Extended Data Fig. 7: Thin section photomicrographs of KC19-14.
From: Late Miocene Arctic warmth and terrestrial climate recorded by North Greenland speleothems
a, Main slab of KC19-14 and a panoramic view of a thin section showing the areas of photomicrographs b-d and e-j (orange dashed rectangles), respectively. b, Semi-regular fluorescent lamination seen under UV. c, Thin “dust lines” rich in opaque inclusions mark possible growth hiatuses in plane-polarised light. d, The same section under cross-polarised light, showing laterally discontinuous interruption of columnar crystal growth. e to g are thin section images of hiatus-1 (as defined in main text, see Extended Data Fig. 6), showing a sharp transition from columnar calcite below to micritic calcite above. h to j are thin section images of ‘KC-hiatus’ (as described in main text, see Extended Data Fig. 6), showing columnar calcite fabric. Ultraviolet fluorescence reveals a ca. 1.5 mm-thin zone lacking regular fluorescent lamination. The micritic zone shows brighter epifluorescence than the columnar calcite. cc: columnar calcite, cmc: columnar microcrystalline calcite, m: micrite, mcr: micro-corrosion.
