|
< March
IODP Expedition 340
Lesser Antilles Volcanism and Landslides
Daily Science Report for 17 April 2012
LOCATION: Steiger Wharf, Curacao
SCIENCE UPDATE: Expedition 340 ended with the first line ashore at 0848 h in Curacao. Overall Expedition 340 has been extremely successful, recovering 2384 m (68% recovery) of volcaniclastic material and hemipelagic sediments with hundreds of interbedded tephra layers from 22 holes at 9 sites.
Daily Science Report for 16 April 2012
LOCATION: Transit to Curacao
SCIENCE UPDATE: Underway to Curacao. All reports have been finalized by the scientists, while the technical staff continued with the final end of expedition tasks (cleaning laboratories, preparing shipments, etc.).
Daily Science Report for 15 April 2012
LOCATION: Transit to Curacao
SCIENCE UPDATE: We finished the coring operations of this expedition when the last core (Core U1401A-1H) was recovered at 0345 h with 9 m of material (99% recovery) reaching 9 m into the formation. The retrieved material consists of interbedded hemipelagic mud and tephra and turbidite layers. At 0430 h, we started to prepare the rig floor for the 475 nmi transit to Curacao. We departed Site U1401 at 1245 h. Scientists are busy finalizing reports and the technical staff continues to finalize end of expedition tasks (cleaning laboratories, preparing shipments, etc.).
Daily Science Report for 14 April 2012
LOCATION: Site U1401 (CARI-12A, 14°39.10'N 61°25.08'W, water depth 2597 mbsl)
SCIENCE UPDATE: We finished Hole U1401A at 1410 h with Cores U1401A-5X to -11X retrieving 1.16 m of material (2% recovery) reaching 82 m into the formation. The material recovered mainly consists of clasts of andesitic lava. Drilling conditions were very poor below the second core due to the coarse-grained and unconsolidated formation. Thus, we decided not to drill deeper than 100 mbsf to not risk losing another bottom hole assembly. However, the material obtained from 0 to 15 mbsf contained deformed hemipelagic sediments and numerous tephra layers - interesting enough for us want to trace the evolution of this section by coring multiple short holes along a transect imaged by the Aguadomar seismic line. By midnight, we had cored Holes U1401B and U1401C. Cores U1401B-1H to -3H extended to 13 mbsf and recovered 12 m of material (96%). Cores U1401C1H to -3H extended to 10 mbsf and recovered 10 m of material (101%).
Daily Science Report for 13 April 2012
LOCATION: Site U1401 (CARI-12A, 14°39.10'N 61°25.08'W, water depth 2597 mbsl)
SCIENCE UPDATE: After severing the drill pipe that was stuck in the hole, we finished Hole U1400C at 0310 h when the end of the remaining drill pipe was raised above the seafloor. After a 7 nmi transit in dynamic positioning mode, the ship was positioned over Site U1401 at 1200 h. We spudded Hole U1401A at 1950 h and we retrieved Cores U1401A-1H to -4H with 15 m of material (101% recovery) reaching 14 m into the formation. The cored material consists of hemipelagic mud, coarse-grained volcaniclastic sand and large clasts of andesitic lava.
Daily Science Report for 12 April 2012
LOCATION: Site U1400 (CARI-07C, 14°32.58'N 61°27.55'W, water depth 2744 mbsl)
SCIENCE UPDATE: After spending the majority of the previous day trying to free the drill string from the formation in Hole U1400C, at 0200 h we decided to to severe the bottom hole assembly (BHA) from the drill pipe. Our first attempt to severe the drill string at the top of the tapered drill collar (the uppermost part of the BHA) did not succeed in freeing the drill string from the formation. So, we decided to severe the drill pipe just below the seafloor (~10 mbsf). However, at 1845 h, this second severing charge did not activate and the rest of the evening was spent recovering the severing tool, fixing it, and lowering it back into the hole for the third attempt to free the drill string.
Daily Science Report for 11 April 2012
LOCATION: Site U1400 (CARI-07C, 14°32.58'N 61°27.55'W, water depth 2744 mbsl)
SCIENCE UPDATE: We finished coring Hole U1400C at 0510 hrs, retrieving Cores U1400C-47X to -49X with 5 m of material (19% recovery) reaching 436 m into the formation. The last cores consisted of normally bedded, undeformed hemipelagic sediments. This indicates that we have reached one of the major scientific objectives of this site – to drill through the transition zone between the chaotic unit and the underlying marine sediments. After coring was finished, we displaced the hole with mud and started to raise the drill string to prepare for wireline logging. Shortly after 0800 hrs with the bit just above ~300 mbsf, the drill string could not be raised further without loss of rotation. The remainder of the day was spent trying to free the bottom hole assembly from the formation.
Daily Science Report for 10 April 2012
LOCATION: Site U1400 (CARI-07C, 14°32.58'N 61°27.55'W, water depth 2744 mbsl)
SCIENCE UPDATE: We retrieved Cores U1400C-32X to -46X with 80 m of material (60% recovery) reaching 400 m into the formation. The retrieved material mainly consists of consolidated hemipelagic sediment with minor amounts of interbedded tephra layers and lava clasts. Sediment deformation is still observed, although it is hard to detect due to deformational features caused by the XCB coring.
Daily Science Report for 9 April 2012
LOCATION: Site U1400 (CARI-07C, 14°32.58'N 61°27.55'W, water depth 2744 mbsl)
SCIENCE UPDATE: We retrieved Cores U1400C-14H to -31X with 120 m of material (74% recovery) reaching 274 m into the formation. The retrieved material consists of deformed hemipelagic sediment with interbedded tephra and volcaniclastic sand layers of variable thickness. The observed sediment deformation indicates that we are probably coring through a slumped unit.
Daily Science Report for 8 April 2012
LOCATION: Site U1400 (CARI-07C, 14°32.58'N 61°27.55'W, water depth 2744 mbsl)
SCIENCE UPDATE: After two unsuccessful attempts to spud Hole U1400C yesterday (7 April), including a bent barrel on the second attempt that required a round trip of the pipe, we spudded Hole U1400C at 0950 h on 8 April. Due to the hard seafloor surface, we drilled without coring to 15 mbsf before starting to APC core. We retrieved Cores U1400C-2H to -13H with 98 m of material (102% recovery) reaching 112 m into the formation. The retrieved material consists of hemipelagic sediment with interbedded tephra and volcaniclastic sand layers. The proportion of sand is much lower than encountered at the other sites cored up to now.
Daily Science Report for 7 April 2012
LOCATION: Site U1400 (CARI-07C, 14°32.58'N 61°27.55'W, water depth 2744 mbsl)
SCIENCE UPDATE: We had to trip out of Hole U1400B to free the stuck core barrel from the drill pipe up on the rig floor. We offset the ship, tripped back to the seafloor and tried to spud Hole U1400C. However the core barrel broke off. During our second attempt to spud the hole, the core barrel became bent and could not be retrieved. Unfortunately, we have to retrieve the entire drill string again tso the core barrel can be extracted from the bottom-hole assembly on the rig floor.
Daily Science Report for 6 April 2012
LOCATION: Site U1400 (CARI-07C, 14°32.58'N 61°27.55'W, water depth 2744 mbsl)
SCIENCE UPDATE: We retrieved Cores U1400B-11H to -28H with 156 m of material (101% recovery) reaching 213 m into the formation. After shooting Core U1400B-28H, the core barrel became stuck and we spent the reminder of the day trying to free the barrel. The cored material consists of hemipelagic sediment with interbedded tephra and volcaniclastic sand layers. Generally, the sediment shows signs of severe deformation and the proportion of coarse-grained sand is much less than at the other sites.
Daily Science Report for 5 April 2012
LOCATION: Site U1400 (CARI-07C, 14°32.58'N 61°27.55'W, water depth 2744 mbsl)
SCIENCE UPDATE: We spudded Hole U1400A at 0030 hr and Cores U1400A-1H to -9H recovered 52 m of volcaniclastic sand from 0-51 mbsf (101% recovery). At 1200 h, we decided to terminate the hole due to the risk of the drill pipe getting stuck in the loose sand. We offset the ship ~700 m to the SE to try to avoid this thick sandy layer and spudded Hole U1400B at 1605 h. By midnight we had retrieved Cores U1400-1H to -10H with 59 m of material (102% recovery) reaching 58 m into the formation. The cored material consists of volcaniclastic sand and hemipelagic mud.
Daily Science Report for 4 April 2012
LOCATION: Site U1400 (CARI-07C, 14°32.58'N 61°27.55'W, water depth 2744 mbsl)
SCIENCE UPDATE: Removing the lines tangled around our drill pipe continued until 1430 h when we were finally able to start our transit to the next site. We arrived on Site U1400 at 1630 h and started to prepare the drill string for coring operations.
Daily Science Report for 3 April 2012
LOCATION: Site U1399 (CARI-08B, 14°23.24'N 61°42.96'W, water depth 2901 mbsl)
SCIENCE UPDATE: After successfully finishing our logging operation in Hole U1399C, we rigged down the logging tools. At 0600 hrs we started to retrieve the drill pipe, when we encountered massive amounts of polypropylene lines wrapped around the drill pipe. The rest of the day was spent removing the polypropylene lines as the drill pipe was raised.
Daily Science Report for 2 April 2012
LOCATION: Site U1399 (CARI-08B, 14°23.24'N 61°42.96'W, water depth 2901 mbsl)
SCIENCE UPDATE: Today was spent logging Hole U1399C, which was drilled just for this purpose. At 0035 hrs we finished drilling the hole to the target depth of 240 mbsf. After this we displaced the hole with heavy mud, raised the bit up to 80 mbsf, and started to rig up the triple combo tool string. After a successful logging run with the triple combo we deployed the VSI tool string to conduct a vertical seismic profile. At the end of the day, we were conducting the final logging run with the FMS-sonic tool.
Daily Science Report for 1 April 2012
LOCATION: Site U1399 (CARI-08B, 14°23.24'N 61°42.96'W, water depth 2901 mbsl)
SCIENCE UPDATE: At 0730 hrs Hole U1399B was terminated at a total depth of 183 mbsf due to severe hole instability. After discussions with science and operations staff, the decision was made to drill a dedicated logging hole. After spacing out and dropping an XCB core barrel, Hole U1399C was spudded at 1115 hrs. At midnight Hole U1399C had been advanced to 221.59 mbsf with a target depth of 240 mbsf.
| 