IODP Expedition 402

Tyrrhenian Continent–Ocean Transition

Daily science report for 29 February 2024

Location: Hole U1614C (40°15.9683′N, 12°42.3174′E; water depth 3579.0 m))

Science Update: After installing the first string of 13⅜ inch casing in Hole U1614C to a depth of 66.0 mbsf, we prepared to drill ahead to a depth ~20 m above the expected basement contact and install a second string of 10¾ inch casing to ~40 m above the basement interface. The drilling BHA with a 12¼ inch bit was made up and deployed. We reentered Hole U1614C at 1100 h using the VIT camera system to guide reentry, and then we retrieved the VIT. The drill ahead successfully penetrated to a depth of 250.0 mbsf, after which the hole was displaced with heavy mud. At the end of the day, we were tripping pipe back to the surface.

Scientists worked on reports for Sites U1612 and U1613 and discussed findings from Hole U1614A.

Daily science report for 28 February 2024

Location: Hole U1614C (40°15.9689′N, 12°42.3163′E; water depth 3579.0 m)

Science Update: At midnight, we completed making up the 13⅜ inch casing string. The stinger with the running tool and BHA were made up and were latched to the reentry cone and casing string, which was deployed through the moonpool at ~0515 h. Pipe was tripped toward the seafloor, and the vibration isolated television (VIT) camera system was deployed after 60 stands of pipe, to follow the reentry cone. At ~1400 h, we installed the top drive and spudded Hole U1614C, jetting in casing to a depth of 66.0 mbsf. With the reentry cone landed on the seafloor, we detached the running tool from the casing at 1550 h, began pulling out of the hole, and recovered the VIT. We then tripped pipe back toward the surface.

The science party continued analysis of material from Hole U1614A. Structural geologists described laminated bedding near the sediment/basement interface, indicating minimal deformation. NGR increases start from Core ~27R toward the basement contact.

Daily science report for 27 February 2024

Location: Hole U1614B (40°15.9792′N, 12°42.3174′E; water depth 3579.0 m)

Science Update: The day was spent conducting a jet-in test in Hole U1614B to verify the length of 13⅜ inch casing that we will be able to install in Hole U1614C. We made up the BHA with a 14¾ inch tricone bit, tripped pipe to the seafloor, and spudded Hole U1614B at 0900 h. The jet-in test was successful, penetrating 65.2 mbsf. We then pulled out of the hole and began making up the Dril-Quip (DQ) running tool to install the reentry cone and casing. The reentry cone was positioned in the moonpool and we began picking up the casing to trip to the seafloor.

Scientists described Cores U1614A-26X through 34X. Cores 26X through 30X contain gray nannofossil oozes, mud with calcareous nannofossils, and layers of dark yellowish brown sandy silt or oxide rich mud. Scattered pyrite deposits and sapropel layers are also encountered. Core 31X had no recovery. Cores 32X and 33X transition through sandy silt, lapilli, ash, nannofossil chalk, and dolomite, before the contact with the basement in Section 33X-4. Recovered basement material consists of lherzolite, dunite, and plagioclase-bearing harzburgite. The rocks are highly or completely altered, with serpentine, clays, and magnetite present as alteration minerals.

Daily science report for 26 February 2024

Location:

Hole U1614A (40°15.9781′N, 12°42.3164′E; water depth 3579.0 m)
Hole U1614B (preliminary: 40°15.9792′N, 12°42.3174′E; water depth 3579.0 m)

Science Update: We recovered Cores U1614A-32X through 34X, advancing 29.1 m to a depth of 280.1 mbsf. The 15.4 m of core material (53% recovery) contained serpentinite rock identified as the basement contact. After recovering this contact, we attempted to XCB drill an additional core, but we experienced high torque after deploying the core barrel. We recovered a ghost core, Core 35G, which contained 2.16 m of fill and ended the hole. A standard cut and slip of drill line occurred with the drill pipe above the seafloor. Pipe was tripped back to the surface and the drill collars were racked. We then laid out the upper guide horn to prepare for a jet-in test for a potential casing installation at this site.

Cores U1614A-11F through 25X were described by the sedimentology and structural geology groups. Cores 11F through 16X contain predominantly volcaniclastic rich gravel, silt, and volcaniclastic rich sandy silt varying in color from olive gray to very dark gray. The gravel is interpreted as fall-in from higher up in the sediment column. Cores 17X through 20X are composed of olive gray tuff interspersed with layers of light gray foraminifer-nannofossil rich silt, which transitions to a nannofossil ooze in Cores 21X through 25X. The oozes include fine laminations and cross-laminations as well as occasional pyrite precipitates.

Daily science report for 25 February 2024

Location: Hole U1614A (40°15.9781′N, 12°42.3164′E; water depth 3579.0 m)

Science Update: Coring in Hole U1614A continued throughout the day, advancing 161.7 m, from 89.3 to 251.0 mbsf, and recovering 78.6 m of sediment (49%). Recovery was higher in HLAPC Cores 13F and 14F (81%) than in XCB Cores 15X through 31X (48%). Hole conditions appear good, although a layer of volcaniclastic-rich gravel may necessitate a casing installation for Hole U1614B.

Cores U1614A-4H through 10F were split and described. Cores 4H though 7H contain the volcaniclastic-rich gravel; the presence of this material in deeper cores may be attributable to fall-in. Cores 8H and 9H transition to a gray nannofossil-rich sandy silt, silty rich sand, or nannofossil-rich silt. Core 10F contains nannofossil ooze. Bioturbation is absent. Physical properties are relatively constant downhole, with intervals of elevated NGR values in the volcaniclastic gravels.

Daily science report for 24 February 2024

Location: Hole U1614A (40°15.9781′N, 12°42.3164′E; water depth 3579.0 m)

Science Update: At midnight, we were positioned above Hole U1614A and tripping pipe toward the seafloor. With the bit located 5 m above the seafloor, we picked up the top drive and spaced out. Prior to spudding, we pumped enough microbial contamination tracer with circulating drilling fluid to fill the drill string. Hole U1614A was spudded at 0645 h, with the first core recovering 5.7 m of sediment as well as the mudline. Cores U1614A-2H through 12F advanced to 89.3 mbsf and recovered 85.36 m of sediment (96%). Measurements with the advanced piston corer temperature (APCT-3) tool were made during Cores 4H and 7H, and all full-length APC cores were oriented. Cores 7H and 9H were partial strokes, where Core 9H experienced 30,000 lb of overpull. As such, Cores 10F through 12F were collected using the half-length APC (HLAPC). Gravel recovered in the tops of multiple cores is interpreted as fall-in.

Scientists described Cores U1614A-1H through 3H. The predominant lithology is a light gray nannofossil-rich silt with sand, transitioning to a greenish gray nannofossil ooze toward the bottom of Core 3H. Sharp, erosive boundaries are observed between layers. Much of the cored material is classified as a turbidite.

Daily science report for 23 February 2024

Location:

Hole U1613A (40°0.0593′N, 10°59.1732′E; water depth 2706.8 m)
Underway to proposed Site TYR-11A (Site U1614)
Site U1614 (preliminary: 40°15.9684′N, 12°42.1374′E; water depth 3580.1 m)

Science Update: The DSI logging toolstring was brought back to the surface and rigged down following the completion of logging. We tripped pipe back to the surface, racked the drill collars, and secured the rig floor. At 0923 h the ship transitioned to cruise mode and began the 80.4 nmi transit to proposed Site TYR-11A (Site U1614). The transit took 7.6 h at an average speed of 10.6 kt. We arrived on site and transitioned back into DP mode at 1755 h. Hole U1614A, a planned advanced piston corer/extended core barrel (APC/XCB) hole to recover the entire sediment column and tag basement, will be positioned 20 m north of the site coordinates. At midnight, we were tripping pipe to the seafloor.

Scientists discussed how to define lithological units at Site U1613 and worked on their site reports.

Daily science report for 22 February 2024

Location: Hole U1613A (40°0.0593′N, 10°59.1732′E; water depth 2706.8 m)

Science Update: The final two cores were drilled for Site U1613, reaching a depth of 223.6 mbsf. Cores U1613A-23R and 24R were drilled as half cores due to low penetration rates, advancing 9.5 m and recovering 2.85 m (30%). To prepare for logging, we swept the hole with 60 bbl of high-viscosity sepiolite. We then ran the rotary shifting tool (RST) to drop the RCB bit at the bottom of the hole. The knobbies were laid out and the top drive set back, and pipe tripped up to 67.1 mbsf. A first logging run was made with the triple combo tool string starting at 1430 h. The tool string encountered a sediment bridge at ~130 mbsf but was able to work through it. A second bridge at ~200 mbsf could not be worked through. Given the poor hole conditions, only a single pass was made with the triple combo. The Formation MicroScanner (FMS) was then removed from the FMS-sonic toolstring and a single pass was made with just the Dipole Sonic Imager (DSI) tool.

Cores U1613A-14R through 24R were split and described. Core 14R contains light gray nannofossil ooze with mud, with red or reddish brown intervals. Magnetic susceptibility correlates with the reddish layers. Downhole lithology transitions through gypsum-rich silt to sandy mudstone. Lithologies at the bottom of Hole U1613A are interpreted as continental basement.

Daily science report for 21 February 2024

Location: Hole U1613A (40°0.0593′N, 10°59.1732′E; water depth 2706.8 m)

Science Update: Coring in Hole U1613A advanced from 125.9 to 214.1 mbsf (Cores 14R through 22R), recovering 32.8 m of core (37%). A hard layer preliminarily identified as sandstone was encountered in the core catcher (CC) of Core 16R. ROP decreased substantially below that depth, varying between 1.4 and 14.7 m/h in Cores 17R through 22R, although the material recovered still appeared to be sedimentary.

Cores U1613A-3R through 13R were split and described. Lithology transitions from a light gray, nannofossil-rich, very fine sand in Cores 3R through 7R to a light gray nannofossil chalk in Cores 9R through 13R. Layers of foraminifer-rich nannofossil chalk were noted along with layers of organic-rich material, glauconite-rich mud, and patches of coarser material. Natural gamma radiation (NGR) and magnetic susceptibility (MS) decrease downhole along this interval, as does alkalinity.

Daily science report for 20 February 2024

Location: Hole U1613A (40°0.0593′N, 10°59.1732′E; water depth 2706.8 m)

Science Update: A new BHA with RCB bit was tripped to the seafloor. Hole U1613A was spudded at 0830 h and the seafloor depth was determined to be 2706.8 m. Coring advanced to 125.9 mbsf (Core U1613A-13R) and recovered 63.9 m of material, or 51%. Core 2R had 0 m of recovery, later attributed to a malfunctioning core catcher, which was removed and repaired.

Core U1613A-1R was split and described. Flow-in disturbance was moderate to strong throughout the core. The core varies in color from light yellowish brown to light brownish gray and contains predominantly nannofossil rich sand.

Daily science report for 19 February 2024

Location:

Hole U1612A (40°11.0320′N, 12°37.9460′E; water depth 3573.8 m)
Underway to proposed Site TYR-07A (Site U1613)
Site U1613 (preliminary: 40°0.0582′N, 10°59.1732′E; water depth 2706.1 m)

Science Update: With the pipe stuck in sediment in Hole U1612A, a severing charge was lowered to the sediment/water interface and detonated at 0235 h. An immediate drop in string weight indicated the pipe was successfully severed and was free. The pipe was tripped back to the surface. The decision was made to discontinue operations at Site U1612 and instead move to proposed Site TYR-07A (Site U1613). The rig floor was secured at 1230 h, the thrusters were raised, and the ship was underway at 1300 h. We completed the 76.4 nmi transit and arrived on site at 1930 h. The ship transitioned from cruise to DP mode at 2007 h. The PDR determined the water depth to be 2706.1 m. A new BHA with a C7 RCB bit was made up and the core barrels were spaced out. At Site U1613, we plan a single RCB hole that will penetrate 70 m into the basement.

Scientists continued analyses of shipboard samples and began writing their Site U1612 chapter.

Daily science report for 18 February 2024

Location: Hole U1612A (40°11.0320′N, 12°37.9460′E; water depth 3573.8 m)

Science Update: Core U1612A-39R was cored in basement material with a 1.5 m/h ROP, advancing 5 m to a depth of 348.7 mbsf with 1 m recovery (20%). The drill pipe became stuck during coring of Core 40R, losing rotation and vertical movement. The decision was made to sever the pipe at the BHA. A severing charge was lowered into the hole to 212 mbsf and detonated. A decrease in string weight was not observed, indicating that the pipe was stuck further up in the sediment column. At midnight, a second severing charge was being lowered to sever at the sediment/water interface.

Cores U1612A-33R through 39R were split and described. Core 33R contains nannofossil chalk and intervals of radiolarian-diatom nannofossil chalk, while Cores 34R and 35R transition to dolomite above the sediment/basement interface recovered in Core 35R. Basement material in Core 35R consists of unconsolidated breccia. The predominant lithology in Cores 36R through 39R is gneissic granitoid.

Shipboard personnel took part in a fire and boat drill. Following COVID mitigation protocols, all personnel took COVID tests. One COVID-positive staff member was moved to a quarantine berth.

Daily science report for 17 February 2024

Location: Hole U1612A (40°11.0320′N, 12°37.9460′E; water depth 3573.8 m)

Science Update: Coring in Hole U1612A advanced from 294.3 to 343.7 mbsf, with a formation change to basement material at 333 mbsf. Cores 31R through 35R advanced 49 m with a recovery of 65%, capturing geological transitions at the sediment/basement interface. Cores 36R through 38R advanced 10.2 m at an average rate of penetration (ROP) of 1.5 m/h, recovering 1.95 m of core (19%).

Cores U1612A-21R through 32R were described by the sedimentology, structural geology, and igneous and metamorphic petrology laboratory groups. The predominant lithology is nannofossil chalk, with intervals of volcaniclastic tuff, dolomite, and silty or muddy nannofossil chalk. Several sapropel and tephra layers were noted, including a faulted sapropel. Nannofossil biostratigraphy indicates a Piacenzian age. Cores 27R through 30R contain clasts of andesite and dacite.

Daily science report for 16 February 2024

Location: Hole U1612A (40°11.0320′N, 12°37.9460′E; water depth 3573.8 m)

Science Update: RCB coring in sediment at Hole U1612A continued with Cores 14R through 30R, advancing 162.1 m to a depth of 274.8 mbsf. We recovered 20.4 m of core (13%), with recovery varying from 0% to 53%. Formation temperature measurements were conducted with the Sediment Temperature 2 (SET2) tool following recovery of Cores 17R and 21R.

Cores U1612A-4R through 20R were split and described. Cored material is slightly to severely disturbed, including biscuiting and cracking. Cores 4R and 16R consist of gray clay. Cores 9R through 13R contain volcaniclastic nannofossil ooze, volcaniclastic sand, and volcaniclastic lapilli. Core 20R is primarily nannofossil chalk and is Calabrian in age.

Daily science report for 15 February 2024

Location: Site U1612 (40°11.0320′N, 12°37.946′E; water depth 3573.8 m)

Science Update: Pipe was tripped to 3543 mbrf. Prior to spudding, a “pig” was pumped through the drill pipe to clear any interior rust or debris. Hole U1612A was spudded using the RCB system. Cores U1612A-1R to 13R advanced to 122.4 meters below seafloor (mbsf) with 16% recovery. Eight of the cores had no recovery or minimal material in the core catcher. Low recovery zones may correlate with the presence of coarse volcaniclastic material.

Cores U1612A-1R and 3R were split and described. Core 1R was severely disturbed. Core 3R is a homogeneous gray clay.

Daily science report for 14 February 2024

Location:

Berth 5 Molo Angioino, Napoli, Italy
Underway to proposed Site TYR-09A (Site U1612)
Site U1612 (preliminary: 40°11.0328′N, 12°37.9458′E; water depth 3572.6 m)

Science Update: At 0651 h, the pilot boarded and the ship departed Napoli, with the last line released at 0724 h. The pilot disembarked at 0755 h and we began the 86.6 nmi transit to proposed Site TYR-09A (Site U1612). We arrived on site at 1530 h, lowered the thrusters, and switched from cruise mode to dynamic positioning (DP) mode. The precision depth recorder (PDR) reading determined the seafloor to be at 3572.6 meters below sea level (mbsl). A bottom-hole assembly (BHA) for rotary core barrel (RCB) drilling was made up and deployed. At midnight, we were tripping pipe and had reached a depth of 1097 meters below rig floor (mbrf).

Training for the collection of shipboard and personal research samples in sediment was conducted for the scientists, including use of the Sample Master software program. JRSO staff and the science party participated in a fire and boat drill, mustering at their assigned life boat stations. The scientists finalized their Methods sections.