From ocean depths to mountain tops: Uplift of the Troodos ophiolite (Cyprus) constrained by low‐temperature thermochronology and geomorphic analysis
From ocean depths to mountain tops: Uplift of the Troodos ophiolite (Cyprus) constrained by low‐temperature thermochronology and geomorphic analysis
复制标题
从海洋深处到山顶：特罗多斯蛇绿岩（塞浦路斯）的隆起受到低温热年代学和地貌分析的限制
DOI：
10.1002/2015tc004069
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发表时间：
2016
期刊：
影响因子：
4.2
通讯作者：
Y. Katzir
中科院分区：
文献类型：
--
作者：
N. Morag;I. Haviv;Y. Katzir
特罗多斯蛇绿岩隆升的时间和方式受到低温热年代学和地貌分析的制约。Troodos深成序列中的锆石（U-Th）/He和磷灰石裂变径迹冷却年龄均为白垩纪（83-106 Ma），与已发表的锆石U-Pb结晶年龄误差在范围内。这表明洋壳的早期冷却和扩张轴岩浆活动在~90 Ma结束。磷灰石（U-Th）/He年龄随着重建的地壳深度从席状岩墙复合体顶部附近的~40 Ma降低到地幔序列内的~4 Ma。年龄-深度曲线中的一个显著拐点确定了折返氦部分保留带的底部，并记录了主Troodos Brachoff在6 ± 2 Ma时开始快速折返。逆热模拟支持这一结论，表明隆升的时间比以前估计的要早。暴露在Troodos结构核心的地幔序列的边界密切重叠的同心带的边界划定的高局部救济和较高的通道陡度指数，表明差异折返和隆起的这一地区相对于其周围地区。该带还与一个显著的负布格重力异常重叠。特罗多斯蛇绿岩隆起的时间和模式表明，它是由蛇纹岩底辟作用驱动的，可能是由中新世沿塞浦路斯弧沿着俯冲作用的重新激活触发的。俯冲带蛇绿岩在世界范围内的普遍存在可能反映了逆冲过程中逆冲地幔楔的广泛蛇纹化作用的重要性。
The timing and mode of uplift of the Troodos ophiolite are constrained by low‐temperature thermochronology combined with geomorphic analysis. Zircon (U‐Th)/He and apatite fission track cooling ages in the Troodos plutonic sequence are all Cretaceous (83–106 Ma) and within error of published zircon U‐Pb crystallization ages. This indicates early cooling of the oceanic crust and termination of spreading axis magmatism at ~90 Ma. Apatite (U‐Th)/He ages decrease with reconstructed crustal depths from ~40 Ma near the top of the sheeted‐dike complex to ~4 Ma within the mantle sequence. A prominent inflection point in the age versus depth curve defines the bottom of the exhumed helium partial retention zone and records the onset of rapid exhumation of the main Troodos massif at 6 ± 2 Ma. Inverse thermal modeling supports this conclusion, indicating that the timing of uplift is earlier than previously estimated. The boundaries of the mantle sequence exposed in the core of the Troodos structure closely overlap the boundaries of a concentric zone delineated by high local relief and higher channel steepness indices, indicating differential exhumation and uplift of this area relative to its surroundings. This zone also overlaps with a prominent negative Bouguer gravity anomaly. The timing and pattern of the Troodos ophiolite uplift suggest that it is driven by serpentinite diapirism, possibly triggered by Miocene reactivation of subduction along the Cyprean Arc. The worldwide ubiquity of suprasubduction zone ophiolites may thus reflect the importance of extensive serpentinization at the overthrusting mantle wedge in obduction processes.