Upper Cretaceous marine sequences in the Gulf Coastal Plain (USA) span the Cretaceous–Paleogene (K–Pg) transition, allowing for detailed studies of one of the most severe extinction events of the Phanerozoic. To improve the temporal resolution of the stratigraphic record that represents environmental change leading up to the K–Pg boundary, we constructed a high-resolution chemostratigraphy and cyclostratigraphy of upper Maastrichtian shallow marine deposits located in the state of Mississippi (USA). Upper Maastrichtian strata in this area consist of alternating decimeter scale chalk and marl rhythmites deposited in a hemipelagic setting. New geochemical proxy records were used to test whether rhythmic sedimentation was driven by Milankovitch cycles. Stable isotopes (δ¹³C_carb, δ¹⁸O_carb), carbonate content (wt% CaCO₃), and elemental concentrations (Ti, K, Fe) integrated with microfossil and ammonite biostratigraphy reveal astronomical forcing in the studied record. Spectral estimation suggests that rhythmic bedding was associated with climate change driven by precession (~20 kyr). Obliquity signals are also apparent in our analysis, and short eccentricity (~100 kyr) is inferred from amplitude modulation of precession. Studied sections were correlated at the precession scale with the recently tuned K–Pg succession near Morello, Italy which is stratigraphically equivalent to the well-characterized K–Pg sites in Gubbio, Italy (Bottaccione, Contessa Highway). Additionally, carbon isotope records from the study area exhibit large scale trends throughout the latest Maastrichtian, similar to those observed in the Morello and Bottaccione sections. Thus, we show that Milankovitch-scale climatic signals and low-amplitude carbon isotope shifts (<0.5‰) of the late Maastrichtian of the Gulf Coastal Plain are well-preserved and can be correlated globally.

墨西哥湾沿岸平原（美国）的上白垩纪海洋序列跨越白垩纪-古近纪（K-Pg）过渡，允许对显生宙最严重的灭绝事件之一进行详细研究。为了提高代表导致 K-Pg 边界的环境变化的地层记录的时间分辨率，我们构建了位于密西西比州（美国）上马斯特里赫特浅海沉积物的高分辨率化学地层学和旋回地层学。该地区的上马斯特里赫特地层由交替沉积在半远洋环境中的分米级白垩和泥灰岩韵律组成。新的地球化学替代记录被用来测试有节奏的沉积是否是由米兰科维奇循环驱动的。稳定同位素 (δ ¹³ C _carb , δ¹⁸ O _carb ), 碳酸盐含量 (wt% CaCO ₃)，以及与微化石和菊石生物地层相结合的元素浓度 (Ti、K、Fe) 揭示了研究记录中的天文强迫。光谱估计表明，有节奏的层理与进动（~20 kyr）驱动的气候变化有关。在我们的分析中，倾斜信号也很明显，并且从进动的幅度调制推断出短偏心率（~100 kyr）。研究的剖面在岁差尺度上与意大利莫雷洛附近最近调谐的 K-Pg 层序相关，这在地层学上相当于意大利古比奥（Bottaccione，Contessa Highway）的特征良好的 K-Pg 站点。此外，研究区的碳同位素记录显示出整个最新马斯特里赫特的大规模趋势，类似于在 Morello 和 Bottaccione 部分观察到的趋势。因此，