Biomolecular Stratigraphy Laboratory, Madrid School of Mines, C/Rios Rosas 21, E-28003 Madrid, Spain

To refine knowledge about terrace phases and uplift history for a tectonically poor deformed region, we apply the synchronous correlation method to reconstruct the chronology of a poorly constrained sequence of raised palaeoshorelines on the Apulian foreland, southern Italy. This work uses new chronological constraints obtained by amino acid racemisation (AAR) and isoleucine/alloisoleucine epimerisation (IE) on Patella spp., Thetystrombus latus (Gmelin), Glycymeris sp., and ostracods and U-series dating on corals Hoplangia durotrix Gosse and Cladocora caespitosa Linneo. This procedure provides a quantitative estimate of the vertical movements and associated rates within a region of the Apulian foreland. The synchronous correlation method uses sea-level highstands and uplift rate(s) as inputs; in particular, for sea-level highstands, the inputs are the age of the highstands and the sea-level elevation of the highstands relative to the present-day sea level. The output is a set of currently expected elevations of each sea-level highstand (the present elevations of palaeoshorelines). We then used regression analysis to assess the robustness between our observed palaeoshorelines and expected elevations of sea-level highstands. Our results show that the best fitting scenario is obtained using the sea-level curves of (i) Waelbroeck et al. (2002) from present to 410 ky BP and (ii) Rohling et al. (2014) from 410 to 590 ky BP as inputs for our synchronous correlation method, with uplift rates ranging from 0.09 mm/y to 0.07 mm/y with a mean value of 0.08 mm/y from 590 ky BP onwards. We recognised palaeoshorelines in the field belonging to the following highstands: 120 ky BP (MIS 5.5, second peak), 127 ky BP (MIS 5.5, first peak), 212 ky BP (MIS 7.3), 330 ky BP (MIS 9.3), 410 (MIS 11), 525 ky BP (MIS 13.3), and 590 ky BP (MIS 15). Our results show field observations of the reoccupation effect of younger palaeoshorelines over older ones due to the relatively slow uplift rates measured in the investigated area as predicted by our synchronous correlation method. In particular, we show a well-mapped and described reoccupation of the MIS 5.5 palaeoshoreline over the MIS 7.3 palaeoshoreline, constrained by new absolute dating. In addition, the data from the Apulian foreland suggest an MIS 7.3 highstand close to the present sea level.

For the first time, the synchronous correlation technique and amino acid racemization (AAR) analyses of Patella spp. and Thetystrombus latus shells are applied to an understudied sequence of raised palaeoshorelines to refine the knowledge about terrace phases and uplift history in the middle-late Pleistocene in a sector of the Apulian foreland (western coast of the Salento Peninsula, southern Italy). These combined methodologies provide the first chronological attribution for middle-late Pleistocene palaeoshorelines and quantitative assessment of vertical crustal movements in this sector of the Apulian foreland, which, to date, has been characterised by a scarcity of reliable chronological data. By applying a synchronous correlation technique driven by new AAR analyses, we iterate different uplift rate scenarios to find the best match between digital terrain model and field-based observed palaeoshorelines and “expected” sea level highstand elevations. Our results show that two uplift rate scenarios could explain the mapped geomorphology: (i) scenario 1 suggests fluctuating uplift rates over time with an uplift rate of 0.15 mm/y until 130 ky BP (middle Pleistocene, interval MIS 15 - MIS 6; that is, 590 - 130 ky BP) and of 0.07 mm/y from 130 ky BP to the present; on the other hand, (ii) scenario 2 suggests a constant uplift rate of 0.12 mm/y over time in the middle-late Pleistocene. The palaeoshorelines recognised in this study are related to the following highstands: 119 ky BP (MIS 5.5 second peak), 125 ky BP (MIS 5.5), 240 ky BP (MIS 7.5), 340 ky BP (MIS 9.3), and 478 ky BP (MIS 13.1) for both scenarios 1 and 2. The two scenarios only differ in the oldest palaeoshoreline: 560 ky BP (MIS 15.3) in scenario 1 and 550 ky BP (MIS 15.1) in scenario 2. Our results highlight how the number of preserved palaeoshorelines is controlled by uplift rates; indeed, in this area, we show that fewer palaeoshorelines are preserved than in regions where higher uplift rates have beeninferred, suggesting a more prominent effect of the “overprinting” or re-occupation of younger sea level highstands over the older sea level highstands. Finally, we discuss geomorphological and geological implications of using a synchronous correlation approach, driven by new age controls, to model raised palaeoshorelines where relatively low uplift rates have been mapped within well-known geodynamically stable regions, such as the Apulian foreland, southern Italy.