Skip to main content
. Author manuscript; available in PMC: 2020 Jun 17.
Published in final edited form as: Geol Mag. 2019 Jun 17;N/A:10.1017/S0016756819000293. doi: 10.1017/S0016756819000293

Figure 4.

Figure 4.

Hand samples and microscopic views of the thrombolite and authigenic aragonite (now dolomite) crystal fans that are typical in the lower half of the Algal Dolomite Member of the Dengying Formation at the Gaojiashan section. (A) Sample slab 14AD-1, showing thrombolite sediments in the lower part and two generations of crystal fans in the middle and upper parts, respectively. Scale in millimeters. (B-C) Closer views of thrombolitic texture in labelled rectangles in A. Note the coarse dolomite cements within a large void of the thrombolitic dolomite matrix. (D-E) Authigenic crystal fans in labelled rectangles in A. Note the crystals with growth discontinuities (arrows). Although the entire rocks have been dolomitized, the relic fabrics of the original aragonite crystals are retained. (F) Divergent fabrics of dolomite crystals with sweeping extinction under XPL in labelled rectangles in A. (G) Dolostone slab 14AD-4 with crystal fans growing above dolomitic sediments. Scale in millimeters. (H-I) Closer views of crystal fans in labelled rectangles in G, showing growth discontinuities (arrows in I) within the aragonite crystals. PPL: plane polarized light; XPL: cross polarized light.