普世北极海洋的冰架是从冰川的深海床形状推断出来的
L Polyak1, M H Edwards, B J Coakley
1Byrd Polar Research Center, Ohio State University, Columbus, Ohio 43210, USA. polyak.l@osu.edu
Nature
|March 22, 2001
概括
普莱斯托时代的冰川可能在北冰洋上形成了厚厚的冰架,而不仅仅是海冰. 地质绘图揭示了广泛的冰川清理和海底特征,支持这个冰架假设.
科学领域:
- 地质地质地质地质地质地
- 海洋学 海洋学 海洋学
- 古气候学 古气候学
背景情况:
- 大多数人认为:北冰洋在世冰川时期被海冰和冰山覆盖.
- 相反的假设:一个厚厚的冰盖 (≥1公里) 覆盖了北冰洋.
- 重建冰川历史需要详细的海底绘图,这在北极地区是有限的.
研究的目的:
- 调查北冰洋石期冰盖的存在和范围.
- 为了解决多年海冰覆盖与厚厚的冰盖之间的争论.
- 分析地质物理数据,寻找北极海底冰川活动的证据.
主要方法:
- 在1999年潜艇SCICEX探险中使用了地质物理绘图系统.
- 分析了从深度高达1公里的背散射图像和下底形仪记录.
- 绘制了北冰洋海底大部分海域的地图.
主要成果:
- 确定了多个海底床形,表明冰川的冲洗和成型.
- 观测到海底山脊山顶的大规模侵蚀.
- 显而易见的冰原特征提供了过去冰架活动的证据.
结论:
- 巨大的,南极类型的冰架,厚度高达1公里,长达数百公里,存在于北冰洋在普世冰川时期.
- 这些发现挑战了北冰洋冰川覆盖的传统观点.
- 海底地形学是极地海洋过去冰川动态的一个关键指标.
相关概念视频
Global Climate Change
Throughout its ~4.5 billion year history, the Earth has experienced periods of warming and cooling. However, the current drastic increase in global temperatures is well outside of the Earth’s cyclic norms, and evidence for human-caused global climate change is compelling. Paleoclimatology, the study of ancient climate conditions, provides ample evidence for human-caused global climate change by comparing recent conditions with those in the past.
Freezing Point Depression and Boiling Point Elevation
Boiling Point Elevation
The boiling point of a liquid is the temperature at which its vapor pressure is equal to ambient atmospheric pressure. Since the vapor pressure of a solution is lowered due to the presence of nonvolatile solutes, it stands to reason that the solution’s boiling point will subsequently be increased. Vapor pressure increases with temperature, and so a solution will require a higher temperature than will pure solvent to achieve any given vapor pressure, including one...
The boiling point of a liquid is the temperature at which its vapor pressure is equal to ambient atmospheric pressure. Since the vapor pressure of a solution is lowered due to the presence of nonvolatile solutes, it stands to reason that the solution’s boiling point will subsequently be increased. Vapor pressure increases with temperature, and so a solution will require a higher temperature than will pure solvent to achieve any given vapor pressure, including one...
Fluid Pressure over Curved Plate of Constant Width
When a curved plate of constant width is submerged in a liquid, the pressure acting normal to the plate varies continuously both in magnitude and direction. Calculating the magnitude and location of the resultant force at a point is often challenging for such cases. One of the methods to determine the resultant force and its location involves separately calculating the horizontal and vertical components of the resultant force. This complex calculation can be simplified by representing the...
Freezing Point Depression and Boiling Point Elevation
When a non-volatile solute is added to a pure solvent, it results in the lowering of the freezing point of the solvent. This phenomenon is called freezing point depression. The extent to which the freezing point is lowered depends on the molality of the solute -the number of moles of solute per kilogram of solvent and the cryoscopic constant of the solvent.From the plot of chemical potential, μ, against temperature, it is evident that the μ of both solid and liquid solvents decrease with...
Deep Sea Microbial Ecology
The deep ocean and its underlying sediments represent vast, largely unexplored microbial habitats that extend far beyond the sunlit photic zone. The photic (euphotic) zone typically spans the upper ~100–200 meters of pelagic waters in the open ocean, but its depth varies geographically and seasonally, where sufficient light supports photosynthetic life. Below this lies the deep sea, spanning roughly 1000–6000 meters (bathypelagic to abyssal zones), with deeper hadal trenches extending beyond...


