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

俄罗斯东北部科里马河流域中新世北极森林的古气候分析希望夏威夷大学穿过第三纪的大部分地区(~65 Ma至~3 Ma)，北极圈以北的森林茁壮成长。这些独特的生态系统每年都受到持续不断的黑暗和光明的长期影响，但却设法在始新世、渐新世和中新世的主要气候过渡期间保持了下来。通过对古新世(如阿拉斯加奇卡隆)、早始新世(如埃尔斯米尔岛)、中始新世(如阿克塞尔海贝格岛)和中新世(如班克斯岛)陆地沉积物的研究，人们对北美洲北极的化石森林有了很多了解。以前NSF资助的工作支持了我们使用加拿大北极始新世植物化石材料的稳定同位素分析重建季节性降水(Schubert等人，2012年)、相对湿度(Jahren和Sternberg，2003,2008)、环境水的同位素组成(Jahren等人，2009)、土壤甲烷生产(Jahren等人，2004)和可能的水传输机制(Jahren和Sternberg，2002)。20世纪70年代和80年代的俄罗斯文献描述了西伯利亚中新世沉积在时间上广泛，化石森林丰富，然而，它们还没有用稳定的同位素技术进行检测。在这份提案中，我们描述了我们计划收集、存档和分析位于西伯利亚东北部Kolyma河流域的Baekovo和Nekkeiveem植物群中的松科和杉科化石。我们将采样的沉积物是中新世晚期(11.6~5.3 Ma；Nikitin，2007)的Khapchan组的一部分；我们将进行一季的野外工作，作为北极星项目II的一部分，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倡议，由R.M.Holmes博士(WHRC；见补充文件中的支持函)指导，以研究流入北冰洋的河流中碳的运输和转化。作为北极星二号的一部分，我们将获得签证、出口许可和切尔斯基附近东北科学站的住房方面的援助，以及使用计划在科利马河流域航行的现有船只包租(联系人：谢尔盖·齐莫夫博士)。我们将使用我们在环内13C剖面微观分析方面的最新创新(Schubert和Jahren，2011)来确定西伯利亚东北部中新世北极森林的降水季节时间(Schubert等人，2012)。这项提案是对批准的供资提案的重大修订，因为供资水平减少了50%，时间限制在两年的供资总额之内。原始提案中对科学目标的主要修改是排除了原始版本中提出的对回收的化石材料进行氧同位素分析。如果有更多的资金可用，收集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得到检验。预算也发生了变化，皮布赖恩·舒伯特现在是路易斯安那大学拉斐特分校的助理教授；他的博士后工资被重新分配到他夏季工资的两个月，转包给ULL。这项研究的学术价值是它有可能通过西伯利亚东北部的中新世沉积物在第三纪北极森林上开辟新的知识领域。从根本上说，我们有兴趣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，北极第三纪森林的一般属性是夏季主导的水文状况，最大光照水平和最大可用水量重合，类似于我们在北美北极始新世森林中观察到的情况。我们首次提出了对这一假设的检验，即通过对科里马河流域化石的稳定同位素分析来确定中新世北极森林中的季节性降水状况。更广泛的影响作为北极星II野外季节的一部分，我们将提供两个教育单元，向学生介绍北极第三纪森林，包括确定简单地层和收集/识别植物化石的动手练习。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年开始以来的演变(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董事和办公室共同投资，以支持提交给基金会的研究和教育计划的提案，以及横向倡议。

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.