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

俄罗斯东北部科累马河流域中新世北极森林的古气候分析

• 批准号: 1250063
• 负责人: Hope Jahren
• 金额: $ 15万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-01 至 2015-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1250063&HistoricalAwards=false
• 关键词: Paleoclimate; Analysis; Miocene; Arctic; Forest

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.

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在第三纪的大部分时间里（~65 Ma到~3 Ma），北极圈北部的森林都很茂盛。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照，但却能够在始新世、渐新世和中新世的主要气候转变中持续存在。从古新世的研究中，人们对北美北极的化石森林有了很多了解（例如，Chickaloon，阿拉斯加），早始新世（例如，Ellesmere岛），始新世中期（例如，阿克塞尔海伯格岛）和中新世（例如，班克斯岛）陆地沉积物。以前NSF资助的工作支持了我们对季节性降水的重建（Schubert等人，2012）、相对湿度（Jahren和斯滕贝格，2003，2008）、环境水的同位素组成（Jahren等人，2009），土壤甲烷产生（Jahren等人，2004年），和可能的水传输机制（Jahren和斯滕贝格，2002年）使用稳定同位素分析的植物化石材料从始新世沉积物的北极加拿大。20世纪70年代和80年代的俄罗斯文献将西伯利亚中新世沉积物描述为时间上广泛且富含化石森林，然而，尚未使用稳定同位素技术对其进行检查。在这个建议中，我们描述了我们的计划，收集，存档和分析松科和杉科化石的Baekovo和Nekkeiveem植物群，位于西伯利亚东北部的科雷马河流域。我们将取样的沉积物是Khapchan地层的一部分，该地层的年龄为中新世晚期（11.6至5.3 Ma; Nikitin，2007年）;我们将进行一个季节的野外工作，作为Polaris项目II的一部分，Polaris项目II是最近在R.M.博士指导下资助的NSF研究和教育计划。霍姆斯（WHRC;参见补充文件中的支持信），以研究流入北冰洋的河流中碳的迁移和转化。作为Polaris II的一部分，我们将在签证，出口许可和Cherskiy附近的东北科学站的住房方面获得帮助，以及使用现有的租船计划航行科雷马河流域（联系人：Sergei Zimov博士）。我们将利用我们最近在环内13 C剖面微分析方面的创新（Schubert和Jahren，2011年）来确定降水的季节性时间（Schubert等人，2012年），西伯利亚东北部的中新世北极森林。这一建议是对核准供资的建议的重大修订，因为需要将供资水平削减50%，并将时间限制在两年的总供资。原始提案中科学目标的主要变化是排除了原始版本中提议的回收化石材料的氧同位素分析。在进一步的资金变得可用的情况下，收集的化石可以分析氧同位素组成，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。预算也被改变，PI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;什么将是博士后工资给他已被重定向到两个月的夏季工资在一个月到一个月。这项研究的智力价值是它的潜力开辟新的知识领域第三纪北极森林通过东北西伯利亚的中新世沉积物。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，第三纪北极森林的一般属性是一个夏季为主的水文制度，最大的光照水平和最大的水的可用性相吻合，类似于我们观察到的始新世森林的北极北美。我们提出了这个假设的第一个测试作为确定的季节性降水制度在中新世北极森林使用稳定同位素分析化石科雷马河流域。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植物化石的收集/鉴定。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，一个EPSCoR州。EPSCoR计划旨在广泛影响EPSCoR管辖范围内的科学能力，并与NSF董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跨领域计划。