Orthopyroxene–magnetite symplectite in olivine gabbros from the lower crustal Oman Ophiolite: Oman Drilling Project, Hole GT2A

Sayantani CHATTERJEE; Debaditya BANDYOPADHYAY; Eiichi TAKAZAWA; Katsuyoshi MICHIBAYASHI

doi:10.2465/jmps.201130f

Orthopyroxene–magnetite symplectite in olivine gabbros from the lower crustal Oman Ophiolite: Oman Drilling Project, Hole GT2A

Journal of Mineralogical and Petrological Sciences ◽

10.2465/jmps.201130f ◽

2021 ◽

Vol 116 (3) ◽

pp. 170-175

Author(s):

Sayantani CHATTERJEE ◽

Debaditya BANDYOPADHYAY ◽

Eiichi TAKAZAWA ◽

Katsuyoshi MICHIBAYASHI

Keyword(s):

Oman Ophiolite ◽

Lower Crustal ◽

Drilling Project

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Unravelling the Remagnetization of the Oman Ophiolite

10.5194/egusphere-egu2020-2063 ◽

2020 ◽

Author(s):

Louise Koornneef ◽

Antony Morris ◽

Michelle Harris ◽

Christopher MacLeod

Keyword(s):

Subduction Zone ◽

Large Scale ◽

Oceanic Lithosphere ◽

Magnetic Fabric ◽

Oman Ophiolite ◽

Mantle Peridotites ◽

Important Exception ◽

Magnetic Techniques ◽

Tectonic Rotation ◽

Lower Crustal

The Oman ophiolite is a natural laboratory for the study of processes operating above a nascent subduction zone. It formed in the Late Cretaceous by supra-subduction zone spreading and shortly afterwards was emplaced onto the Arabian continental margin. Twelve massifs in the ophiolite expose complete sections of the Neotethyan oceanic lithosphere, including upper mantle peridotites, lower crustal gabbros, and upper crustal sheeted dykes and lava flows.&#160;Previous palaeomagnetic studies have suggested that the southern massifs of the ophiolite were affected by a large-scale remagnetization event during emplacement, that completely replaced original remanences acquired during crustal accretion. In contrast, primary magnetizations are preserved throughout the northern massifs. This study aimed to: (i) apply palaeomagnetic, magnetic fabric and rock magnetic techniques to analyse crustal sections through the southern massifs of the Oman ophiolite to investigate further the extent and nature of this remagnetization event; and (ii) use any primary magnetizations that survived this event to document intraoceanic rotation of the ophiolite prior to emplacement.&#160;Our new data confirms that remagnetization appears to have been pervasive throughout the southern massifs, resulting in presence of shallowly-inclined NNW directions of magnetization at all localities. An important exception is the crustal section exposed in Wadi Abyad (Rustaq massif) where directions of magnetization change systematically through the gabbro-sheeted dyke transition. Demagnetization characteristics are shown to be consistent with acquisition of a chemical remanent overprint that decreased in intensity from the base of the ophiolite upwards. The top of the exposed Wadi Abyad section (in the sheeted dyke complex) appears to preserve original SE-directed remanences that are interpreted as primary seafloor magnetizations. Similar SE primary remanences were also isolated at a control locality in the Salahi massif, outside of the region of remagnetization. Net tectonic rotation analysis at these non-remagnetised sites shows an initial NNE-SSW strike for the supra-subduction zone ridge during spreading, comparable with recently published models for the regional evolution of the ophiolite.

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Petrogenesis of the crust-mantle transition zone and the origin of lower crustal wehrlite in the Oman ophiolite

Geochemistry Geophysics Geosystems ◽

10.1029/2000gc000132 ◽

2001 ◽

Vol 2 (9) ◽

pp. n/a-n/a ◽

Cited By ~ 66

Author(s):

Kenneth T. Koga ◽

Peter B. Kelemen ◽

Nobumichi Shimizu

Keyword(s):

Transition Zone ◽

Mantle Transition Zone ◽

Oman Ophiolite ◽

Lower Crustal

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Lower-crustal cracking front at fast-spreading ridges: Evidence from the East Pacific Rise and the Oman Ophiolite

Ophiolites and oceanic crust: new insights from field studies and the Ocean Drilling Program ◽

10.1130/0-8137-2349-3.261 ◽

2000 ◽

Cited By ~ 19

Author(s):

Craig E. Manning ◽

Christopher J. MacLeod ◽

Patricia E. Weston

Keyword(s):

East Pacific Rise ◽

Oman Ophiolite ◽

East Pacific ◽

Spreading Ridges ◽

Fast Spreading ◽

Lower Crustal

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Integrated Tubulars Supply Model Provides Cost Savings to Drilling Projects

Proc. Indon. Petrol. Assoc., Digital Technical Conference, 2020 ◽

10.29118/ipa20-f-103 ◽

2020 ◽

Author(s):

M. Hamzah

Keyword(s):

Supply Chain ◽

Cost Savings ◽

Asia Pacific ◽

Potential Cost ◽

Alternative Scheme ◽

Safety Stocks ◽

Storage Location ◽

Supply Planning ◽

Drilling Site ◽

Drilling Project

Classical Oil Country Tubular Goods (OCTG) procurement approach has been practiced in the indus-try with the typical process of setting a quantity level of tubulars ahead of the drilling project, includ-ing contingencies, and delivery to a storage location close to the drilling site. The total cost of owner-ship for a drilling campaign can be reduced in the range of 10-30% related to tubulars across the en-tire supply chain. In recent decades, the strategy of OCTG supply has seen an improvement resulting in significant cost savings by employing the integrated tubular supply chain management. Such method integrates the demand and supply planning of OCTG of several wells in a drilling project and synergize the infor-mation between the pipes manufacturer and drilling operators to optimize the deliveries, minimizing inventory levels and safety stocks. While the capital cost of carrying the inventory of OCTG can be reduced by avoiding the procurement of substantial volume upfront for the entire project, several hidden costs by carrying this inventory can also be minimized. These include storage costs, maintenance costs, and costs associated to stock obsolescence. Digital technologies also simplify the tasks related to the traceability of the tubulars since the release of the pipes from the manufacturing facility to the rig floor. Health, Safety, and Environmental (HSE) risks associated to pipe movements on the rig can be minimized. Pipe-by-pipe traceability provides pipes’ history and their properties on demand. Digitalization of the process has proven to simplify back end administrative tasks. The paper reviews the OCTG supply methods and lays out tangible improvement factors by employ-ing an alternative scheme as discussed in the paper. It also provides an insight on potential cost savings based on the observed and calculated experiences from several operations in the Asia Pacific region.

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