FORMATION AND EMPLACEMENT AGES OF THE SSZ-TYPE NEOTETHYAN OPHIOLITES IN CENTRAL ANATOLIA, TURKEY: PALAEOTECTONIC IMPLICATIONS
FORMATION AND EMPLACEMENT AGES OF THE SSZ-TYPE NEOTETHYAN OPHIOLITES IN CENTRAL ANATOLIA, TURKEY: PALAEOTECTONIC IMPLICATIONS
复制标题
土耳其安纳托利亚中部 SSZ 型新乙阶蛇绿岩的形成和安置年龄：古构造意义
DOI：
10.4454/ofioliti.v25i2.123
复制
发表时间：
2000
期刊：
影响因子：
1.3
通讯作者：
S. Özkan
中科院分区：
文献类型：
--
作者：
Kenan M. Yaliniz;M. C. Göncüoğlu;S. Özkan
被肢解的蛇绿岩的孤立露头作为异地单元（中安纳托利亚蛇绿岩，CAO）出现在中安纳托利亚晶体杂岩中，代表了牛里德-阿纳托里德台地变质的被动北边缘。地层观测和化学数据均表明，CAO 形成于新特提斯洋瓦尔达尔-伊兹密尔-安卡拉-埃尔津坎 (VIAE) 段内的超俯冲带（前弧）环境中。
萨里卡拉曼蛇绿岩的表蛇绿岩沉积盖层是 CAO 的代表单元，其特征是外碎屑、火山成因、深海沉积物，后者夹有泥石流。在该单元最低层的中上层成员中发现的最重要的浮游有孔虫群落表明其年龄为早中土伦阶到早桑托阶。从侵入基底岩石和 Sarikaraman 蛇绿岩的碰撞后花岗岩中收集的 K/Ar 数据 (81-65 Ma) 表明 CAO 的侵位年龄为早桑托尼世到中坎帕尼世之前。大量的外碎屑火山沉积物与 CAO 的远洋石灰岩和放射虫沉积物交替出现，表明沉积环境是邻近火山弧的边缘海。泥石流的发生还表明沉积盆地受到构造作用的影响，导致先前存在的单元以及弧衍生的火山和沉积物发生重大滑动和质量重力改造。
将 CAO 的地层、形成和仰冲年龄与新特提斯 VIAE 段东部（土耳其）和西部（希腊）的其他超俯冲带型蛇绿岩进行了比较。这一比较表明，西部洋内俯冲肯定更古老。因此，我们推测，在该海洋分支闭合期间，重要的转换断层将 VIAE 海洋内的大陆微板块（例如牛里德-阿纳托里德微板块）分开。
Isolated outcrops of dismembered ophiolitic rocks occur as allochthonous units (Central Anatolian Ophiolites, CAO) in the Central Anatolian Crystalline Complex, which represents the metamorphosed passive northern edge of the Tauride- Anatolide Platform. Both stratigraphic observations and chemical data indicate that the CAO formed in a supra-subduction zone (fore arc) setting within the Vardar-Izmir- Ankara-Erzincan (VIAE) segment of the Neotethys.
The epi-ophiolitic, sedimentary cover of the Sarikaraman Ophiolite, which is a representative unit of the CAO, is characterized by epiclastic, volcanogenic, deep-sea sediments, with the latter being intercalated with debris-flows. The most significant planktonic foraminiferal association found in the lowest pelagic member of this unit indicates an early-middle Turonian to early Santonian age. K/Ar data (81-65 Ma) collected from post-collisional granitoids intruding both the basement rocks and the Sarikaraman Ophiolite imply a post-early Santonian to pre-middle Campanian emplacement age for the CAO. The high volume of epiclastic volcanogenic sediments that occur alternated with both the pelagic limestones and the radiolarites of the CAO suggests that the depositional setting was a marginal sea adjacent to a volcanic arc. The occurrence of debris-flows indicates also that the depositional basin was affected by tectonism, that resulted in major slides and mass-gravity reworking of preexisting units and of arc-derived volcanics and sediments.
The stratigraphy and the age of formation and obduction of the CAO were compared with other supra-subduction zone type ophiolites of both the eastern (Turkey) and the western (Greece) parts of the VIAE segment of the Neotethys. This comparison indicates that the western intraoceanic subduction is definitely older. Accordingly, we surmise that important transform faults were separating the continental micro-plates within the VIAE-ocean (e.g. the Tauride-Anatolide microplate) during the closure of this oceanic branch.