Geochronology, Petrology, and Geochemistry of the Jurassic White Mountain Batholith, New Hampshire

新罕布什尔州侏罗纪白山岩基的年代学、岩石学和地球化学

• 批准号: 2327629
• 负责人: Jill VanTongeren
• 金额: $ 30.03万
• 依托单位: Tufts University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-03-15 至 2027-02-28
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2327629&HistoricalAwards=false
• 关键词: Geochronology; Petrology; Geochemistry; Jurassic; White

The White Mountains of New Hampshire are composed of metamorphic rocks formed during the formation of the supercontinent Pangea and igneous rocks emplaced and erupted during the subsequent opening of the Atlantic Ocean. The igneous rocks include granites (New Hampshire is known as the Granite State) and volcanic rocks that form spectacular cliff faces such as the iconic 'Old Man of the Mountain' in Franconia Notch State Park. The geologic trigger for this phase of magmatism, however, remains largely unknown. The PI will train undergraduate students at Tufts University to sample the rocks throughout the region in order to obtain chemical and age information that can be used to link the magmatism to a particular geologic process that gave rise to the New Hampshire we see today. The results will be disseminated in a series of peer-reviewed journal articles, and at professional scientific conferences. As a capstone to the project, the PI and students will develop a dedicated summer-long exhibition at the Museum of the White Mountains in Plymouth, New Hampshire in order to communicate the results to the general public. The exhibit will include examples of rocks and minerals (both large-scale slabs and microscope slides) that are typical of the region, videos of tectonic plate motions during the opening of the Atlantic, primers on geologic dating techniques, and trail guides for hikers interested in learning more about geology in the White Mountains.In this project, the PI and undergraduate students at Tufts University will focus on establishing a detailed geochronologic, petrologic, and geochemical dataset for the main phase of magmatism in the White Mountain Magma Series (WMMS), the White Mountain Batholith. The White Mountain Batholith (WMB) is composed of a series of porphyritic syenites, hornblende granites, biotite granites, and comendite (Na-rich rhyolite) tuffs. Recently published ages from Kinney et al. (2022) reveal that the WMB is not a monolithic pluton, but is instead composed of two distinct magmatic centers: the western batholith and the eastern batholith. Magmatism first initiated in the western portions of the batholith (198 -190 Ma) and then appears to jump to the eastern portions approximately 10 Myr later (184 - 180 Ma). The researcher's work will establish the timing of emplacement between various units and plutons, the depths of emplacement, and the petrogenetic relationships between each unit. Undergraduate student training is a central focus of this work and the PI will train a total of six undergraduate students at Tufts University on scientific research projects over the three year period. Students will obtain high precision U-Pb zircon ages for key sample localities across the batholith to constrain the timing of emplacement, as well as obtain whole rock major and trace element compositions and Rb-Sr and Sm-Nd isotopic compositions for each lithological unit in the western, eastern, and central batholiths. Their results will be an essential first step in distinguishing between various geodynamic scenarios for the origin of the WMMS. A summer-long dedicated exhibition at the Museum of the White Mountains (Plymouth, NH), and associated public lecture series, will provide a capstone to the project and allow the PI and students to communicate their results to the general public.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

新罕布什尔州的怀特山脉由盘古大陆形成期间形成的变质岩和随后大西洋开口期间就位和喷发的火成岩组成。 火成岩包括花岗岩（新罕布什尔州被称为花岗岩州）和火山岩，形成壮观的悬崖面，例如弗兰科尼亚山口州立公园的标志性“山中老人”。 然而，这一阶段岩浆作用的地质触发因素仍然很大程度上未知。 该项目负责人将培训塔夫茨大学的本科生对整个地区的岩石进行采样，以获得化学和年龄信息，这些信息可用于将岩浆活动与形成我们今天看到的新罕布什尔州的特定地质过程联系起来。 研究结果将在一系列同行评审的期刊文章和专业科学会议上传播。作为该项目的高潮，PI 和学生将在新罕布什尔州普利茅斯的怀特山博物馆举办一个专门的夏季展览，以便向公众传达成果。 展览将包括该地区典型的岩石和矿物示例（包括大型板片和显微镜幻灯片）、大西洋开放期间构造板块运动的视频、地质年代测定技术入门知识以及为感兴趣的徒步旅行者提供的路线指南在这个项目中，塔夫茨大学的 PI 和本科生将重点为白山岩浆作用的主要阶段建立详细的地质年代学、岩石学和地球化学数据集。白山岩浆系列（WMMS），白山岩基。 白山岩基 (WMB) 由一系列斑状正长岩、角闪石花岗岩、黑云母花岗岩和珠光岩（富钠流纹岩）凝灰岩组成。 Kinney 等人最近发表的年龄。 (2022)揭示WMB并不是一个整体的岩体，而是由两个不同的岩浆中心组成：西部岩基和东部岩基。 岩浆活动首先在岩基的西部部分开始（198 -190 Ma），然后在大约 10 Myr 后（184 - 180 Ma）似乎跳跃到东部部分。 研究人员的工作将确定各个单元和岩体之间的侵位时间、侵位深度以及每个单元之间的成岩关系。 本科生培养是这项工作的重点，PI将在三年内为塔夫茨大学的科研项目总共培训六名本科生。 学生将获得整个岩基关键样品位置的高精度 U-Pb 锆石年龄，以限制侵位时间，并获得整个岩石的主量和微量元素组成以及每个岩性单元的 Rb-Sr 和 Sm-Nd 同位素组成。西部、东部和中部岩基。 他们的结果将是区分 WMMS 起源的各种地球动力学情景的重要第一步。 在怀特山博物馆（新罕布什尔州普利茅斯）举行的夏季专门展览以及相关的公开讲座系列将为该项目提供一个顶峰，并允许 PI 和学生向公众传达他们的成果。该奖项反映了通过使用基金会的智力价值和更广泛的影响审查标准进行评估，NSF 的法定使命被认为值得支持。