Early–Middle Pleistocene transitions: Linking terrestrial and marine realms

Abstract

Marked by a progressive increase in the amplitude of climate oscillations and a shift towards a quasi-100 kyr frequency, the Early-Middle Pleistocene transition (EMPT), previously known as the Mid-Pleistocene Transition (or Mid-Pleistocene Revolution) (1.4-0.4 Ma), represents a fundamental shift in the Earth's climate state. The physical and biotic responses to this transition, amplified by the growth of Northern Hemisphere ice sheets, have been profound. Two important paleomagnetic episodes characterize the EMPT, the Jaramillo Subchron (1.07-0.99 Ma) and the Matuyama-Brunhes Chron boundary (~773 ka). The latter has been chosen as the primary guide for the Lower-Middle Pleistocene Subseries boundary, as it lies at the approximate midpoint of the EMPT and aids in global recognition both in marine and terrestrial deposits. The Jaramillo Subchron has received less attention, but the late Early Pliocene is important in Europe because it saw the progressive transition from the Villafranchian to Galerian mammal faunas, and expansion of hominins into western and northern Europe. The Jaramillo Subchron is represented by Marine Isotope Stages (MIS) 31 to 28, with MIS 30 already showing the asymmetrical (saw-tooth) pattern characteristic of the Middle Pleistocene. Indeed, while variation in the 40-kyr band (obliquity) remains strong throughout the EMPT, low frequency variability begins at around 1250-1200 kyr, which coincides with a progressive increase in global ice volume. The early phase of the EMPT is characterized by important glaciations beginning with MIS 36 and continuing to MIS 22, a major intensification of the East Asian monsoon system, intensification of loess deposition in northern Europe, development of open landscapes in western Siberia, increased fluvial incision, higher amplitude sea-level change, and spread of large mammals across northern Eurasia, and a strong reduction in the North Atlantic thermohaline circulation. In Europe, the loss of thermophilous plant taxa during the EMPT and indeed throughout the Quaternary is a reminder of the progressive cooling that took place in this region.

Evolution of Uranium Isotopic Compositions of the Groundwater and Rock in a Sandy-Clayey Aquifer

“…What is obtained is: t 1 = 0.9 Ma, which should roughly correspond to the period of a sharp cold snap in the region and filling of the paleo-valley by clay material [30][31][32][33]. The duration of the subsequent removal of hydrogenic uranium from the NDD slopes can be estimated from the equation [14]:…”

Cryptic diversity of marine gastropod Monodonta labio (Trochidae): did the early Pleistocene glacial isolation and sea surface temperature gradient jointly drive diversification of sister species and/or subspecies in the Northwestern Pacific?

“…The MPT is the fundamental changes in climate between 1,250,000 and 700,000 years ago, when the earth's dominant periodicity of climate cycles shifted from 41,000 to 100,000 years with no relation to orbital forcing (Pisias & Moore, ). During this period, a secular expansion of subarctic water masses lowered the SST in the Pacific during both glacial and inter‐glacial epochs, and reached a maximum at nearly 1.0 mya (Head & Gibbard, ). Winter SST declined from 24–25 to 17–18°C even in the northern ancient SCS, a region that is close to the core of the West Pacific Warm Pool (Li et al., ).…”

Filling the North Sea Basin: Cenozoic sediment sources and river styles

“…A substantial change marked the beginning of the Quaternary, with glaciation extending to lower altitudes and sea-level in southern Norway and periglacial frost-dominated climates becoming established over the region. An even greater impact occurs in response to further intensification of cold climates following the Middle Pleistocene Transition (Gibbard & Lewin, 2009;Head & Gibbard, 2015). There is a Pleistocene incision question concerning drivers, feedbacks and timings.…”

“…1 million years ago), the glacial-interglacial climate oscillations became more profound than previously leading to the development of substantial ice sheets in the Alps, Scandinavia, Wales and Scotland at this time (Head & Gibbard, 2015). Although glaciation had advanced into the lowland regions surrounding the Baltic by ca.…”