Machalski Marcin, Duda Piotr
Institute of Paleobiology, Polish Academy of Sciences, Twarda 51/55, 00-818, Warsaw, Poland.
Faculty of Science and Technology, University of Silesia in Katowice, Będzińska 39, 41-205, Sosnowiec, Poland.
Sci Rep. 2024 Aug 14;14(1):18893. doi: 10.1038/s41598-024-69846-x.
Burrowed discontinuity surfaces associated with condensed fossil concentrations demarcate breaks (hiatuses) in the Phanerozoic marine sedimentary record. Such intervals may be difficult to interpret in view of complex anatomy and varied fossil signatures. Transformation of a discontinuity surface into a heavily burrowed 'pseudobreccia' may further complicate the record, but this issue has remained unexploited to date. The richly fossiliferous Cretaceous-Paleogene (Maastrichtian-Danian) boundary interval exposed in Poland provides opportunities to test the influence of burrow-generated pseudobreccia on the preservation of associated hiatal fossil concentrations. Here, we document pseudobreccia anatomy and fossil-sediment relationships by three-dimensional X-ray computed tomography imaging. In the pseudobreccia zone, we identify a distinctive assemblage of late Maastrichtian fossils, which underwent subsurface preparation by burrowers in a hitherto unreported ichno-taphonomic process. Recognition of pseudobreccia is a prerequisite for the interpretation of the stratigraphy, sedimentology and fossil record of such intervals, which is of special interest for periods of major biotic turnovers, like the end-Cretaceous mass extinction.
与浓缩化石富集相关的潜穴间断面划定了显生宙海洋沉积记录中的间断（间断期）。鉴于其复杂的解剖结构和多样的化石特征，这些间隔可能难以解释。间断面转变为强烈潜穴化的“假角砾岩”可能会使记录进一步复杂化，但这一问题至今仍未得到充分研究。在波兰暴露的富含化石的白垩纪 - 古近纪（马斯特里赫特阶 - 达宁阶）边界间隔提供了检验潜穴形成的假角砾岩对相关间断期化石富集保存影响的机会。在此，我们通过三维X射线计算机断层扫描成像记录假角砾岩的解剖结构和化石 - 沉积物关系。在假角砾岩带，我们识别出一个独特的晚马斯特里赫特期化石组合，这些化石在一个迄今未报道的遗迹埋藏学过程中经过了潜穴生物的地下改造。识别假角砾岩是解释此类间隔的地层学、沉积学和化石记录的前提条件，对于像白垩纪末大灭绝这样的重大生物更替时期尤为重要。
