## 4 Results
### Geochemical Data  
Three intervals of high phosphorous values appeared in section 1, the lower one (sample H1) was mixed with chalks and was indicated by high Ca values. In this horizon, there are observable high Fe, Al, Ti, and Al values associated with the high phosphorous values (Figure 6). The isotopic ratio \(\varepsilon\)Nd showed high values, and reversely in the \(\delta\)43/42 Ca ratio. The second interval that represents high phosphorous in the Hawar section showed quite low values of Fe, Al, Si, and Ti (samples H4, 5, and 6) where the \(\varepsilon\)Nd ratio was and \(\delta\)43/42 Ca was high. The top interval (samples H8, 9, 10, 11, and 12) represented high phosphorous values which were associated with a low \(\varepsilon\)Nd ratio and a high \(\delta\)43/42 Ca ratio. Geochemically, high Al, Si, Fe, Si, and Ti values only showed anomalies at sample H11, and these elements do not show any value in samples H3, 8, 9, 10, and 12.  
Oil shale was recognized at the base of section 2 (sample D7 and 8). It was characterized by low Al, Si, Fe, Ti, and P. The isotopic ratio \(\delta\)143/144 Nd was high, and the \(\delta\)43/42 Ca ratio was high too. The first phosphate horizon appeared in samples D8 and 9 in combination with a carbonate background; in this horizon, there was significant increase in Al, Fe, Si, and Ti (Figure 7). The \(\delta\)143/144 Nd showed a slight increase and a decline in the \(\delta\)43/42 Ca isotopic signature. During the main regression stage of the sea, which is represented in samples D11-16, phosphorous showed high values and was accompanied with high Al, Si, Fe, and Ti. The \(\delta\)143/144 Nd and the \(\delta\)43/42 Ca isotope are in their minimum values. After a major transgression, the retrieved carbonate system indicated high Ca values in samples D18-21. In this interval, the third enrichment of phosphorous was detected with low values of Al, Si, Fe, and Ti and a slight increase in the \(\delta\)43/42 Ca isotope.  
Figure 6: Geochemical data plot against its stratigraphic positions of samples 1.  
A phosphatic carbonate succession appeared at the base of section 3 (samples HS 3, 4, 5, and 6) represented by high Ca and P and a decline in Al, Fe, Si, and Ti values (Figure 8). Those values were correlated to the petrographic observation that bone fragments were enriched in this horizon, indicating that skeletal phosphate was present in the early stage of phosphate precipitation. Samples HS 7, 8, 9, 10, 11, and 12 showed sequences of two events: First, there is a relative drop in phosphorous associated with high Al, Fe, Si and Ti values, which could indicate that the terrigenous input acted as a dilution factor for the concentration of phosphorous in the water column. Second, high phosphorous values were combined with low Al, Fe, Si, and Ti values and relatively higher Ca values. In both events, the \(\delta\)143/144 Nd ratio was relatively high, while the \(\delta\)43/42 Ca isotope was low. The top phosphate horizon, similar to the bottom, was characterized by high Ca values, low Al, Fe, Si, and Ti values, and a relatively higher \(\delta\)43/42 Ca ratio. Above, the influx of terrigenous input, indicated with high Al, Fe, Si, and Ti values, characterized the top of the section where phosphorous disappeared in the water column.  
The REE patterns, normalized to post-Archean Australian Shale (PAAS; Ref. [39]) are shown in Figure 9.  
The REE patterns show consistent negative Ce anomalies in the analyzed samples, reflecting similar results from previous studies [40, 41].  
Figure 7: Geochemical data plot against its stratigraphic positions of section 2 samples.