Paleoclimate Analysis of a Miocene Arctic Forest from the Kolyma River Basin, Northeastern Russia

俄罗斯东北部科雷马河流域中新世北极森林的古气候分析[j]。Hope jahren夏威夷大学在第三纪（~65 Ma ~ ~3 Ma）的大部分时间里，森林在北极圈以北蓬勃发展。这些独特的生态系统每年都要经历长时间的连续黑暗和光明，但却成功地度过了始新世、渐新世和中新世的主要气候转变。从古新世（如阿拉斯加的Chickaloon）、始新世早期（如阿拉斯加的chacaloon）的研究中，我们对北美北极的化石森林有了很多了解。中始新世（如阿克塞尔海贝格岛）和中新世（如班克斯岛）陆相沉积物。以前nsf资助的工作支持了我们对季节性降水（Schubert等人，2012）、相对湿度（Jahren和Sternberg， 2003年，2008年）、环境水的同位素组成（Jahren等人，2009年）、土壤甲烷产生（Jahren等人，2004年）和可能的水输送机制（Jahren和Sternberg， 2002年）的重建，这些重建使用了加拿大北极始新世沉积物植物化石材料的稳定同位素分析。20世纪70年代和80年代的俄罗斯文献将西伯利亚中新世的沉积物描述为短暂的广泛和惊人的丰富的化石森林，然而，它们尚未使用稳定同位素技术进行检查。在这个提案中，我们描述了我们在西伯利亚东北部Kolyma河流域的Baekovo和Nekkeiveem植物区系中收集、归档和分析松科和杉科化石的计划。我们将取样的沉积物是中新世晚期Khapchan组的一部分（11.6 ~ 5.3 Ma; Nikitin, 2007）；作为北极星项目II的一部分，我们将进行一个季节的实地考察。北极星项目II是美国国家科学基金会最近资助的一项研究和教育计划，由R.M. Holmes博士（WHRC；见补充文件中的支持信）指导，研究流入北冰洋的河流中碳的运输和转化。作为北极星II的一部分，我们将获得签证、出口许可和在切尔斯基附近的东北科学站的住房方面的帮助，以及使用预定在科雷马河流域航行的现有包租船（联系人：谢尔盖·齐莫夫博士）。我们将采用我们最近的创新，对环内ä13C剖面进行微分析（Schubert和Jahren， 2011），以确定西伯利亚东北部中新世北极森林降水的季节时间（Schubert等人，2012）。这项建议是对核准的供资建议的重大修订，因为供资水平减少了50%，而且总供资时间限制在两年以内。原始提案中科学目标的主要变化是排除了原始版本中提出的对回收化石材料进行氧同位素分析。如果有进一步的资金支持，收集到的化石可能会被分析氧同位素组成，我们关于古相对湿度的假设可以在以后的单独支持下进行测试。预算也有所改变，因为PI布莱恩·舒伯特现在是路易斯安那大学拉斐特分校的助理教授；他的博士后工资已经被转包到ULL的两个月的夏季工资中。这项研究的学术价值在于，它有可能通过西伯利亚东北部中新世的沉积物开辟第三纪北极森林的新知识领域。从根本上说，我们感兴趣的是了解我们为加拿大北极始新世构建的气候情景是全球性的和长期的，还是仅限于西半球和/或古近纪。我们假设第三纪北极森林的一般属性是夏季主导的水文制度，其中最大光照水平和最大水分可用性相吻合，类似于我们在北美北极始新世森林中观察到的情况。我们提出了对这一假设的第一个测试，即利用来自科雷玛河流域的化石的稳定同位素分析来确定中新世北极森林的季节性降水制度。作为北极星II野外季节的一部分，我们将提供两个教育模块，向学生介绍第三纪北极森林，包括动手练习，以定义简单的地层学和收集/鉴定植物化石。我们的模块将在网站上形成一个单独的博客，记录北极星项目自2008年成立以来的演变（http://www.thepolarisproject.org/journals/blog/）。最后，我们注意到，我们在夏威夷大学的研究服务于夏威夷州，这是一个EPSCoR州。EPSCoR计划旨在广泛影响EPSCoR辖区的科学能力，并与NSF理事会和办事处共同投资，以支持提交给基金会研究和教育计划的提案，以及横切倡议。

Paleoclimate Analysis of a Miocene Arctic Forest from the Kolyma River Basin, Northeastern RussiaA. Hope JahrenUniversity of HawaiiThroughout most of the Tertiary (~65 Ma to ~3 Ma), forests have thrived north of the Arctic Circle. These unique ecosystems were subject to prolonged periods of continuous darkness and light each year, yet managed to persist through the major climate transitions of the Eocene, Oligocene, and Miocene. Much is known about the fossil forests of Arctic North America from studies of Paleocene (e.g., Chickaloon, Alaska), early Eocene(e.g., Ellesmere Island), middle Eocene (e.g., Axel Heiberg Island), and Miocene (e.g., Banks Island) terrestrial sediments. Previous NSF-funded work has supported our reconstructions of seasonal precipitation (Schubert et al., 2012), relative humidity (Jahren and Sternberg, 2003, 2008), the isotopic composition of environmental water (Jahren et al., 2009), soil-methane production (Jahren et al., 2004), and possible water transport mechanisms (Jahren and Sternberg, 2002) using stable isotope analyses of plant fossil materials from the Eocene sediments of Arctic Canada. Russian literature from the 1970s and 80s described the Miocene sediments of Siberia as temporally extensive and spectacularly rich in fossil forests, however, they have not yet been examined using stable isotope techniques. In this proposal, we describe our plan to collect, archive, and analyze Pinaceae and Taxodiaceae fossils from the Baekovo and Nekkeiveem floras, located in the Kolyma River Basin of northeastern Siberia. The sediments we will sample are part of the Khapchan Formation which is late Miocene in age (11.6 to 5.3 Ma; Nikitin, 2007); we will perform one season of fieldwork as part of the Polaris Project II, a recently funded NSF research and education initiative under the direction of Dr. R.M. Holmes (WHRC; see letter of support within Supplementary Documents) to study transport and transformation of carbon in rivers flowing into the Arctic Ocean. As part of Polaris II, we will receive assistance with visas, export permission, and housing at the Northeast Science Station near Cherskiy, as well as the use of an existing boat charter scheduled to navigate the Kolyma River Basin (contact: Dr. Sergei Zimov). We will employ our recent innovations in microanalysis of intra-ring ä13C profiles (Schubert and Jahren, 2011) for determination of the seasonal timing of precipitation (Schubert et al., 2012) for the Miocene Arctic forests of northeastern Siberia. This proposal represents a significant revision of the proposal approved for funding, as necessitated by the 50% reduction in the level of funding, and the restriction of time to two years of total funding. The main alteration of the scientific goals within the original proposal is the exclusion of oxygen isotope analyses of recovered fossil material that were proposed in the original version. In the event that further funding becomes available, collected fossil may be analyzed for oxygen isotope composition, and our hypotheses about paleorelative humidity can be tested under separate support at a later date. The budget has also been altered in that PI Brian Schubert is now an Assistant Professor at University of Louisiana at Lafayette; what would have been postdoc salary to him has been redirected into two months of his summer salary within a subcontract to ULL.The Intellectual Merit of this study is its potential to open up new intellectual territory on Tertiary Arctic forests via the Miocene sediments of Northeastern Siberia. Fundamentally, we are interested to learn whether the climate scenarios we have constructed for the Canadian Arctic Eocene were global and long-standing, or limited to the Western Hemisphere and/or to the Paleogene. We hypothesize that a general attribute of Tertiary Arctic forests is a summer-dominated hydrologic regime where maximum light levels and maximum water availability coincide, similar to what we observed for the Eocene forests of Arctic North America. We propose a first test of this hypothesis as the determination of the seasonal precipitation regime within Miocene Arctic forests using stable isotope analyses of fossils from the Kolyma River Basin. The Broader Impacts As part of the Polaris II field seasons, we will provide two educational modules introducing students to the Tertiary Arctic forests including hands-on exercises to define simple stratigraphy and collection/identification of plant fossils. Our module will form a separate blog on the website documenting the evolution of the Polaris Project since its inception in 2008 (http://www.thepolarisproject.org/journals/blog/). Finally, we note that our research at the University of Hawaii serves the State of Hawaii, an EPSCoR state. The EPSCoR program is designed to broadly impact science capabilities in EPSCoR jurisdictions, and coinvests with NSF Directorates and Offices in support of proposals submitted to the Foundation's research and education programs, and crosscutting initiatives.