The Cretaceous–Paleogene (K–Pg) boundary interval represents one of the most significant mass extinctions and ensuing biotic recoveries in Earth history. Earliest Paleocene fossil mammal faunas corresponding to the Puercan North American Land Mammal Age (NALMA) are thought to be highly endemic and potentially diachronous, necessitating precise chronostratigraphic controls at key fossil localities to constrain recovery dynamics in continental biotas following the K–Pg mass extinction. The Laramide synorgenic sedimentary deposits within the Denver Basin preserve one of the most continuous and fossiliferous records of the K–Pg boundary interval in North America. However, poor exposure in much of the Denver Basin makes it difficult to correlate between outcrops. In order to constrain fossil localities across the basin, previous studies have relied upon chronostratigraphic methods such as magnetostratigraphy. Here we present a new high-resolution magnetostratigraphy of 10 lithostratigraphic sections spanning the K–Pg boundary interval at Corral Bluffs located east of Colorado Springs in the southern part of the Denver Basin. Fossil localities from Corral Bluffs have yielded limited dinosaur remains, mammal fossils assigned to the Puercan NALMA, and numerous fossil leaf localities. Palynological analysis identifying the K–Pg boundary in three sections and two independent but nearly identical ²⁰⁶Pb/²³⁸U age estimates for the same volcanic ash, provide key temporal calibration points. Our paleomagnetic analysis has identified clear polarity reversal boundaries from Chron C30n to Chron C28r across the sections. It is now possible to place the fossil localities at Corral Bluffs within the broader basin-wide chronostratigraphic framework and evaluate them in the context of K–Pg boundary extinction and recovery.

中文翻译：

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构建横跨白垩纪-古生界的生物恢复的时间表，科拉夫布拉夫，科罗拉多州丹佛盆地

白垩纪-古生界（K-Pg）的边界区间代表了地球历史上最重要的物种灭绝和随之而来的生物恢复。人们认为对应于Puercan北美陆地哺乳动物时代（NALMA）的最早的古新世化石哺乳动物是高度流行的，并且可能是历时性的，因此有必要在关键化石地区进行精确的地层学控制，以限制K-Pg灭绝后大陆生物群的恢复动态。丹佛盆地内的拉拉酰胺同生沉积沉积物保留了北美K–Pg边界区间最连续和化石记录之一。但是，丹佛盆地大部分地区的暴露不良，很难使露头之间相互关联。为了限制整个盆地的化石分布，以前的研究依靠年代地层方法，例如磁地层学。在这里，我们提出了一个新的高分辨率地层学，包括10个岩石地层剖面，横跨丹佛盆地南部科罗拉多斯普林斯东部的Corral Bluffs的K–Pg边界区间。来自科拉夫布拉夫斯的化石地方已经产生了有限的恐龙残骸，分配给普尔坎纳尔玛的哺乳动物化石以及许多化石叶子地方。孢粉学分析在三个部分和两个独立但几乎相同的区域确定了K–Pg边界 来自科拉夫布拉夫斯的化石地方已经产生了有限的恐龙遗迹，分配给普尔坎纳尔玛的哺乳动物化石以及许多化石叶子地方。孢粉学分析在三个部分和两个独立但几乎相同的区域确定了K–Pg边界 来自科拉夫布拉夫斯的化石地方已经产生了有限的恐龙残骸，分配给普尔坎纳尔玛的哺乳动物化石以及许多化石叶子地方。孢粉学分析在三个部分和两个独立但几乎相同的区域确定了K–Pg边界同一火山灰的²⁰⁶ Pb / ²³⁸ U年龄估算提供了关键的时间校准点。我们的古磁分析已经确定了从Chron C30n到Chron C28r整个断面的清晰极性反转边界。现在可以在更广泛的盆地年代地层学框架内的科拉夫布拉夫斯地区放置化石，并在K–Pg边界消灭和恢复的背景下对其进行评估。