Although the heterogeneous nature of the chemical composition of Earth's mantle is now well established, the origin and longevity of the heterogeneities continue to be debated. In order to further study early-Earth heterogeneities, we present a set of Sm-Nd, Lu-Hf, Re-Os, and Hf-W isotope and lithophile and siderophile element abundance data for komatiites and basalts from the ∼3.53 Ga Coonterunah, ∼3.34 Ga Kelly, and ∼3.18 Ga Ruth Well and Regal systems of the Pilbara Craton in Western Australia. The Sm-Nd, Lu-Hf, and Re-Os isotope data yield isochrons consistent with the accepted emplacement ages of the respective komatiite-basalt lavas. The mantle sources evolved with long-term ¹⁴⁷Sm/¹⁴⁴Nd = 0.200 to 0.214 and ¹⁷⁶Lu/¹⁷⁷Hf = 0.0355 to 0.0395, spanning the entire range of the time-integrated Sm/Nd and Lu/Hf measured in the Archean and Proterozoic komatiite-basalt systems to-date. Unlike with the other early Archean komatiites and basalts, the coupled ¹⁴³Nd-¹⁷⁶Hf isotope systematics of the Pilbara lavas provide no evidence for the involvement of early magma ocean processes in the evolution of their mantle sources. Episodes of variable degrees of partial mantle melting and melt extraction can account for the observed large variations in the time-integrated Sm/Nd and Lu/Hf ratios in the early Archean mantle domains.

In contrast to the highly variable Nd-Hf systematics, the initial γ¹⁸⁷Os values vary within a narrow range from +0.9 to −0.4 indicating that the Pilbara mantle sources evolved with chondritic time-integrated Re/Os. The apparent discrepancy between the depletions in incompatible lithophile trace elements and near-chondritic Re/Os observed globally is reconciled via a model whereby early low-degree mantle melting events fractionated Sm from Nd and Lu from Hf, but had little effect on the Re/Os ratio. This in turn would imply early formation and long-term isolation of a basaltic crust highly enriched in incompatible lithophile trace elements.

The calculated total HSE abundances in the komatiite mantle sources range from ∼30% in the Coonterunah to ∼70% in the Regal system, of those in the estimates for the modern BSE, indicative of a 2.4× increase in HSE abundances from 3.53 to 3.18 Ga.

All four komatiite-basalt systems exhibit positive ¹⁸²W anomalies ranging between +11.4 and +7.7 ppm. The ¹⁸²W/¹⁸⁴W compositions and calculated HSE abundances in the Pilbara komatiite-basalt sources are inversely correlated and are most consistent with grainy late accretion of large differentiated planetesimals. Regression of the combined ¹⁸²W-HSE data for the komatiite systems allows an estimate of the W isotopic composition of the pre-late accretion BSE of +17±7. This estimate is similar to that of the Moon of +25±5 and lends further support to the notion regarding an initially common W isotopic composition in the Earth-Moon system.

Regression of the available HSE abundance data for komatiite mantle sources worldwide provides an estimate for the time of complete homogenization of late accreted materials within the mantle by 2.5±0.2 Ga. Calculations indicate an average survival time of late accreted planetesimals in the Earth's mantle of 1.9±0.2 Ga, which constrains the average mantle stirring rates for the HSE in the Hadean and Archean.

尽管地球地幔化学成分的异质性现已得到充分证实，但异质性的起源和寿命仍在争论中。为了进一步研究早期地球的异质性，我们提供了一组来自~3.53 Ga Coonterunah 的科马提岩和玄武岩的 Sm-Nd、Lu-Hf、Re-Os 和 Hf-W 同位素以及亲石和亲铁元素丰度数据， 〜3.34 Ga Kelly 和〜3.18 Ga Ruth Well 和西澳大利亚皮尔巴拉克拉通的 Regal 系统。Sm-Nd、Lu-Hf 和 Re-Os 同位素数据产生的等时线与相应科马提岩-玄武岩熔岩公认的侵位年龄一致。地幔源长期演化为¹⁴⁷ Sm/ ¹⁴⁴ Nd = 0.200 到 0.214 和¹⁷⁶ Lu/ ¹⁷⁷Hf = 0.0355 到 0.0395，跨越了迄今为止在太古代和元古代科马提岩-玄武岩系统中测量的时间积分 Sm/Nd 和 Lu/Hf 的整个范围。与其他早期太古代科马提岩和玄武岩不同，皮尔巴拉熔岩的耦合¹⁴³ Nd- ¹⁷⁶ Hf 同位素系统没有提供早期岩浆海洋过程参与其地幔源演化的证据。部分地幔熔融和熔体提取的不同程度的事件可以解释在早期太古代地幔域中观察到的时间积分 Sm/Nd 和 Lu/Hf 比率的巨大变化。

与高度可变的 Nd-Hf 系统学相反，初始 γ ¹⁸⁷ Os 值在 +0.9 到 -0.4 的狭窄范围内变化，表明 Pilbara 地幔源演化为球粒陨石时间积分 Re/Os。全球观察到的不相容亲石微量元素和近球粒状 Re/Os 的消耗之间的明显差异是通过一个模型来协调的，该模型早期低度地幔熔融事件将 Sm 与 Nd 分馏，Lu 与 Hf 分馏，但对 Re/ Os 比率。这反过来又意味着玄武岩地壳的早期形成和长期隔离，其中富含不相容的亲石微量元素。

计算得出的科马提岩地幔源中的总 HSE 丰度范围从 Coonterunah 的 ~30% 到 Regal 系统的 ~70%，这是现代 BSE 估计中的那些，表明 HSE 丰度从 3.53 到 3.18 增加了 2.4 倍嘎。

所有四个科马提岩-玄武岩系统都表现出¹⁸² W正异常，范围在 +11.4 和 +7.7 ppm 之间。Pilbara 科马提岩-玄武岩源中的¹⁸² W / ¹⁸⁴ W 组成和计算出的 HSE 丰度呈负相关，并且与大型分化星子的粒状晚期增生最为一致。对科马提岩系统的组合¹⁸² W-HSE 数据进行回归，可以估计 +17±7 的晚期吸积 BSE 的 W 同位素组成。这一估计与月球的 +25±5 的估计相似，并进一步支持了关于地月系统中最初常见的 W 同位素组成的概念。

对全球科马提岩地幔源的可用 HSE 丰度数据的回归提供了地幔内晚期吸积物质完全同质化时间 2.5±0.2 Ga 的估计。计算表明，地幔中晚期吸积星子的平均存活时间为 1.9 ±0.2 Ga，它限制了冥界和太古代中 HSE 的平均地幔搅拌速率。