Characterisation of igneous terranes by zircon dating: implications for UHP occurrences and suture identification in the Central Rhodope, northern Greece
Characterisation of igneous terranes by zircon dating: implications for UHP occurrences and suture identification in the Central Rhodope, northern Greece
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通过锆石测年对火成岩地体进行表征：对希腊北部罗多彼中部超高压发生和缝合线识别的影响
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发表时间：
2010
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通讯作者：
T. Reischmann
中科院分区：
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作者：
Philippe Turpaud;T. Reischmann
超高压（UHP）和高压（HP）残留物与海洋物质的发生表明存在的缝合带内的罗多彼地块。增生的火成岩的特征及其与超高压/榴辉岩产状的关系提供了新的限制这个缝合线的位置。正片麻岩原岩的单颗粒锆石蒸发和高分辨率离子探针测年确定了两组侵入时代：石炭二叠纪和晚侏罗世-早白垩世。在构造上，晚侏罗世片麻状杂岩逆掩一个含石炭-二叠纪正片麻岩的单元。由糜棱岩、榴辉岩、角闪岩和超高压云母片岩组成的“混杂岩带”将这两个单元分隔开来。我们解释这些意见，在两个不同的火成岩，色雷斯（石炭纪）和Rhodope（晚侏罗世）岩，分离的Neuralsuture，并组装在关闭的特提斯洋盆。地球化学特征表明，晚侏罗世岩石类似于俯冲岩浆作用，可能与造成“混杂岩带”内变质沉积物超高压变质作用的俯冲作用相同。所观察到的超高压高压-高压残余物仅限于构造接触带，这表明一个单一的俯冲/碰撞事件可以解释超高压残余物和榴辉岩在中央罗多彼的发生，俯冲的岩石被折返，只有在Neuralsitu缝合。
The occurrence of ultra high pressure (UHP) and high pressure (HP) relicts associated with oceanic material suggests the presence of a suture zone within the Rhodope Massif. Characterisation of the accreted igneous terranes and their relationship with the UHP/eclogite occurrences provide new constraints on the location of this suture. Single-zircon evaporation and sensitive high-resolution ion microprobe dating of orthogneiss protoliths define two groups of intrusion ages: Permo-Carboniferous and Late Jurassic–Early Cretaceous. Structurally, the Late Jurassic gneissic complex overthrust a unit with Permo-Carboniferous orthogneisses. A “melange zone” marked by mylonites, eclogites, amphibolites, and UHP micaschists separates these two units. We interpret these observations in terms of two distinct igneous terranes, the Thracia (Permo-Carboniferous) and Rhodope (Late Jurassic) terranes, separated by the Nestos suture, and assembled during the closure of an oceanic basin of the Tethys. Geochemically, the Late-Jurassic rocks are akin to subduction magmatism, possibly the same subduction that caused the UHP metamorphism of metasediments within the “melange zone”. Observed UHP–HP relicts are restricted to the tectonic contact zone, suggesting that a single subduction/collison event can explain the occurrences of UHP relicts and eclogites in the Central Rhodope, and that subducted rocks are exhumed only within the Nestos suture.