Research on climate change based on carbonate porosity analysis in Jinping, China

2d(1)–2d(3). Figs 1c(3) and 2d(4)–2d(6) were used to analyze the distribution of the gray val- ues and RGB values in the polarized light microscopic images of carbonate rock. Fig 2d(7) presents the threshold value for analyzing the gray value and RGB values of the carbonate rock polarized microscopic image in Figs 1c(3), 2d(4)–2d(6). Fig 2e shows the porosity of the car- bonate slides obtained using the R value threshold in Fig 2d(7). Fig 2f shows the porosity of the carbonate slides obtained using the G value threshold in Fig 2d(7). Fig 2g shows the porosity of the carbonate slides obtained using the B value threshold in Fig 2d(7). Fig 2h shows the porosity of the carbonate slides obtained using the gray value threshold in Fig 2d(7). Fig 2i shows the average porosity of the carbonate slides obtained using the RGB value thresholds and the gray value threshold. If the local polarized light microscopic images of carbonate rocks are suitable for karst research using image analysis technology, the average value of the above mentioned thresholds (Fig 2i) and the measured value using TCRM should be similar. Fig 2j shows the porosity of the rock specimen corresponding to the carbonate rock slide measured using the TCRM method. The results shown in Fig 2i and 2j reveal that the average porosity obtained via image threshold analysis is very close to the porosity value measured using the TCRM method. This demonstrates that the image analysis method is a reliable method of obtaining the porosity of carbonate rocks.

Carbonate rocks are widely distributed in the Jinping area. These carbonate formations are distributed along P1(q+m)- J1. This constitutes an ideal time axis for climate change research in carbonate rock areas. The carbonate rocks in the Jinping area have experienced typical karstifi- cation. Porous carbonate rocks were formed in the Jinping area. The carbonate pores in these Fig 2. Comparison between carbonate image analysis and TCRM. https://doi.org/10.1371/journal.pone.0281630.g002 PLOS ONE Research on climate change based on carbonate porosity analysis in Jinping PLOS ONE | https://doi.org/10.1371/journal.pone.0281630 March 30, 2023 5 / 21