Dating basal peat: The geochronology of peat initiation revisited

Attributing the start of peat growth to an absolute timescale requires dating bottom deposits overlying mineral sediment, often called basal . Peat initiation is reflected in stratigraphy as a gradual transition from sediment increasingly organic material, up where it peat. So far, varying criteria have been used define peat, resulting divergent approaches date initiation. The lack universally applicable and quantitative definition, combined with multiple concerns that raised previously regarding radiocarbon may result apparent ages are either too old or young for timing Here, we aim formulate updated recommendations We provide conceptual framework supports use matter (OM) gradient reproducible definition mineral-to-peat (i.e., stratigraphical range reflecting timespan process) layer defined deposit). Selection samples challenging due poor preservation plant macrofossils representativity humic humin dates age uncertain. therefore analyse based on three highly detailed sequences dates, including fractions obtained bulk samples. Our case study peatland Netherlands currently harbours bog vegetation, but biostratigraphical analyses show during vegetation was mesotrophic. Results most accurate recommendable 14 C If these unattainable, fraction provides best alternative interpreted terminus-ante-quem potential large difference between (up ?1700 years macrofossil ages, even larger differences humins) suggests studies reusing existing should take great care data interpretation. potentially long process (with medians ?1000, ?1300 ?1500 within our peatland) demonstrates choices sampling size resolution need be well substantiated. summarise findings set peats, advocate widespread OM determination obtain low-cost, eases intercomparison studies. • present transition. Basal needs clearly parameter. certain rather than event. Plant accurate, humic/humin likely young. A presented.