Drilling Program

Over two drilling seasons the comprehensive drilling program has sampled the Samail Ophiolite sequence from crust to basal thrust in nine diamond-cored and six rotary-drilled boreholes. The total cumulative drilled length is 5458.15 m, 3221.15 m of which was cored at ~100% recovery. These cores were logged to IODP standards aboard the DV Chikyu during two 60-day description campaigns. In addition to sampling and analysis of rock core and cuttings, the operations include ongoing geophysical logging, fluid sampling, hydrological measurements and microbiological sampling.

Map of Drill Sites

All OmanDP Drill Sites and Boreholes

Gabbro Transect (GT) Sites

Crust-Mantle Transition (CM) Sites

Active Alteration (BA) Sites

Basal Thrust (BT) Site

Core characterisation onboard DV Chikyu

 

 

Map of OmanDP Drill Sites

 

All boreholes drilled in OmanDP Phases 1 and 2












Phase Site code and Hole Site # and Hole Location and Site Name Easting Northing Type of borehole Target depth (m) Deviation from vertical (°) Trend of inclined Borehole Total depth (m) Date occupied Date departed
1 GT2A 2A Wadi Gideah, Northern Sharqiyah, Mid-crustal section. 22°51.793' 58°31.198' Wireline diamond coring 400 30 054 406.55 25 Dec 2016 20 Jan 2017
1 GT1A 1A Wadi Gideah, Northern Sharqiyah - Lower crustal section 22°53.535' 58°30.904' Wireline diamond coring 400 0   403.05 22 Jan 2017 08 Feb 2017
1 GT3A 3A Wadi Abdah, Sheeted dike-gabbro transition 23°06.845' 58°12.703' Wireline diamond coring 400 0   400.00 11 Feb 2017 04 Mar 2017
1 BA1A 5A Wadi Lawayni, Northern Sharqiyah - Active serpentinisation 22°52.873' 58°42.036' Rotary 400 0   400.00 20 Feb 2017 02 Mar 2017
1 BA2A 6A Wadi Tayin, Northern Sharqiyah - Active serpentinisation 22°55.468' 58°39.977' Rotary 400 0   400.00 05 Mar 2017 09 Mar 2017
1 BT1B 4B Wadi Mansah, Samail - Basal Thrust 23°21.861' 58°20.149' Wireline diamond coring 300 15 030 300.05 06 Mar 2017 23 Mar 2017
2 CM1A 7A Wadi Zeeb, Northern Sharqiyah - Base of crust to mantle transition zone 22°54.435' 58°20.149' Wireline diamond coring 400 30 000 404.15 15 Nov 2017 13 Dec 2017
2 CM2A 8A Wadi Zeeb, Northern Sharqiyah - Mantle transition zone to Mantle 22°54.658' 58°20.144' Rotary 400 0   400.00 23 Nov 2017 13 Dec 2017
2 CM2B 8B Wadi Zeeb, Northern Sharqiyah - Mantle transition zone to Mantle 22°54.660' 58°20.149' Wireline diamond coring 300 0   300.00 19 Dec 2017 04 Jan 2018
2 CM1B 7B Wadi Zeeb, Northern Sharqiyah - Base of crust to mantle transition zone 22°54.433' 58°20.149' Rotary 300 0   237.00 19 Dec 2017 27 Jan 2018
2 BA3A 9A Wadi Lawayni, Northern Sharqiyah - Active serpentinisation 22°51.970' 58°42.634' Wireline diamond coring 300 0   302.70 08 Jan 2018 22 Jan 2018
2 BA1B 5B Wadi Lawayni, Northern Sharqiyah - Active serpentinisation 22°52.874' 58°42.035' Wireline diamond coring 400 0   401.70 24 Jan 2018 12 Feb 2018
2 BA1C 5C Wadi Lawayni, Northern Sharqiyah - Active serpentinisation 22°52.895' 58°42.087' Rotary 400 0   400.00 03 Feb 2018 21 Feb 2018
2 BA4A 10A Wadi Lawayni, Northern Sharqiyah - Active serpentinisation 22°53.101' 58°41.703 Wireline diamond coring 300 0   302.70 14 Feb 2018 27 Feb 2018
2 BA1D 5D Wadi Lawayni, Northern Sharqiyah - Active serpentinisation 22°52.874' 58°42.035' Rotary 400 0   400.00 24 Feb 2018 15 Mar 2018

 

Gabbro Transect (GT) Sites

Wadi Gideah in the Wadi Tayin massif provides the opportunity to study an intact crustal section. Wadi Gideah drains southward from a divide near the crust-mantle transition. Around the Wadi, the crustal section dips gently to the south, exposing deeper levels upstream, to the north, and shallower levels to the south, culminating with submarine lava flows in the “Ibra syncline”. The section is well mapped by different groups, and recently this Wadi has been extensively sampled by Oman DP PIs Koepke, T. Müller, Bähre, Garbe-Schönber, S. Müller and Ildenfonse in order to establish a reference profile through the whole Samail paleocrust, considering petrological, geochemical and structural features, providing the basic framework for the two 400 m long cores drilled at sites, GT1 (lower crust) and GT2 (mid-crust) and GT3 (dike/gabbro transition).

 

 
 

 

Active Alteration (BA) Sites

 

Basal Thrust (BT) Site

Basal thrust between Samail mantle with listvenite bands and metamorphic sole

Site BT1 is located on the north side of the wide gravel plain of Wadi Mansah (MOD Mountain) (23.366°N, 58.184°E). Geologically, the drill site is just above the basal thrust of the ophiolite, juxtaposing mantle peridotites in the hanging wall and underlying metasediments and metabasalts of the metamorphic sole and the Hawasina Group sediments. Extensive bands of listvenites (fully carbonated peridotites) occur within partially serpentinized residual mantle peridotites. A 300 m deep, fully cored borehole was drilled in the listvenite, passing through bands of serpentinised mantle, sampling the fault gouge of the basalt thrust and the metabasalts and phyllitic metasediments of the metamorphic sole and the Hawasina Group. Objectives are to perform thorough sampling of contacts between listvenite and serpentinised harzburgite, listvenite and the metamorphic sole, and the metamorphic sole and underlying Hawasina sediments. The goal is to conduct a detailed study of mass transfer from subducting sediments into mantle peridotites.

 

 

Core Characterisation Onboard DV Chikyu

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