气候变化领域集成服务门户(CCPortal): Exhumation history of the Variscan orogen in western Iberia as inferred from new K-Ar and 40Ar/39Ar data on granites from Portugal

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DOI	10.1016/j.tecto.2021.228863
	Exhumation history of the Variscan orogen in western Iberia as inferred from new K-Ar and 40Ar/39Ar data on granites from Portugal
	Hildenbrand A.; Marques F.O.; Quidelleur X.; Noronha F.
发表日期	2021
ISSN	00401951
卷号	812
英文摘要	Exhumation of the roots of collapsing orogens is a key process in the evolution of mountain belts, which is critical for the understanding of orogenic cycles. From new structural analyses, K-Ar and 40Ar/39Ar on muscovite, biotite and K-feldspar, and available U-Pb ages, we constrain the cooling and exhumation history of granitic batholiths from the main structural zones of the Variscan orogen in Iberia. We show that: (1) the oldest Ar dated granites (ca. 335 Ma on biotite) record exhumation of gneisses crystallized much earlier (up to ca. 530‐510 Ma U-Pb age); (2) granitoids crystallized at ca. 330 Ma record mostly ductile stretching (L-tectonites striking around N-S), consistent with N-S extension (Variscan intra-orogenic collapse); (3) most granites crystallized between ca. 320 and 305 Ma record ductile stretching consistent with deformation along NW-SE to ENE-WSW shear zones during the late-Variscan compression (C3); (4) granites crystallized after 305 Ma record mostly isotropic strain (no visible ductile foliation or lineation), consistent with their emplacement during/after the final collapse of the Variscan orogeny (E2); (5) comparison between Ar ages on micas and zircon U-Pb ages shows two contrasting situations: (i) similar ages, reflecting crystallization and fast cooling, which can be explained by relatively shallow intrusion and/or fast tectonic uplift; (ii) significant difference between U-Pb and Ar ages, supporting crystallization of deeper seated intrusions and their subsequent uplift for several Ma to tens of Ma; (6) thermochronological modelling on K-feldspar supports significant tectonic exhumation in the core of the chain between ca. 315 and 285 Ma, followed by late-stage passive denudation; 7) Late Carboniferous to early Permian tectonic exhumation was accompanied by significant formation of ore-deposits. Tin deposits occur in pegmatites and/or quartz veins associated with muscovite-rich syn-C3 granites and those of tungsten in quartz veins, breccia pipes and skarns associated with the E2 biotite-rich granites. © 2021 Elsevier B.V.
关键词	40Ar/39Ar and K-Ar dating 40Ar/39Ar thermochronology Collapse stage Long-term exhumation Multi-diffusion domain approach (MDD)Variscan orogeny Western Iberia
英文关键词	Argon; Binary alloys; Biotite; Deposits; Feldspar; Granite; Lead alloys; Mica; Quartz; Structural geology; Tectonics; Tin deposits; Tungsten deposits; Uranium alloys; Zircon; Ductile stretching; Orogenic collapse; Orogenic cycles; Shallow intrusions; Tectonic exhumation; Tectonic uplift; Variscan Orogen; Variscan orogenies; Potassium compounds; argon-argon dating; deformation; exhumation; granite; Hercynian orogeny; potassium-argon dating; thermochronology; uranium-lead dating; Iberian Peninsula; Portugal
语种	英语
来源期刊	Tectonophysics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/207987
作者单位	Université Paris-Saclay, CNRS, GEOPS, Orsay, 91405, France; Universidade de Lisboa, Lisboa, Portugal; Universidade do Porto, ICT, Porto, 4169-007, Portugal
推荐引用方式 GB/T 7714	Hildenbrand A.,Marques F.O.,Quidelleur X.,et al. Exhumation history of the Variscan orogen in western Iberia as inferred from new K-Ar and 40Ar/39Ar data on granites from Portugal[J],2021,812.
APA	Hildenbrand A.,Marques F.O.,Quidelleur X.,&Noronha F..(2021).Exhumation history of the Variscan orogen in western Iberia as inferred from new K-Ar and 40Ar/39Ar data on granites from Portugal.Tectonophysics,812.
MLA	Hildenbrand A.,et al."Exhumation history of the Variscan orogen in western Iberia as inferred from new K-Ar and 40Ar/39Ar data on granites from Portugal".Tectonophysics 812(2021).