Petrology of Lasail plutonic complex, northern Oman ophiolite, Oman: An example of arc-like magmatism associated with ophiolite detachment

Nobutaka Tsuchiya, Tomoyuki Shibata, Masako Yoshikawa, Yoshiko Adachi, Sumio Miyashita, Tatsuro Adachi, Nobuhiko Nakano, Yasuhito Osanai

研究成果: ジャーナルへの寄稿記事

11 引用 (Scopus)

抄録

Lasail plutonic complex (4.7. ×. 3.8. km), as a typical example of late stage intrusive rocks, is located to the south of Wadi Jizi, and intrudes into the base of V1 volcanic rocks and sheeted dike complex. The Lasail plutonic complex consists of various rock types ranging from ultramafic cumulates to tonalite, and is associated with minor amounts of axis stage gabbro to quartz diorite. These rocks are classified into the following eleven rock types: massive gabbro 1, quartz diorite 1 (axis stage intrusive rocks), olivine websterite, olivine gabbronorite, gabbronorite, hornblende gabbronorite, leucogabbronorite (layered gabbros), massive gabbro 2, diorite, quartz diorite 2, and tonalite (late stage intrusive rocks). The layered gabbros are intruded by the massive gabbro 2, and often occur as large irregular blocks in the massive gabbro 2. The massive gabbro 2 intrudes into the layered gabbros, and sometimes grades into hornblende gabbronorite layer of the layered gabbros. In some places, anastomosing veins of the hornblende quartz gabbronorite injected into the gabbronorite, which continue to the layer of leucogabbronorite. These gabbroic rocks are intruded by small intrusions of diorite, quartz diorite 2, and tonalite. The quartz diorite 2 forms rather larger intrusive bodies that intrude into the gabbroic rocks in the higher level. The tonalite occurs as thin dike and sheet mainly in the layered gabbros. N-MORB normalized trace element patterns for the massive gabbro 2 are characterized by enrichment of LILEs relative to REEs, and resemble to 'subduction component' from the island arc tholeiite except a weak enrichment for middle to light REE and P. In contrast, the massive gabbro 1 (axis stage gabbro) shows rather flat pattern similar to MORB with no remarkable 'subduction component'. From the examination of Sr and Nd isotopic signature, the Lasail plutonic rocks are characterized by higher ε-Sr values than those of MORB. This suggests that the primitive magma of Lasail complex was influenced by the rocks with higher ε-Sr values than those of MORB, e.g., the axis stage rocks interacted with seawater. These lines of evidence suggests that the massive gabbro 2 was formed by the partial melting of residual MORB mantle which is contaminated with slab melt derived from the axis stage rocks interacted with seawater. In addition, petrogenesis of felsic rocks in the Lasail complex can be explained by the partial melting model of pre-existing layered gabbro. U-Pb zircon ages analyzed by LA-ICPMS are 100. ±. 2 and 99. ±. 2. Ma for late stage tonalite and 100. ±. 1. Ma for axis stage quartz diorite. These ages are slightly older than the ages reported for felsic rocks in the Oman ophiolite (ca., 95. Ma), and suggest that the conversion from ridge stage to detachment stage took place rapidly.

元の言語英語
ページ(範囲)120-138
ページ数19
ジャーナルLITHOS
156-159
DOI
出版物ステータス出版済み - 1 1 2013

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Petrology
gabbro
ophiolite
petrology
magmatism
diorite
Rocks
Quartz
tonalite
rock
mid-ocean ridge basalt
quartz
hornblende
felsic rock
Levees
partial melting
dike
olivine
rare earth element
subduction

All Science Journal Classification (ASJC) codes

  • Geology
  • Geochemistry and Petrology

これを引用

Petrology of Lasail plutonic complex, northern Oman ophiolite, Oman : An example of arc-like magmatism associated with ophiolite detachment. / Tsuchiya, Nobutaka; Shibata, Tomoyuki; Yoshikawa, Masako; Adachi, Yoshiko; Miyashita, Sumio; Adachi, Tatsuro; Nakano, Nobuhiko; Osanai, Yasuhito.

:: LITHOS, 巻 156-159, 01.01.2013, p. 120-138.

研究成果: ジャーナルへの寄稿記事

Tsuchiya, Nobutaka ; Shibata, Tomoyuki ; Yoshikawa, Masako ; Adachi, Yoshiko ; Miyashita, Sumio ; Adachi, Tatsuro ; Nakano, Nobuhiko ; Osanai, Yasuhito. / Petrology of Lasail plutonic complex, northern Oman ophiolite, Oman : An example of arc-like magmatism associated with ophiolite detachment. :: LITHOS. 2013 ; 巻 156-159. pp. 120-138.
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title = "Petrology of Lasail plutonic complex, northern Oman ophiolite, Oman: An example of arc-like magmatism associated with ophiolite detachment",
abstract = "Lasail plutonic complex (4.7. ×. 3.8. km), as a typical example of late stage intrusive rocks, is located to the south of Wadi Jizi, and intrudes into the base of V1 volcanic rocks and sheeted dike complex. The Lasail plutonic complex consists of various rock types ranging from ultramafic cumulates to tonalite, and is associated with minor amounts of axis stage gabbro to quartz diorite. These rocks are classified into the following eleven rock types: massive gabbro 1, quartz diorite 1 (axis stage intrusive rocks), olivine websterite, olivine gabbronorite, gabbronorite, hornblende gabbronorite, leucogabbronorite (layered gabbros), massive gabbro 2, diorite, quartz diorite 2, and tonalite (late stage intrusive rocks). The layered gabbros are intruded by the massive gabbro 2, and often occur as large irregular blocks in the massive gabbro 2. The massive gabbro 2 intrudes into the layered gabbros, and sometimes grades into hornblende gabbronorite layer of the layered gabbros. In some places, anastomosing veins of the hornblende quartz gabbronorite injected into the gabbronorite, which continue to the layer of leucogabbronorite. These gabbroic rocks are intruded by small intrusions of diorite, quartz diorite 2, and tonalite. The quartz diorite 2 forms rather larger intrusive bodies that intrude into the gabbroic rocks in the higher level. The tonalite occurs as thin dike and sheet mainly in the layered gabbros. N-MORB normalized trace element patterns for the massive gabbro 2 are characterized by enrichment of LILEs relative to REEs, and resemble to 'subduction component' from the island arc tholeiite except a weak enrichment for middle to light REE and P. In contrast, the massive gabbro 1 (axis stage gabbro) shows rather flat pattern similar to MORB with no remarkable 'subduction component'. From the examination of Sr and Nd isotopic signature, the Lasail plutonic rocks are characterized by higher ε-Sr values than those of MORB. This suggests that the primitive magma of Lasail complex was influenced by the rocks with higher ε-Sr values than those of MORB, e.g., the axis stage rocks interacted with seawater. These lines of evidence suggests that the massive gabbro 2 was formed by the partial melting of residual MORB mantle which is contaminated with slab melt derived from the axis stage rocks interacted with seawater. In addition, petrogenesis of felsic rocks in the Lasail complex can be explained by the partial melting model of pre-existing layered gabbro. U-Pb zircon ages analyzed by LA-ICPMS are 100. ±. 2 and 99. ±. 2. Ma for late stage tonalite and 100. ±. 1. Ma for axis stage quartz diorite. These ages are slightly older than the ages reported for felsic rocks in the Oman ophiolite (ca., 95. Ma), and suggest that the conversion from ridge stage to detachment stage took place rapidly.",
author = "Nobutaka Tsuchiya and Tomoyuki Shibata and Masako Yoshikawa and Yoshiko Adachi and Sumio Miyashita and Tatsuro Adachi and Nobuhiko Nakano and Yasuhito Osanai",
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T1 - Petrology of Lasail plutonic complex, northern Oman ophiolite, Oman

T2 - An example of arc-like magmatism associated with ophiolite detachment

AU - Tsuchiya, Nobutaka

AU - Shibata, Tomoyuki

AU - Yoshikawa, Masako

AU - Adachi, Yoshiko

AU - Miyashita, Sumio

AU - Adachi, Tatsuro

AU - Nakano, Nobuhiko

AU - Osanai, Yasuhito

PY - 2013/1/1

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N2 - Lasail plutonic complex (4.7. ×. 3.8. km), as a typical example of late stage intrusive rocks, is located to the south of Wadi Jizi, and intrudes into the base of V1 volcanic rocks and sheeted dike complex. The Lasail plutonic complex consists of various rock types ranging from ultramafic cumulates to tonalite, and is associated with minor amounts of axis stage gabbro to quartz diorite. These rocks are classified into the following eleven rock types: massive gabbro 1, quartz diorite 1 (axis stage intrusive rocks), olivine websterite, olivine gabbronorite, gabbronorite, hornblende gabbronorite, leucogabbronorite (layered gabbros), massive gabbro 2, diorite, quartz diorite 2, and tonalite (late stage intrusive rocks). The layered gabbros are intruded by the massive gabbro 2, and often occur as large irregular blocks in the massive gabbro 2. The massive gabbro 2 intrudes into the layered gabbros, and sometimes grades into hornblende gabbronorite layer of the layered gabbros. In some places, anastomosing veins of the hornblende quartz gabbronorite injected into the gabbronorite, which continue to the layer of leucogabbronorite. These gabbroic rocks are intruded by small intrusions of diorite, quartz diorite 2, and tonalite. The quartz diorite 2 forms rather larger intrusive bodies that intrude into the gabbroic rocks in the higher level. The tonalite occurs as thin dike and sheet mainly in the layered gabbros. N-MORB normalized trace element patterns for the massive gabbro 2 are characterized by enrichment of LILEs relative to REEs, and resemble to 'subduction component' from the island arc tholeiite except a weak enrichment for middle to light REE and P. In contrast, the massive gabbro 1 (axis stage gabbro) shows rather flat pattern similar to MORB with no remarkable 'subduction component'. From the examination of Sr and Nd isotopic signature, the Lasail plutonic rocks are characterized by higher ε-Sr values than those of MORB. This suggests that the primitive magma of Lasail complex was influenced by the rocks with higher ε-Sr values than those of MORB, e.g., the axis stage rocks interacted with seawater. These lines of evidence suggests that the massive gabbro 2 was formed by the partial melting of residual MORB mantle which is contaminated with slab melt derived from the axis stage rocks interacted with seawater. In addition, petrogenesis of felsic rocks in the Lasail complex can be explained by the partial melting model of pre-existing layered gabbro. U-Pb zircon ages analyzed by LA-ICPMS are 100. ±. 2 and 99. ±. 2. Ma for late stage tonalite and 100. ±. 1. Ma for axis stage quartz diorite. These ages are slightly older than the ages reported for felsic rocks in the Oman ophiolite (ca., 95. Ma), and suggest that the conversion from ridge stage to detachment stage took place rapidly.

AB - Lasail plutonic complex (4.7. ×. 3.8. km), as a typical example of late stage intrusive rocks, is located to the south of Wadi Jizi, and intrudes into the base of V1 volcanic rocks and sheeted dike complex. The Lasail plutonic complex consists of various rock types ranging from ultramafic cumulates to tonalite, and is associated with minor amounts of axis stage gabbro to quartz diorite. These rocks are classified into the following eleven rock types: massive gabbro 1, quartz diorite 1 (axis stage intrusive rocks), olivine websterite, olivine gabbronorite, gabbronorite, hornblende gabbronorite, leucogabbronorite (layered gabbros), massive gabbro 2, diorite, quartz diorite 2, and tonalite (late stage intrusive rocks). The layered gabbros are intruded by the massive gabbro 2, and often occur as large irregular blocks in the massive gabbro 2. The massive gabbro 2 intrudes into the layered gabbros, and sometimes grades into hornblende gabbronorite layer of the layered gabbros. In some places, anastomosing veins of the hornblende quartz gabbronorite injected into the gabbronorite, which continue to the layer of leucogabbronorite. These gabbroic rocks are intruded by small intrusions of diorite, quartz diorite 2, and tonalite. The quartz diorite 2 forms rather larger intrusive bodies that intrude into the gabbroic rocks in the higher level. The tonalite occurs as thin dike and sheet mainly in the layered gabbros. N-MORB normalized trace element patterns for the massive gabbro 2 are characterized by enrichment of LILEs relative to REEs, and resemble to 'subduction component' from the island arc tholeiite except a weak enrichment for middle to light REE and P. In contrast, the massive gabbro 1 (axis stage gabbro) shows rather flat pattern similar to MORB with no remarkable 'subduction component'. From the examination of Sr and Nd isotopic signature, the Lasail plutonic rocks are characterized by higher ε-Sr values than those of MORB. This suggests that the primitive magma of Lasail complex was influenced by the rocks with higher ε-Sr values than those of MORB, e.g., the axis stage rocks interacted with seawater. These lines of evidence suggests that the massive gabbro 2 was formed by the partial melting of residual MORB mantle which is contaminated with slab melt derived from the axis stage rocks interacted with seawater. In addition, petrogenesis of felsic rocks in the Lasail complex can be explained by the partial melting model of pre-existing layered gabbro. U-Pb zircon ages analyzed by LA-ICPMS are 100. ±. 2 and 99. ±. 2. Ma for late stage tonalite and 100. ±. 1. Ma for axis stage quartz diorite. These ages are slightly older than the ages reported for felsic rocks in the Oman ophiolite (ca., 95. Ma), and suggest that the conversion from ridge stage to detachment stage took place rapidly.

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