The structure of marine isotope Stage 11 and its alignment with the Holocene

Abstract

Marine Isotope Stage 11 (MIS 11) has long been used to estimate the natural length of the present Holocene interglacial, due to their similarity in terms of astronomically-driven insolation variations. It is debated, however, which part of MIS 11 should be aligned to the Holocene, according to different alignment strategies. Here, we use a well-dated, high-resolution Asian summer monsoon (ASM) record covering the whole of MIS 11 (from 445 to 320 thousand years ago (ky)) from stalagmite J33 from Jinfo Cave in Southwest China, to attempt to resolve the issue. The oxygen isotope (δ18O) record of stalagmite J33 enables MIS 11 to be divided into 5 stages: MIS 11a–11e. Among them, MIS 11a, MIS 11c and MIS 11e are relatively strong monsoon periods, while MIS 11b and MIS 11d are relatively weak monsoon periods. According to the similarities and differences of Earth orbital parameters between MIS 11 and MIS 1, we propose a new alignment strategy in which the interglacial maxima and their preceding glacial terminations can be aligned. This new comparison scheme shows that the “missing” parts of the Holocene correspond to MIS 11d and MIS 11e, which explains why the MIS 11 interglacial period was longer than the current Holocene interglacial.