Building Earth with pebbles made of chondritic components

Pebble accretion provides new insights into Earth’s building blocks and early protoplanetary disk conditions. Here, we show that mixtures of chondritic components: metal grains, chondrules, calcium-aluminum-rich inclusions (CAIs), and amoeboid olivine aggregates (AOAs) match Earth’s major element composition (Fe, Ni, Si, Mg, Ca, Al, O) within uncertainties, whereas no combination of chondrites and iron meteorites does. Our best fits also match the e54Cr and e50Ti values of Earth precisely, whereas the best fits for chondrites, or components with a high proportion of E chondrules, fail to match Earth. In contrast to some previous studies, our best-fitting component mixture is predominantly carbonaceous, rather than enstatite chondrules. It also includes 15 wt% of early-formed refractory inclusions (CAIs + AOAs), which is similar to that found in some C chondrites (CO, CV, CK), but notably higher than NC chondrites. High abundances of refractory materials are lacking in NC chondrites, bec..., , , # Building Earth with pebbles made of chondritic components [https://doi.org/10.5061/dryad.41ns1rnqp](https://doi.org/10.5061/dryad.41ns1rnqp) ## Description of the data and file structure The data represent the compositions found by our best-fitting Component and Chondrite models. It also shows the best-fitting mixtures of various pebbles in those models ( e.g., chondrites and chondritic components) obtained by inversions. Here, IM= Iron meteorite; Chon = Chondrite; MG = Metal grain; Ch = Chondrule; C = Carbonaceous; E/EL/EH = Enstatite; O = Ordinary; CAIs = Calcium-aluminum-rich-inclusions; AOAs = Amoeboid-olivine-aggregates. Elemental composition is given in mg/g. Pebble proportion is given in wt%.Âpebble吸积（pebble accretion）为地球的构成物质与早期原行星盘环境提供了全新的研究视角。本研究表明，球粒陨石质组分（包括金属颗粒、球粒、富钙铝包裹体（CAIs）以及橄榄石不规则集合体（AOAs））的混合物，其主要元素组成（Fe、Ni、Si、Mg、Ca、Al、O）在误差范围内与地球的元素组成相吻合；而任何球粒陨石与铁陨石的组合均无法实现这一匹配。我们的最优拟合模型同样精准匹配了地球的ε⁵⁴Cr与ε⁵⁰Ti同位素比值，而针对球粒陨石或高比例E型球粒的组分所得到的最优拟合结果则无法契合地球的同位素特征。与部分既往研究不同，本研究得到的最优拟合组分混合物以碳质球粒相关成分为主，而非顽火辉石球粒。该混合物还包含15 wt%的早期形成难熔包裹体（CAIs + AOAs），这一占比与部分C型球粒陨石（CO、CV、CK型）中的含量水平相近，但显著高于普通球粒陨石。普通球粒陨石中缺乏高丰度的难熔物质，…… # 以球粒陨石质组分构成的卵石颗粒构建地球 https://doi.org/10.5061/dryad.41ns1rnqp ## 数据与文件结构说明 本数据集收录了通过最优拟合组分模型与球粒陨石模型得到的元素组成结果，同时展示了上述模型中各类卵石颗粒（pebble）的最优拟合混合物（如球粒陨石与球粒陨石质组分），该结果通过反演方法获得。其中，IM=铁陨石（Iron meteorite）；Chon=球粒陨石（Chondrite）；MG=金属颗粒（Metal grain）；Ch=球粒（Chondrule）；C=碳质（Carbonaceous）；E/EL/EH=顽火辉石型（Enstatite）；O=普通型（Ordinary）；CAIs=富钙铝包裹体（Calcium-aluminum-rich-inclusions）；AOAs=橄榄石不规则集合体（Amoeboid-olivine-aggregates）。元素组成以mg/g为单位，卵石颗粒占比以wt%为单位。