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Tempo and duration of short-term environmental perturbations across the Cretaceous-Paleogene boundary

机译：穿越白垩纪-古近系边界的短期环境扰动的速度和持续时间

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The complex interplay between extraterrestrial events and earth-bound processes that triggered one of the greatest biological crises of the Phanerozoic requires a high resolution timescale. Detailed magnetic susceptibility measurements at the Contessa Highway and Bottaccione sections (Italy) span the Cretaceous-Paleogene boundary and reveal clear orbital signatures in the sedimentary record. Identification of precession and 405 kyr eccentricity cycles allows an estimate of 324+/-40 kyr for the duration of the Maastrichtian part of Chron C29r. We present in the same high resolution time frame sites in Spain and the North and South Atlantic and bio-horizons, biotic changes, stable isotopic excursions and the decrease in Osmium isotopes recorded in these sections. The onset of ~(187)Os/~(188)Os decrease coincides with the δ~(13)C negative excursion K-PgEI, thus suggesting a first pulse in Deccan volcanism at 66.64 Ma. The K-PgE3 δ~(13)C negative excursion is possibly the expression of a second pulse at 66.26 Ma. Late Maastrichtian δ~(13)C negative excursions are of low intensity and span durations of one to two eccentricity cycles, whereas early Danian excursions are brief (about 30 kyr) and acute. Biotic response to late Maastrichtian perturbations occurred with a delay of ca. 200 kyr after the beginning of K-PgEl shortly before K-PgE3. The biotic perturbation could be thus either a delayed response to K-PgEl, or a direct response to K-PgE3, and possibly, a threshold response to the stepwise buildup of CO_2 atmospheric injections. No delay is evident in response to early Danian hyperthermal events. These differences suggest that short-lived, volcanically-derived environmental perturbations were buffered within the stable late Maastrichtian oceanic realm whereas they were amplified by the more sensitive and highly disturbed early Danian oceanic ecosystem.
机译：外星事件与地球活动之间复杂的相互作用引发了生代时代最大的生物危机之一，因此需要高分辨率的时间尺度。在Contessa高速公路和Bottaccione断面（意大利）进行的详细磁化率测量横跨白垩纪-古近纪边界，并在沉积记录中揭示了清晰的轨道特征。识别进动和405 kyr的偏心周期可以使Chron C29r的Maastrichtian部分持续时间估算为324 +/- 40 kyr。我们在西班牙，北大西洋和南大西洋以及生物地平线，生物变化，稳定的同位素偏移以及这些部分中记录的O同位素减少的高分辨率时限站点中呈现。 〜（187）Os /〜（188）Os减少的发生与δ〜（13）C负偏移K-PgEI一致，因此暗示Deccan火山活动中的第一个脉冲为66.64 Ma。 K-PgE3δ〜（13）C负偏移可能是第二脉冲在66.26 Ma处的表达。马斯特里赫特晚期δ〜（13）C负向偏移强度较低，跨度为一到两个偏心周期，而大安早期则为短时偏移（约30 kyr），且剧烈。对后期Maastrichtian扰动的生物反应发生的时间约为ca。在K-PgE3开始之前不久，在K-PgE1开始后200 kyr。因此，生物干扰可能是对K-PgE3的延迟响应，或者是对K-PgE3的直接响应，可能是对CO_2大气注入逐步积累的阈值响应。对于早期的大年高温事件没有明显的延迟。这些差异表明，短暂的，源自火山的环境扰动被缓冲在稳定的马斯特里赫特晚期海洋域内，而它们却被更敏感和高度动荡的早期达尼安海洋生态系统所放大。

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