Accurately dating phenocrysts in Holocene volcanic rocks poses many challenges but is critical to placing magmatic processes that occur prior to eruption into a temporal frame-work. We dated alkali feldspar (i.e., orthoclase Or10 to Or46) crystals in four young phonolites from the Teide–Pico Viejo volcanic complex, Tenerife (Spain), using (226Ra)/(230Th) isotopes. Partition coefficients of Ra (DRa) and DRa/DBa of feldspars were predicted using an approach based on the lattice strain model, which yielded crystallization ages that overlap or predate known eruption ages for the Lavas Negras (ca. 1 ka), Montaña Blanca (ca. 2 ka), Arenas Blancas (ca. 2–4 ka), and Teide H (ca. 6 ka) phonolites. Crystallization of feldspar may occur up to the time of eruption, with >8 ka crystals also present, possibly suggesting extended magma differentiation times. However, feldspars yielding finite (226Ra)/(230Th) ages are mostly in equilibrium with the groundmass, unlike >8 ka crystals, which were therefore identified as antecrysts/xenocrysts. The 87Sr/86Sr ratios of feldspars indicate that crystallization predated late-stage assimilation, affecting 87Sr/86Sr ratios of some melts. The (226Ra)/(230Th) ages also constrain the tempo of phonolite magma evolution on Tenerife. Integration of (226Ra)/(230Th) ages with feldspar major elements, trace elements, and isotopes provides a powerful means for investigating crystallization histories using a dominant mineral that controls the overall magmatic evolution of phonolites on thousand-year time scales.Accurately dating crystals in rocks from active volcanoes has been an elusive goal. Most methods provide an eruption age (e.g., 40Ar/39Ar dating) that is useful in reconstructing the eruption history of a volcano (Lanphere et al., 2007; Ramos et al., 2016; Preece et al., 2018) but offers limited pre-eruption crystal-lization and magmatic information. In contrast, feldspar (226Ra)/(230Th) crystallization ages provide (1) eruption age constraints, (2) time frames connected to magma differentiation reflected in feldspar Ca, Ba, and Sr variations, and (3) links to magmatic sources when correlated to Sr and Pb isotopes in the same feldspars (Ramos et al., 2019). The unmatched ability to determine such constraints at a single-crystal level using a dominant mineral such as feldspar can elucidate the time scales over which magmas crystallize, evolve, and reside prior to eruption. The volcanically active island of Tenerife in the Canary Islands, Spain (Fig. 1), home to Las Cañadas caldera and the Teide–Pico Viejo (T-PV) complex, provides an opportunity to use feldspar (226Ra)/(230Th) ages to evaluate Holocene phonolitic magma evolution. The origins of recent T-PV phonolitic eruptions are enigmatic, and feldspar ages, major and trace elements, and isotopes can be used to identify the processes affecting magmas, potential magmatic sources, and the time scales of magmatic differentiation and storage. The timing of phonolite evolution is controversial given that most uranium-series isotopes reflect disequilibrium (Turner et al., 2017), but (226Ra)/(230Th) ages better constrain these time scales.The island of Tenerife results from the Canary hotspot, which appeared at ca. 70 Ma (Geldmacher et al., 2001). The volcanic evolution of Tenerife involved construction of a basaltic shield complex starting at ca. 12 Ma, followed by formation of a central mafic-phonolitic volcanic complex and the Las Cañadas edifice from ca. 3.8 Ma onward, including several basanite to phonolite magmatic cycles (Fuster et al., 1968; Ancochea et al., 1990; Cas et al., 2022).The Las Cañadas edifice is composed of the post-shield, volcanic Lower Group (3.5–1.59 Ma) overlain by the Upper Group (1.59–0.175 Ma), which consists of the Ucanca (1.59–1.18 Ma), Guajara (0.85–0.57 Ma), and Diego Hernández (0.37 to ca. 0.18 Ma) formations (Huertas et al., 2002; Brown et al., 2003; Edgar et al., 2007). The Upper Group mafic to felsic volcanic cycles ended with voluminous (5–15 km3) pyroclastic eruptions that produced numerous east-to-west–migrating caldera collapses (Martí et al., 1994; Cas et al., 2022). The most recent, ca. 0.18 Ma, resulted in the present form of Las Cañadas caldera, a 16 × 9 km depression in the center of Tenerife (Fig. 1). Younger, predominately effusive activity within the caldera formed two stratovolcanoes, Teide and Pico Viejo, as well as Montaña Blanca and other satellite vents (Ablay et al., 1995, 1998), which represent more explosive volcanism (García et al., 2012; Dorado et al., 2021). Along with monogenetic basaltic volcanism outside the caldera, the T-PV complex is the focus of most of the current activity on Tenerife, with 13 identified eruptions in the past ~2 k.y. (Geyer and Martí, 2010; Di Roberto et al., 2016).We collected four phonolitic lavas (Fig. 1) from Las Cañadas caldera (Table 1). Lavas were processed to obtain clean groundmass and feldspar crystals/fragments (Figs. S1 and S2 in the Supplemental Material1) using procedures described in the Supplemental Material. Major elements of alkali feldspar were analyzed by microprobe (Table S5; Fig. S3), and partition coefficients DCa, DSr, and DBa were determined using the concentrations measured from groundmass and feldspar (Table S1); these were then used to construct Onuma curves (Figs. S4–S7) to predict DRa and DRa/DBa of feldspars (Onuma et al., 1968). Groundmass and feldspar Ra concentrations were then age corrected to determine the age at which the calculated feldspar DRa/DBa was recorded (Tables S2 and S4; Fig. S8); this was interpreted as the crystallization age of the feldspar. Additionally, we measured Sr and Pb isotopes of groundmass and individual feldspar crystals/fragments/separates (Table S3).Alkali feldspars in Tenerife phonolites reflect a range of ages, major and trace elements, and isotope ratios (Figs. 2 and 3) that constrain the timing of petrogenetic processes. We place these feldspar variations in the context of (226Ra)/(230Th) ages for T-PV eruptions.The Lavas Negras lava flow, which has a 14C eruption age of 1150 ± 140 yr B.P. (Carracedo et al., 2007) and a K/Ar age of 800 ± 300 a (Quidelleur et al., 2001), hosts feldspars that vary from orthoclase Or16 to Or31, with many having higher Or cores (Fig. 2A). Lavas Negras feldspars reflect two populations. One population has an average age of ca. 1.3 ka (n = 4; Fig. 3A) with individual ages overlapping the eruption age, consistent with crystallization occurring up to the time of eruption with little crystal residence time. Ba and Sr concentrations vary widely (1716–2849 ppm and 200–502 ppm, respectively). A second population does not yield parabolic Onuma curves for divalent cations, likely due to compositional zoning, and so crystallization ages were not calculated because the assumption of crystal-melt equilibrium cannot be valid. These feldspars have overlapping but different Ba and Sr concentrations (1126–5503 ppm and 88–374 ppm, respectively) as compared to the first population of feldspars. The 87Sr/86Sr ratios (~0.7032 versuŝ0.7031) and 208Pb/206Pb ratios (~2.002) of groundmass are similar to both feldspar populations (Fig. 3), consistent with closed-system differentiation.Feldspars from the 2025 ± 40 a (Ablay et al., 1995) Montaña Blanca lava have similar compositions to those from Lavas Negras (Fig. 2B), with only slightly higher Or (Or20 to Or33). Single feldspars and the feldspar separate have Ba concentrations of ~5000–7000 ppm and Sr of ~300–460 ppm. All single feldspars/fragments >1 mg were however “dead” to radium (i.e., contained no measurable radium as a result of 226Ra decay in the absence of parental 230Th, which is incompatible in feldspar) and older than 8 ka (Fig. 3B). The feldspar separate, which is composed of ~20 individual <1 mg crystals, yielded an age of 5331 ± 533 a. This younger age likely results from the presence of both old (>8 ka) >1 mg and young (<8 ka) <1 mg feld-spars. Mineral separate results indicate larger feldspars are likely antecrystic/xenocrystic compared to younger, smaller phenocryst ~1 mg in mass. Ages of feldspar in Montaña Blanca high-light the importance of dating both single-crystal and feldspar separates in lavas with mixed feld-spar populations.Montaña Blanca antecrystic or xenocrystic feldspars are characterized by less radiogenic 87Sr/86Sr (0.7031 vs. 0.7047) and higher 208Pb/206Pb ratios (>2.005 versus ~2.003) compared to accompanying groundmass, confirming that feldspar crystallization predated the open-system effects that affected the melt. In addition, variable isotope ratios between the groundmass and feldspar undermined crystalmelt equilibrium.The Arenas Blancas lava has not been dated but directly underlies the ca. 2 ka Montaña Blanca flow (Fig. 1; Ablay and Martí, 2000). Feldspars in this phonolite fall into at least two compositional populations, one with Or < 25 and a second with Or25–32 (Fig. 2C). The first population has lower Or, higher CaO (1.4 wt%), and radium “dead” antecrystic or xenocrystic feldspars. Ba and Sr concentrations are >5000 ppm and >318 ppm, respectively. The second feldspar population with higher Or has lower CaO (~0.96 wt%) and uniform Ba and Sr concentrations (~2200 and ~125 ppm, respectively). These feldspars yielded ages of ca. 4 ka (Fig. 3), and they provide an upper age limit for the Arenas Blancas eruption. The presence of >8 ka feldspar, however, indicates that the Arenas Blancas magma remobilized preexisting antecrysts/xenocrysts.Arenas Blancas groundmass is characterized by slightly higher 87Sr/86Sr ratios (0.7035 versus 0.7032) than feldspars, confirming latestage assimilation after ca. 4 ka. To test whether added Sr from assimilation could affect DRa and feldspar ages, the effects of adding 25% and 50% of total groundmass Sr (i.e., 2 or 4 ppm of 8 ppm total) from assimilation were estimated (see the Supplemental Material). Calculated ages, however, varied by ~10% for both, which is the error for ca. 4 ka feldspars, and so Ra/Th feldspar ages are assumed to be robust despite minor assimilation. In contrast to Sr, phenocryst 208Pb/206Pb ratios overlap the groundmass.Teide H, located along the northern flank of Teide outside Las Cañadas caldera proper, is the oldest phonolite considered here. Teide H feldspars reflect at least two compositions, Or > 36 and Or15–29. The lower Or population is also shifted toward higher CaO concentrations. The feldspar separate was radium “dead,” and so single feldspar crystals were not analyzed. As a result, the only age constraint for this flow comes from an ~6000 yr maximum melt (226Ra)/(230Th) age (Brown, 2021). Teide H feldspars have similar 87Sr/86Sr ratios to the groundmass (0.7032 versus 0.7033) but more radiogenic 208Pb/206Pb (>2.005 versus 2.002), indicating that Teide H feldspars are likely antecrystic or xenocrystic and do not reflect crystal-melt equilibrium.Feldspar ages from Tenerife phonolites illuminate magmatic and petrogenetic characteristics of phonolitic volcanism and are consistent with preexisting age constraints. Such ages provide a direct, unequivocal means of distinguishing phenocrysts from antecrysts/xenocrysts and therefore offer petrogenetic insights when accompanied by chemical profiles and Sr and Pb isotopes of the same crystals.Three of the phonolites host >8 ka feldspars that are several thousands of years older than their eruption ages. In the Arenas Blancas lava, these antecrysts/xenocrysts are accompanied by phenocrysts in Pb isotopic equilibrium with the groundmass, indicating a maximum residence time of 2 k.y. In contrast, apparent phenocrysts in Montana Blanca are out of Pb isotope equilibrium with the groundmass (Table S3). The youngest phonolite (Lavas Negras) hosts anorthoclase phenocrysts that formed within a few hundred years of eruption, plus a zoned crystal population of unknown age. Whole rocks and most crystals yielding finite Ra ages have similar Pb isotope ratios (Fig. 3), suggesting derivation from a common reservoir feeding Teide phonolite eruptions during the past few thousand years. In Arenas Blancas and Montaña Blanca, the youngest feldspars are in equilibrium with the groundmass, whereas the >8 ka crystals span a range of Pb isotope ratios (Tables S2 and S3). Pb isotope ratios are variable (208Pb/206Pb = 1.969–2.030) in older Tenerife rocks (Palacz and Wolff, 1989; Simonsen et al., 2000). Therefore, the most parsimonious explanation is that the older crystals are xenocrysts introduced during assimilation of older rocks. Alternatively, they could be crystals derived from an isotopically variable, crystal-rich mush reservoir. The Ra-bearing Lavas Negras feldspars also span a range in Pb isotope ratios, consistent with the presence of an assimilant that affected the melt that crystallized feldspar much younger than 8 ka.For T-PV phonolites, Sr and Pb isotopes in feldspar phenocrysts and host groundmass were generally in equilibrium prior to latestage assimilation. Groundmass 87Sr/86Sr and 143Nd/144Nd are near-constant at ~0.7031 and ~0.51288, respectively, consistent across the whole island (Simonsen et al., 2000), with the exception of high 87Sr/86Sr in some Sr-poor phonolites. Elevated 87Sr/86Sr ratios are likely due to seawater contamination (Palacz and Wolff, 1989), either directly or through assimilation of seawater-altered rock, although feldspars in the rocks remained unaffected (Fig. 3; Table S3). Seawater has low Pb contents and thus would have had limited impact on 208Pb/206Pb during alteration. Feldspar crystals, whether phenocrystic or xenocrystic, retained 87Sr/86Sr of ~0.7031–0.7032 (Fig. 3) but variable 208Pb/206Pb, with xenocrysts commonly retaining higher 208Pb/206Pb. These older remobilized feldspars retained different Pb signatures to their host melts, which likely originated from inheritance from feldspar crystallizing in magmas with variable 208Pb/206Pb values.The (226Ra)/(230Th) ages of individual feldspar crystals in young (<8 ka) Tenerife phonolites are consistent with previously determined eruption ages and stratigraphic constraints, better constrain the ages of undated lavas, and serve to identify xenocryst/antecryst populations. Lavas Negras hosts the youngest crystals (ca. 1.0 ka to 1.4 ka) that formed up to the time of eruption without the effects of late-stage assimilation. These feldspars have limited Sr and Pb isotopic variations that support crystal-melt equilibrium. In contrast, alkali feldspars from Montaña Blanca are >8 ka and likely xenocrystic, although a separate yielding a younger age (ca. 5.4 ka) indicates the presence of younger (<8 ka) crystals <1 mg in mass. Arenas Blancas phonolite hosts a mixed population of older (>8 ka) antecrysts or xenocrysts and younger (ca. 4 ka) phenocrysts, which are clearly identified in both major and trace elements, while the separate from the oldest Teide H phonolite is composed of feldspar >8 ka with Pb isotopes indicating a likely antecrystic or xenocrystic origin. The 208Pb/206Pb ratios indicate that phonolitic lavas were also associated with a limited range of parental magmas, while 87Sr/86Sr ratios are uniform and similar to most lavas erupted on Tenerife unless affected by late-stage assimilation. The contrast between feldspars with finite (226Ra)/(230Th) ages and Ra-dead crystals that are out of equilibrium with the groundmass serves to unequivocally distinguish phenocrysts from antecrysts/xenocrysts and places direct constraints on the tempo of magmatic evolution. Time scales of ~1000 years are consistent with calculated evolution times for phonolites (Wolff, 2017) and somewhat shorter than those for rhyolitic systems (Bachmann and Bergantz, 2004). Integration of (226Ra)/(230Th) ages with feldspar major elements, trace elements, and isotopes provides a powerful pathway for investigating crystallization histories using a dominant mineral phase that controls the overall magmatic evolution of Tenerife phonolites on thousand-year time scales.This research was funded by the New Mexico State University Johnson Mass Spectrometry Laboratory (Las Cruces, New Mexico) and a Geological Society of America Lipman Grant awarded to Brown. Dorado was supported by a Spanish FPU (Training programme for Academic Staff) grant (FPU18/02572), a mobility grant (EST19/00297) from the Ministry of Universities of Spain, and the European Commission European Volcano Early Warning System (EVE) (ref. DG ECHO H2020 826292). We also express our appreciation to Scott Boroughs for technical assistance, and Graham Edwards and Mark Stelton for thoughtful reviews of the manuscript.

中文翻译：

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释放碱性长石：Ra/Th 年龄以及对全新世硬岩浆岩浆作用的化学和同位素约束，加那利群岛

对全新世火山岩中的斑晶进行准确测年提出了许多挑战，但对于将喷发前发生的岩浆过程纳入时间框架至关重要。我们使用（226Ra）/（230Th）同位素对来自特内里费岛（西班牙）泰德-皮科维耶霍火山复合体的四个年轻音长石晶体中的碱性长石（即正长石 Or10 至 Or46）晶体进行了测定。使用基于晶格应变模型的方法预测长石的 Ra (DRa) 和 DRa/DBa 分配系数，该方法产生的结晶年龄与 Lavas Negras (ca. 1 ka)、Montaña Blanca ( ca. 2 ka)、Arenas Blancas (ca. 2–4 ka) 和 Teide H (ca. 6 ka) 音岩。长石的结晶可能会在喷发时发生，同时也存在大于 8 ka 的晶体，这可能表明岩浆分化时间延长。然而，产生有限 (226Ra)/(230Th) 年龄的长石大多与基体平衡，这与>8 ka 的晶体不同，因此被确定为前晶/异晶。长石的 87Sr/86Sr 比值表明结晶早于后期同化，影响了一些熔体的 87Sr/86Sr 比值。(226Ra)/(230Th) 年龄也限制了特内里费岛的响岩岩浆演化速度。(226Ra)/(230Th) 年龄与长石主要元素、微量元素和同位素的整合提供了一种强有力的手段，可以使用一种主导矿物来研究结晶历史，这种矿物在千年时间尺度上控制着响岩的整体岩浆演化。准确地确定晶体年代来自活火山的岩石一直是一个难以捉摸的目标。大多数方法提供了喷发年龄（例如，40Ar/39Ar 测年）可用于重建火山的喷发历史（Lanphere 等，2007；Ramos 等，2016；Preece 等，2018），但提供的喷发前结晶和岩浆信息有限. 相比之下，长石 (226Ra)/(230Th) 结晶年龄提供 (1) 喷发年龄限制，(2) 与反映在长石 Ca、Ba 和 Sr 变化中的岩浆分异相关的时间框架，以及 (3) 当与同一长石中的 Sr 和 Pb 同位素相关（Ramos 等人，2019 年）。使用长石等主要矿物在单晶水平上确定此类限制的无与伦比的能力可以阐明岩浆在喷发前结晶、演化和停留的时间尺度。西班牙加那利群岛火山活跃的特内里费岛（图1），Las Cañadas 破火山口和 Teide-Pico Viejo (T-PV) 复合体的所在地，提供了使用长石 (226Ra)/(230Th) 年龄来评估全新世声岩岩浆演化的机会。近期T-PV声岩喷发的起源是神秘的，长石年龄、主量元素和微量元素以及同位素可用于识别影响岩浆的过程、潜在的岩浆来源以及岩浆分化和储存的时间尺度。鉴于大多数铀系列同位素反映了不平衡状态（Turner et al., 2017），但（226Ra）/（230Th）年龄更好地限制了这些时间尺度。特内里费岛来自加那利热点，出现在约。70 Ma（Geldmacher 等人，2001 年）。特内里费岛的火山演化涉及从 ca 开始建造玄武岩盾构复合体。12 Ma，随后形成中央镁铁质-声岩火山杂岩和大约从 ca 开始的 Las Cañadas 大厦。3.8 Ma 以后，包括几个玄武岩到音岩岩浆旋回（Fuster et al., 1968; Ancochea et al., 1990; Cas et al., 2022）。 3.5–1.59 Ma) 被上群 (1.59–0.175 Ma) 覆盖，该群由 Ucanca (1.59–1.18 Ma)、Guajara (0.85–0.57 Ma) 和 Diego Hernández (0.37 至约 0.18 Ma) 地层组成 ( Huertas 等人，2002；Brown 等人，2003；Edgar 等人，2007）。上群镁铁质到长英质火山循环以大量（5-15 km3）火山碎屑喷发结束，这些喷发产生了许多东西向迁移的破火山口崩塌（Martí 等，1994；Cas 等，2022）。最近的，约。0.18 Ma，形成了现在的 Las Canadas 火山口，特内里费岛中心一个 16 × 9 公里的洼地（图 1）。火山口内较年轻的、主要是活跃的活动形成了两个平流火山 Teide 和 Pico Viejo，以及 Montaña Blanca 和其他卫星喷口（Ablay 等人，1995 年，1998 年），它们代表了更具爆炸性的火山活动（García 等人，2012 年；多拉多等人，2021）。除了破火山口外的单一成因玄武质火山活动外，T-PV 复合体是特内里费岛当前大部分活动的焦点，在过去约 2 世纪内发现了 13 次火山喷发（Geyer 和 Martí，2010；Di Roberto 等，2016 )。我们从 Las Canadas 火山口（表 1）收集了四个 phonolitic 熔岩（图 1）。使用补充材料中描述的程序处理熔岩以获得干净的基质和长石晶体/碎片（补充材料中的图 S1 和 S2）。通过微探针分析碱性长石的主要元素（表 S5；图 S3），并使用从地块和长石中测量的浓度确定分配系数 DCa、DSr 和 DBa（表 S1）；然后将这些用于构建 Onuma 曲线（图 S4-S7）以预测长石的 DRa 和 DRa/DBa（Onuma 等人，1968 年）。然后对地块和长石 Ra 浓度进行年龄校正，以确定记录计算出的长石 DRa/DBa 的年龄（表 S2 和 S4；图 S8）；这被解释为长石的结晶时代。此外，我们测量了地块和单个长石晶体/碎片/分离体的 Sr 和 Pb 同位素（表 S3）。2和3）限制了成岩过程的时间。我们将这些长石变化置于 T-PV 喷发的 (226Ra)/(230Th) 年龄的背景下。 Lavas Negras 熔岩流，其 14C 喷发年龄为 1150 ± 140 年 BP (Carracedo et al., 2007) 和a K/Ar 年龄为 800 ± 300 a (Quidelleur et al., 2001)，长石从正长石 Or16 到 Or31 不等，其中许多具有更高的 Or 核心（图 2A）。Lavas Negras 长石反映了两个种群。一个人口的平均年龄约为。1.3 ka（n = 4；图 3A），个别年龄与喷发年龄重叠，这与在喷发时发生的结晶相一致，晶体停留时间很小。Ba 和 Sr 浓度变化很大（分别为 1716-2849 ppm 和 200-502 ppm）。第二个群体不会产生二价阳离子的抛物线大沼曲线，可能是由于成分分区，因此没有计算结晶年龄，因为晶体 - 熔体平衡的假设不成立。与第一批长石相比，这些长石具有重叠但不同的 Ba 和 Sr 浓度（分别为 1126-5503 ppm 和 88-374 ppm）。地块的 87Sr/86Sr 比率（~0.7032 与 0.7031）和 208Pb/206Pb 比率（~2.002）与两种长石种群相似（图 3），与封闭系统分化一致。来自 2025 ± 40 a ( Ablay et al., 1995) Montaña Blanca 熔岩具有与 Lavas Negras 相似的成分（图 2B），仅略高 Or（Or20 至 Or33）。单长石和长石分离的 Ba 浓度约为 5000–7000 ppm，Sr 浓度约为 300–460 ppm。所有单长石/碎片 > 然而，1 mg 对镭“死”（即，由于 226Ra 在没有亲本 230Th 的情况下衰变而不含可测量的镭，这在长石中是不相容的）并且超过 8 ka（图 3B）。由约 20 个单独的 <1 mg 晶体组成的长石分离物产生的年龄为 5331 ± 533 a。这种较年轻的年龄可能是由于存在老的（>8 ka）>1 mg 和年轻的（<8 ka）<1 mg 的长石。矿物分离结果表明，与质量约 1 毫克的较年轻、较小的斑晶相比，较大的长石可能是前晶/异晶。Montaña Blanca 的长石年龄强调了在混合长石种群的熔岩中确定单晶和长石分离年代的重要性。Montaña Blanca 前晶或异晶长石的特征在于放射性较少的 87Sr/86Sr（0.7031 对 0.000）。7047）和更高的 208Pb/206Pb 比率（>2.005 对 ~2.003）与伴随的基体相比，证实长石结晶早于影响熔体的开放系统效应。此外，地块和长石之间的不同同位素比率破坏了结晶熔体平衡。Arenas Blancas 熔岩尚未确定年代，但直接位于约 10 年。2 ka Montaña Blanca 流（图 1；Ablay 和 Martí，2000 年）。这种响岩中的长石至少分为两个组成种群，一个是 Or < 25，另一个是 Or25-32（图 2C）。第一个种群具有较低的 Or、较高的 CaO（1.4 wt%）和镭“死”的前晶或异晶长石。Ba 和 Sr 浓度分别为 >5000 ppm 和 >318 ppm。具有较高 Or 的第二个长石群具有较低的 CaO (~0. 96 wt%）和均匀的 Ba 和 Sr 浓度（分别为 ~2200 和 ~125 ppm）。这些长石产生了大约年龄。4 ka（图 3），它们为 Arenas Blancas 喷发提供了年龄上限。然而，>8 ka 长石的存在表明 Arenas Blancas 岩浆重新活化了先前存在的前晶/异种晶。Arenas Blancas 地块的 87Sr/86Sr 比值（0.7035 对 0.7032）略高于长石，这证实了大约在 ca. 4卡。为了测试从同化中添加的 Sr 是否会影响 DRa 和长石年龄，估计了从同化中添加 25% 和 50% 的总地面质量 Sr（即 8 ppm 的 2 或 4 ppm）的影响（见补充材料）。然而，计算的年龄对于两者都有约 10% 的差异，这是 ca 的误差。4 ka长石，因此，尽管有轻微的同化作用，但 Ra/Th 长石年龄被认为是稳健的。与 Sr 相比，斑晶 208Pb/206Pb 的比率与地块重叠。位于 Las Canadas 火山口外的 Teide 北侧的 Teide H 是这里考虑的最古老的响岩。Teide H 长石反映了至少两种成分，即 Or > 36 和 Or15-29。较低的 Or 种群也向较高的 CaO 浓度移动。分离的长石是“死”镭，因此没有分析单个长石晶体。因此，这种流动的唯一年龄限制来自约 6000 年的最大熔体 (226Ra)/(230Th) 年龄（布朗，2021 年）。Teide H 长石具有与地块相似的 87Sr/86Sr 比率（0.7032 对 0.7033），但放射性更强的 208Pb/206Pb（>2.005 对 2.002），表明 Teide H 长石可能是前晶型或异晶型的，不反映晶体熔体平衡。来自特内里费岛音岩的长石年龄阐明了音岩火山活动的岩浆和岩石成因特征，并且与先前存在的年龄限制一致。这样的年龄提供了一种直接、明确的方法来区分斑晶与前晶/异种晶，因此当伴随着相同晶体的化学剖面和 Sr 和 Pb 同位素时，可以提供岩石成因见解。三个 phonolites 承载 >8 ka 长石，这些长石是几千年比它们的喷发年龄还要大。在 Arenas Blancas 熔岩中，这些前晶/异晶伴随着与基体 Pb 同位素平衡的斑晶，表明最大停留时间为 2 ky。蒙大拿布兰卡的明显斑晶与地层的 Pb 同位素不平衡（表 S3）。最年轻的响岩（Lavas Negras）拥有在喷发后几百年内形成的斜长石斑晶，以及年龄未知的带状晶体群。产生有限 Ra 年龄的整块岩石和大多数晶体具有相似的 Pb 同位素比（图 3），这表明在过去的几千年中，它们是由一个常见的储层喂养泰德响岩喷发的。在 Arenas Blancas 和 Montaña Blanca，最年轻的长石与地层处于平衡状态，而大于 8 ka 的晶体跨越了一系列 Pb 同位素比（表 S2 和 S3）。在较老的特内里费岩石中，Pb 同位素比率是可变的（208Pb/206Pb = 1.969–2.030）（Palacz 和 Wolff，1989；Simonsen 等，2000）。所以，最简单的解释是，较老的晶体是在较老的岩石同化过程中引入的异种晶体。或者，它们可能是源自同位素可变、富含晶体的糊状储层的晶体。含 Ra 的 Lavas Negras 长石也跨越了 Pb 同位素比的范围，这与影响熔体的同化物的存在一致，该熔体使长石结晶的时间远低于 8 ka。对于 T-PV 响岩，长石斑晶和 Sr 和 Pb 同位素宿主地层在最晚同化之前通常处于平衡状态。地面质量 87Sr/86Sr 和 143Nd/144Nd 分别接近恒定在 ~0.7031 和 ~0.51288，在整个岛屿上是一致的（Simonsen 等，2000），除了一些 Sr 贫乏的海岩中的高 87Sr/86Sr。升高的 87Sr/86Sr 比率可能是由于海水污染（Palacz 和 Wolff，1989 年），直接或通过海水改变的岩石同化，尽管岩石中的长石没有受到影响（图 3；表 S3）。海水铅含量低，因此在蚀变过程中对 208Pb/206Pb 的影响有限。长石晶体，无论是斑晶还是异晶，保留 87Sr/86Sr 约为 0.7031–0.7032（图 3），但变化为 208Pb/206Pb，异晶通常保留更高的 208Pb/206Pb。这些较老的再活化长石对其宿主熔体保留了不同的 Pb 特征，这可能源于长石在具有可变 208Pb/206Pb 值的岩浆中结晶的遗传。年轻（< 8 ka) Tenerife phonolites 与先前确定的喷发年龄和地层限制一致，更好地限制了未定年熔岩的年龄，并用于识别异晶/前晶种群。Lavas Negras 拥有最年轻的晶体（约 1.0 ka 至 1.4 ka），这些晶体在喷发时形成，没有后期同化的影响。这些长石具有有限的 Sr 和 Pb 同位素变化，支持晶体熔体平衡。相比之下，来自 Montaña Blanca 的碱性长石 >8 ka 并且可能是异晶，尽管单独产生的年龄较小（约 5.4 ka）表明存在质量小于 1 mg 的较年轻（<8 ka）晶体。Arenas Blancas phonolite 拥有年龄较大 (>8 ka) 前晶或异晶和较年轻 (ca. 4 ka) 斑晶的混合种群，在主要元素和微量元素中都可以清楚地识别出来，而与最古老的 Teide H 音岩分开的是由 > 8 ka 的长石组成，其中 Pb 同位素表明可能是前晶或异晶起源。208Pb/206Pb 比率表明，声质熔岩也与有限范围的母岩浆有关，而 87Sr/86Sr 比率是均匀的，与特内里费岛喷发的大多数熔岩相似，除非受到后期同化的影响。具有有限 (226Ra)/(230Th) 年龄的长石与与基体不平衡的 Ra-dead 晶体之间的对比有助于明确区分斑晶与前晶/异种晶，并直接限制岩浆演化的速度。大约 1000 年的时间尺度与计算的音岩演化时间一致（Wolff，2017），并且比流纹岩系统的时间短一些（Bachmann 和 Bergantz，2004）。(226Ra)/(230Th) 年龄与长石主量元素、微量元素和同位素的整合为使用控制特内里费风岩在千年时间尺度上的整体岩浆演化的主导矿物相提供了研究结晶历史的有力途径。研究由新墨西哥州立大学约翰逊质谱实验室（新墨西哥州拉斯克鲁塞斯）和美国地质学会利普曼授予布朗的资助。Dorado 得到了西班牙 FPU（学术人员培训计划）赠款 (FPU18/02572)、西班牙大学部的流动性赠款 (EST19/00297) 和欧盟委员会欧洲火山预警系统 (EVE) 的支持。参考 DG ECHO H2020 826292）。