Abstract Presented here are cyclostratigraphic time-series data, using magnetic susceptibility (χ) results from Devonian Moroccan rocks to establish a floating-point age chronology, and a method that can be applied to any geological stage using geochemical or geophysical datasets as a climate proxy. The χ data are fit to an independent uniform climate model for the entire Eifelian Stage. The procedure used comprised: (a) definition of a uniform c. 405 kyr eccentricity climate model for the Eifelian, with a published duration for the Eifelian; and (b) graphical testing of the model using χ data derived from outcrop samples, here including data from the Global Boundary Stratotype Section and Point for the Emsian–Eifelian and Eifelian–Givetian stage boundaries, and an overlapping succession from Bou Tchrafine, Morocco. The time-series methods used here identify χ cycles that conform to the c. 405 kyr by graphically comparing the χ zonation with the climate model. Well-established conodont zonations developed using graphic correlation are then compared with this model, allowing time estimates for Eifelian conodont zone ranges. The time-series data indicate that the Eifelian Stage in the Middle Devonian lasted for c. 6.28 myr, the Lower Eifelian Choteč bio-event lasted for c. 600 kyr, and the Kačák bio-event in the Upper Eifelian lasted for c. 370 kyr.

Abstract Applying time-series analyses using Fourier transform and multi-taper methods to low-field, mass-specific magnetic susceptibility (χ) measurements on marine samples from well-studied shale and limestone outcrops of the Upper Ordovician (Edenian Stage; Upper Katian) Kope Formation, northern Kentucky, corroborates direct visual identification in outcrops of Milankovitch eccentricity ( c. 405 and 100 ka), obliquity and precessional climate cycles. Because individual outcrops were too short and deposition too chaotic to yield significant time-series results, it was necessary to build a c. 50 m thick composite sequence from three well-correlated outcrops to quantify the cyclicity. Time-series analysis was then performed using χ measured for 1004 closely spaced samples covering the section. Milankovitch bands are recorded in the time-series data from the composite. We tested this result by comparison of these bands to cyclic packages in outcrop, which correspond to thicknesses represented in the time-series datasets. This is particularly well defined for the eccentricity and obliquity cycles, with precessional bands being evident but as less well-defined packages of beds.

Abstract Here we establish a magnetostratigraphy susceptibility zonation for the three Middle Permian Global boundary Stratotype Sections and Points (GSSPs) that have recently been defined, located in Guadalupe Mountains National Park, West Texas, USA. These GSSPs, all within the Middle Permian Guadalupian Series, define (1) the base of the Roadian Stage (base of the Guadalupian Series), (2) the base of the Wordian Stage and (3) the base of the Capitanian Stage. Data from two additional stratigraphic successions in the region, equivalent in age to the Kungurian–Roadian and Wordian–Capitanian boundary intervals, are also reported. Based on low-field, mass specific magnetic susceptibility (χ) measurements of 706 closely spaced samples from these stratigraphic sections and time-series analysis of one of these sections, we (1) define the magnetostratigraphy susceptibility zonation for the three Guadalupian Series Global boundary Stratotype Sections and Points; (2) demonstrate that χ datasets provide a proxy for climate cyclicity; (3) give quantitative estimates of the time it took for some of these sediments to accumulate; (4) give the rates at which sediments were accumulated; (5) allow more precise correlation to equivalent sections in the region; (6) identify anomalous stratigraphic horizons; and (7) give estimates for timing and duration of geological events within sections.

Abstract The magnetostratigraphy susceptibility technique is used to establish high-resolution correlation among Paleocene–Eocene boundary sequences in Egypt, Spain, and the U.S.A. This work initially focuses on the Global boundary Stratotype Section and Point (GSSP), defining the base of the Ypresian Stage (lowest Eocene), located in the Dababiya Quarry near Luxor in Upper Egypt. The base of the Eocene represents the beginning of the Paleocene–Eocene Thermal Maximum (PETM) identified by a negative carbon isotope (δ 13 C) excursion. While onset of the CIE is somewhat gradual in most reported Paleocene–Eocene (P–E) sections, at the GSSP it is very abrupt and begins immediately after an unusual lithologic change that magnetic susceptibility (MS) and other data indicate represents a short erosional or nondepositional hiatus. Comparison of MS zones from five well-studied marine sequences (the Dababiya Quarry GSSP, Jebal El Qreiya, also in Upper Egypt, Zumaia in northern Spain, Alamedilla in southern Spain, and the MGS-1 Harrell Core from southeastern Mississippi, U.S.A.) with that from the GSSP site shows a period of reduced sedimentation and nondeposition through the boundary interval in the GSSP. This interval, estimated to have lasted for ~ 10,000 years, is less than the biostratigraphic resolution for the site. Due to the hiatus in the GSSP, we have chosen the P–E section in Zumaia as the MS reference section for the P–E boundary interval. Because the correlation between the Zumaia section in Spain and the MGS-1 Core from the U.S.A. is excellent, and because the MGS-1 data set represents a longer interval of time than does the Zumaia data set, we use the MS data from the MGS-1 Core to extend the MS zones from Zumaia and establish a MS composite reference section (MS CRS) for the P–E boundary interval sampled. Orbital-forcing frequencies for the Zumaia reference section are then identified, via spectral analysis. Extending the MS zones into the MS CRS allows age assignment to MS zones for all five sections with a resolution of ~ 26,000 years. Application of Modern Stratigraphic Techniques: Theory and Case Histories SEPM Special Publication No. 94, Copyright © 2010 SEPM (Society for Sedimentary Geology), ISBN 978-1-56576-199-5, p. 167–179.