Collaborative Research: Deep Drilling of Lake Junin, Peru: Continuous Tropical Records of Glaciation, Climate Change and Magnetic Field Variations Spanning the Late Quaternary

合作研究：秘鲁胡宁湖深钻：晚第四纪冰川作用、气候变化和磁场变化的连续热带记录

• 批准号: 1405030
• 负责人: Anders Noren
• 金额: $ 19.26万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-06-01 至 2019-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1405030&HistoricalAwards=false
• 关键词: Collaborative; Research; Deep; Drilling; Lake

Our ability to understand the full complexity of climate change and forecast future regional trends requires that we extend the available instrumental records into the geologic past. Over the past several decades paleoclimatologists have developed myriad proxy indicators of past regional climate that are recorded in natural archives such as ice cores, cave deposits, and lake sediment, among many other archives. Proxy paleoclimate records from the tropics are particularly important because this region is the ?heat engine? of Earth. Long- and short-term changes in ocean-atmosphere circulation that are manifested in such phenomenon as the El Nino Southern Oscillation (ENSO), the mean position of the Intertropical Convergence Zone, and the response of the tropics to high latitude climatic ?events? are critical to understand because these phenomena can have a profound impact on regional water balance, which directly affects potable water supplies, hydroelectricity generation, and agricultural productivity. The longest continuous records of climate change in the tropics are limited to those derived from the relatively few old lake basins in the region. Lake Junin, the largest lake located entirely within Peru, is among the oldest lake basins in South America. It contains a sediment record that is at least 200 m long that may extend more than 250,000 years. Lake Junin is exceptional in the length of record that it contains, but also in the climate signals that it records. Considerable prior research has documented that Lake Junin records the waxing and waning of nearby alpine glaciers and changes in regional water balance through the isotope geochemistry of calcium carbonate deposited on the lake bottom at a rate of approximately 0.2 to 1.0 mm/yr. This research will develop these and other proxy climate records for the full length of recovered core; the records generated will comprise one of the longest continuous records of climate and environmental change from the inner tropics. The Lake Junin Drilling Project has several broader impacts. These include the joint renovation of an abandoned lodge for future shared use as the first shoreline outpost for officials of the Junin National Reserve, as a visitor center, and as a lake access point for ecotourism. Capacity building activities in the Junin Project include collaboration with Peruvian universities, training of geoscientists, as well as Peruvian and American student training. A specific team will be responsible for the organization of lectures at villages in the region to inform citizens about the significance of the drilling, and will work closely with the national park service to instruct the rangers on how to use the science to promote conservation efforts around the lake. During the drilling, a team will facilitate interactions with local and international media. The team expect to involve U.S. and Peruvian students in all aspects of Junin drilling, and much of the paleoecological research related to the Junin cores will be conducted by graduate students. Training opportunities during the drilling phase of operations are also planned for geoscientists from Peruvian universities. Numerous U.S. undergraduate and graduate students, and one postdoctoral fellow will be involved in all phases of the proposed research. The material collected during this project will set the stage for significant future research. LacCore, the National Lacustrine Core Facility at the University of Minnesota, will facilitate this by overseeing the long-term storage, curation, and access to data and samples obtained in this project.Technical Explanation Lake Junin, located at 4000 m asl in the inner-tropics of the Southern Hemisphere, is a prime target for drilling because it contains a thick (200 m) sediment package deposited at a high rate (0.2 to 1.0 mm/yr). Abundant research conducted on and around Lake Junin provides a compelling rationale for deep drilling. Moraine mapping coupled with cosmogenic radionuclide dating indicate that paleoglaciers reached the lake edge, but have not overridden the lake in as much as one million years. Lake Junin is one of the few lakes in the tropical Andes that predates the maximum extent of glaciation and is in a geomorphic position to record the waxing and waning of glaciers in nearby cordillera. Sediment coring of Lake Junin began in the 1970s; two cores spanning the past 50,000 years reveal that sedimentation has alternated between clastic sediments deposited during peak glacial periods and authigenic calcite (marl) precipitated from the water column during interglacial times. The lake also contains ideal sediments for multiproxy analysis that can be reliably dated using both the radiocarbon and U/Th methods. The oxygen isotopic composition of marl and ostracod carapaces demonstrate that authigenic calcite in Lake Junin primarily records the isotopic composition of precipitation and secondarily the degree of evaporative enrichment of lake water. Lake Junin contains a continuous record of tropical hydroclimate over interglacial and interstadial intervals for much of the past several hundred thousand years that is both comparable to, and an extension of stable isotope records from regional ice cores and speleothems. New organic geochemical proxies compliment the marl isotope record and offer the potential for a truly continuous isotope paleoclimate record through glacial and interglacial intervals alike. Lake Junin is ideally situated, both from logistical and scientific standpoints, to provide continuous high-resolution, independently-dated, long-term records of glaciation, and the variability of phenomena such as ENSO, the South America Summer Monsoon, and the Intertropical Convergence Zone. Because of the strong, demonstrated U/Th dating potential of Junin marl, we will be able to address critical issues regarding the synchrony of climate change in the tropics with that in high latitude regions of both hemispheres, the rate and timing of ecosystem response to climatic perturbations, and the dynamics of the geomagnetic field from a tropical perspective. Lake Junin is a scientifically mature site that will yield critical scientific insights that only drilling coupled with analysis can unlock.The primary objective of the proposed research is to develop the first continuous, high-resolution, absolute-dated late Quaternary record of climate change, water balance (P/E), glaciation, vegetation, and paleomagnetic secular variation for the tropical Andes. The well-dated Junin record will allow the team to develop proxy records spanning 200,000yr, which will document the timing of wet/dry cycles, glacial advances/retreats, and the impacts of climatic phenomena such as the changing strength and variability of ENSO, the South America Summer Monsoon, and shifts in the location and range of the Intertropical Convergence Zone. In addition, this study will provide an opportunity to date (via U-Th) the 40ka sections of both the Titicaca and Sabana de Bogota records through correlation of pollen, stable isotope, and paleomagnetic time series. This study will also enable important insights into the response of tropical vegetation to climate change in the upper Amazon Basin, and will provide a rare southern equatorial perspective on the evolution of Earth?s geomagnetic field.

我们了解气候变化和预测未来地区趋势的全部复杂性的能力要求我们将可用的工具记录扩展到地质历史。在过去的几十年中，古气候学家开发了过去地区气候的无数替代指标，这些指标记录在自然档案中，例如冰芯，洞穴沉积物和湖泊沉积物，以及许多其他档案。来自热带地区的代理古气候记录特别重要，因为该区域是“热发动机？地球。长期和短期变化的海洋 - 大气循环的变化在诸如El Nino Southern振荡（ENSO）等现象中表现出来，热带收敛区的平均位置以及热带对高纬度气候？事件的反应？对于理解而言至关重要，因为这些现象可能会对区域水平衡产生深远的影响，这直接影响饮用水供应，水力发电产生和农业生产力。 热带气候变化的最长连续记录仅限于该地区相对较少的旧湖盆地的记录。朱宁湖是完全位于秘鲁内部的最大湖泊，是南美最古老的湖泊盆地之一。它包含一个至少200 m长的沉积物记录，可能会延长超过250，000年的历史。朱宁湖在其中包含的记录长度上是出色的，但在其记录的气候信号中也是如此。相当多的先前研究表明，朱宁湖记录了附近高山冰川的上蜡和减弱，以及通过碳酸钙地球化学的变化，以大约0.2至1.0 mm/yr的速度沉积在湖底上的碳酸钙地球化学。这项研究将开发这些和其他代理气候记录，以全长回收核心；生成的记录将构成内部热带地区气候和环境变化的最长连续记录之一。 朱宁湖钻探项目具有更广泛的影响。其中包括将一个废弃小屋的联合翻新，以供将来共享，作为朱宁国家预备役官员，作为游客中心的第一个海岸线前哨基地，以及作为生态旅游的湖泊入学点。 Junin项目的能力建设活动包括与秘鲁大学的合作，地球科学家的培训以及秘鲁和美国学生培训。一个特定的团队将负责该地区村庄的讲座组织，以告知公民钻探的重要性，并将与国家公园管理局紧密合作，以指示流浪者如何利用科学来促进湖泊周围的保护工作。在钻探过程中，团队将促进与本地和国际媒体的互动。该团队期望让美国和秘鲁学生参与Junin Drilling的各个方面，而与Junin核心有关的许多古生态研究将由研究生进行。 还计划为秘鲁大学的地球科学家提供操作钻探阶段的培训机会。许多美国的本科生和研究生，以及一名博士后研究员将参与拟议研究的所有阶段。 该项目期间收集的材料将为未来的重大研究奠定阶段。明尼苏达大学国家湖泊核心设施拉克塞尔（Laccore mm/yr）。在朱宁湖及其周围进行的大量研究为深度钻探提供了令人信服的理由。冰or式的映射加上宇宙放射性核素约会，这表明古流胶器到达了湖边，但在多达一百万年的时间内没有超过湖泊。朱宁湖是热带安第斯山脉（Andes）的少数湖泊之一，其早于冰川的最大程度，并且处于地貌位置，可记录附近山科列拉（Cordillera）冰川的上蜡和减弱。朱宁湖的沉积物加油始于1970年代。跨越过去50，000年的两个核心表明，在冰川期间沉积的碎屑沉积物与在冰川间时期从水柱沉淀的正质方解石（MARL）之间的沉积物交替。该湖还包含用于多氧分析的理想沉积物，可以使用放射性碳和U/TH方法可靠地进行日期。 MARL和Ostracod甲壳的氧同位素组成表明，Junin湖中的身材方解石主要记录降水的同位素组成，其次是湖水蒸发富集的程度。朱宁湖在过去几十万年前的大部分时间里，在冰川间和内部间隔内都有一个连续的记录，与稳定的同位素记录相当，从区域冰核和棘突中扩展了稳定的同位素记录。新的有机地球化学代理称赞MARL同位素的记录，并通过冰川和冰期间隔都提供了真正连续的同位素古气候记录。从后勤和科学的角度来看，Junin湖都位于理想位置，可提供连续的高分辨率，独立的，长期的冰川状态，以及ENSO，ENSO，南美夏季季风和中间地带收敛区等现象的可变性。由于Junin Marl具有强大的U/Th年代培训潜力，我们将能够解决有关热带气候变化同步的关键问题，而在两个半球的高纬度地区，生态系统响应的速度和时间和时间响应速度和时间是气候扰动的速度和时间，以及从Tropcect的地球目的的角度来看的动力学。朱宁湖是一个科学成熟的地点，将产生关键的科学见解，仅钻探与分析可以解锁。拟议的研究的主要目标是开发首个连续的，高分辨率的，绝对日期的季Quaternary气候变化记录，水平平衡，水平平衡（P/E），冰川，植被，植被，植被，植被和古质量杂物。良好的朱宁记录将使团队能够制定跨越200,000年的代理记录，该记录将记录湿/干循环，冰川进步/撤退的时间，以及气候现象的影响，例如ENSO，ENSO，South America Summer Summer季风的不断变化的强度和可变性，以及互化互动区的位置和范围的变化。此外，这项研究将通过花粉，稳定同位素和古流磁性时间序列的相关性，为titicaca和Sabana de Bogota记录的40KA段提供至今的机会。这项研究还将能够对热带植被对上亚马逊盆地的气候变化的反应进行重要见解，并将为地球地磁场的演变提供罕见的南方赤道观点。