# Study on Sedimentary Evolution of the Hanjiang River Delta during the Late Quaternary
## 3 Results
### Abundance of Foraminifera and Ostracods  
Benthic foraminifers and ostracods are mainly divided into nearshore species (living in estuaries and nearby tidal flats with salinitie of 1-31), inland shelf species (living in continental shelf waters below 50 m with salinitie of 20-31) and euryhaline species (living in open waters above 50 m with salinitie >31). Microscopically, foraminifera fossils were found in a small number of layers in each borehole. Some layers had more foraminifera than others. The abundance of ostracods was low, and they were better preserved. The abundance of fossil species is shown in Tables 3 and 4. A total of 22 samples were collected from borehole ZK03. We found 18 species of benthic foraminifera, of which 13 were calcareous transparent shells, 5 were porcelain shell types, and no cemented shell type was found. These species were mainly located in the middle of the formation (17 m, 25-29 m, 34.5 m). The dominant species of foraminiferal fauna in the borehole were Asterorotalia subtrispinosa and Ammonia, which had the highest abundance in the 25-27 m layer, with an average of 100/50 g dry sample. This fauna is a typical coastal shallow water assemblage dominated by warm water and contains a certain salty sea-land transitional facies. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Borehole Number** & **Depth/m** & **Dating Materials** & **Average Calendar Age/ka BP** & **Error/ka** \\ \hline ZK03 & 34.5 & mud & 24.1 & \(\pm\)0.18 \\ ZK03 & 37.5 & mud & 27.9 & \(\pm\)0.26 \\ ZK03 & 39.7 & mud & 37.4 & \(\pm\)0.70 \\ HK01 & 2 & foraminifera & 2.4 & \(\pm\)0.03 \\ HK01 & 8.5 & mud & 8.1 & \(\pm\)0.05 \\ HK01 & 24.3 & mud & 30.2 & \(\pm\)0.31 \\ HK03 & 3 & foraminifera & 3.2 & \(\pm\)0.04 \\ HK03 & 5.2 & foraminifera & 5.0 & \(\pm\)0.04 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: AMS14C results obtained for borehole samples. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Borehole Number** & **Depth/m** & **Dating Materials** & **Age/ka BP** & **Error/ka** \\ \hline ZK03 & 40.9 & Grey medium fine sand & 55.8 & \(\pm\)5.8 \\ ZK03 & 64.7 & Dark gray argillaceous fine sand & 96.7 & \(\pm\)13 \\ ZK03 & 74.1 & Bluish gray muddy silty sand & 74.2 & \(\pm\)8.2 \\ ZK01 & 38.0 & Graysibl velocity medium sand & 52.6 & \(\pm\)7.5 \\ HK01 & 26.1 & Dark gray medium sand & 17.3 & \(\pm\)2.3 \\ HK01 & 33.1 & Dark gray sandy clay & 55.9 & \(\pm\)6.1 \\ ZK02 & 21.8 & Dark gray medium fine sand & 67.2 & \(\pm\)5.3 \\ HK05 & 13.5 & Graysibl yellow sandy clay & 16.2 & \(\pm\)1.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: OSL results obtained for borehole samples. +++ ==ERROR: No output for this page== \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c c c} \hline \hline
**Delling Number** & **Depth/in** & **Depth/in** & **Depth/in** & **Depth/in** & **Depth/in** & **Depth/in** & **Depth/in** & **Depth/in** & **Depth/in** & **Depth/in** & **Depth/in** & **Depth/in** & **Depth/in** & **Depth/in** & **Depth/in** & **Depth/in** \\ \hline ZK03 & 17 & 0 & 0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\ \hline ZK03 & 25 & 3 & 1 & 0 & 0 & 1 & 1 & 0 & 0 & 3 & 2 & 2 & 1 & 0 & 0 & 0 & 0 \\ \hline ZK03 & 27 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 2 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\ \hline ZK03 & 29 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\ \hline ZK03 & 345 & 17 & 22 & 8 & 2 & 1 & 0 & 0 & 2 & 4 & 3 & 4 & 3 & 2 & 2 & 4 & 2 \\ \hline HK03 & 3 & 1 & 0 & 0 & 0 & 1 & 0 & 2 & 0 & 1 & 0 & 0 & 0 & 0 & 0 \\ \hline HK03 & 5.2 & 47 & 8 & 1 & 3 & 4 & 0 & 1 & 1 & 6 & 4 & 7 & 2 & 3 & 2 & 1 & 2 \\ \hline HK01 & 2 & 17 & 15 & 8 & 16 & 14 & 3 & 3 & 5 & 21 & 13 & 14 & 13 & 18 & 15 & 9 & 17 \\ \hline HK01 & 4 & 14 & 6 & 2 & 4 & 4 & 0 & 0 & 0 & 5 & 7 & 4 & 5 & 2 & 4 & 6 & 16 \\ \hline HK02 & 10.3 & 1 & 2 & 2 & 0 & 0 & 0 & 0 & 0 & 1 & 1 & 0 & 0 & 0 & 0 & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Statistics of ostraced abundance in some layers of ZK03, HK03, HK01 and HK06 holes.