NSFGEO-NERC: An investigation of the possible co-evolution of Si and O isotopes in rocks and minerals from the Hadean to present
Lead Research Organisation:
University of St Andrews
Department Name: Earth and Environmental Sciences
Abstract
Project Summary
Overview
This project involves the design, execution, and application of high temperature and high pressure laboratory experiments to understand the isotope geochemistry of natural mineral samples. Specifically, this research will explore Si- and O-isotope geochemistry of igneous rocks and minerals - including detrital zircon - with three integrated objectives. This first involves systematic experimental work to quantify Si isotope equilibrium fractionation among co-existing minerals at igneous temperatures, including zircon, quartz, and feldspars. Second, these experiments will be used as a stepping stone to interpret Si- and O- isotope geochemistry of whole rock and mineral samples. Finally, the project will focus specifically on applying the results of experiments and natural, in-context, samples to detrital zircon samples to decipher the environments of crystallization. Zircons older than 4 billion years represent a key target for application because rocks from this time period are either sparse or altogether absent. This work will therefore result in new knowledge about the environments and conditions that may have prevailed on the earliest Earth.
Intellectual merit
This research is intellectually meritorious because it will result in: (i) the first published experimental data for Si isotope fractionation for igneous minerals and will fill a key gap in knowledge that will enable researchers to understand Si isotopes in igneous rocks on firmer ground; (ii) a systematic comparison of the possible co-variation of O- and Si- isotopes in natural rocks and minerals; (iii) and the first in-situ data for Si isotopes in zircon, which will be investigated along with O-isotopes. Silicon isotopes in zircon will offer a new way to explore crustal evolution from the Hadean onwards. When coupled with oxygen isotope work, these two systems could lead to yield new ways to peer into sedimentary cycling and to explore early Earth magmas from before the existence of the known sedimentary or igneous rock record.
Broader impacts
The broader impacts of this project come from the training of undergraduate and graduate students in high temperature experimental techniques and crystal synthesis, and isotope analysis. The practical training on these instruments will result in a broad skillset, highly applicable to many areas in the geosciences. The students will also have the opportunity to attend and network at national and international scientific conferences. As part of the broader impacts of this grant, we will also host high school science teachers from the surrounding Rochester area to introduce them to the technology and the science we undertake in the Early Earth and Experimental Geochemistry Laboratory at Rochester. These 2-3 day summer workshops expose science teachers to cutting edge science and technology and data that they can take back into their classrooms. Finally, at St Andrews, the co-PI will initiate a meeting of an international science outreach scheme, aimed at presenting cutting-edge research outside of the classroom environment, to the general public.
Overview
This project involves the design, execution, and application of high temperature and high pressure laboratory experiments to understand the isotope geochemistry of natural mineral samples. Specifically, this research will explore Si- and O-isotope geochemistry of igneous rocks and minerals - including detrital zircon - with three integrated objectives. This first involves systematic experimental work to quantify Si isotope equilibrium fractionation among co-existing minerals at igneous temperatures, including zircon, quartz, and feldspars. Second, these experiments will be used as a stepping stone to interpret Si- and O- isotope geochemistry of whole rock and mineral samples. Finally, the project will focus specifically on applying the results of experiments and natural, in-context, samples to detrital zircon samples to decipher the environments of crystallization. Zircons older than 4 billion years represent a key target for application because rocks from this time period are either sparse or altogether absent. This work will therefore result in new knowledge about the environments and conditions that may have prevailed on the earliest Earth.
Intellectual merit
This research is intellectually meritorious because it will result in: (i) the first published experimental data for Si isotope fractionation for igneous minerals and will fill a key gap in knowledge that will enable researchers to understand Si isotopes in igneous rocks on firmer ground; (ii) a systematic comparison of the possible co-variation of O- and Si- isotopes in natural rocks and minerals; (iii) and the first in-situ data for Si isotopes in zircon, which will be investigated along with O-isotopes. Silicon isotopes in zircon will offer a new way to explore crustal evolution from the Hadean onwards. When coupled with oxygen isotope work, these two systems could lead to yield new ways to peer into sedimentary cycling and to explore early Earth magmas from before the existence of the known sedimentary or igneous rock record.
Broader impacts
The broader impacts of this project come from the training of undergraduate and graduate students in high temperature experimental techniques and crystal synthesis, and isotope analysis. The practical training on these instruments will result in a broad skillset, highly applicable to many areas in the geosciences. The students will also have the opportunity to attend and network at national and international scientific conferences. As part of the broader impacts of this grant, we will also host high school science teachers from the surrounding Rochester area to introduce them to the technology and the science we undertake in the Early Earth and Experimental Geochemistry Laboratory at Rochester. These 2-3 day summer workshops expose science teachers to cutting edge science and technology and data that they can take back into their classrooms. Finally, at St Andrews, the co-PI will initiate a meeting of an international science outreach scheme, aimed at presenting cutting-edge research outside of the classroom environment, to the general public.
Planned Impact
impacts of the proposed activities
Undergraduate and graduate students will be trained in techniques and procedures involved in high pressure research, electron beam microscopy, and mass spectrometry. The practical training on these instruments will result in a broad skill set, highly applicable to many areas in the geosciences. The students will also have the opportunity to attend and network at national and international scientific conferences. The overall benefit is that the students supported by this work will obtain the expertise needed to pursue careers in the geosciences.
Public outreach
As part of the broader impacts of this grant, we will host high school science teachers from the surrounding area to introduce them to the technology and the science we undertake in the Early Earth and Experimental Geochemistry Laboratory at Rochester. This work will be undertaken in collaboration with Michael Occhino, Director of Science and Education at the Warner School of Education (see letter of collaboration), and is part of the Math Science
Partnership Grant administered by the latter. These 2-day workshops expose science teachers to cutting edge science and technology and data that they can take back into their classrooms. This program is new, and we are still evaluating its benefits, but this has led to email exchanges with project partner Trail and the students of the hosted teachers, which, in one case has led to student assistance with a class project (for her Global Environment course).
We will continue this program for the duration of this award.
Co-PI Savage is a new lecturer at St Andrews, and will initiate a monthly meeting of the popular scientific outreach scheme 'Pint of Science'. Here, university scientists present their research in an approachable way, outside the classroom environment, to the general community. There are a number of schemes in the UK, but so far none in St Andrews, a major omission. The research proposed above, regarding the earliest history of Earth and development of the planet to
one which can support liquid water and hence life, can easily capture the imagination and is perfect for presentation at such events as 'Pint of Science'.
Undergraduate and graduate students will be trained in techniques and procedures involved in high pressure research, electron beam microscopy, and mass spectrometry. The practical training on these instruments will result in a broad skill set, highly applicable to many areas in the geosciences. The students will also have the opportunity to attend and network at national and international scientific conferences. The overall benefit is that the students supported by this work will obtain the expertise needed to pursue careers in the geosciences.
Public outreach
As part of the broader impacts of this grant, we will host high school science teachers from the surrounding area to introduce them to the technology and the science we undertake in the Early Earth and Experimental Geochemistry Laboratory at Rochester. This work will be undertaken in collaboration with Michael Occhino, Director of Science and Education at the Warner School of Education (see letter of collaboration), and is part of the Math Science
Partnership Grant administered by the latter. These 2-day workshops expose science teachers to cutting edge science and technology and data that they can take back into their classrooms. This program is new, and we are still evaluating its benefits, but this has led to email exchanges with project partner Trail and the students of the hosted teachers, which, in one case has led to student assistance with a class project (for her Global Environment course).
We will continue this program for the duration of this award.
Co-PI Savage is a new lecturer at St Andrews, and will initiate a monthly meeting of the popular scientific outreach scheme 'Pint of Science'. Here, university scientists present their research in an approachable way, outside the classroom environment, to the general community. There are a number of schemes in the UK, but so far none in St Andrews, a major omission. The research proposed above, regarding the earliest history of Earth and development of the planet to
one which can support liquid water and hence life, can easily capture the imagination and is perfect for presentation at such events as 'Pint of Science'.
People |
ORCID iD |
| Paul Savage (Principal Investigator) |
Publications
Chowdhury W
(2023)
Eoarchean and Hadean melts reveal arc-like trace element and isotopic signatures
in Nature Communications
Delvigne C
(2021)
Silicon Isotope Analyses of Soil and Plant Reference Materials: An Inter-Comparison of Seven Laboratories
in Geostandards and Geoanalytical Research
Deng Z
(2019)
Titanium isotopes as a tracer for the plume or island arc affinity of felsic rocks.
in Proceedings of the National Academy of Sciences of the United States of America
Inglis E
(2019)
Isotopic fractionation of zirconium during magmatic differentiation and the stable isotope composition of the silicate Earth
in Geochimica et Cosmochimica Acta
Mendybaev R
(2021)
Experiments quantifying elemental and isotopic fractionations during evaporation of CAI-like melts in low-pressure hydrogen and in vacuum: Constraints on thermal processing of CAIs in the protoplanetary disk
in Geochimica et Cosmochimica Acta
Moynier F
(2020)
Metal-silicate silicon isotopic fractionation and the composition of the bulk Earth
in Earth and Planetary Science Letters
Trail D
(2019)
Experimentally determined Si isotope fractionation between zircon and quartz
in Geochimica et Cosmochimica Acta
Trail D
(2018)
Origin and significance of Si and O isotope heterogeneities in Phanerozoic, Archean, and Hadean zircon.
in Proceedings of the National Academy of Sciences of the United States of America
Tuller-Ross B
(2019)
Potassium isotope fractionation during magmatic differentiation of basalt to rhyolite
in Chemical Geology
| Description | Understanding how, when and where life first arose on Earth is fundamental to understanding how life might evolve on other planets in the Universe, but also to understanding what our earliest ancestors were. The crust or its chemically weathered derivatives likely served as a niche for the origin of life. In particular, hydrothermal settings such as we find today at mid-ocean ridges, and/or chemical sediments such as chert (a silica-rich rock) are common candidates, as these should provide the energy and suitable environmental conditions for life. However, as we look further and further back in time, the rock record becomes more and more sparse, because Earth is continuously destroying old rocks (and along with them, any fossil evidence of life), and forming new ones, in the process of plate tectonics. This means even though the Earth is about 4.5 billion years old, few bona fide terretrial rocks still exist that are older than 2.5 billion years, and so far no rocks that date from the first 500 million years of Earth's history have been found. Nevertheless, some evidence for Earth's earliest inhabitants does exist, in the rare ancient rocks and minerals that we do have in our collection. In particular, the earliest confirmed fossil is found in a 3.4 billion year old chert from Australia. Other potential evidence for life has been suggested in 3.8 billion year old and, more recently, 3.7 - 4.3 billion year old hydrothermal vent-related precipitates in Greenland [1] and Canada [2] but these are by no means uncontroversial [3]. Most recently, a study has used a genetics-based 'molecular clock' to suggest that all life on Earth evolved from a common ancestor that arose >3.9 billion years ago [4]. This last age is particularly significant, as around 3.9-3.8 billion years ago it is thought that Earth was undergoing a period of intense meteorite impacts called the 'Late Heavy Bombardment'. Many believe that this would be deleterious to life, vaporising any surface water and destroying any pre-existing crust (and potential habitats for life). Because of the lack of any bona fide terrestrial rocks from before ~4.0 billion years, there is no direct evidence of what Earth's crust and surface environments looked like from before this time - hence there has, up to now, been no confirmation that the ideal niche(s) for life to thrive existed on the earliest Earth. Studies have thus turned to (geo)chemical signatures within detrital zircons from this time. Zircons are extremely hardy minerals that can survive multiple periods of weathering untouched, and can be dated using the radiogenic isotopes of uranium. It turns out that a suite of zircons found in the Jack Hills of Western Australia date back to 4.4 billion years old, making them the oldest pieces of Earth so far discovered. Analysing the chemistry of these zircons can give us clues as to the composition of the melts from which these zircons first formed, and hence the sorted of crustal material that was being consumed to form such melts. In this study, we developed a method - based on the coupled analysis of Si and O isotopes in zircon - to recognise the existence of material involved in water-rock interactions that was subsequently involved in the melts which formed these ancient zircons[5]. Our work provides evidence for the first time for the existence of chemical sediments, such as cherts and Banded Iron Formations on Earth >4 Ga - implying that the niche for life on Earth existed much earlier than the first fossil evidence. Furthermore, we added to a growing body of work further support that the vast majority of Earth's earliest continental crust was generated by melting rocks that had previously interacted with a silica-rich early ocean. This suggests Earth was habitable relatively early on it its history - providing evidence to suggest that other (exo)planets that exist in the 'goldilocks' zone could also support life very early in their existences - planets such as Mars. [1] The Akilia Gneiss; https://www.nature.com/articles/384055a0 [2] Nuvvuagittuq belt in Quebec, Canada; https://www.nature.com/articles/nature21377 [3] 'The Akilia controversy'; http://jgs.lyellcollection.org/content/166/2/335 [4] https://www.nature.com/articles/s41559-018-0644-x [5] Another single zircon from this same locality has previously been found to contain an inclusion of carbon, potentially of biogenic origin. |
| Exploitation Route | These are important findings regarding the earliest history of our planet. They will hopefully be used in taking account of where, when and how life and Earth evolved together - and also indicate how early life may start to evolve on other planetary bodies. |
| Sectors | Environment,Other |