Lateral growth of the continental crust through deep level subduction–accretion: a re-evaluation of central Greek Rhodope
Lateral growth of the continental crust through deep level subduction–accretion: a re-evaluation of central Greek Rhodope
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DOI：
10.1016/s0024-4937(98)00055-3
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发表时间：
1999
期刊：
影响因子：
3.5
通讯作者：
S. Barr;S. Temperley;J. Tarney
中科院分区：
文献类型：
--
作者：
S. Barr;S. Temperley;J. Tarney
希腊北方和保加利亚南部的罗多彼地块被认为是前阿尔卑斯（可能是海西或前寒武纪）大陆地壳的一部分，在中生代和第三纪期间积极参与了欧洲边缘会聚构造。另外，我们建议，为中央希腊罗多彼，岩性协会和构造历史是一致的，通过深层次俯冲-增生，这涉及到海洋和大陆边缘的亲和力，从下盘到上盘的近连续transferral材料的过程中，向南渐进中生代地壳生长内向北的古特提斯俯冲系统。中希腊罗多彼岩包括一系列的片岩、片麻岩和混合岩，其成分变化很大，经历了强烈的构造混合。广泛产出的大理岩与斜长角闪岩、退变质榴辉岩、变质辉长岩和超镁铁质岩有关。整个地区有大量的石英-闪长片麻岩，与砂屑变杂砂岩序列、泥质岩和石英岩有关。夹层大理岩片和薄的含锰和富铁硅质带的存在是显着的。在俯冲-增生杂岩中暴露的各种组分首先向北俯冲到地壳深部，经受高压、榴辉岩相变质作用，并底侵到上覆欧亚板块的基底。后一次增生事件的特征是强烈的西南向韧性逆冲推覆作用和普遍的角闪岩相变质叠加。伴随着混合岩化作用和壳内熔体的生成，以及随后与俯冲作用有关的岩浆作用。深俯冲-增生导致大陆边缘向南生长，这反过来又导致俯冲后退，允许岩浆弧从北部侵入。随后的伸展构造折返作用使该杂岩上升到欧亚大陆南缘的现今位置。这一新的解释可能会影响到其他高品位的地形内的收敛和碰撞系统，已被假定为代表古老的或预先存在的大陆地壳。如果是这样的话，那么深层次俯冲-增生作为大陆地壳生长机制的重要性迄今被低估了。
The Rhodope Massif of northern Greece and southern Bulgaria has been variably interpreted as a fragment of pre-Alpine (possibly Hercynian or Precambrian age) continental crust that was actively involved in European margin convergent tectonics during the Mesozoic and Tertiary. Alternatively we propose that, for central Greek Rhodope, the lithological associations and tectonothermal history are consistent with progressive south-directed Mesozoic crustal growth through deep level subduction–accretion, a process which involved the near continuous transferral of material of oceanic and continental margin affinity, from footwall to hanging wall within a north-directed Palaeotethyan subduction system. Central Greek Rhodope comprises a sequence of schists, gneisses and migmatites of wide compositional variation that have undergone intense tectonic intermixing. Extensive occurrences of marble are associated with amphibolites, variably retrogressed eclogites, meta-gabbros and ultramafic rocks. Quartzo-feldspathic gneisses are abundant throughout the area, and are associated with psammitic meta-greywacke sequences, pelites and quartzites. The presence of intercalated marble slivers and thin manganiferous and iron-rich siliceous bands is significant. The various components exposed in the subduction–accretion complex were first underthrust northwards to deep crustal levels, subjected to high pressure, eclogite facies metamorphism and underplated to the base of the overriding Eurasian plate. This latter accretion event was characterised by intense southwest-directed ductile thrusting and pervasive amphibolite facies metamorphic overprinting. It was accompanied by migmatisation and intracrustal melt generation, and followed by subduction related magmatism. Deep level subduction–accretion leads to southward growth of the continental margin, which in turn leads to subduction retreat allowing the encroachment of the magmatic arc from the north. Subsequent extensional tectonic exhumation brought the complex up to its present position within the southern margin of Eurasia. This new interpretation may have implications for other high grade terrains within convergent and collisional systems that have been assumed to represent ancient or pre-existing continental crust. If so, then the importance of deep level subduction–accretion as a mechanism of continental crustal growth has hitherto been underestimated.