瑞士日内瓦大学Romain Vaucher课题组报道了西班牙Tremp盆地下始新世三角洲层序沉积物供给变化控制。该项研究成果发表在2024年10月9日出版的《地质学》上。

据了解，在解释沉积序列时，沉积物供应的变化往往被忽视，大多数研究都强调可容纳空间的变化。

课题组成员对Tremp盆地中一个受时间约束良好的浅海序列进行了研究，以验证早始新世沉积供应变化对三角洲序列发育的控制作用。研究分析了Morillo灰岩和Castigaleu组(52.2-50.6Ma)的古环境记录(沉积相和δ¹³C_org值)。三角洲体系的第一次进积以厚的三角洲前缘砂岩的突然出现为标志，并与实测δ¹³C_org记录中第一次负碳同位素偏移(CIEs)有关。随后的进积阶段与随后的CIEs负偏一致。与之相反，CIEs正偏对应于粒度更细、更远端的前三角洲沉积。

沉积过程中发生了一系列高温事件，在δ¹³C_carb参考曲线上被识别为全球CIEs负偏，研究人员初步将其与δ¹³C_org数据联系起来。因此，在下始新世浅海层序沉积过程中，层序生成的主要触发因素是气候引起的沉积物供应的高频变化，特别是高温事件而不是可容空间的变化。这种联系强调了形成浅海环境地层结构的气候动力学，和沉积响应之间的复杂相互作用。

附：英文原文

Title: Sediment supply variation control on Lower Eocene delta sequences (Tremp Basin, Spain)

Author: Romain Vaucher, Claire Musajo, Jorge E. Spangenberg, Miquel Poyatos-Moré, Christian Zeeden, Cai Puigdefabregas, Marine Prieur, Sébastien Castelltort, Thierry Adatte

Issue&Volume: 2024-10-09

Abstract: Sediment supply variations are often overlooked when interpreting depositional sequences, with most studies instead emphasizing changes in accommodation space. Here, we investigated a temporally well-constrained shallow-marine succession in the Tremp Basin to test the control of sediment supply variations on the development of deltaic sequences during the early Eocene. We analyzed the paleoenvironmental record (sedimentary facies and δ¹³C_org values) of the Morillo Limestone and the Castigaleu Formation (52.2-50.6 Ma). The first progradation of the deltaic system is marked by the abrupt appearance of thick delta-front sandstones and associated with the first negative carbon isotopic excursions (CIEs) in the measured δ¹³C_org record. Subsequent phases of progradation align with subsequent negative CIEs. Conversely, positive CIEs correspond to finer-grained, more-distal prodelta deposits. A series of hyperthermal events occurred during the deposition, globally identified as negative CIEs on δ¹³C_carb reference curves, which we tentatively correlate with our δ¹³C_org data. We therefore suggest that during deposition of this Lower Eocene shallow-marine succession, the primary trigger behind sequence generation was the high-frequency climate-induced variation in sediment supply, specifically the hyperthermal events, rather than changes in accommodation. This linkage underscores the complex interactions between climate dynamics and sedimentary responses that shape the stratigraphic architecture of shallow-marine settings.

DOI: 10.1130/G52548.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G52548.1/649100/Sediment-supply-variation-control-on-Lower-Eocene