Cenozoic uplift of Nuussuaq and Disko, West Greenland—elevated erosion surfaces as uplift markers of a passive margin
Cenozoic uplift of Nuussuaq and Disko, West Greenland—elevated erosion surfaces as uplift markers of a passive margin
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DOI：
10.1016/j.geomorph.2006.03.006
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发表时间：
2006-10
期刊：
影响因子：
3.9
通讯作者：
J. Bonow;P. Japsen;K. Lidmar-Bergström;J. Chalmers;A. Pedersen
中科院分区：
文献类型：
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作者：
J. Bonow;P. Japsen;K. Lidmar-Bergström;J. Chalmers;A. Pedersen
在格陵兰岛西部中部的努斯瓦克和迪斯科发现了高原的遗迹。我们将高原解释为主要由河流系统形成的侵蚀面（峰顶侵蚀面），并逐渐接近其以前的基准面，随后上升到现在的高度。它东西延伸150多公里，地势相对较低，沿断层断裂，西部向西倾斜，东部向东倾斜，努苏瓦克和迪斯科中部的最高海拔约为2公里。顶部侵蚀面切割了前寒武纪基底岩和古新世-始新世熔岩，限制了它的年龄远远小于Nuussuaq盆地的最后一次裂谷事件，这一次裂谷事件发生在马斯垂克晚期和达尼世。地质记录表明，Nuussuaq盆地在古新世-始新世火山活动期间经历了数公里的沉降，始新世后期又被海侵。对比磷灰石裂变径迹分析和镜质组反射率成熟度数据，认为侵蚀面形成可能是由40 ~ 30 Ma的隆升侵蚀事件引起的。在11至10 Ma之间的隆升事件开始之前，地面地层已经完成，并造成了山谷切口。这一代山谷向新的基准面递变，形成了一个较低的侵蚀面，最多在山顶侵蚀面以下1公里处，从而表明其隆起的幅度。这一代山谷的形成被第三次抬升事件打断，同样是1公里级的抬升事件，将地貌抬升到接近现在的位置。与裂变径迹记录的对比表明，这次隆升事件开始于7至2 Ma之间。隆起最初一定是由构造运动引起的。由于侵蚀和冰盖的装卸造成的均衡补偿增加了隆起的幅度，但没有显著改变地表的形态。本文认为，西格陵兰被动边缘古地表（不符合当前气候或构造条件的地表）的海拔高度可以用来确定新近纪隆升事件的幅度和横向变化。报告还指出，西格陵兰岛的地貌与许多其他被动边缘的地貌惊人地相似。
Remnants of a high plateau have been identified on Nuussuaq and Disko, central West Greenland. We interpret the plateau as an erosion surface (the summit erosion surface) formed mainly by a fluvial system and graded close to its former base level and subsequently uplifted to its present elevation. It extends over 150 km east–west, being of low relative relief, broken along faults, tilted westwards in the west and eastwards in the east, and having a maximum elevation of ca. 2 km in central Nuussuaq and Disko. The summit erosion surface cuts across Precambrian basement rocks and Paleocene–Eocene lavas, constraining its age to being substantially younger than the last rift event in the Nuussuaq Basin, which took place during the late Maastrichtian and Danian. The geological record shows that the Nuussuaq Basin was subjected to subsidence of several kilometres during Paleocene–Eocene volcanism and was transgressed by the sea later during the Eocene. By comparing with results from apatite fission track analysis and vitrinite reflectance maturity data, it is suggested that formation of the erosion surface was probably triggered by an uplift and erosion event starting between 40 and 30 Ma. Surface formation was completed prior to an uplift event that started between 11 and 10 Ma and caused valley incision. This generation of valleys graded to the new base level and formed a lower erosion surface, at most 1 km below the summit erosion surface, thus indicating the magnitude of its uplift. Formation of this generation of valleys was interrupted by a third uplift event also with a magnitude of 1 km that lifted the landscape to near its present position. Correlation with the fission-track record suggests that this uplift event started between 7 and 2 Ma. Uplift must have been caused initially by tectonism. Isostatic compensation due to erosion and loading and unloading of ice sheets has added to the magnitude of uplift but have not significantly altered the configuration of the surface. It is concluded that the elevations of palaeosurfaces (surfaces not in accordance with present climate or tectonic conditions) on West Greenland's passive margin can be used to define the magnitude and lateral variations of Neogene uplift events. The striking similarity between the landforms in West Greenland and those on many other passive margins is also noted.