The major and trace element concentrations of Kazhdumi Formation at Soroosh, Nowrooz, Foroozan and Hendijan oil fields are listed in Appendix 1 and Appendix 2, respectively.

The Major element distributions reflect the mineralogy of the studied samples. Sandstones are higher in SiO₂ content than shales (Figure 4). The clearly quartz-rich sandstones have SiO₂ content that range between 71.7 wt% and 97.1 wt%. They are also depleted of P₂O₅, the alkalis (Na₂O and K₂O) and alkali earth elements (MgO and CaO). This parallel depletion can be attributed to the weathering conditions in the source area [28] . Similarly, shales are higher in K₂O, Fe₂O₃ and TiO₂ contents than sandstones (except sideritic sandy samples are higher in Fe₂O₃), which reflect their association with clay-sized phases [29] [30] . Al₂O₃ abundances were used as a normalization factor to make comparisons among the different lithologies, because of its immobile nature during weathering, diagenesis, and metamorphism (e.g., Bauluz et al., [31] ). In Figure 4, major oxides are plotted against Al₂O₃. Average UCC (upper continental crust) and PAAS (post-Archean Australian shale) values [32] are also included for comparison. Among other major elements, Fe₂O₃, MgO, K₂O, TiO₂ and P₂O₅ are consequently showing positive correlations with Al₂O₃, whereas CaO, Na₂O and MnO do not exhibit a trend (Figure 4). The positive correlations of the major oxides with Al₂O₃ indicate that they are associated with clay minerals [33] .

The Kazhdumi Formation samples were normalized to UCC [32] and are given in Figure 5 Relative to UCC the concentrations of most major elements in the sandstones were generally similar, except for Na₂O and K₂O, with consistently yields much lower average relative concentration values (Figure 5(a)). The depletion of Na₂O and K₂O in samples can be interpreted by absence or smaller amount of Na-rich plagioclase and K-feldspar in them, consistent with the petrographic data.

In comparison with UCC, the shale samples are low in MgO, CaO, MnO and high in Al₂O₃ and TiO₂. Al and Ti are easily absorbed by clays and concentrate in the finer, more weathered materials [33] . In addition, XRD analysis of the shale samples reveals that they are associated with the mineral anatase (TiO₂). On average, the shale samples have lower SiO₂ abundances relative to UCC therefore the observed variations are probably due to quartz dilution effect [31] [34] . In addition, sideritic sandstone samples are low in SiO₂ and high in Fe₂O₃ due to siderite (FeCo₃) content base on XRD analysis.

In order to determine the source of sediments using trace-elements (for example, Th, Co, Ni, Sc, Zr, Hf and Nb), it is necessary to ascertain that the element is relatively immobile in the sedimentary cycle [12] [40] [41] .

Th abundances are higher in felsic than in mafic igneous source rocks and in their weathered products, whereas Co, Sc and Cr are more concentrated in mafic than felsic igneous rocks and in their weathered products. Mafic and felsic source rocks differ significantly in the ratios such of La/Sc, Th/Sc, La/Co, Th/Co and Cr/Th and hence provide useful information about the provenance of sedimentary rocks (e.g., Cullers et al., [42] ; Cullers, [43] ; Cullers and Podkovyrov, [44] ). In this study, La/Sc, Th/Sc, La/Co, Th/Co and Cr/Th values of the Late Lower Cretaceous (Albian) sandstones are more similar to values for sediments derived from felsic source rocks than to those for mafic source rocks, thus suggesting felsic source rocks (Table 1).

Floyd and Leveridge [45] stated that the elemental ratio of La/Th plotted versus the concentration of hafnium demonstrates the degree of recycling in sandstones and it also provides information about the provenance. A La/Th versus Hf plot for the Albian sandstones at Soroosh, Nowrooz, Foroozan and Hendijan oil fields shows felsic source rocks, an intense recycling and sedimentary source and a passive margin tectonic setting for these sandstones (Figure 6).

¹Cullers [43] ; Cullers and Podkovyrov [44] ; Cullers et al. [42] . ²McLennan [40] ; Taylor and McLennan [32] .

Th/U in sedimentary rocks is of interest, as weathering and recycling typically result in loss of U, leading to an elevation in the Th/U ratio. The Th/U ratio in most upper crustal rocks is typically between 3.5 and 4 and Th/U values higher than 4 may indicate intense weathering in source areas or sediment recycling [13] . Th/U ratios in the sandstones from Kazhdumi Formation range from 4.67 to 19.25, 6.11 to 19.30, 6.76 to 9.14 and 5.12 to 10.97 respectively for Soroosh, Nowrooz, Foroozan and Hendijan samples, indicating the derivation of these sandstones from recycling of the crust.

Th/Sc ratio commonly reflects the average composition of the source rocks. Scandium and Th are transferred quantitatively from source to sediment; hence, the ratio is used to deduce the composition of the source rock [McLennan et al., 1993]. When Th/Sc is plotted on the diagram of Zr/Sc-Th/Sc (Figure 7), the recycled source rocks for the sandstone samples from the Soroosh, Nowrooz and Foroozan subsurface section are further supported by their high Zr/Sc ratio. Strongly enriched Zr in zircon can be easily recycled and Sc is present in labile phases. Therefore, the Zr/Sc ratio is considered as one of the proxy to evaluate the presence or absence of recycling [13] , but samples from Hendijan oil field fallow the trend of first order sediments and show a simple positive correlation between these ratios.

Felsic provenance for Kazhdumi samples, is further supported by the TiO₂ versus Ni bivariate plot (Figure 8). Even though few samples plot outside the field assigned for felsic source. On a La/Sc versus Th/Co bivariate diagram (Figure 9), most of the samples plot near to the silicic rock provenance composition.

Furthermore, the V-Ni-Th*10 (Figure 10) ternary diagram also suggests that the Kazhdumi sandstones were derived from felsic source rocks.

The post-Archean pelites have low concentrations of mafic elements, particularly Ni and Cr, when compared to Archean pelites [13] . The reason for the high concentrations of Ni and Cr in the Archean pelites is due to the deficiency of ultra-mafic rocks in the post-Archean Period [32] . The Kazhdumi sandstones plot in the post- Archean field (Figure 11) suggest that the felsic component was dominant in the source area of the Kazhdumi Formation.

Trace elements are generally thought to be quantitatively transported into clastic sedimentary rocks after weathering, and thus, they may reflect the signature of parent materials and these elements can be used in sedimentary rocks to determine their provenance and tectonic setting (e.g., McLennan et al. [13] ; Bahlburg [50] ; Burnett and Quirk [51] ; Zimmermann and Bahlburg [52] ; Cingolani et al. [53] ; Li et al. [54] ).

The negative Sr-anomaly, which is suggesting the older recycled environments/passive margin setting, is common in most of the sandstone samples at Kazhdumi subsurface sections (Figure 5(b)). Positive Zr anomaly at Samples suggest a slight influence of mature sedimentary detritus (zircon) of a passive continental margin (e.g., Mader and Neubauer [55] ).

Furthermore, we used the triangle diagram Th?Sc?Zr/10 and discrimination diagram of La/Sc versus Ti/Zr [12] , to understand the tectonic setting of studied samples based on these plots. Most of the samples cluster within or close to the passive continental margin field (Figure 12); therefore, they may have been derived from such tectonic setting, although some samples plot in continental island arc. This interpretation must be made cautiously, because specific tectonic settings do not necessarily produce rocks with unique geochemical signatures [50] .

The intensity and duration of weathering in clastic sediments can be evaluated by examining the relationships among alkali and alkaline rare earth elements [56] [57] . Nesbitt and Young [58] defined the Chemical Index of Alteration (CIA) formula to evaluate the degree of chemical weathering:

where the oxides are expressed as molar proportions and CaO* represents the Ca in silicate fractions only. Another good measure to calculate the degree of chemical weathering is Plagioclase Index of Alteration (PIA; Fedo et al., [59] ), which can be calculated by the following equation (molecular proportions):

Above mentioned indexes of alteration may not help us to obtain acceptable results specially in samples with high fluctuation in calcium contents [43] . So that this is observed in most of samples in this study. However, this alteration index doesn’t give certain results because of high carbonate contents. Accordingly, Cullers [43] defined the Chemical Index of Weathering (CIW) formula to calculate the degree of chemical weathering for the sandstones with high CaO content, which can be calculated by the following equation:

where the oxides are expressed as molar proportion. CIW is variable form 50 in non-weathered sediments to 100 in intense weathered sediments. The high CIW values in the Soroosh, Nowrooz, Foroozan and Hendijan samples (90.8, 96.7, 83.9 and 96.4 respectively) indicate a moderate to intense weathering of first cycle sediments, or it may alternatively reflect recycling under semi-arid to semi-humid climate conditions. CIW values also signify a dominant felsic source and sediment recycling processes [28] .

The study area was a tectonically passive carbonate platform from the Late Permian to about Late Cretaceous [21] . The Albian to Cenomanian is evident by shallow-marine carbonate and intra-shelf basins [60] [61] . Eus-

tatic sea-level fluctuations and local differential subsidence controlled sediment deposition during the mentioned interval [61] .

Following a period of subaerial exposure in the early-middle Aptian, which lasted for approximately 1.5 MM yrs [62] , the Albian clastics comprised the initial deposits of a mid-Cretaceous transgressive cycle in eastern Arabia. Eustatic sea-level during this time was relatively low [63] . The Kazhdumi/Nahr Umr/Burgan Formations represent a major of terrigenous clastic sediments from the Arabian Shield to the west and from the Interior Homocline area of Central Saudi Arabia [Early Paleozoic clastic rocks), which prograded eastwards onto the Aptian carbonate platform. The pre-Wasia unconformity surface was exposed, and the uplifted Hail Rutbah Arch was deeply eroded; recycled sediments were transported and deposited as the Wasia/Kazhdumi clastics [64] .

A thick wedge of alluvial-plain and lower coastal plain sandstones comprise the prolific reservoir facies of the Kazhdumi/Nahr Umr/Burgan sandstones of Iran offshore, South Iraq, Kuwait and extend to NE Soudi Arabia [65] . This setting conforms to a classic ramp model, which terrestrial and near-shore marine, coarse to medium grained sandstones, grading into a very large area offshore of shallow water shales, which was a much as 500 km wide [62] [66] . The fine grained clastics grade eastwards into impure carbonates in the extreme northern part of the UAE, and marginal to the NW Oman Mountains [62] . The Nahr Umr and its equivalent is not a starved basin but a marine-shelf where the shallow setting led to continued reworking of fine grained clastic sediments during storms, with the development of multiple local unconformities of short duration [21] .

The Albian clastics in South Iraq and Kuwait comprise the delta-front of the Saudi Arabia succession. Towards Iran, clastics intercalated with carbonates represent increasingly marine delta-front conditions. In Bahrain and western Qatar, the Nahr Umr consists largely of sands and sandstones, but in eastern Qatar it contains many shale bands, with marly shales and glauconitic sands near the top. The proportion of sand diminishes toward Abu Dhabi. In northern United Arab Emirates and Oman, argillaceous limestone, calcareous shale and marl were deposited in a shallow, mixed shelf environment [21] (Figure 13).

Considering paleogeographic data during the Late Lower Cretaceous (Albian) and geochemical studies, the source of sandstones for the Kazhdumi Formation might be assigned to uplifted shoulders of a rifted basin (Neo-Tethys) in its post-rift stage (Arabian basement), but the effect of recycling due to tectonic events on these sandstones might be considered (Figure 14). Such provenance interpretation has to be considered with caution because the role of sedimentary environment and diagenesis.