In the Pohang area of Korea, heulandite occurs as cements in conglomerate and sandstone of a Miocene marine fan-delta system resting on Eocene dacitic volcanics. Three types of heulandite cements are distinguishable in the fan-delta sediments on the basis of texture, chemical composition and authigenic mineral association. The earliest type I heulandite (Si/(A1+Fe): 3.5–3.8) occurs as microcrystalline (10–30 μm) in situ crystallites that replace volcanic matrix and are intermixed with early-formed smectite. Type II heulandite (Si/(A1+Fe): 3.2–3.6) occurs as medium-grained (30–60 μm) crystal aggregates rimming intergranular cavities. Type III heulandite (Si/(A1+Fe): 3.6–4.1) is the last to form and is a composite phase of heulandite-clinoptiloite, which occurs as unusually coarse (50–200 μm) single-crystal cement associating with late-formed smectite and hematite.

These characteristic heulandite cements were formed by alteration of volcaniclastic sediment during shallow burial (burial temperature: 40–60 °C) and uplift in marine pore fluid diluted by meteoric water. Sr isotope data for heulandite II (87Sr/86Sr: 0.706565–0.706598) and heulandite III (87Sr/86Sr: 0.707347–0.707432) indicate that the pore fluid was progressively mixed with meteoric water during burial and uplift but the Ca in the pore-filling heulandites has been derived mainly from dissolution of carbonate cements. Heulandite III, heulandite-clinoptilolite, was formed with an unusual coarsening and chemical zoning at somewhat diluted and disequilibrium conditions caused by the migration of oxygen-rich meteoric water during or after uplifting.

This study presents the results of a detailed paleoclimate investigation on stalagmite YL-1 (Yelini Cave, Türkiye). YL-1 grew between 117.13 (+0.57/−0.44) ka and 114.87 (+1.63/−2.89) ka within Greenland Stadial 26, indicating a positive moisture balance during the stadial conditions in this semi-arid region. Rainfall is significantly affected by sub-cloud and surface evaporation and decreasing net effective winter precipitation is recorded by high isotope values. Enriched δ18O and δ13C at 116.65 (+0.51/−0.39) ka are interpreted as a drought event that took place ca. 400 years before the end of the MIS 5e. This event, which was reported simultaneously in marine and terrestrial archives in the Northern Hemisphere, is a result of decreased cyclone activity linked to weakening of the Atlantic meridional overturning circulation. 87Sr/86Sr values of YL-1 are close to the host-rock values. Decreased 87Sr/86Sr ratio at 116.67 (+0.54/−0.38) ka reflects the intensified water–rock interaction due to lower precipitation. Along with prior calcite precipitation effect, this is also observed by increased Mg/Ca and Sr/Ca, while low P, Cu, Be, Y, and Zr concentrations indicate a lowered amount of soil-derived colloidal material. The MIS 5e/5d transition is marked by reduced insolation and enriched δ18O at 116.24 (+0.53/−0.86) ka. The Greenland Interstadial 25 phase at 115.87 (+0.83/−1.71) ka is represented by more negative δ18O and δ13C.