Fig. 6
From: Development of a quartz-based geothermometer for biogenic chert
(a) Relationship between the quartz crystallinity index (CI) and grain size (GS) of the biogenic chert and metachert samples. The dotted line is the approximate line of CI vs. GS (for the group of datapoints with GS ≤ 1.94 μm). Paleotemperatures of the mudstone samples present nearby the chert samples are also shown. Cpt: cryptocrystalline chert, Cst: crystalline chert, M: Middle, U: Upper, Sil.: Silurian, Dev.: Devonian, Trias.: Triassic, Jura.: Jurassic. (b) Relationship between the correlation coefficient (R value) of CI and GS and the maximum crystal size (μm) in the group of datapoints. Refer to Table 2 for the data. GS: grain size, n: number of the data.
