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Table T1. Definition of IODP depth scales used during Expedition 320/321. (See table notes.)

Depth scale Acronym Origin Method description Submethod Unit Previous name* Previous unit*
Drillers depth scale:
Drilling depth below rig floor DRF Drill floor Add lengths of all drill string components deployed beneath rig floor from bit to point on rig floor where length of deployed portion of last string is measured   m Depth mbrf
Drilling depth below seafloor DSF Seafloor Subtract distance between rig floor and sea level from an estimate of seafloor depth at DRF scale using one of the submethods Mudline core m Depth mbsf
Core depth scale:
Core depth below seafloor CSF Seafloor Measure core sample or measurement offset below core top and add to core top DSF scale using one of the submethods Let overlap if long m Depth mbsf
Core composite depth below seafloor CCSF Seafloor Align cores from one hole or multiple adjacent holes based using one of the submethods to create a newly constructed depth scale A. Append if long
B. Scale by factor to approximate CSF		 m Depth mcd
Wireline depth scale:
Wireline log depth below rig floor WRF Drill floor Measure length of wireline extended beneath rig floor.   m Depth mbrf
Wireline log depth below seafloor WSF Seafloor Subtract distance between rig floor and sea level from an estimate of seafloor depth at WRF scale using one of the submethods. Seafloor signal m Depth mbsf
Wireline log matched depth below seafloor WMSF Seafloor Pick log data from one run as reference and map other run data using several tie points. Natural gamma ray logs m Depth mbsf

Notes: * = ODP depth scale conventions. Drillers depth scale is based on length of drill pipe lowered below drill floor. Core depth scale is based on actual length of core recovered and drillers depth, which can vary with time as core expands or contracts. Wireline depth scale is based on wireline length between downhole tool and shipboard winch. See IODP Depth Scale Terminology at www.iodp.org/program-policies/.

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