Planar deformation features (PDFs) in quartz are a commonly used and well‐documented indicator of shock metamorphism in terrestrial rocks. The measurement of PDF orientations provides constraints on the shock pressure experienced by a rock sample. A total of 963 PDF sets were measured in 352 quartz grains in 11 granite samples from the basement of the Chicxulub impact structure’s peak ring (IODP‐ICDP Expedition 364 drill core), with the aim to quantify the shock pressure distribution and a possible decay of the recorded shock pressure with depth, in the attempt to better constrain shock wave propagation and attenuation within a peak ring. The investigated quartz grains are highly shocked (99.8% are shocked), with an average of 2.8 PDF sets per grain; this is significantly higher than in all previously investigated drill cores recovered from Chicxulub and also for most K‐Pg boundary samples (for which shocked quartz data are available). PDF orientations are roughly homogenous from a sample to another sample and mainly parallel to {103} and {104} orientations (these two orientations representing on average 68.6% of the total), then to {102} orientation, known to form at higher shock pressure. Our shock pressure estimates are within a narrow range, between ~16 and 18 GPa, with a slight shock attenuation with increasing depth in the drill core. The relatively high shock pressure estimates, coupled with the rare occurrence of basal PDFs, i.e., parallel to the (0001) orientation, suggest that the granite basement in the peak ring could be one of the sources of the shocked quartz grains found in the most distal K‐Pg boundary sites.

中文翻译：

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Chicxulub峰环花岗岩中冲击石英颗粒的表征和冲击压力估算

石英的平面变形特征（PDFs）是陆上岩石震动变质的一种常用且有据可查的指标。PDF方向的测量对岩石样品承受的冲击压力提供了限制。在Chicxulub冲击结构的顶环（IODP‐ICDP Expedition 364钻芯）的地下室中，对11个花岗岩样品中的352个石英样品进行了963组PDF测量，目的是量化冲击压力分布和可能的衰减为了更好地限制峰值环内的冲击波传播和衰减，记录了随深度变化的冲击压力。所研究的石英颗粒受到极大的冲击（99.8％受到冲击），平均每颗2.8个PDF集。这显着高于以前从Chicxulub回收的所有钻探岩心以及大多数K-Pg边界样品（可获得冲击石英数据）。PDF方向从一个样本到另一个样本大致相同，并且主要平行于{103}和{10 4}方向（这两个方向平均占总数的68.6％），然后到{10 2}方向，已知会在较高的冲击压力下形成。我们的冲击压力估算值在16 GPa至18 GPa之间的狭窄范围内，随着钻芯深度的增加，冲击衰减会略有降低。较高的冲击压力估算值，以及罕见的基础PDF出现，即与（0001）方向平行，表明峰环中的花岗岩基底可能是最常见的冲击石英晶粒的来源之一。远端K-Pg边界部位。