STRATIGRAPHIC FRAMEWORK FOR THE PLUME MODE OF MANTLE CONVECTION
STRATIGRAPHIC FRAMEWORK FOR THE PLUME MODE OF MANTLE CONVECTION
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DOI：
10.1016/j.gr.2017.06.003
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发表时间：
2019-09
影响因子：
6.1
通讯作者：
A. Friedrich;H. Bunge;S. Rieger;L. Colli;S. Ghelichkhan;R. Nerlich
中科院分区：
文献类型：
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作者：
A. Friedrich;H. Bunge;S. Rieger;L. Colli;S. Ghelichkhan;R. Nerlich
地幔对流是一个基本的行星过程。其板块模式是用板块构造学来建立和表达的。其羽流模式也是通过区域间地质格局来建立和表达的。我们开发了基于事件的地层框架来说明 Griffiths 等人的羽流模型预测的表面效应。 (1989) 和 Griffiths 和 Campbell (1990) 以及基于不整合面和间断分析大陆尺度地质图的方法。上升羽流的表面表现持续数千万年，并且速率在几百万年内变化。随着羽流上升，其表面表现变窄，但幅度增加，在地质记录中留下独特的地质和地层图案，不仅在羽流头部中心上方，而且在其边缘上方以及距中心数千公里的远端区域。为了可视化这些模式，我们构建了连续地质图、年代地层剖面和间断图。侵蚀的穹顶隆起（Şengör，2001）和溢流玄武岩（Duncan 和 Richards，1991；Ernst 和 Buchan，2001a）是羽流地层分析的诊断起点。穹顶的机械塌陷导致狭窄裂谷（Burke 和 Dewey，1973）、排水网络重组（Cox，1989）和洪水玄武岩喷发。在边缘区域，垂直运动、变形和表面响应的模式是短暂且复杂的。起初，羽流边缘与中心区域一起抬升，但随后随着羽流进一步上升而下沉；随着羽流头部变平，羽流边缘经历了新的向外迁移的表面隆起、侵蚀、广泛的地壳断层和排水重组。拐点迁移首先以羽流上升速率的 1/2 向内发生，然后以软流圈流动速率向外发生。区域间尺度的不整合面地层序列记录了这两次反演。远端区域没有经历任何与羽流相关的隆起，产生了该事件的完整沉积记录；沉积记录中与事件相关的时间间隙（间断）向中心增加，但事件视界在远端区域保存得最好；可以通过从中心向外追踪其触点来识别它。我们从区域间地质图中提取了系统和系列间断，并构建了间断图作为古动态地形的代理，并作为与数值模型结果进行比较的基础。区域间尺度的地质图非常适合可视化大陆地区动态地形的与羽流相关的地质记录。然而，在区域间尺度上需要分阶段分辨率的地质记录和间断信息。羽流地层框架是基于事件的、区域间的，但不是全球性的，其随时间变化的幅度明显大于全球海平面升降的幅度。全球地层综合需要在评估海平面上升贡献之前整合板块地层和羽流地层框架。
Mantle convection is a fundamental planetary process. Its plate mode is established and expressed by plate tectonics. Its plume mode also is established and expressed by interregional geological patterns. We developed both an event-based stratigraphic framework to illustrate the surface effects predicted by the plume model of Griffiths et al. (1989) and Griffiths and Campbell (1990) and a methodology to analyze continent-scale geological maps based on unconformities and hiatuses. The surface expression of ascending plumes lasts for tens-of-millions-of-years and rates vary over a few million years. As the plume ascends, its surface expression narrows, but increases in amplitude, leaving distinct geological and stratigraphic patterns in the geologic record, not only above the plume-head center, but also above its margins and in distal regions a few thousands-of-kilometers from the center. To visualize these patterns, we constructed sequential geological maps, chronostratigraphic sections, and hiatus diagrams. Dome-uplift with erosion (Şengör, 2001) and the flood basalts (Duncan and Richards, 1991; Ernst and Buchan, 2001a) are diagnostic starting points for plume-stratigraphic analyses. Mechanical collapse of the dome results in narrow rifting (Burke and Dewey, 1973), drainage-network reorganization (Cox, 1989), and flood-basalt eruption. In the marginal region, patterns of vertical movement, deformation and surface response are transient and complex. At first, the plume margin is uplifted together with the central region, but then it subsides as the plume ascents farther; With plume-head flattening, the plume margin experiences renewed outward-migrating surface uplift, erosion, broad crustal faulting, and drainage reorganization. Knickpoint migration occurs first inward-directed at ½ the rate of plume ascent and later outward-directed at the rate of asthenospheric flow. Interregional-scale unconformity-bounded stratigraphic successions document the two inversions. The distal regions, which did not experience any plume-related uplift, yield complete sedimentary records of the event; Event-related time gaps (hiatuses) in the sedimentary record increase towards the center, but the event horizon is best preserved in the distal region; it may be recognized by tracing its contacts from the center outwards. We extracted system- and series-hiatuses from interregional geological maps and built hiatus maps as proxies for paleo-dynamic topography and as a basis for comparison with results from numerical models. Interregional-scale geological maps are well suited to visualize plume-related geological records of dynamic topography in continental regions. However, geological records and hiatus information at the resolution of stages will be needed at interregional scales. The plume-stratigraphic framework is event-based, interregional, but not global, with time-dependent amplitudes that are significantly larger than those of global eustatic sea-level fluctuations. Global stratigraphic syntheses require integration of plate- and plume-stratigraphic frameworks before eustatic contributions may be assessed.