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Science Daily WEEK 3: Part 1 More Cores on Deck
Submitted by Teresa Greely on Wed, 03/28/2012 - 21:43
The following are science results as summarized by 340 Staff Scientist, Nicole Stroncik. We started our third week with coring operations off Martinique at Site U1397 (CARI-10B) and at the end of the week we are in the middle of our coring operations on Site U1398 (CARI-09B). Site U1397 (14°54.41’N, 61°25.35’W), located west of the island of Martinique (photo below), was chosen to characterize the eruptive history of this volcanic island in space and time. If target depth is reached the sediments recovered should span a time interval of about 1 Ma and may identify and date layers related to the emplacement of debris avalanches from Montagne Pelée and Pitons du Carbet volcanoes. Read on for more findings…
Daily Science Report for 19 March 2012
We started coring Hole U1397A at 04:25 in a water depth of 2482 meters and a target drill depth of 314 meters below seafloor (mbsf). By midnight we retrieved 20 Cores to 122 mbsf with recovery of 118 m of material. The cores recovered are really beautiful and consist of tephra layers intercalated in coarse sand grained background sediment. The number of tephra layers is enormous, averaging about 50 per core. The tephra layers consist of ash and pumice, the pumice being andesitic in composition.(Note: this image is not from core hole U1397, rather an example of tephra layers; photo credits, 340 Co-Chief Scientist, Anne Le Friant)
Daily Science Report for 20 March 2012
In the last 24 hours we retrieved 15 Cores with recovery of 26 m of material reaching ~266 mbsf. After Core U1397A-35X at 23:00 was on deck we terminated Hole U1397A for scientific reasons (often related to time limits at each site and/or recovery rates from a particular hole) and prepared for spudding Hole U1397B. The material cored mainly consists of tephra and debris flow deposits of variable composition and grain size.
Daily Science Report for 21 March 2012
We spudded Hole U1397B at 02:52 and retrieved 23 Cores with recovery rate of 120 m of material reaching ~171 mbsf. The material cored is similar to the material cored in Hole U1397A and consists of alternating sequences of volcanic fallouts, volcaniclastic A sedimentary deposit formed by a turbidity current.
Daily Science Report for 22 March 2012
We finished Hole U1397B and started to prepare the drill floor for logging operations. We retrieved 10 Cores and recovered 11 m of material reaching a total depth of 254 mbsf. Drilling conditions became problematic below ~220 mbsf. Nonetheless we were able to retrieve material from the debris flow itself. This material consisted partly of large pieces of fresh to hydrothermally altered andesite. It appears that we probably have cored through some large debris flow blocks typical in deposits like this.
Science Dailies for Week 3 are continued in the next blog, Part 2