| Age and generation of Fogang granite batholith and Wushi diorite-hornblende gabbro body |
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| 作者姓名： | XU XiSheng? LU WeiMin & HE ZhenYu State Key Laboratory of Crust-Mantle Evolution and Mineralization |
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| 作者单位： | XU XiSheng?，LU WeiMin & HE ZhenYu State Key Laboratory of Crust-Mantle Evolution and Mineralization，Department of Earth Sciences，Nanjing University，Nanjing，210093，China |
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| 摘 要： | Fogang granitic batholith, the largest Late Mesozoic batholith in the Nanling region, has an exposure area of ca. 6000 km2. Wushi diorite-hornblende gabbro body is situated at the northeast part of the ba- tholith. Both the granitic batholith main body and the diorite-hornblende gabbro body belong to high-K calc alkaline series. Compared with the granitic main body, the Wushi body has lower Si (49%―55%), higher Fe, Mg, Ca, lower REE, less depletion of Eu, Ba, P, Ti, and obvious depletion of Zr, Hf. Zircon LA-ICP-MS dating and the mineral-whole rock isochron dating reveal that Fogang granitic main body and Wushi body were generated simultaneously at ca. 160 Ma. The Fogang granitic main body has high (87Sr/86Sr)i ratios (0.70871―0.71570) and low εNd(t) values (?5.11―?8.93), suggesting the origins of the granitic rocks from crustal materials. Their Nd two-stage model ages range from 1.37―1.68 Ga. The Sr and Nd isotopic compositions and the Nd model ages of the granitic rocks may suggest that the giant Fogang granitic main body was generated from a heterogeneous source, with participation of mantle component. Wushi diorite-hornblende gabbro is an unusual intermediate-basic magmatic rock series, with high (87Sr/86Sr)i ratios (0.71256―0.71318) and low εNd(t) values (?7.32―?7.92), which was possibly formed through mixing between the mantle-derived juvenile basaltic magma and the magma produced by the dehydration melting of lower crustal basaltic rocks.
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| 收稿时间： | 24 April 2006 |
| 修稿时间： | 17 July 2006 |
Age and generation of Fogang granite batholith and Wushi diorite-hornblende gabbro body |
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| Xu?XiSheng,Lu?WeiMin,He?ZhenYu.Age and generation of Fogang granite batholith and Wushi diorite-hornblende gabbro body[J].Science in China(Earth Sciences),2007,50(2):209-220. |
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| Authors: | Xu XiSheng Lu WeiMin He ZhenYu |
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| Institution: | State Key Laboratory of Crust-Mantle Evolution and Mineralization,Department of Earth Sciences, Nanjing University, Nanjing, 210093, China |
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| Abstract: | Fogang granitic batholith, the largest Late Mesozoic batholith in the Nanling region, has an exposure area of ca. 6000 km2. Wushi diorite-homblende gabbro body is situated at the northeast part of the batholith. Both the granitic batholith main
body and the diorite-homblende gabbro body belong to high-K calc alkaline series. Compared with the granitic main body, the
Wushi body has lower Si (49%–55%), higher Fe, Mg, Ca, lower REE, less depletion of Eu, Ba, P, Ti, and obvious depletion of
Zr, Hf. Zircon LA-ICP-MS dating and the mineral-whole rock isochron dating reveal that Fogang granitic main body and Wushi
body were generated simultaneously at ca. 160 Ma. The Fogang granitic main body has high (87Sr/86Sr)i ratios (0.70871–0.71570) and low ɛ
Nd(t) values (−5.11–−8.93), suggesting the origins of the granitic rocks from crustal materials. Their Nd two-stage model ages
range from 1.37–1.68 Ga. The Sr and Nd isotopic compositions and the Nd model ages of the granitic rocks may suggest that
the giant Fogang granitic main body was generated from a heterogeneous source, with participation of mantle component. Wushi
diorite-homblende gabbro is an unusual intermediate-basic magmatic rock series, with high (87Sr/86Sr)i ratios (0.71256–0.71318) and low ɛ
Nd(t) values (−7.32–−7.92), which was possibly formed through mixing between the mantle-derived juvenile basaltic magma and the
magma produced by the dehydration melting of lower crustal basaltic rocks.
Supported by the National Natural Science Foundation of China (Grant Nos. 40221301, 401 25007 and 401 32010) |
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| Keywords: | granite higher initial 87Sr/86Sr diorite isotopic dating source component Nanling |
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