Cenozoic Extension in Bulgaria and Northern Greece: the Northern Part of the Aegean Extensional Regime
Cenozoic Extension in Bulgaria and Northern Greece: the Northern Part of the Aegean Extensional Regime
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保加利亚和希腊北部的新生代扩张：爱琴海扩张制度的北部
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发表时间：
2000
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影响因子：
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通讯作者：
L. Royden
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作者：
C. Burchfiel;R. Nakov;T. Tzankov;L. Royden
摘要著名的新生代爱琴海伸展机制始于公元前。25 Ma，地壳变薄，大部分现在被淹没。在北安纳托利亚断层的西部延续以北，爱琴海伸展体系存在于保加利亚中部和南部、希腊北方、马其顿前南斯拉夫共和国（FYR）和阿尔巴尼亚东部。在这里，该系统暴露在陆地上，并提供了一个机会，以重建系统的延伸演化。南部的巴尔干半岛的半岛形成了爱琴海伸展体系的北方部分;变形不像爱琴海那么大，但这部分伸展体系的重建将对其动力学提供重要的制约。在经历了一段与始新世晚期-渐新世晚期岩浆活动相关的弧正常伸展之后，希腊北方的主要岩石圈伸展似乎在26 - 21 Ma之间开始，包括在奥林匹亚山以东、萨索斯岛和卡瓦拉附近的东-东北-西-西南伸展。这一时期的伸展可能伴随着一个短时期的同时代压缩弧北部早中新世的时间，或者可能稍早在土耳其西北部的色雷斯盆地。中晚中新世东北-西南方向的伸展似乎斜向老岩浆弧发展，并在16.3-13.6 Ma向北迁移到保加利亚西南部的Sandanski Graben（可能也进入Mesta和Padesh Grabens），并在Blagoevgrad和Djerman Grabens约16.3-13.6 Ma。九马。保加利亚西南部的扩展由c重组。在希腊北方，斯特里蒙谷拆离断层的延伸终止于c. 3.5但在新的断层系统上继续延伸。根据有限的构造和地层数据，推测在此期间，前南斯拉夫的马其顿共和国和阿尔巴尼亚东部也可能发生了相关的伸展。这种东北-西南向的延伸被解释为与西Hellenides俯冲边界北方的海沟回滚沿着有关。在希腊北方和保加利亚西南部的桑丹斯基地堑的伸展工作进行得很好之后，保加利亚中部的南北向伸展才开始沿着东西走向的断层进行。在索菲亚地堑、巴尔干地堑及其以东的地堑中，南北向延伸始于c。在北方色雷斯盆地的普罗夫迪夫、扎戈尔和通贾地堑中，可能大约在同一时间开始：这些地堑的南北延伸一直持续到现在。南北向延伸的原因尚不清楚，可能与沿着Hellenides俯冲带中心部分的海沟回滚有关，或者与Hellenides西部和土耳其西部分别顺时针和逆时针旋转的更多局部原因有关。到上新世晚期，一个主要的侵蚀面，亚第四纪表面，在保加利亚中部的大面积地区形成了一个主要的不整合面，标志着盆地地区第四纪沉积的开始。保加利亚中西部的许多大小地堑边界断层取代了这一侵蚀面，并证明了第四纪南北延伸的广泛程度。南北向的延伸向西延伸，规模可能逐渐减小，穿过保加利亚西南部古老的西北走向地堑（西米特利和杰曼地堑），进入前南斯拉夫的马其顿共和国东部。上新世晚期（？）第四纪以来，希腊北方发育了复杂的北东-西南向伸展格局，并伴随有北东-东西向的右旋断裂，在更多的局部伸展区之间形成了转换断裂。这个断层系统覆盖了较老的西北向伸展断层，如斯特里蒙拆离断层，可能与右侧北安纳托利亚断层向北爱琴海的扩展和其北部平行断层的形成有关。这两个不同的构造体制延伸到前南斯拉夫的马其顿共和国，在那里，第三个体制的东西延伸在前南斯拉夫的马其顿共和国西部和阿尔巴尼亚东部是目前，并在那里延伸可能代表的东西延伸体制的延续中晚中新世开始。根据地震活动性和全球定位系统研究确定的活动变形表明，希腊北方，可能还有保加利亚西南部和前南斯拉夫的马其顿共和国，主要是南北延伸。这种变形模式一定是在晚第四纪时期形成的。除亚得里亚海附近的山脉外，南部巴尔干半岛的地区的所有山地地形都可能是中新世-新近纪伸展作用的结果。
Abstract The well-known Cenozoic Aegean extensional regime, initiated at c. 25 Ma, thinned the crust so that most of it now lies submerged. North of the western continuation of the North Anatolian Fault the Aegean extensional regime is present in central and southern Bulgaria, northern Greece, Former Yugoslavian Republic (FYR) of Macedonia and eastern Albania. Here the system is exposed on land and offers an opportunity to reconstruct the extensional evolution of the system. The southern Balkan peninsula forms the northern part of the Aegean extensional system; deformation is not as great as in the Aegean, but reconstruction of this part of the extensional regime will provide important constraints on its dynamics. Following a period of arc-normal extension associated with Late Eocene-Late Oligocene magmatism, major lithospheric extension appears have begun between 26 and 21 Ma in northern Greece, involving east-northeast-west-southwest extension east of Mount Olympos, on the Island of Thasos and near Kavala. This period of extension may have been accompanied by a short period of coeval compression north of the arc during Early Miocene time or perhaps a little earlier in the Thrace Basin of northwestern Turkey. Northeast-southwest directed Middle-Late Miocene extension appears to have developed obliquely to the older magmatic arc and migrated northward into southwestern Bulgaria in the Sandanski Graben (and perhaps also into the Mesta and Padesh Grabens) by 16.3–13.6 Ma, and in the Blagoevgrad and Djerman Grabens by c. 9 Ma. Extension in south-western Bulgaria was reorganized by c. 5 Ma and in northern Greece extension on the Strymon Valley detachment fault ended by c. 3.5 Ma, but extension continued on new fault systems. From limited structural and stratigraphic data, it is speculated here that related extension may have also occurred during this time in FYR Macedonia and eastern Albania. This northeast-southwest extension is interpreted to be related to trench roll-back along the northern part of the subduction boundary in the western Hellenides. North-south extension along east-west striking faults in central Bulgaria began only after extension was well underway in northern Greece and the Sandanski Graben of south-western Bulgaria. Within the Sofia Graben, the Sub-Balkan grabens, and grabens to their east, north-south extension began at c. 9 Ma, and may have begun about the same time in the Plovdiv, Zagore and Tundja Grabens of the northern Thracian Basin: north-south extension has continued to the present in these grabens. The cause of the north-south extension is unclear and may be related to trench roll-back along the central part of the subduction zone in the Hellenides, or more local causes of clockwise and counterclockwise rotation of the western Hellenides and western Turkey, respectively. By Late Pliocene time a major erosion surface, the sub-Quaternary surface, was developed over a large area of central Bulgaria creating a major unconformity that marks the beginning of Quaternary deposition in the basinal areas. Many large and small graben-bounding faults in west-central Bulgaria displace this erosion surface and demonstrate the widespread extent of Quaternary north-south extension. North-south extension extended westward, with probably decreasing magnitude, across the older northwest trending graben of southwest Bulgaria (the Simitli and Djerman Grabens) and into eastern FYR Macedonia. During latest Pliocene(?) and Quaternary time, northern Greece developed a complex pattern of northeast-southwest extension associated with northeast to east-west striking right-lateral faults forming transfer faults between more local extensional areas. This system of faults overprinted the older northwest trending extensional faults, such as the Strymon Detachment, and may be related to the propagation of the right-lateral North Anatolian Fault into the north Aegean Sea and formation of parallel faults to its north. These two different tectonic regimes extend into FYR Macedonia, where a third regime of east-west extension in western FYR Macedonia and eastern Albania is present, and where extension may represent the continuation of the east-west extensional regime initiated in Middle-Late Miocene time. Active deformation determined from seismicity and Global Positioning System studies suggest northern Greece, and perhaps southwest Bulgaria and FYR Macedonia, is dominated by north-south extension. This pattern of deformation must have developed as recently as perhaps Late Quaternary time. Except for mountains near the Adriatic Sea all of the mountainous topography in the southern Balkan region may be the result of Miocene-Recent extension.