, bivalve fragments, small benthic foraminifers). Large (6 cm) and several small (1 cm) brown concretions (possibly celestite) are present in Section U1463C-17H-2A. Biostratigraphy suggests the material recovered from 150 mbsf is about 1.6–1.93 Ma.
Daily Science Report for 15 September 2015
Location: Hole U1463B (18°57.9190′S, 117°37.4340′E; 145.4 mbsl) and Hole U1463C (18°57.9295′S, 117°37.4336′E)
Science Update: We recovered the final core (U1463B-60X) to 530.0 mbsf at 0005 h. Overall recovery for Hole U1463B was 75% (399.0 m recovered of 530.0 m cored). Cores U1463B-59X and 60X consist of lithified creamy gray and light brown dolostone with common dissolution cavities, sparse anhydrite nodules, and very few infilled subvertical veins. Brown and light brown patches are scattered throughout the dolostone. Sand-sized pyrite and/or glauconite grains and bioclasts (mainly bivalves, bryozoan, forams) occur throughout, but the bioclasts are less abundant deeper in the cores.
After coring was completed, we conditioned the hole for downhole logging and set the end of the drill pipe at 82.1 mbsf. The triple combination tool string was assembled and deployed at 0710 h. It reached a total depth of 454.7 mbsf (~75 m above the bottom of the cored hole) and then collected data up to the end of the pipe. The tool string was back on the rig floor at 0930 h. Next, the Versatile Seismic Imager (VSI) tool string was assembled, the protected species watch for using seismic sources was initiated, and the seismic source was prepared for use. However, whales were commonly seen within the exclusion zone until 1315 h, so deployment of the VSI tool string was delayed until 1445 h. Shortly afterwards another whale sighting occurred, so we terminated the VSP and pulled the tool string back to the rig floor. For our last logging run, we assembled the Formation MicroScanner and sonic imager (FMS-sonic) tool string and deployed it at 1705 h. It reached 445.7 mbsf (~84 m above the bottom of the cored hole) and collected data over two passes of the entire open borehole. It arrived back on the rig floor at 2030 h. We then pulled the drill pipe clear of the seafloor and ended Hole U1463B at 2230 h. The vessel was offset 20 m south and the day ended while conducting a slip and cut of the drill line.
Daily Science Report for 14 September 2015
Location: Hole U1463B (18°57.9190′S, 117°37.4340′E; 145.4 mbsl)
Science Update: We recovered Cores U1463B-39X to 59X to 525.2 mbsf. Core recovery overall has been steadily decreasing with depth. Recovery between Cores U1463B-39X and 48X (to 412.44 mbsf) was relatively high (75%), but dropped sharply after 48X, which is consistent with a lithology change. Cores U1463B-49X to 59X averaged 11% recovery.
Cores U1463B-24H to 58X were described. Cores U1463B-24H to 38X consist of unlithified to partially lithified, olive gray and greenish gray mudstone and wackestone with common small benthic foraminfers and, occasionally, bryozoans. Disseminated pyrite is present from Core U1463B-28H onwards and bioturbation is moderate to common. Cores U1463B-39X to 42X are lithified light to dark greenish gray mudstone with parallel laminations and wackestone (42X). Cores U1463B-43X to 52X are mainly greenish gray to light gray packstone with several coarser sand-sized intervals (45X and 46X). This coarser-grained material contains pyrite, carbonate and quartz grains, and bivalve fragments. Below this, the lithology changes; these changes parallel what was seen at Site U1462. Core U1463B-54X is a creamy gray mudstone underlain by light gray to brown dolostone with karstic cavities and anhydrite nodules (Cores U14363B-57X and 58X). Core U1463B-58X also contained a transported sand bed noted by a sharp scoured basal contact. The sand is dark gray and glauconite-rich. Below this, there is a second transported deposit that contains gravel to pebble size lithic clasts contained in a dark gray packstone matrix. Preliminary biostratigraphy (nannofossils) indicate the material at the base of Core U14363B-48X is late Miocene in age.
Daily Science Report for 13 September 2015
Location: Hole U1463B (18°57.9190′S, 117°37.4340′E; 145.4 mbsl)
Science Update: We continued coring with the APC system and recovered Cores U1463B-9H to 30H to 271.2 mbsf. We then switched to the HLAPC system and recovered Cores U1463B-31F to 33F to 284.4 mbsf, where piston coring refusal was reached. We switched to the XCB system and recovered Cores U1463B-34X to 38X to 330.5 mbsf. Recovery remains high (95%) on average.
Cores U1463B-1H to 23H were described and show three distinct lithologies. Cores U1463B-1H to 8H (middle Pleistocene age) are variable and composed of unlithified creamy gray and light greenish gray wackestone, mudstone, floatstone, rudstone, or packstone with macrofossils. Cores U1463B-9H to 12H (middle to early Pleistocene age) consist of alternating unlithified creamy gray and light greenish gray mudstone with fine and coarse sand-sized grains and sparse bivalve fragments. Cores U1463B-13H to 23H (early Pleistocene age) are composed of unlithified, olive gray and dark greenish gray homogeneous mudstone with fine sand and sand-sized grains, moderate bioturbation, and sparse shell fragments (bivalves, tubes, echinoid spines, gastropods) and benthic foraminfers.
Daily Science Report for 12 September 2015
Location:
• Hole U1462C (19°49.2764′S, 115°42.6186′E)
• In transit to Site U1463 (proposed site NWS-2A)
• Hole U1463A (18°57.9181′S, 117°37.4217′E; 145.8 mbsl)
• Hole U1463B (18°57.9190′S, 117°37.4340′E; 145.4 mbsl)
Science Update: Before departing Site U1462, we conducted a short camera survey of the seafloor around the site and then departed for Site U1463 at 0400 h. After arriving at Site U1463 (1530 h), we started XCB coring in Hole U1463A at 1925 h. Cores U1463A-1X and 2X were recovered to 19.4 mbsf. In contrast to previous sites, this surficial material was soft, so we decided to terminate Hole U1463A and begin a piston coring hole. Hole U1463B was started at 2100 h; we recovered Cores U1463B-1H to 8H to 74.4 mbsf with 100% recovery.
The science party participated in a review meeting for Site U1462.
Daily Science Report for 11 September 2015
Location: Hole U1462C (19°49.2764′S, 115°42.6186′E; 87.2 mbsl)
Science Update: We began the day with the first logging tool string (triple combination) deployment. The triple combination logged to 896 mbsf and was back on the rig floor at 0300 h. We decide to run the Versatile Seismic Imager (VSI) next because of the upcoming daylight; the tools were assembled and deployed to the bottom of the hole. The protected species watch began at first light, and after the soft ramp up of the seismic source, VSI operations began at 0740 h. We successfully logged at ~25 m intervals (10 min each) from 770 to 107 mbsf. The tool string was back on the rig floor at 1355 h. We then assembled the final tool string, the Formation MicroScanner and sonic imager (FMS-sonic), and deployed it at 1550 h. We made two passes with the FMS-sonic to 770 mbsf, and the tool string was back on the rig floor by 2145 h. The drill pipe cleared the sea floor at 2235 h, after which the subsea camera system was installed. The camera system was deployed at 2320 h; our intention is to conduct a 50 m box survey of the sea floor.
The science party is finalizing analyses and preparing reports from Site U1462.
Daily Science Report for 10 September 2015
Location: Hole U1462C (19°49.2764′S, 115°42.6186′E; 87.2 mbsl)
Science Update: We completed coring with the recovery of Cores U1462C-166R to 178R to 950.0 mbsf by 1030 h. Core recovery averaged 12% in this final section. Overall for Hole U1462C, we recovered 398.29 m of 917.0 m cored (43%). The final cores (U1462C-158R to 178R) were described. The lithology alternates between light brown dolomite with abundant skeletal components and moldic porosity and a light brownish gray dolomite-rich coarse-grained packstone with carbonate and pyrite grains. Both lithologies contain anhydrite nodules ranging in size from a few centimeters to up to 10 cm. The anhydrite has a chicken-wire structure. Below the final biostratigraphic datum (Core U1462C-153R, 827.65 mbsf; >5.59 Ma), microfossils are either absent or unidentifiable. Based on the lithology and age constraints, we feel confident we cored the Bare Formation.
After the completion of coring, we released the bit and experienced a loss of rotation and excess pressure. After working the pipe free, additional high viscosity mud was pumped through. The drill pipe was then pulled up to 307.1 mbsf and the hole was displaced with heavy mud in preparation for downhole logging. The drill pipe was pulled to logging depth (74.2 mbsf) and the first logging tool string (triple combination) was assembled. The triple combination tool string was deployed at 2330 h.
Daily Science Report for 9 September 2015
Location: Hole U1462C (19°49.2764′S, 115°42.6186′E; 87.2 mbsl)
Science Update: We recovered Cores U1462C-137R to 165R to 886.9 mbsf. Core recovery continued to average 87% until Core U1462C-159R (854.28 mbsf), after which recovery dropped sharply to 6% on average. This corresponds to a striking lithology change between Cores U1462C-130R to 157R. While Cores U1462C-130R to 143R were similar in lithology to previous cores in this hole (lithified, olive gray packstone with fine and medium sand-sized grains, common to sparse benthic foraminifers and bivalve fragments, and disseminated pyrite), additional features emerge from Core U1462C-144R (781.9 mbsf). This includes an overall coarsening of the sand-sized grains and pyrite, an increase in bivalve fragments, and the appearance of bryozoans and echinoderm spines. In Core U1462C-157C (842.8 mbsf), the lithology distinctly changes. It is a lithified light brownish gray packstone with coarse sand-sized grains of pyrite and carbonate with white rounded nodules (up to 4 mm long). By Section U1462C-157C-CC, these white nodules ranged in size from a few centimeters to a maximum of 5 cm × 8 cm, and appear to have a chicken-wire texture. X-ray diffraction and thin section analysis should confirm whether the white nodules are anhydrite, as suspected. Preliminary biostratigraphy indicates that the material at the base of Core U1462C-153R (827.65 mbsf) is late Miocene in age (>5.59 Ma; nannofossils).
Daily Science Report for 8 September 2015
Location: Hole U1462C (19°49.2764′S, 115°42.6186′E; 87.2 mbsl)
Science Update: We recovered Cores U1462C-108R to 136R to 714.0 mbsf. Core recovery continued to improve, so we switched to full length (9.7 m) advances after Core U1462C-132R (675.66 mbsf). Recovery after this core was 87%.
Cores U1462C-100R to 129R were described and consist of lithified, olive gray packstone with fine and medium sand-sized grains, common to sparse benthic foraminifers, and disseminated pyrite as well as pyrite nodules. Bioturbation ranges from slight to moderate with burrows infilled with both benthic foraminifers and pyrite. There were two intervals (~30 cm thick) of mass-wasting in Core U1462C-126R. These were noted by sharp, inclined basal contacts. Above the contacts benthic foraminifers, carbonate grains, and pyrite are more abundant. Preliminary biostratigraphy indicates that the material in Sample U1462C-113R-CC (584.75 mbsf) is >3.7 Ma (nannofossils) and the material in Sample U1462C-117R-CC (605.72 mbsf) is >3.85 Ma (planktic foraminifers).
Daily Science Report for 7 September 2015
Location: Hole U1462C (19°49.2764′S, 115°42.6186′E; 87.2 mbsl)
Science Update: We recovered Cores U1462C-72R to 107R to 557.2 mbsf. Core recovery improved after Core U1462C-74R from 24% on average to 62%. In general, recovery has improved with depth, similar to Hole U1462A. We are still advancing 4.8 m with each core (instead of 9.7 m).
Cores U1462C-65R to 99R were described and consist of lithified, olive gray packstone with very fine to coarse sand-sized grains. Bioturbation ranges from slight to moderate with burrows infilled with packstone, black grains, or minerals (e.g., celestite). Intervals with parallel laminae are common and the contacts are sharp, bioturbated, or scoured. Bioclasts are common and are mainly bivalve fragments, gastropods, and small benthic foraminifers. Preliminary biostratigraphy (nannofossils) indicates that the material in Sample U1462C-87R-CC (457.92 mbsf) is >2.39 Ma.
Daily Science Report for 6 September 2015
Location: Hole U1462C (19°49.2764′S, 115°42.6186′E; 87.2 mbsl)
Science Update: We managed to work the stuck pipe free by 0445 h and then proceeded to condition the hole. No fill was found at the bottom of the hole and a mud sweep was pumped through. Coring resumed at 0630 h and we recovered Cores U1462C-45R to 71R to 382.4 mbsf. Core recovery continued to be low, averaging 24%, despite our attempts to improve it by advancing 4.8 m with each core (instead of 9.7 m).
Cores U1462C-32R to 64R were described and consist of lithified to partially lithified light greenish gray, olive gray, and dark greenish gray packstone with very fine to medium sand-sized grains. Bioturbation is slight to moderate below ~290 m. Burrows are infilled with packstone material and some mineralization was noted. Bioturbated, scoured, and sharp contacts occur between Cores U1462C-47R to 55R (251.8–290.64 mbsf). Bioclasts are mainly composed of bivalve fragments, but gastropods and tubes are also present. Small benthic forams became common from Core U1462C-62R (324.1 mbsf). Preliminary biostratigraphy (nannofossils) indicates that the material in Sample U1462C-42R-CC (227.43 mbsf) is a maximum of 1.73 Ma.
Daily Science Report for 5 September 2015
Location: Hole U1462C (19°49.2764′S, 115°42.6186′E; 87.2 mbsl)
Science Update: We began the day with a deployment of the subsea camera system; the intention was to do a 50 m box survey of the seafloor around the site. However, the camera system failed due to a flooded, shorted connector, and the survey was terminated at 0300 h. After offsetting the vessel 20 m, we finished preparations for coring with the RCB system. Hole U1462C was started at 0400 h. We drilled down to 33.0 mbsf and began coring. Cores U1462C-2R to 44R penetrated to 242.0 mbsf and recovered 19.54 m of core (9%). At this point (2030 h), excess torque on the drill string was noted and we began to work the stuck pipe, which continued until midnight.
Cores U1462C-2R to 44R were described. Cores U1462C-2R to 31R consist mainly of lithified, beige to light bluish gray non-skeletal packstone with ooids. Macrofossils are common and include bivalves, gastropods, and benthic foraminifers. Fine sedimentary structures are also common and consist of parallel laminae, graded bedding, cross bedding, and sharp, wavy, and scoured contacts. Cores U1462C-32R to 44R are lithified, dark greenish gray packstone with coarse sand-sized black and green grains. Macrofossils are scarce and dominated by bivalves.
Daily Science Report for 4 September 2015
Location: Hole U1462A (19°49.2857′S, 115°42.5984′E; 87.1 mbsl) and Hole U1462B (19°49.2801′S, 115°42.6091′E; 87.2 mbsl)
Science Update: We continued downhole logging with the FMS-sonic and completed its deployment (to 799 mbsf) by 0200 h. We then prepared to deploy the VSI. The tool string was ready at 0455 h and we began the environmental watch at 0620 h. The VSI was run into the hole to 787 mbsf while the soft ramp up of the seismic source initiated. The ramp-up was attempted two additional times until we terminated the VSI at 1200 h due to an abundance of humpback whales. Operations at Hole U1462A were completed at 1310 h after which we offset the vessel 20 m. We prepared to start Hole U1462B with the XCB coring system; the plan was to target the upper ~50 m only. We began coring at 1430 h and recovered Cores U1462B-1X to 9X to 52.3 mbsf. Of those 52.3 m cored, 1.99 m were recovered (4%). Hole U1462B was completed at 2255 h.
Cores U1462B-1X to 8X (0-43.17 mbsf) were described. Cores U1462B-1X and 2X consist of lithified creamy gray non-skeletal ooid-rich packstone with dissolution features, karstic cavities, and mineral coatings. This material looks very similar to beach rock. Cores U1462A-3X and 4X had no recovery. Cores U1462B-5X to 7X are lithified and partly lithified light bluish gray non-skeletal ooid-rich packstone with sand-sized grains and abundant glauconite. Core U1462B-8X consists of unlithified creamy gray grainstone with gravel-sized grains, and abundant macrofossil (bivalves, barnacles, gastropods) and lithic (glauconite, carbonate cement) fragments.
Daily Science Report for 3 September 2015
Location: Hole U1462A (19°49.2857′S, 115°42.5984′E; 87.1 mbsl)
Science Update: We recovered Cores U1462A-92X to 100X to 855.0 mbsf by 0845 h, which completed coring in Hole U1462A. Of 855 m cored in Hole U1462A, we recovered 320.54 m of material (37%). We raised the bit to 300 mbsf and displaced the hole with heavy mud in preparation for downhole logging. We then raised the bit up to logging depth (82.1 mbsf) and prepared the first logging tool string (triple combination without sources). The tool string was deployed at 1540 h and reached 799 mbsf. After the successful triple combination deployment, we prepared the FMS-sonic and deployed it at 2100 h. It also reached 799 mbsf. We will continue with logging tomorrow and attempt a third run with the Versatile Seismic Imager (VSI) tool string.
The remaining cores from this hole were described. Cores U1462A-91X to 93X (730.30–758.84 mbsf) consist of lithified gray packstone with quartz, fine to medium sand-sized grains, and moderate bioturbation. Core U1462A-94X is lithified olive gray wackestone with slight bioturbation and common benthic foraminifers, while Core U1462A-95X is lithified olive gray packstone with quartz, common small benthic foraminifers, and macrofossils, including fragments of bivalves, bryozoan, and echinoderms. There is a lithologic shift after this core at ~830 mbsf to more siliciclastic sediments. Cores U1462A-96X to 100X consist of lithified dark greenish gray to gray coarse-grained, poorly sorted sandstone with moderate bioturbation and disseminated pyrite. Large benthic foraminifers and bivalve fragments are common but echinoderm fragments are very sparse. Common sedimentary structures include parallel laminations, and beds with bioturbated and wavy, sub-horizontal contacts. In particular, Core U1462A-100X contains lithified, light gray, poorly sorted conglomerates composed of gray and white sub-rounded and gravel-sized clasts. The matrix surrounding these grains is light brown, porous, and contains black grains (pyrite). These black minerals sometimes rim the white grains. Preliminary biostratigraphy indicates the material at the base of Core U1462A-93X is late Miocene to early Pliocene in age.
Daily Science Report for 2 September 2015
Location: Hole U1462A (19°49.2857′S, 115°42.5984′E; 87.1 mbsl)
Science Update: We recovered Cores U1462A-71X to 91X to 811.1 mbsf. After Core U1462A-86X (777.56 mbsf), core recovery dropped sharply from 98% to 8%, coincident with a lithology change. We plan to continue XCB coring to 855 mbsf, after which we will attempt downhole logging. Cores U1462A-66X to 90X were described. Cores U1462A-66X to 82X consist of lithified dark greenish gray packstone with fine and/or coarse sand grains, moderate bioturbation, and parallel and wavy laminae. Disseminated pyrite and nodules are present in the deeper cores where foraminifers are sparse. Cores U1462A-83X to 86X (730.3–777.56 mbsf) are densely laminated lithified dark greenish gray packstone with sand and coarse sand-sized grains, common pyrite, and sparse foraminifers. Core U1462A-84X in particular contains abundant sand-size beds with scoured, wavy, and bioturbated contacts. Overall, there is a trend towards more sand-sized grains with depth. Cores U1462A-87X to 90X (777.3–801.75 mbsf) are lithified packstone (87X), grainstone (88X and 89X) and wackestone (90X) with a greater amount of terrigenous grains (quartz, mica, and clay); foraminifers are absent or very sparse. Preliminary biostratigraphy indicates the material at the base of Core U1462A-85X is <4.2 Ma (calcareous nannofossils) and >4.08 Ma (planktic foraminifers).
Daily Science Report for 1 September 2015
Location: Hole U1462A (19°49.2857′S, 115°42.5984′E; 87.1 mbsl)
Science Update: We recovered Cores U1462A-51X to 70X to 644.0 mbsf. Core recovery averaged 45% over this interval. Cores U1462A-40X to 65X were described. Cores U1462A-40X to 62X were similar to the deeper material recovered yesterday, consisting of lithified olive gray packstone with moderate bioturbation, benthic foraminifers, and macrofossil fragments. There was, however, also a greater amount of coarse sand-sized grains and sand beds with sharp, sub-horizontal contacts in this interval, suggesting pulses of coarse sand were being transported to the site. Cores U1462A-63X to 65X consist of lithified olive gray packstone with fine sand grains, moderate bioturbation, bivalve fragments, and sparse foraminifers. Preliminary biostratigraphy indicates the material at the base of Core U1462A-63X is 3.7 Ma.