地幔板是如何驱动板块构造的
Clinton P Conrad1, Carolina Lithgow-Bertelloni
1Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109, USA. cpconrad@umich.edu
概括
压缩的构造板拉动地球的板块,但不清楚是如何. 这项研究表明,上层地幔板直接拉动板块,而下层地幔板块则使用地幔流来进行吸引驱动的板块运动.
科学领域:
- 地质物理学 地质物理学
- 构造学 构造学 构造学 构造学
- 地力学是什么?地力学是什么?
背景情况:
- 地球构造板运动背后的驱动力受到争论.
- 沉浮板块和覆盖着的构造板块之间的机械合仍然不太清楚.
- 两种拟议的机制是直接拉 (机械固定) 和吸 (地幔流动激发).
研究的目的:
- 为了研究板块拉力与板块吸收在驱动当今构造板块运动中的相对贡献.
- 为了确定俯冲板块和构造板块之间的合机制.
主要方法:
- 对地质历史的分析. 沉降.
- 估计板块拉动和板块吸收对于当前板块运动的相对重要性.
主要成果:
- 板块运动最好用上层地幔板块固定在板块上的模型来解释,通过板块拉力提供约50%的驱动力.
- 下层地幔板被粘性地幔力支,并通过板块吸收促进板块运动.
结论:
- 板块拉动和板块吸收都是构造板块动态中的重要机制.
- 沉积板块的位置 (上层和下层地幔) 决定了它们与构造板块相互作用的主要方式.
相关概念视频
Mechanism of Lamellipodia Formation
Cells migrating in response to external stimuli form lamellipodia, which are thin membrane protrusions supported by a mesh of linked, branched, or unbranched actin filaments. These actin filaments interact with myosin motor proteins, creating the dynamic actomyosin complex within the cytoskeleton. Contractility, or the ability to generate contractile stress, is inherent to the actomyosin complex. It helps cells detect the stiffness of the surrounding ECM and exert contractile force for...
Elements of Block Diagrams
Block diagrams serve as a visual representation of the input-output relationships within a system. An illustrative example is a heating system, where the set temperature activates the furnace to warm the room to the desired level. Block diagrams are versatile, modeling linear systems through Laplace transform variables and nonlinear systems using time domain variables.
A block diagram typically includes essential elements such as comparators, blocks, and feedback loops. Each of these elements...
A block diagram typically includes essential elements such as comparators, blocks, and feedback loops. Each of these elements...
Block Diagram Reduction
The process of deriving the transfer function of a control system often involves reducing its block diagram to a single block. This simplification can be achieved through a series of strategic operations, including relocating branch points and comparators. These operations preserve the overall function of the system while allowing for easier manipulation and combination of blocks.
The first step in this process is the identification and relocation of a branch point. A branch point, where a...
The first step in this process is the identification and relocation of a branch point. A branch point, where a...
Wood Products
Wood products encompass a broad range of materials crafted from wood strands, veneers, lumber, and even waste wood-like shreds, designed for both structural and nonstructural purposes. Various specialized wood products have been developed to enhance strength, durability, and versatility in building applications.
Glue-laminated wood, often referred to as glulam, combines multiple smaller pieces of dimensional lumber using adhesives to form a single, larger piece. Cross-laminated timber consists...
Glue-laminated wood, often referred to as glulam, combines multiple smaller pieces of dimensional lumber using adhesives to form a single, larger piece. Cross-laminated timber consists...
Wood Panel Products
Wood panel products are essential materials used in construction for applications such as flooring, siding, and roofing, typically available in standard dimensions of 4 feet by 8 feet, with thicknesses varying from one-quarter of an inch to one and one-eighth inches. Among the most common types of wood panels is plywood, which is produced by gluing multiple layers of thin wood veneers under pressure. The grain of the outer veneers runs lengthwise, while the grains of the interior layers run...
Design Example: Maintaining Level of an Embankment
Constructing a roadway embankment over uneven terrain requires precise leveling to ensure stability and proper drainage. Surveyors use a leveling instrument and staff to calculate ground elevations and determine the required fill material at each point along the embankment alignment.The process begins by positioning a leveling instrument near a benchmark with a known elevation. A backsight reading establishes the instrument height, which serves as a reference for subsequent measurements. A...


