Soft-sediment deformation structures crop out in the Lower Cretaceous succession of the Gubbio anticline in the Umbria-Marche Apennines of Italy. The deformation interval is ~13 m thick and occurs between the upper Hauterivian–lower Aptian Maiolica Formation and the Aptian Marne a Fucoidi Formation. It can be observed along the anticline for a distance of 12 km. Different types of deformation structures are distributed in several outcrops, with detachment extensional structures prevailing in the southeast sector. Imbricated slides, slump structures, and chaotic layers are distributed vertically and longitudinally in the middle and/or lower part of the deformed sediments. In the northwest sector of the anticline, compressional duplex structures can be considered the lower section of a large sediment failure. Geometrical and kinematic analysis of the fold axis trends and sliding surfaces have led to infer a single, large gravitational event possibly Albian in age. The synsedimentary deformation could be activated by several internal trigger mechanisms induced by external regional tectonic events such as earthquakes. An orthogonal system of calcite veins crossing the limestone layers represents the primary pathway for fluid-driven breaching of joint seals. These fluids can be related to the significant increase in the total organic carbon in the Hauterivian–Aptian layer of the Maiolica and Marne a Fucoidi Formations. This suggests the possibility that the limestone layer, sandwiched and sealed between clay of the organic-rich black shales, could have favored a pore pressure increase approaching lithostatic stress. With a thin overburden, lithostatic stress is more easily reached at low hydrostatic pressure. This slump sheet occurrence suggests the existence of a local paleoslope dipping toward the north-northwest, where the mass involved in the deformation is distributed over an estimated area of 60 km 2 for a volume of 0.8 km 3 of displaced sediments. The restoration and rotation of the slump fold hinges to the Early Cretaceous direction, in line with available paleomagnetic data, have shown that the strike of the slope corresponds to the main trend of the oldest Jurassic extensional lineaments and is linked to transform faults of the westernmost Tethys rifting systems.

A bed by bed analysis of the Bonarelli Level (late Cenomanian) in the Bottaccione Gorge and the Contessa Valley (Gubbio, Italy, area) reveals ichnofabric variations that follow lithofacies changes. Ichnofabric analysis has been approached in ~60 samples for every section, using thin sections of rocks and wet cut surfaces for three-dimensional observations. The ichnofabric includes five ichnotaxa: Chondrites isp., Planolites isp., Thalassinoides isp., Trichichnus linearis , and Zoophycos isp.; their abundance and preservation fluctuate with the substrate consistency, oxygen content, and productivity. The ichnotaxa are absent in many beds that show primary lamination and were deposited under true anoxic conditions, but it is surprising that they are present in many thin beds inside the Bonarelli interval (10 in Bottaccione and 14 in Contessa). In the underlying and overlying Scaglia Bianca (late Cenomanian) carbonate deposits, the presence of a totally bioturbated background, together with superimposed discrete trace fossils (the same ichnotaxa as in the Bonarelli Level), reveals the absence of anoxic conditions (except for cherty layers), but the presence of minor fluctuations between aerobic and slightly dysaerobic conditions is marked by changes in ichnotaxa abundance.

Paleomagnetic results from the San Juan Basin, New Mexico, indicate that dinosaur extinction in that area occurred after marine extinctions at the Cretaceous/Tertiary boundary in Italy and in other marine sequences. Evidence of diachronous Cretaceous extinction in the San Juan Basin is strongly dependent upon correlation of San Juan Basin magnetozone γ + with magnetic anomaly 29. Study of magnetic minerals in San Juan Basin sediments by Butler led to the realization that the dominant carrier of detrital remanent magnetization in those sediments is titanomagnetite with Curie temperature of about 180°C. In addition, isothermal remanent magnetization acquisition was studied in order to detect minor content of hematite in the sedimentary rocks. Results show no clear evidence for overprinting associated with magnetozone γ + or any other normal magnetozones. However, sediments of magnetozone γ + and adjacent sediments have a higher than normal hematite content. More detailed tests are planned, utilizing knowledge already gained of magnetic properties in those rocks, for better identification of possible magnetic normal overprinting. Those tests, when applied to magnetozone γ + will provide a more secure determination for synchronous or diachronous extinctions at the end of Cretaceous time.