Source fertility modulates crustal thickness variation along the Gakkel Ridge

IF 4.8 1区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Earth and Planetary Science Letters Pub Date : 2025-09-07 DOI:10.1016/j.epsl.2025.119617

Jianggu Lu , Yejian Wang , Tao Zhang , William L. Griffin , Weiwei Ding , Yinxia Fang , Yanhui Dong , Weiqi Zhang , Hanlin Wang , Suzanne Y. O’Reilly , Jiabiao Li

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引用次数: 0

Abstract

The ultraslow-spreading Gakkel Ridge shows marked variation in crustal thickness at 31–100°E, decreasing from ∼7.5–8.9 km in the east to ∼2 km in the west, with peridotite exposures, but the causes of the crustal thickness variations remain unclear. This is explored using elemental and isotopic systematics of glasses and basalts from two segments at 85°E and 100°E (eastern Gakkel Ridge) combined with literature data from 31 to 85°E. Geochemical evidence suggests that the primary endmember composition of the samples had high Al₂O₃, N-MORB-like Sr-Nd-Hf-Pb isotopic systematics and slightly LREE-enriched patterns. The mantle source is probably an aluminum-rich fertile lherzolite related to deeper asthenospheric domains propagating south across the central Arctic at ∼150 km depth.

Thermodynamic modelling shows that the source potential temperatures and final depths of melting of the basalts at 31–100°E volcanic centres are all similar and thus cannot account for the variations in crustal thickness along the ridge. Integrating literature data that suggest the existence of prior refractory mantle residues along the Gakkel ridge, we propose that the sub-ridge uppermost mantle is a mixture of fertile and refractory mantle domains and the lateral variations in the proportion of fertile mantle domains modulate the change in crustal thickness along the axis.

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震源肥力调节Gakkel脊的地壳厚度变化

超低扩张的Gakkel脊在31-100°E处地壳厚度变化明显，从东部~ 7.5-8.9 km到西部~ 2 km，有橄榄岩暴露，但地壳厚度变化的原因尚不清楚。利用85°E和100°E （Gakkel Ridge东部）两段玻璃和玄武岩的元素和同位素系统，结合31至85°E的文献资料，对这一点进行了探讨。地球化学证据表明，样品的主要端元组成具有高Al2O3、n - morb类Sr-Nd-Hf-Pb同位素系统和轻度lree富集模式。地幔源可能是一种富含铝的肥沃橄榄岩，与较深的软流圈域有关，该软流圈域向南传播，穿过北极中部，深度约150公里。热力学模拟表明，在31-100°E火山中心的玄武岩源潜在温度和最终熔融深度都是相似的，因此不能解释沿脊地壳厚度的变化。综合前人在Gakkel脊上存在的难熔地幔残余物的文献资料，我们认为次脊上地幔是一个可育地幔域和难熔地幔域的混合体，可育地幔域比例的横向变化调节了地壳厚度沿轴线的变化。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Earth and Planetary Science Letters 地学-地球化学与地球物理

CiteScore

10.30

自引率

5.70%

发文量

475

审稿时长

2.8 months

期刊介绍： Earth and Planetary Science Letters (EPSL) is a leading journal for researchers across the entire Earth and planetary sciences community. It publishes concise, exciting, high-impact articles ("Letters") of broad interest. Its focus is on physical and chemical processes, the evolution and general properties of the Earth and planets - from their deep interiors to their atmospheres. EPSL also includes a Frontiers section, featuring invited high-profile synthesis articles by leading experts on timely topics to bring cutting-edge research to the wider community.