The silicate mineral fraction of shallow marine carbonates archives dust contributions to the Central Persian Terranes along the northeastern margin of Gondwana (∼30°S paleolatitude), enabling reconstruction of atmospheric dust loading and circulation for intervals of the late Paleozoic ice age. The Central Persian Terranes hosted cyclic deposition of warm water carbonates from middle Pennsylvanian to earliest Permian time, and our data set includes two ∼28 m sections from the Moscovian and Asselian sampled at 20 cm intervals. Bounding surfaces between successive cycles (high-frequency sequences) are recognized by either abrupt basinward shifts in facies or subtle exposure features; these high-frequency sequences range from 1 m to 5 m thick and are interpreted to record glacioeustatic variations. Time series analysis of the dust fraction through the studied interval supports the hypothesis of orbital forcing for the dust signal. The stratigraphic pattern of the dust flux indicates minimal flux during interglacial highstands (0.19–0.27 g/cm2/kyr) and peak flux during glacial lowstands (3.77–4.57 g/cm2/kyr) after accounting for hiatal time at sequence boundaries. Grain size analysis of the dust for all samples (n = 230) reveals modal sizes (volume-based) of 1–15 µm through the Moscovian interval and 10–75 µm through the Asselian interval. Dust deposition increased during glacial times relative to interglacial times by a factor of 16 to 19. Additionally, the Asselian interval exhibits higher dust flux overall relative to the Moscovian interval, which is interpreted to reflect the more extreme icehouse conditions of the Asselian. Variation in the dust content through the studied sections provides an indicator of temporal changes in atmospheric loading that varied at both glacial–interglacial and higher-frequency (<104 yr) scales. Geochemical data reveal that the Arabian–Nubian Shield and southwestern Pangaea (South America) are the most likely sources of dust deposition in the Central Persian Terranes, with sources shifting during different phases. Increased dust flux during glacials likely reflects multiple factors, including enhanced aridity in the source region, exposure of shelf regions, and potential changes in winds. However, the discrepancy in model reconstructions of the amplitude of glacial–interglacial dust variations indicates that increased production of dust sourced by dynamic glaciation played a large role in enhancing dust flux during glacial phases.

中文翻译：

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晚古生代冰期高峰期在冈瓦纳东北部的大气尘埃通量

浅层海相碳酸盐的硅酸盐矿物馏分记录了冈瓦纳东北缘（约30°S纬度）对中波斯地带的粉尘贡献，从而能够在古生代晚期的冰期间隔内重建大气粉尘的负荷和循环。波斯中部地区是从宾夕法尼亚州中部到最早的二叠纪时期的温水碳酸盐的周期性沉积，我们的数据集包括以20 cm的间隔从莫斯科和阿瑟利亚地区采集的约2〜28 m断面。连续周期（高频序列）之间的边界面可以通过相的突然盆地向移动或微弱的曝光特征来识别。这些高频序列的厚度范围为1 m至5 m，并被解释为记录冰川恒流变化。通过研究间隔进行的粉尘分数的时间序列分析支持了粉尘信号的轨道强迫的假设。尘埃通量的地层模式表明，在考虑了序列边界上的食宿时间之后，在冰间期高空期间的通量最小（0.19-0.27 g / cm2 / kyr），在冰期低潮期间的峰值通量（3.77-4.57 g / cm2 / kyr）。对所有样品（n = 230）的粉尘粒度分析显示，模态尺寸（基于体积）在Moscovian区间为1–15 µm，在Asselian区间为10–75 µm。在冰川时期，相对于冰川间期，尘埃沉积增加了16到19倍。此外，相对于Moscovian区间，阿瑟尔岩层总体上表现出更高的尘埃通量，这被解释为反映了阿瑟尔岩层的更极端的冰场条件。通过研究部分得出的粉尘含量变化提供了指示大气负荷的时间变化的指标，该变化在冰川-冰川间和高频（<104年）尺度上均发生变化。地球化学数据显示，阿拉伯-努比亚盾牌和西南Pangea（南美）是中波斯地带最可能的尘埃沉积源，其源头在不同阶段发生了变化。冰川期间尘埃通量的增加可能反映了多种因素，包括源区的干旱增加，架子区的暴露以及风的潜在变化。然而，冰川间冰尘变化幅度的模型重建中的差异表明，由动态冰川作用产生的粉尘产量的增加在冰川期增加粉尘通量方面发挥了重要作用。