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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >The Oligocene Alps: Domal unroofing and drainage development during early orogenic growth
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The Oligocene Alps: Domal unroofing and drainage development during early orogenic growth

机译：渐新世阿尔卑斯山：造山带早期发育过程中的顶房顶和排水发育

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The source of huge volumes of quartzofeldspathic detritus feeding Oligo-Miocene foredeep turbidites of the Apennines has long remained an unsolved geological enigma. In this article we reinterpret the available sandstone petrography, fission-track, stratigraphic, and geomorphological evidence to demonstrate that the Adriatic foredeep was dominantly sourced by a "Himalayan-type tectonic aneurysm" growing in the Central Alps since the late Oligocene: the Lepontine Dome. The Lepontine Dome is the envelope of distinct subdomes that formed stepwise from cast to west during northwestward indentation of Adria beneath the axial Alps. Focused erosion of domal culminations cut by antecedent drainage started suddenly in the late Oligocene, with unroofing of recently-emplaced plutons and young amphibolite-facies gneisses. Exhumation was tectonically driven, and possibly accelerated by positive feedback between erosion and uplift of hot weak rocks from depth. The huge volumes of resulting detritus (Gonfolite-Macigno elastic wedge) were transported southward for hundreds of kilometers along the rapidly subsiding foredeep, formed since middle Eocene times in front of the Alpine retrobelt and nascent Apennine forebelt. Such massive sediment influx, following 15 +/- 2 Myr of starvedforedeep sedimentation, testifies to rapid formation of mountain relief in the Central Alps, synchronous to dextral activity along the Insubric Fault. The Lepontine Dome remains today as the only deeply-dissected region in the Alps, where medium-grade metamorphic rocks of the axial belt are extensively exposed. The relationships between geological structures and drainage patterns still mirror those formed originally at Oligocene times. River headwaters have not been significantly displaced since then, and their thalwegs constrain finite lateral displacement relative to the Southalpine retrowedge to a maximum of 10-20 km. Our reconstruction has wide implications, not only for a better understanding of the Tertiary evolution of the Alps-Apennines orogenic couple, but also for general relationships among tectonic activity, relief formation, drainage development, erosion distribution, and long-distance sediment transfer during continental collision and orogenic growth.
机译：长期以来，尚未解决的巨大的石英长石碎屑源是亚平宁山脉的中新世的奥利哥-中新世前缘深浊度。在本文中，我们重新解释了可用的砂岩岩相学，裂变径迹，地层学和地貌学证据，以证明自渐新世晚期以来，中部阿尔卑斯山生长的“喜马拉雅型构造动脉瘤”主要来源于亚得里亚海前缘：Lepontine Dome 。 Lepontine圆顶是轴向亚阿尔卑斯山脉下方的阿德里亚向西北凹陷期间，从铸件到西部逐步形成的独特亚壳的包裹体。在渐新世晚期，由于前期排水作用而导致的对顶峰状侵蚀的集中侵蚀突然开始，其中新近放置的岩体和年轻的角闪岩相片麻岩都没有屋顶。掘尸工作是构造性驱动，可能是由于热弱岩石从深度侵蚀和隆起之间的正反馈而加速的。产生的大量碎屑（Gonfolite-Macigno弹性楔形物）沿着快速沉降的前深部向南输送了数百公里，该深部自始新世中期以来在阿尔卑斯后生带和新生的亚平宁前带形成。在15 +/- 2 Myr饥饿的深层沉积之后，如此大量的沉积物涌入证明了中阿尔卑斯山快速形成山地救济，与沿非地下断层的右旋活动同步。如今，Lepontine穹顶仍然是阿尔卑斯山中唯一一个深度解剖的区域，轴向带的中级变质岩被广泛暴露。地质构造和排水模式之间的关系仍然反映出渐新世时期最初形成的那些关系。从那以后，河源头一直没有发生明显的位移，它们的海th将相对于南阿尔卑斯山脉后缘的有限的横向位移限制在最大10-20 km。我们的重建具有广泛的意义，不仅有助于更好地了解阿尔卑斯-亚平宁山脉造山带的第三纪演化，而且还有助于构造活动，地貌形成，排水发育，侵蚀分布和大陆上的长距离沉积物转移之间的一般关系。碰撞和造山生长。

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