THE SCOPE AND SIGNIFICANCE OF TUNGSTEN ISOTOPE VARIATIONS: IMPLICATIONS FOR MANTLE EVOLUTION

在过去的十年里，钨的同位素变化在现代和古代的岩石中得到了记录，但它们在限制地幔演化方面的作用仍然存在争议。这是因为它们在地幔中的来源和保存方式尚不清楚。然而，钨同位素组成可能对地幔演化提供无与伦比的限制，因为钨是少数几个能够追踪吸积作用、早期行星分化和潜在地核-地幔相互作用的最后阶段的同位素示踪剂之一。为了有效地利用这种示踪剂，必须强有力地确定钨同位素变化的范围，并将其纳入物理地幔演化模型。我们的出发点是对最普遍的岩石类型进行调查，采样地幔：大洋中脊玄武岩。我们将通过综合新的和现有的钨同位素数据和热化学地幔对流的数值模型来检验关于地幔中钨同位素异常的来源和保存方式的假说。拟议的数据、技术和解释的集成是新颖的，并有可能显著推动对地幔演化的理解，超越钨同位素社区。计划再产生三个更广泛的影响。(1)通过协调不同学科的专家的早期职业科学家，发展跨学科伙伴关系。这包括支持博士后助理进行最先进的研究。(2)促进教学和参与科学，为罗格斯大学的本科生提供有组织的研究计划，由阿雷斯蒂本科生研究中心和附属于该大学的多样性和包容性中心提供便利。(3)进一步发展罗格斯大学地球与行星科学系的行星科学研究轨道。随着最近在洋岛玄武岩中发现钨同位素不均一性，现在有必要了解大洋中脊玄武岩是否具有钨同位素变化，并研究这些变化的原因。使用成熟的分析方法，我们将在成分多样的大洋中脊样品中测量高精度的钨同位素组成。这项任务将解决这样一个问题，即几乎没有关于确定据称钨同位素组成正常的地幔储集层的研究报告。为了推动钨同位素研究向社会提供更广泛的科学意义，我们将通过将我们新的和现有的钨同位素数据与热化学地幔对流的数值模型相结合，测试关于地幔中钨同位素异常起源的主要假说的合理性。这些结果预计将对我们理解地球的动态演变产生广泛的影响。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Tungsten isotopic variations have been documented in modern and ancient rocks over the past decade, yet their role in constraining mantle evolution remains debated. This is because their origin and mode of preservation in the mantle are unclear. Tungsten isotopic compositions, however, could provide unparalleled constraints on mantle evolution as tungsten is one of the few isotopic tracers able to track the final stages of accretion, early planetary differentiation, and potentially ongoing core-mantle interaction. To effectively utilize this tracer, the scope of tungsten isotopic variations must be robustly identified and incorporated into physical mantle evolution models. Our starting point is a survey of the most ubiquitous rock type sampling the mantle: mid-ocean ridge basalts. We will test hypotheses of the origin and preservation modes of tungsten isotopic anomalies in the mantle by synthesizing new and existing tungsten isotopic data with numerical models of thermochemical mantle convection. The proposed integration of data, techniques, and interpretations is novel and has the potential to significantly advance the understanding of mantle evolution beyond the tungsten isotope community. Three additional broader impacts planned. (1) Development of interdisciplinary partnerships by coordinating early career scientists who are experts in different disciplines. This includes support for a postdoctoral associate to conduct state-of-the-art research. (2) Advancement of teaching and participation in science by providing a structured research program for an undergraduate student at Rutgers University facilitated by the Aresty Research Center for Undergraduates and diversity and inclusion centers affiliated with the university. (3) Further development of the planetary science research track at the Department of Earth and Planetary Sciences, Rutgers University.With the recent discoveries of tungsten isotopic heterogeneity in ocean island basalts, it is now necessary to understand if mid-ocean ridge basalts possess tungsten isotopic variation and investigate what causes these variations. Using proven analytical methods, we will measure high-precision tungsten isotopic compositions in samples from compositional diverse mid-ocean ridges. This task will address the issue that little research has been reported to define mantle reservoirs which are purportedly normal for tungsten isotopic composition. To advance broader scientific implications provided by tungsten isotopic studies to the community, we will test the plausibility of the leading hypotheses of the origin of tungsten isotopic anomalies in the mantle by integrating our new and existing tungsten isotopic data with numerical models of thermochemical mantle convection. These results are anticipated to have broad implications for our understanding the dynamic evolution of our planet.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.