Timing and extent of late neogene glacials/interglacials using magnetostratigraphy

正在进行的研究揭示了地球气候系统的复杂性。全球变暖(和变冷)的现实影响着所有人。生活质量与经济生产率、环境健康和人口动态密切相关，每一个都受到气候变化的影响或适应。加拿大的冰川和冰川消融是最极端和最基本的气候事件之一。对加拿大北部和西部地区的调查揭示了大量含有300万年前古气候指标的沉积物。这些地区的沉积物出现在对全球变暖和降温特别敏感的气候带中。这些沉积记录跨越了广泛的时间尺度，从几十年到数百万年不等，并以不同的分辨率表示。使用替代数据的一个长期问题是陆地和海洋记录的对比。每个记录都包含有助于解释对方的有价值的信息。磁性地层学提供了将这两个环境的沉积和化石记录关联起来的最佳机会。这在很大程度上是因为地球磁场的逆转在地球表面上基本上是同步的，并且与记录所在的沉积相类型无关。正在进行的研究将集中在：(1)新的磁性地层学，将更好地限制冰盖的时间和范围。尤其重要的是对冰川冰盖和冰川喷发的古地磁测量(冰川作用的直接证据)，以及在非冰期发展起来的古土壤。(2)对黄金和钻石产区的冰前、冰川和非冰川沉积物进行磁性指纹识别，可以提供有关来源、年龄、沉积方式和与冰缘关系的有价值的信息，解释为什么只有一些沉积物含有砂岩。(3)在过去的4年中，从冰川暴发洪水沉积的温石中发展了古分子记录。在这里，磁性地层学提供了一种手段来评估沉积的时间长度，并更好地理解了冰川消融的动力学。

Ongoing studies reveal complexities of Earth's climate system.  Realities of global warming (and cooling) affect all people.  Quality of life is strongly allied to economic productivity, environmental health, and population dynamics, and each are affected by or adapt to climate changes. Glaciation and deglaciation of Canada rank amongst the most extreme and fundamental climatic events. Investigations of northern and western regions of Canada reveal extensive suites of sediments containing paleoclimatic proxies extending back 3.0 million years.  Sediments from these regions occur in climate zones that are particularly sensitive to global warming and cooling.   Sedimentary records span a wide spectrum of time scales, ranging from decades to millions of years and are expressed with varying powers of resolution.  A longstanding issue in use of proxy data is correlation of terrestrial and marine records.  Each contains valuable information that can assist in the interpretation of the other.  Magnetostratigraphy affords the best opportunity to correlate sedimentary and fossil records from these two environments, largely because reversals of the Earth's magnetic field are essentially synchronous over the surface of the earth and are independent of the type of sedimentary facies in which the record is held. Ongoing research will focus on: (1) new magnetostratigraphies that will better constrain timing and extent of ice sheets.  Particularly important are paleomagnetic measurements of glacial tills and outwash (direct evidence of glaciation), and paleosols which develop during ice-free periods.  (2)  The magnetic "finger-printing" of preglacial, glacial, and non-glacial sediments in gold and diamond producing areas can  provide valuable information about provenance, age, mode of deposition, and relationship to ice margins, explaining why only some deposits contain placers. (3) In the past 4 years paleosecular records have been developed from rythmites deposited by glacial outburst floods.  Here magnetostratigraphy provides a means to assess length of time over which deposits were laid down, and a better understanding of dynamics of deglaciation.