Miocene paleotopography of the Central Alps
Miocene paleotopography of the Central Alps
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DOI：
10.1016/j.epsl.2012.05.017
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发表时间：
2012-07-01
影响因子：
5.3
通讯作者：
Mancktelow, N.
中科院分区：
文献类型：
--
作者：
Campani, M.;Mulch, A.;Mancktelow, N.
重建地表高程、地表隆起和地形起伏的历史对于了解山脉的生长、探索其地形极限以及将这些与地球动力学和地球表面过程之间的相互作用联系起来是基本的。在这里，我们的目标是通过稳定同位素古海拔测量来量化中欧阿尔卑斯山中新世的古海拔。我们方法的新颖性使我们的分析对过去的气候变化不那么敏感，因为相同年龄的稳定同位素代用品是从阿尔卑斯山造山带的高内部和邻近的前陆盆地进行分析的。前陆盆地位于或接近海平面，追踪上游降雨量和成分变化的综合影响，而高阿尔卑斯山地点还记录了海拔对降水中稳定同位素的影响。我们比较了沿Simplon滑脱与大气水相互作用的云母和绿泥石中的氢同位素比值(D)与北阿尔卑斯前陆盆地含碳酸盐古土壤的大气水组成。Simplon滑脱是一条发育在高海拔地区的主要正断层。白云母(-126‰)和绿泥石(-135V)的D值。从脆性的上盘以及邻近下盘糜棱岩中重结晶的白云母(-108ppm)和黑云母(-140ppm)提供了沿Simplon拆离的局部同构造大气水相互作用的明确证据。详细的40Ar/39Ar年代学和裂变径迹年代学将同位素交换的时间限制在14.5 Ma左右，当时下盘糜棱岩经历了韧性到脆性的转变。在中新世海平面附近发育的北阿尔卑斯山前陆古土壤中测得的成土碳酸盐中氧同位素年龄当量比值(O-18)可作为我们的低海拔参考点。这些古土壤中的O-18值变化在+19到+25ppm之间，平均值为+20ppm(约14.5 Ma)，测年精度约为100ka。利用前陆盆地和高阿尔卑斯单峰拆离带大气水组成的相对差异，我们的同位素数据与Simplon地区中中新世最小平均海拔差2350(+700/-500)m相一致。我们的结果表明，中新世阿尔卑斯山的海拔至少与今天相当，并且很可能是自那时以来大西洋衍生的水汽输送到中欧和欧亚大陆的重要障碍。(C)2012 Elsevier B.V.保留所有权利。重建地表高程、地表隆起和起伏历史对于了解山脉的增长、探索其地形界限并将这些与地球动力学和地球表面过程之间的相互作用联系起来是基本的。在这里，我们的目标是通过稳定同位素古海拔测量来量化中欧阿尔卑斯山中新世的古海拔。我们方法的新颖性使我们的分析对过去的气候变化不那么敏感，因为相同年龄的稳定同位素代用品是从阿尔卑斯山造山带的高内部和邻近的前陆盆地进行分析的。前陆盆地位于或接近海平面，追踪上游降雨量和成分变化的综合影响，而高阿尔卑斯山地点还记录了海拔对降水中稳定同位素的影响。我们比较了沿Simplon滑脱与大气水相互作用的云母和绿泥石中的氢同位素比值(D)与北阿尔卑斯前陆盆地含碳酸盐古土壤的大气水组成。Simplon滑脱是一条发育在高海拔地区的主要正断层。白云母(-126‰)和绿泥石(-135V)的D值。从脆性的上盘以及邻近下盘糜棱岩中重结晶的白云母(-108ppm)和黑云母(-140ppm)提供了沿Simplon拆离的局部同构造大气水相互作用的明确证据。详细的40Ar/39Ar年代学和裂变径迹年代学将同位素交换的时间限制在14.5 Ma左右，当时下盘糜棱岩经历了韧性到脆性的转变。在中新世海平面附近发育的北阿尔卑斯山前陆古土壤中测得的成土碳酸盐中氧同位素年龄当量比值(O-18)可作为我们的低海拔参考点。这些古土壤中的O-18值变化在+19到+25ppm之间，平均值为+20ppm(约14.5 Ma)，测年精度约为100ka。利用前陆盆地和高阿尔卑斯单峰拆离带大气水组成的相对差异，我们的同位素数据与Simplon地区中中新世最小平均海拔差2350(+700/-500)m相一致。我们的结果表明，中新世阿尔卑斯山的海拔至少与今天相当，并且很可能是自那时以来大西洋衍生的水汽输送到中欧和欧亚大陆的重要障碍。(C)2012爱思唯尔B.V.保留所有权利。
Reconstructing surface elevation, surface uplift, and relief histories is fundamental to understanding the growth of mountain ranges, to explore their topographic limits, and relate these to the interplay between geodynamic and Earth surface processes. Here, we aim to quantify Miocene paleoelevation of the Central European Alps through stable isotope paleoaltimetry. The novelty of our approach, which renders our analysis less sensitive to past climate change, is that stable isotope proxies of identical age are analyzed from both the high internal parts of the Alpine orogen and the adjacent foreland basin. Whereas the foreland basin was at or near sea level and traces the combined effects of upstream changes in rainfall amount and composition, the high Alpine site additionally records the effect of elevation on stable isotopes in precipitation. We compare hydrogen isotopic ratios (delta D) in mica and chlorite that interacted with meteoric water along the Simplon detachment, a major normal fault that developed at high elevations, with meteoric water compositions deduced from carbonate-bearing paleosols of the North-Alpine foreland basin. delta D values of muscovite (- 126 parts per thousand) and chlorite (- 135V.) from the brittle hanging wall and of recrystallized muscovite (-108 parts per thousand) and biotite (-140 parts per thousand) from adjacent footwall mylonites provide unequivocal evidence for localized syntectonic meteoric water interaction along the Simplon detachment. Detailed 40Ar/39Ar and fission track geochronology constrains the timing of isotopic exchange to ca. 14.5 Ma, when the footwall mylonites passed through the ductile to brittle transition. Age-equivalent oxygen isotope ratios (delta O-18) measured within pedogenic carbonate from North-Alpine foreland paleosols that developed near Miocene sea level serve as our low-elevation point of reference. delta O-18 values in these paleosols, dated with ca. 100 ka precision, vary between +19 and +25 parts per thousand (SMOW) with average values of +20 parts per thousand at ca. 14.5 Ma. Using the relative differences between meteoric water compositions in the foreland basin and the high Alpine Simplon detachment, our isotope data are consistent with a mid-Miocene minimum average elevation difference of 2350 (+700/-500) m for the Simplon region. Our results indicate that Miocene Alpine elevations were at least comparable to those of today and are likely to have acted as an important barrier to Atlantic-derived moisture transport into central Europe and Eurasia since that time. (C) 2012 Elsevier B.V. All rights reserved.Reconstructing surface elevation, surface uplift, and relief histories is fundamental to understanding the growth of mountain ranges, to explore their topographic limits, and relate these to the interplay between geodynamic and Earth surface processes. Here, we aim to quantify Miocene paleoelevation of the Central European Alps through stable isotope paleoaltimetry. The novelty of our approach, which renders our analysis less sensitive to past climate change, is that stable isotope proxies of identical age are analyzed from both the high internal parts of the Alpine orogen and the adjacent foreland basin. Whereas the foreland basin was at or near sea level and traces the combined effects of upstream changes in rainfall amount and composition, the high Alpine site additionally records the effect of elevation on stable isotopes in precipitation. We compare hydrogen isotopic ratios (delta D) in mica and chlorite that interacted with meteoric water along the Simplon detachment, a major normal fault that developed at high elevations, with meteoric water compositions deduced from carbonate-bearing paleosols of the North-Alpine foreland basin. delta D values of muscovite (- 126 parts per thousand) and chlorite (- 135V.) from the brittle hanging wall and of recrystallized muscovite (-108 parts per thousand) and biotite (-140 parts per thousand) from adjacent footwall mylonites provide unequivocal evidence for localized syntectonic meteoric water interaction along the Simplon detachment. Detailed 40Ar/39Ar and fission track geochronology constrains the timing of isotopic exchange to ca. 14.5 Ma, when the footwall mylonites passed through the ductile to brittle transition. Age-equivalent oxygen isotope ratios (delta O-18) measured within pedogenic carbonate from North-Alpine foreland paleosols that developed near Miocene sea level serve as our low-elevation point of reference. delta O-18 values in these paleosols, dated with ca. 100 ka precision, vary between +19 and +25 parts per thousand (SMOW) with average values of +20 parts per thousand at ca. 14.5 Ma. Using the relative differences between meteoric water compositions in the foreland basin and the high Alpine Simplon detachment, our isotope data are consistent with a mid-Miocene minimum average elevation difference of 2350 (+700/-500) m for the Simplon region. Our results indicate that Miocene Alpine elevations were at least comparable to those of today and are likely to have acted as an important barrier to Atlantic-derived moisture transport into central Europe and Eurasia since that time. (C) 2012 Elsevier B.V. All rights reserved.