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

Data

Download dataset as tab-delimited text — use the following character encoding:

1 Event	2 Latitude	3 Longitude	4 Elevation [m]	5 Sample label	6 Layer	7 Depth sed [m]	8 Main lith	9 Mode	10 Area [%] (Olivine; modal proportions pe...)	11 Grain size mean [µm] (Olivine)	12 Shape (Olivine)	13 Habit (Olivine)	14 Feature (Olivine)	15 Area [%] (Plagioclase; modal proportion...)	16 Grain size mean [µm] (Plagioclase)	17 Shape (Plagioclase)	18 Habit (Plagioclase)	19 Feature (Plagioclase)	20 Area [%] (Clinopyroxene; modal proporti...)	21 Grain size mean [µm] (Clinopyroxene)	22 Shape (Clinopyroxene)	23 Habit (Clinopyroxene)	24 Feature (Clinopyroxene)
OM10-Sam	23.0930	58.1041	720	OM10-Sam_11	6	0.0400	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	7.339072959	2000	subhedral	prismatic	oikocrysts, reaction rim	47.90658022	500	subhedral	elongate	chadacrysts	44.75434682	2000	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_10-1	5	0.1050	olivine-bearing gabbro (<5% olivine)	fine grained (>0.2 - 1 mm)	1.220955708	1500	subhedral	prismatic	oikocrysts, reaction rim	43.04506259	300	subhedral	elongate	chadacrysts	56.46424400	1000	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_10-2	5	0.1385	olivine-bearing gabbro (<5% olivine)	fine grained (>0.2 - 1 mm)	1.127061143	500	subhedral	prismatic	oikocrysts, reaction rim	47.11037581	300	subhedral	elongate	chadacrysts	52.00000000	1000	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_10-3	5	0.1735	gabbro	fine grained (>0.2 - 1 mm)						48.81963738	300	subhedral	elongae	chadacrysts	51.00000000	1000	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_9-1	5	0.4995	olivine gabbro (>5% olivine)	fine grained (>0.2 - 1 mm)	10.000000000	1000	subhedral	prismatic	oikocrysts, reaction rim	54.00000000	200	subhedral	elongate	chadacrysts	36.00000000	500	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_9-2	5	0.5305	olivine gabbro (>5% olivine)	fine grained (>0.2 - 1 mm)	18.331098510	1000	subhedral	prismatic	oikocrysts, reaction rim	52.00000000	200	subhedral	elongate	chadacrysts	30.00000000	1000	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_8-1	4	0.6490	gabbro	fine grained (>0.2 - 1 mm)						49.03601024	200	subhedral	elongate		51.40796674	700	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_8-2	4	0.6710	olivine-bearing gabbro (<5% olivine)	fine grained (>0.2 - 1 mm)	0.573987574	1750	subhedral	prismatic	reaction rim	52.24129648	200	subhedral	elongate	chadacrysts	47.00000000	500	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_8-3	4	0.7020	olivine-bearing gabbro (<5% olivine)	fine grained (>0.2 - 1 mm)	1.000000000	1500	subhedral	prismatic		49.37075854	300	subhedral	elongate	chadacrysts	50.00000000	500	subhedral	prismatic, elongated	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_7-1	4	0.8890	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	3.000000000	1000	subhedral	prismatic, elongated		57.00000000	300	subhedral	elongate, prismatic	chadacrysts	40.00000000	400	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_7-2	4	0.9095	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	11.000000000	800	subhedral	prismatic		52.00000000	300	subhedral	elongated, prismatic	chadacrysts	37.00000000	400	subhedral	prismatic, elongated	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_7-3	4	0.9340	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	13.205144570	600	subhedral	prismatic, elongated	reaction rim	53.00000000	300	subhedral	elongated, prismatic	chadacrysts	34.00000000	400	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_6-1	3	1.0790	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	8.914144530	600	subhedral	prismatic, elongated	reaction rim	57.07179209	300	subhedral	elongted	chadacrysts	34.00000000	400	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_6-2	3	1.0870	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	6.851653078	600	subhedral	prismatic	reaction rim	60.00000000	200	subhedral	prismatic, elongated	chadacrysts	33.46851708	400	subhedral	prismatic, elongated	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_5-1	3	1.2500	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	9.000000000	600	subhedral	prismatic, elongated	reaction rim	54.00000000	200	subhedral	prismatic, elongated	chadacrysts	37.00000000	300	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_5-2	3	1.2755	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	10.964008040	700	subhedral	prismatic	reaction rim	56.00000000	300	subhedral	prismatic, elongated	chadacrysts	33.00000000	500	subhedral	prismatic, irregular	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_5-3	3	1.3195	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	23.299917660	1000	subhedral	prismatic	oikocrysts, reaction rim	49.00000000	300	subhedral	prismatic, elongated	chadacrysts	28.00000000	400	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_4-1	2	1.7300	olivine-bearing gabbro (<5% olivine)	fine grained (>0.2 - 1 mm)	2.046182863	2000	subhedral	prismatic, elongated	oikocrysts, reaction rim	57.00000000	800	subhedral	prismatic, elongated	chadacrysts	41.00000000	600	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_4-2	2	1.7650	olivine-bearing gabbro (<5% olivine)	medium grained (>1 - 5 mm)	2.202231537	2000	subhedral	prismatic, elongated	oikocrysts, reaction rim	58.30407993	500	subhedral	prismatic, elongated	chadacrysts	40.09304592	700	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_4-3	2	1.8000	olivine-bearing gabbro (<5% olivine)	fine grained (>0.2 - 1 mm)	1.035594163	1000	subhedral	prismatic, elongated	oikocrysts, reaction rim	62.00000000	400	subhedral	prismatic, elongated	chadacrysts	36.95400847	500	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_4-4	2	1.8300	olivine-bearing gabbro (<5% olivine)	medium grained (>1 - 5 mm)	1.862180286	1500	subhedral	prismatic, elongated	oikocrysts, reaction rim	68.00000000	500	subhedral	prismatic, elongated	chadacrysts	30.00000000	500	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_3-1	2	1.9800	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	11.834882580	2000	subhedral	prismatic, irregular	oikocrysts, reaction rim	29.00000000	500	subhedral	prismatic, elongated	chadacrysts	59.00000000	2000	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_3-2	2	2.0000	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	13.043560220	2000	subhedral	prismatic, irregular	oikocrysts, reaction rim	24.00000000	500	subhedral	prismatic, elongated	chadacrysts	63.00000000	2500	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_3-3a	2	2.0200	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	10.000000000	1500	subhedral	prismatic, irregular	oikocrysts, reaction rim	34.00000000	500	subhedral	prismatic, elongated	chadacrysts	56.00000000	2000	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_3-3b	1	2.0700	olivine-bearing gabbro (<5% olivine)	medium grained (>1 - 5 mm)	0.700000000	1800	sudhedral to euhedral	prismatic	oikocrysts, reaction rim	55.71963184	400	subhedral	elongated	chadacrysts	43.00000000	1500	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_2-1	1	2.2000	olivine-bearing gabbro (<5% olivine)	fine grained (>0.2 - 1 mm)	4.000000000	2000	subhedral	prismatic, elongated	oikocrysts, reaction rim	62.00000000	300	subhedral	prismatic, elongated	chadacrysts	34.00000000	1000	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_2-2	1	2.2210	olivine-bearing gabbro (<5% olivine)	fine grained (>0.2 - 1 mm)	9.382527177	1500	subhedral	prismatic	oikocrysts, reaction rim	62.00000000	300	subhedral	prismatic, elongated	chadacrysts	29.00000000	800	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_2-3	1	2.2510	olivine-bearing gabbro (<5% olivine)	fine grained (>0.2 - 1 mm)	5.088570910	1500	subhedral	prismatic	oikocrysts, reaction rim	71.00000000	300	subhedral	prismatic, elongated	chadacrysts	24.00000000	700	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_1-1	1	2.6795	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	17.000000000	2000	subhedral	prismatic, irregular	inclusion-bearing, reaction rim	34.00000000	400	subhedral	prismatic, elongated	chadacrysts	49.00000000	2000	subhedral	prismatic	oikocryst
OM10-Sam	23.0930	58.1041	720	OM10-Sam_1-2	1	2.7120	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	14.000000000	1800	subhedral	prismatic, irregular, elongated	oikocrysts, reaction rim	61.00000000	300	subhedral	prismatic, elongated	chadacrysts	25.00000000	1800	subhedral	prismatic	oikocryst
OM10-War	22.9833	58.2650	719	OM10_War_DS1-11	11	0.0050	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	15.000000000	1500	subhedral	prismatic, elongated	oikocrysts	65.00000000	400	subhedral	prismatic, elongated	chadacrysts	20.00000000	1500	subhedral	prismatic	rare oikocrysts
OM10-War	22.9833	58.2650	719	OM10_War_DS1-10	10	0.0120	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	15.000000000	1500	subhedral	prismatic, irregular	oikocrysts	55.00000000	700	subhedral	prismatic, elongated	chadacrysts	30.00000000	1500	subhedral	prismatic
OM10-War	22.9833	58.2650	719	OM10_War_DS1-9	9	0.0190	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	12.000000000	1500	subhedral	prismatic, irregular	oikocrysts	58.00000000	500	subhedral	prismatic, elongated	chadacrysts	30.00000000	1200	subhedral	prismatic
OM10-War	22.9833	58.2650	719	OM10_War_DS1-8	8	0.0250	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	18.000000000	1000	subhedral	prismatic, irregular	oikocrysts	62.00000000	500	subhedral	prismatic, elongated	chadacrysts	20.00000000	1000	subhedral	prismatic	rare oikocrysts
OM10-War	22.9833	58.2650	719	OM10_War_DS1-7	7	0.0310	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	10.000000000	1000	subhedral	prismatic, irregular	oikocrysts	60.00000000	600	subhedral	prismatic, elongated	chadacrysts	30.00000000	800	subhedral	prismatic
OM10-War	22.9833	58.2650	719	OM10_War_DS2-6	6	0.0380	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	16.000000000	1200	subhedral	prismatic, irregular		57.00000000	600	subhedral	prismatic, elongated		27.00000000	700	subhedral	prismatic
OM10-War	22.9833	58.2650	719	OM10_War_DS2-5	5	0.0410	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	18.000000000	1200	subhedral	prismatic, irregular		55.00000000	500	subhedral	prismatic, elongated		27.00000000	500	subhedral	prismatic
OM10-War	22.9833	58.2650	719	OM10_War_DS2-4	4	0.0480	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	15.000000000	1300	subhedral	prismatic, irregular		50.00000000	500	subhedral	prismatic, elongated		35.00000000	600	subhedral	prismatic
OM10-War	22.9833	58.2650	719	OM10_War_DS2-3	3	0.0560	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	20.000000000	1300	subhedral	prismatic, irregular		50.00000000	500	subhedral	prismatic, elongated		30.00000000	600	subhedral	prismatic
OM10-War	22.9833	58.2650	719	OM10_War_DS2-2	2	0.0620	olivine gabbro (>5% olivine)	medium grained (>1 - 5 mm)	7.000000000	1000	subhedral	prismatic, irregular		62.00000000	500	subhedral	prismatic, elongated		30.00000000	600	subhedral	prismatic
OM10-War	22.9833	58.2650	719	OM10_War_DS2-1	1	0.0700	olivine-bearing gabbro (<5% olivine)	fine grained (>0.2 - 1 mm)	3.000000000	1500	subhedral	irregular, elongated	skeletal	55.00000000	400	subhedral	prismatic, elongated	chadacrysts	42.00000000	500	subhedral	prismatic