Abstract Mid-ocean ridge basalts (MORBs) are the most abundant eruptive tholeiitic products on Earth. Many experiments have been performed to investigate the solidification of basalts but under limited thermal ranges of cooling (ΔTc) and cooling rates (ΔT/Δt). We analyze the experimental charges solidified from previous studies: the BIR1A basalt from USGS was solidified using ΔT/Δt of 1, 7, 60, 180, 1800 and 9000 °C/h, in the ΔTc between 1300 and 800 °C, at atmospheric conditions. The previous studies allowed determining the glass-forming ability (GFA) of sub-alkaline silicate liquids, but do not give information on their textures. Here, we quantify the evolution of sizes, shapes, number of crystals per area (#/A), CSDs and growth rates (Gs) of plg (plagioclase), cpx (clinopyroxene) and sp. (spinel). Textures were investigated by image analysis on thousands of crystals and are one of the most complete datasets ever obtained from laboratory studies: they reflect rapid, intermediate and sluggish cooled parts of MORB from liquidus to solidus. Faceted plg grows only at ΔT/Δt ≤ 60 °C/h, while cpx and sp. became dendritic at ΔT/Δt between 60 and 180 °C/h. As ΔT/Δt increase, crystal size ranges decrease from 1000 to 10 μm at 1 °C/h to 100–1 at 60 °C/h μm for plg, from 400 to 8 μm at 1 °C/h to 25–0.5 μm at 1800 °C/h μm for cpx, and from 90 to 6 μm at 1 °C/h to 6–0.5 at 1800 °C/h μm, for sp. The #/A increases with increasing ΔT/Δt, except for cpx between 60 and 180 °C/h. As ΔT/Δt increases, CSDs of plg, cpx and sp increase their slopes (m) and population densities per size (n0), reduce the size ranges and tend to be log-linear. At low ΔT/Δt, CSDs are composed of several log-linear segments, which slopes are related to different pulses of crystal nucleation, and subsequent growth by coarsening. The CSDs parameters (slope, m, and nucleation density per size, n0) linearly scale each other and both are highly correlated with ΔT/Δt. Maximum (Gmax) and average (GCSD) growth rates are computed respectively by averaged major axis (Lmax) of the five longest crystals and by the m of CSDs. Both the Gs are a function of experimental time (t) and increase with the increasing of ΔT/Δt, changing up to two orders of magnitude. The Gmax of cpx is correlated with m and n0 and can be used in natural MORB to retrieve either ΔT/Δt and Gmax. The plg and cpx crystals with sizes between 0.1 and 1 mm are abundant in the experimental charges obtained at low ΔT/Δt. In volcanic rocks, these crystal sizes are generally considered representative of intra-telluric conditions (phenocrysts and microphenocrysts). Our data demonstrate that crystals with mm-sizes may also grow in syn-to-post-depositional conditions. The continuous evolution of textures in response to ΔT/Δt variations implies that kinetic effects can fully capture the solidification of MORBs. As a result, the widely accepted assumption that phenocrysts represent the products of evolution processes in volcanic conduits or magma reservoirs could be not valid for some basaltic lavas.

中文翻译：

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从洋中脊玄武岩熔体中以可变冷却速率结晶的斜长石、单斜辉石和尖晶石的质地、晶体尺寸分布和生长速率的演变

摘要 大洋中脊玄武岩（MORBs）是地球上最丰富的喷发拉斑岩产物。已经进行了许多实验来研究玄武岩的凝固，但在有限的冷却温度范围 (ΔTc) 和冷却速率 (ΔT/Δt) 下。我们分析了之前研究中固化的实验电荷：来自 USGS 的 BIR1A 玄武岩使用 1、7、60、180、1800 和 9000 °C/h 的 ΔT/Δt 固化，ΔTc 介于 1300 和 800 °C 之间，在大气条件下使适应。以前的研究允许确定亚碱性硅酸盐液体的玻璃形成能力 (GFA)，但没有提供有关其质地的信息。在这里，我们量化了 plg（斜长石）、cpx（单斜辉石）和 sp 的大小、形状、每面积晶体数量 (#/A)、CSD 和生长速率 (Gs) 的演变。（尖晶石）。通过对数千个晶体的图像分析来研究纹理，并且是从实验室研究中获得的最完整的数据集之一：它们反映了 MORB 从液相线到固相线的快速、中间和缓慢冷却部分。多面 plg 仅在 ΔT/Δt ≤ 60 °C/h 时生长，而 cpx 和 sp。在 60 到 180 °C/h 之间的 ΔT/Δt 下变成枝晶。随着 ΔT/Δt 的增加，晶体尺寸范围从 1°C/h 时的 1000 到 10 μm 减小到 60°C/h 时的 100–1 μm（对于 plg，从 400 到 8 μm，1°C/h 到 25–0.5） μm 在 1800 °C/h μm 对于 cpx，从 90 到 6 μm 在 1 °C/h 到 6–0.5 在 1800 °C/h μm，对于 sp。#/A 随着 ΔT/Δt 的增加而增加，除了 cpx 在 60 到 180 °C/h 之间。随着 ΔT/Δt 的增加，plg、cpx 和 sp 的 CSD 会增加其斜率 (m) 和每个尺寸的种群密度 (n0)，减小尺寸范围并趋于对数线性。在低 ΔT/Δt 时，CSD 由几个对数线性段组成，其斜率与晶体成核的不同脉冲有关，随后通过粗化生长。CSD 参数（斜率、m 和每个尺寸的成核密度，n0）相互线性缩放，并且两者都与 ΔT/Δt 高度相关。最大 (Gmax) 和平均 (GCSD) 生长速率分别由五个最长晶体的平均长轴 (Lmax) 和 CSD 的 m 计算。两个 Gs 都是实验时间 (t) 的函数，并且随着 ΔT/Δt 的增加而增加，最多变化两个数量级。cpx 的 Gmax 与 m 和 n0 相关，可用于自然 MORB 以检索 ΔT/Δt 和 Gmax。尺寸在 0.1 和 1 mm 之间的 plg 和 cpx 晶体在低 ΔT/Δt 下获得的实验电荷中很丰富。在火山岩中，这些晶体大小通常被认为是大地内条件（斑晶和微斑晶）的代表。我们的数据表明，毫米尺寸的晶体也可能在同步到沉积后的条件下生长。响应 ΔT/Δt 变化的织构的连续演变意味着动力学效应可以完全捕捉 MORB 的凝固。因此，广泛接受的假设，即斑晶代表火山管道或岩浆储层中演化过程的产物，对于某些玄武岩熔岩可能无效。响应 ΔT/Δt 变化的织构的连续演变意味着动力学效应可以完全捕捉 MORB 的凝固。因此，广泛接受的假设，即斑晶代表火山管道或岩浆储层中演化过程的产物，对于某些玄武岩熔岩可能无效。响应 ΔT/Δt 变化的织构的连续演变意味着动力学效应可以完全捕捉 MORB 的凝固。因此，广泛接受的假设，即斑晶代表火山管道或岩浆储层中演化过程的产物，对于某些玄武岩熔岩可能无效。