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DOI | 10.1130/B32028.1 |
Origins of mafic microgranular enclaves and enclave swarms in granites: Field and geochemical relations | |
Rodriguez, Carmen1,2; Castro, Antonio1,3 | |
2019-03-01 | |
发表期刊 | GEOLOGICAL SOCIETY OF AMERICA BULLETIN |
ISSN | 0016-7606 |
EISSN | 1943-2674 |
出版年 | 2019 |
卷号 | 131页码:635-660 |
文章类型 | Article |
语种 | 英语 |
国家 | Spain; Portugal |
英文摘要 | Mafic microgranular enclaves from polygenetic and monogenetic swarms in the Gredos sector of the Central System batholith (central Spain) were sampled and studied to elucidate field, geochronological, and geochemical relations. Among-enclave variations in terms of major elements demonstrate contamination with the pelitic country rocks, and not with the host granitic magma. Magmatic enclaves from monogenetic swarms in Gredos are interpreted as fragments from the chilled margins generated at the sidewall of ascent conduits. In situ U-Pb zircon age determinations by sensitive high-resolution ion microprobe yielded two sets of ages. One corresponds to the ages of crystallization at 290 +/- 3.1 Ma and 300 +/- 3.4 Ma of two enclaves from two different monogenetic swarms. These ages are slightly younger than the zircon ages of the host granodiorites (ca. 319-312 Ma). A secondary set of ages present in the two studied samples (at 322 +/- 6.7 Ma and 320 +/- 8.5 Ma) corresponds to the age of the main Variscan regional migmatization of host Neoproterozoic pelitic metasediments. These older ages are interpreted as xenocrystic cores that were derived from the pelitic host during magma ascent. Together with the geochemical relations, they prove quenching against the regional host in conduits and not against the host granodiorite as classically thought. Monogenetic swarms can be seen as high-energy pulses denoting the switching from steady-state to transient flow regimes within magma ascent conduits. By contrast, polygenetic swarms are generated by collapse of accumulated resisters of igneous and metamorphic origin that were previously present in migmatites at the top of subhorizontal, layer-type intrusions. |
领域 | 地球科学 |
收录类别 | SCI-E |
WOS记录号 | WOS:000460031700015 |
WOS关键词 | CENTRAL SIERRA-NEVADA ; SOLIDIFICATION FRONT ; TUOLUMNE BATHOLITH ; MAGMATIC EROSION ; AVILA BATHOLITH ; IBERIAN MASSIF ; CENTRAL SYSTEM ; GREDOS MASSIF ; CENTRAL SPAIN ; ROCKS |
WOS类目 | Geosciences, Multidisciplinary |
WOS研究方向 | Geology |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/24844 |
专题 | 地球科学 |
作者单位 | 1.Univ Huelva, Dept Ciencias Tierra, Huelva 21007, Spain; 2.Univ Evora, Inst Ciencias Terra, P-7002554 Evora, Portugal; 3.Inst Geociencias IGEO CSIC, Madrid 28040, Spain |
推荐引用方式 GB/T 7714 | Rodriguez, Carmen,Castro, Antonio. Origins of mafic microgranular enclaves and enclave swarms in granites: Field and geochemical relations[J]. GEOLOGICAL SOCIETY OF AMERICA BULLETIN,2019,131:635-660. |
APA | Rodriguez, Carmen,&Castro, Antonio.(2019).Origins of mafic microgranular enclaves and enclave swarms in granites: Field and geochemical relations.GEOLOGICAL SOCIETY OF AMERICA BULLETIN,131,635-660. |
MLA | Rodriguez, Carmen,et al."Origins of mafic microgranular enclaves and enclave swarms in granites: Field and geochemical relations".GEOLOGICAL SOCIETY OF AMERICA BULLETIN 131(2019):635-660. |
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