Citation:

PANGAEA.914257

Name: Petrographic observations and phase properties for sample sets from Wadi Somerah (OM10-Sam) and Wadi Wariyah (OM10-War), Oman
Published: 2020-03-31
License: https://creativecommons.org/licenses/by/4.0/
Keywords: Formation of Layered Gabbros; Lower Oceanic Crust; Oman Ophiolite

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Published: 2020-03-31 • DOI registered: 2020-12-25

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Abstract:

As largest and best-exposed paleo-fast-spread oceanic crust on land, the Samail ophiolite in the Sultanate of Oman represents an ideal natural laboratory for investigating processes at fast-spreading mid-ocean ridges. We studied two layered gabbro sequences from different stratigraphic depths: one from the middle of the plutonic crust showing dm-scale modal layering with olivine abundance gradually decreasing from layer base to top (Wadi Somerah, Sumail block) and one located near the crust-mantle boundary showing mm-scale layers being enriched in olivine (Wadi Wariyah, Wadi Tayin block). Petrographic analyses were performed at the Institut für Mineralogie (Leibniz Universität Hannover, Germany) for thin-section description. Plagioclase and Clinopyroxene are present in all samples, most of the samples also include olivine as primary phase and are therefore described as olivine gabbro. The olivine content increases per layer towards the layer base. Grain sizes of the three primary phases olivine, plagioclase and clinopyroxene vary between 0.2 and 5 mm. Olivine usually forms the largest grains, plagioclase the smallest ones. The grain shapes are generally subhedral, their habit is prismatic or, occasionally, irregular or elongated. Some olivine grains show reaction rims or contain plagioclase chadacrysts. Poikilitic clinopyroxene also containing plagioclase as chadacrysts is very common. The described phases are only the primary minerals not taking the low to medium degree of alteration and therefore presence of secondary phases into account.

Keyword(s):

Formation of Layered Gabbros; Lower Oceanic Crust; Oman Ophiolite

Related to:

Mock, Dominik; Neave, David Axford; Müller, S; Garbe-Schönberg, Dieter; Namur, Olivier; Ildefonse, Benoit; Koepke, Jürgen (2021): Formation of igneous layering in the lower oceanic crust from the Samail Ophiolite, Sultanate of Oman. Journal of Geophysical Research: Solid Earth, 126, e2020JB019573, https://doi.org/10.1029/2020JB019573

Coverage:

Median Latitude: 23.038146 * Median Longitude: 58.184530 * South-bound Latitude: 22.983333 * West-bound Longitude: 58.104060 * North-bound Latitude: 23.092960 * East-bound Longitude: 58.265000

Minimum DEPTH, sediment/rock: 0.0050 m * Maximum DEPTH, sediment/rock: 2.7120 m

Event(s):

OM10-Sam (Wadi Somerah, Sumail block) * Latitude: 23.092960 * Longitude: 58.104060 * Elevation: 720.0 m * Location: Oman * Method/Device: Drilling/coring

OM10-War (Wadi Wariyah, Wadi Tayin block) * Latitude: 22.983333 * Longitude: 58.265000 * Elevation: 719.0 m * Location: Oman * Method/Device: Drilling/coring

Comment:

OM10-Sam: layer 6= 0-8 cm, layer 5= 8-57 cm, layer 4= 57-95 cm, layer 3= 95-136 cm, layer 2= 136-205 cm, layer 1= 205-285 cm

OM10-War: layer 1= 0-0.7 cm, layer 2= 0.7-1.5 cm, layer 3= 1.5-2.1 cm, layer 4= 2.1-2.6 cm, layer 5= 2.6-3.2 cm, layer 6= 3.2-3.9 cm, layer 7= 3.9-4.3cm, layer 8= 4.3-5 cm, layer 9= 5-5.8 cm, layer 10= 5.8- 6.3 cm, layer 11= 6.3-7.2 cm

Parameter(s):

#	Name	Short Name	Unit	Principal Investigator	Method/Device	Comment
1	Event label	Event		Mock, Dominik
2	Latitude of event	Latitude		Mock, Dominik
3	Longitude of event	Longitude		Mock, Dominik
4	Elevation of event	Elevation	m	Mock, Dominik
5	Sample code/label	Sample label		Mock, Dominik
6	Layer number	Layer		Mock, Dominik
7	DEPTH, sediment/rock	Depth sed	m	Mock, Dominik		Geocode
8	Main Lithology	Main lith		Mock, Dominik
9	Mode, grain size, description	Mode		Mock, Dominik	Polarisation microscopy (Leica Leitz DMRP)
10	Mode, area	Area	%	Mock, Dominik	Polarisation microscopy (Leica Leitz DMRP)	Olivine; modal proportions per phase in area % by visual estimation
11	Grain size, mean	Grain size mean	µm	Mock, Dominik	Polarisation microscopy (Leica Leitz DMRP)	Olivine
12	Shape	Shape		Mock, Dominik	Polarisation microscopy (Leica Leitz DMRP)	Olivine
13	Habit	Habit		Mock, Dominik	Polarisation microscopy (Leica Leitz DMRP)	Olivine
14	Feature	Feature		Mock, Dominik	Polarisation microscopy (Leica Leitz DMRP)	Olivine
15	Mode, area	Area	%	Mock, Dominik	Polarisation microscopy (Leica Leitz DMRP)	Plagioclase; modal proportions per phase in area % by visual estimation
16	Grain size, mean	Grain size mean	µm	Mock, Dominik	Polarisation microscopy (Leica Leitz DMRP)	Plagioclase
17	Shape	Shape		Mock, Dominik	Polarisation microscopy (Leica Leitz DMRP)	Plagioclase
18	Habit	Habit		Mock, Dominik	Polarisation microscopy (Leica Leitz DMRP)	Plagioclase
19	Feature	Feature		Mock, Dominik	Polarisation microscopy (Leica Leitz DMRP)	Plagioclase
20	Mode, area	Area	%	Mock, Dominik	Polarisation microscopy (Leica Leitz DMRP)	Clinopyroxene; modal proportions per phase in area % by visual estimation
21	Grain size, mean	Grain size mean	µm	Mock, Dominik	Polarisation microscopy (Leica Leitz DMRP)	Clinopyroxene
22	Shape	Shape		Mock, Dominik	Polarisation microscopy (Leica Leitz DMRP)	Clinopyroxene
23	Habit	Habit		Mock, Dominik	Polarisation microscopy (Leica Leitz DMRP)	Clinopyroxene
24	Feature	Feature		Mock, Dominik	Polarisation microscopy (Leica Leitz DMRP)	Clinopyroxene

License:

Creative Commons Attribution 4.0 International (CC-BY-4.0)

Size:

746 data points

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