IODP Expedition 334

Costa Rica Seismogenesis Project (CRISP)

Daily Science Report for 31 March 2011

LOCATION: Site U1379 (CRIS-4A) Lat. 8°40.8496' N, Long. 84°2.0169' W

SCIENCE UPDATE: Cores U1379C-94X to 104X (786.77-890.61 mbsf) were retrieved with an average recovery rate of 55%. Core U1379C-104X was the first core drilled into the basement at this site, sampling a mélange type of rock containing, among others, basaltic clasts with large, bright-green, pristine olivine. The material we are coring is consistent with the LWD data for this section. The core recently described (610-720 mbsf) is composed of dark greenish gray, sandy clayey silt showing several fining upward units ranging from sandy clayey silt at the base to silty clay at the top. From 632 to 670 mbsf this sequence is interrupted by olive green to dark gray calcareous cemented very fine-grained sand with interbedded lenses of fine- to medium-grained sand with moderate bioturbation. Frequent ash layers of variable thickness as well as shell fragments and foraminifera have also been retrieved. The ash layers consist of fresh to altered glass shards, feldspar, hornblende and biotite. According to the observed nannofossil community we are still close to the Pleistocene/Pliocene boundary.

Daily Science Report for 30 March 2011

LOCATION: Site U1379 (CRIS-4A) Lat. 8°40.8496' N, Long. 84°2.0169' W

SCIENCE UPDATE: Cores U1379C-81X to 93X (679.99-786.77 mbsf) were retrieved during the last 24 hrs. Being spoiled by the high average recovery rates so far, we now have to live with an average recovery rate of 71% for these cores. Drilling into sandier layers presumably causes this drop in the rate, which is in accordance with the LWD data for this section. We will verify this when these cores have been split and described. The material we are looking at now (520–610 mbsf) has not changed much relatively to previously described sediments. We still see a monotonous clay sequence, which is interrupted by thicker sequences of sandier layers with abundant shell fragments and more frequent ash layers. The contact between the clay and sandy layers is often characterized by rip-up clasts, which are indicative of turbidites. The nannofossil community observed indicates that these are lower Pleistocene sediments.

Daily Science Report for 29 March 2011

LOCATION: Site U1379 (CRIS-4A) Lat. 8°40.8496' N, Long. 84°2.0169' W

SCIENCE UPDATE: Cores U1379C-69X to 80X (575.44–679.99 mbsf) were retrieved with an average recovery rate of 97%. The main lithology is still this monotonous clay sequence. However, between ~460 and 500 mbsf this monotonous sequence is interrupted by thick sandy layers up to 30 cm thick containing abundant shell fragments. These sandy layers have been interpreted as turbidites. At ~480 mbsf we retrieved at least two different ash layers totaling a thickness of about 30 cm, corresponding with a distinct peak in the natural gamma radiation measured by LWD. The nannofossil community observed in the cores indicate that we are slowly approaching the Pleistocene/Pliocene boundary.

Daily Science Report for 28 March 2011

LOCATION: Site U1379 (CRIS-4A) Lat. 8°40.8496' N, Long. 84°2.0169' W

SCIENCE UPDATE: Cores U1379C-51X to 68X (408.12–575.44 mbsf) were retrieved with an average recovery rate of 107%. There have been no major lithological changes in the material cored. We are still retrieving the same monotonous clay sequence that frequently alternates with dm-sized sandy layers and is sometimes interrupted by ash layers. Up to now these ash layers could not be related to any eruption and thus we have to wait until we get the geochemical fingerprints for this during post-cruise research. The consolidation stage of the sediments has increased slightly going deeper. Rarely bedding structures are visible and a few normal faults have been observed in the different cores. The nannofossil community observed in the cores is slowly changing, but is still of mid-Pleistocene age.

Daily Science Report for 27 March 2011

LOCATION: Site U1379 (CRIS-4A) Lat. 8°40.8496' N, Long. 84°2.0169' W

SCIENCE UPDATE: Cores U1379C-33X to 50X (236.26-408.12 mbsf) were recovered at an average rate of 102%. We are still coring a monotonous sequence of mainly silty clay to clay that frequently alternates with dm-sized sandy layers. This sequence is sometimes interrupted by thin discontinuous beds consisting of carbonate mud and horizons of hardened carbonate mud clasts in mostly a clayey matrix. The material cored is still of late to mid-Pleistocene age. The first results from the analysis of fluid geochemistry show that the sulfate/methane transition zone (SMTZ) occurs around 25 mbsf.

Daily Science Report for 26 March 2011

LOCATION: Site U1379 (CRIS-4A) Lat. 8°40.8496' N, Long. 84°2.0169' W

SCIENCE UPDATE: Cores U1379C-14H to U1379C-32X (78.70-236.26 mbsf) were retrieved with an average recovery rate of 87.53%. We are still coring a very monotonous sequence of mainly greenish gray, extremely compact, silty clay to clay, which is very rarely interrupted by sandy layers sometimes containing shell fragments and carbonate concretions. Generally, the amount of shell fragments within the normal background sedimentation decreases from the upper part of the sequence toward the lower parts and overall the clay is very barren in terms of its nannofossil content. The material we are coring is still late to mid-Pleistocene as indicated by the nannofossils.

Daily Science Report for 25 March 2011

LOCATION: Site U1379 (CRIS-4A) Lat. 8°40.8496' N, Long. 84°2.0169' W

SCIENCE UPDATE: We arrived back at Site U1379 at 0530 hr and immediately started picking up of the bottom hole assembly. At 0952 hr we started drilling Hole U1379B and got the first core on deck at 0955 hrs. At 1130 hr we completed Hole U1379B with the second core on deck advancing 10.5 m in total into the formation and a total core recovery rate of 83%. This hole was mainly drilled for high-resolution geochemical and microbiological sampling to precisely determine the boundary of sulfate/methane transition in the sediment and the associated microbiological changes. The material drilled consists mainly of dark gray silty to sandy clay with a number of shells and shell fragments distributed within the clay. At 1253 hrs we started drilling Hole U1379C. By midnight we had retrieved 13 cores (0–78.70 mbsf) with core recovery rates varying between 87 and 106%. The first 0.98 m of Core U1379C-1H consists of coarse sand with abundant shells, shell fragments and foraminifera. The following interval from 0.98 to 78.70 m consists of interbedded of massive dark gray clay to massive dark gray silty clay. Down to a depth of 36.61 mbsf, local bioturbation can be observed in the recovered material. Nannofossils indicate an upper to mid-Pleistocene age.

Daily Science Report for 24 March 2011

LOCATION: Site U1379 (CRIS-4A) Lat. 9°23.5' N, Long. 84°43.4' W

SCIENCE UPDATE: After plugging and abandoning the hole with 10.5 ppg heavy mud and downloading the LWD data we started our transit back to Puntarenas. We arrived at Puntarenas at 0800 hrs and off loaded the LWD tools. The science party was allowed to leave the ship until 1700 hrs. At 2047 hrs we started our transit back to Site U1379 (CRIS-4A). Last minor refinements of research plans / sample requests were made.

Daily Science Report for 23 March 2011

LOCATION: Site U1379 (CRIS-4A) Lat. 8°40.8501' N, Long. 84°2.0166' W

SCIENCE UPDATE: The science party continues to get ready to receive core. In the morning the Operations Superintendent conducted a ship tour for the remaining scientists from the night shift. LWD operations continued smoothly and at 0300 hrs we fulfilled one of the aims of this expedition by drilling into the basement at this site. The sediment/basement boundary was clearly marked by a sudden increase in resistivity. At 1100 hrs we started to plug and abandon the hole with 10.5 ppg heavy mud. The total depth drilled in Hole U1379A was 962 mbsf.

Daily Science Report for 22 March 2011

LOCATION: Site U1379 (CRIS-4A) Lat. 8.6808° N, Long. 84.0336° W

SCIENCE UPDATE: The science party continues to prepare for the arrival of the first core. Details of the personal sampling plans were further refined. The scientific party started migrating onto shifts. The Operations Superintendent conducted ship tours for the day and the night shift scientists, respectively. At 1030 hrs the entire science party met and agreed on extending the time for LWD operations for another 24 hr. LWD operations continued smoothly reaching 860 mbsf into formation at the end of the day. Measured pressures in the hole while drilling still follow the expected hydrostatic trend.

Daily Science Report for 21 March 2011

LOCATION: Site U1379 (CRIS-4A) Lat. 8.6808° N, Long. 84.0336° W

SCIENCE UPDATE: Scientists continue practicing sampling, core description, and analytical methods. The revision of the first drafts of the "Methods" chapter for the expedition reports has been completed. At 1400 hrs all scientists, Transocean crew and USIO staff gathered on the helicopter deck for a minute of silence to express our respect for our 8 Japanese colleagues who are onboard and supporting the expedition despite the situation back in their home country. Our LWD operations continued smoothly and by 0000 hrs we have reached a total depth into the formation of 656 mbsf.

Daily Science Report for 20 March 2011

LOCATION: Site U1379 (CRIS-4A) Lat. 8.6808° N, Long. 84.0336° W

SCIENCE UPDATE: Preparations for core processing and description continued. All lab groups have submitted their first draft of the "Methods" chapter for the expedition reports. Co-Chief Scientists and Expedition Project Manager have reviewed most of them. Today Dave Canover and Rodie Batiza from NSF visited the ship. The visit started at 0645 hrs and they left the ship at 1600 hrs, during that time both got a detailed tour and introduction to all of the ship's facilities. Today’s science talks were from Steffen Kutterolf, talking about volcanism along the mid-American subduction zones, and from Paula Vanucchi on the Costa Rica Subduction Zone. We started drilling Hole U1379A ~8 mi upslope from our last site and tagged the seafloor at 0955 hrs. Drilling again progressed smoothly with high total drilling rates of 20-30 m/hr, the depth into formation at 00:00 hrs was to about 366 mbsf. Measured pressures in the hole while drilling follow the expected hydrostatic trend.

Daily Science Report for 19 March 2011

LOCATION: Site U1378 (CRIS-3B) Lat. 8.5924° N, Long. 84.0772° W

SCIENCE UPDATE: Lab teams composed of scientists and technical staff continue learning labs, instruments, and how to document the methods they want to apply. Drilling proceeded slowly due to hole cleaning issues. At 1730 hrs we decided to stop drilling and Hole U1378A was filled with heavy mud and we started to pull out of the hole. The total depth reached in the formation was 455 mbsf. In the afternoon Ivonne Arroyo gave a talk on the seismicity of the Costa Rica Subduction Zone and Evan Solomon gave one on fluid geochemistry and fluid flux in this area.

Daily Science Report for 18 March 2011

LOCATION: Site U1378 (CRIS-3B) Lat. 8.5924° N, Long. 84.0772° W

SCIENCE UPDATE: This day was mainly dedicated to refine the research plans/sample requests during meetings including the science party, the co-chiefs, the curator and the expedition project manager. Based on the results of these meetings, the curator started to develop the sampling plan. Preparations for core processing and description continued. In the afternoon Udo Barckhausen gave a talk on the tectonic structure and evolution of the plate assembly (Cocos Plate, Nazca Plate, Pacific Plate) offshore the west coast of Costa Rica and Rob Harris gave a talk on head flow, fluid flow and seismicity along the Costa Rica Subduction Zone. We started drilling Hole U1378A after making up the logging while drilling bottom hole assembly and tagged the seafloor at 0425 hrs. Drilling progressed smoothly to 330 mbsf (17:20 hr) with high total drilling rates of 20-30 m/hr down. We are now drilling at slower rates and reached about 385 mbsf (0000 hrs). The low-resolution LWD measurements transmitted in real time to the surface show that the data being acquired are of good quality. Pressures measured in the hole while drilling are being monitored in real time for safety and are following the expected hydrostatic trend.

Daily Science Report for 17 March 2011

LOCATION: Site U1378 (CRIS-3B) Lat. 8.5924° N, Long. 84.0772° W

SCIENCE UPDATE: The JOIDES Resolution departed Puntarenas at 01:00 hr and started the 8-hour transit to the Site U1378 (Prospectus SIte CRIS-3B), the deeper site on the slope offshore the Osa Peninsula. We arrived on site at 09:45 hr. Science meetings, shipboard orientations and core description training resumed. Scientists started writing the "Methods" chapter for the expedition reports, met with their respective laboratory technicians, were introduced to analytical instruments and continued working on the templates for core description. In the afternoon Peter Sak from the science party gave an introduction into the tectonic history of the Costa Rica Subduction Zone. At 02:30 hr calibration of the Logging While Drilling tools started (taking one hour) and afterwards assembly of the drill string began. The Logging While Drilling tools are being run without the Li-batteries, which have not arrived.

Daily Science Report for 16 March 2011

LOCATION: Puntarenas, Costa Rica

SCIENCE UPDATE: Scientists and technical staff began shipboard orientations. Activities included personnel introductions, overview of expedition science objectives by co-chief scientists and on logging-while-drilling operations by the logging staff scientist. DESCLogik templates that are provided to capture descriptive data into the database have been distributed to scientists for review. Core describers got a first detailed introduction to DESCLogik and started learning core description. The Curator, the Co-Chiefs and the Expedition Project Manager reviewed the research plans/sample requests. Arriving shipments were loaded. Part of the LWD tools shipment arrived and was also loaded. Co-Chiefs, Operations Superintendent, Logging Staff Scientist and Expedition Project Manager reviewed and discussed the operation plan.

Daily Science Report for 15 March 2011

LOCATION: Puntarenas, Costa Rica

SCIENCE UPDATE: Expedition 334 Co-Chief Scientists and scientists boarded the ship at 10:00 am and started to explore their new home. The Captain and ship's officers held a safety and introductory meeting and a lifeboat muster was conducted for the expedition participants afterward. In the afternoon the science party got a guided tour through the laboratories. Co-Chief Scientists and Expedition Project Manager discussed upcoming science meeting schedule. Arriving shipments were loaded but we are still waiting for LWD equipment.