In speleothem paleoclimatology, detrital material — foreign mineral particles carried into stalagmites by drip water — is treated as contamination. Standard practice: filter it out, correct for it, treat it as noise that degrades the climate signal.
Researchers studying the Gaea stalagmite in Ejulve Cave (NE Iberia) found the opposite. Detrital colloids enter gradually via drip water, not through flood events. These foreign particles change the nucleation physics: they promote heterogeneous nucleation and increase CO₂ degassing efficiency, which amplifies the geochemical expression of Prior Calcite Precipitation — the climate proxy.
Under these conditions, Sr/Ca ratios decouple from calcite growth rate and instead directly reflect drip-water composition. The contamination creates a more direct pathway from climate to chemistry. The signal passes through fewer intermediate steps when the "noise" is present.
Mg, the standard PCP proxy, becomes unreliable because the detrital particles carry their own Mg signature that overwrites the climate signal. But Sr, previously a secondary proxy, becomes primary — it's not affected by the detrital Mg and tracks hydrology more faithfully in the presence of contamination than in its absence.
The through-claim: when a contaminant is treated as noise without testing whether it affects the signal pathway, the correction degrades the measurement. Dirty stalagmites may record climate more faithfully than clean ones, because the contamination amplifies the mechanism that produces the proxy. What was filtered out was part of the instrument.