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The levels of Total Petroleum Hydrocarbons (TPH) have been reported for ten commercially important fish species from the northwestern Gulf of Suez, Egypt. Target compounds were analytically determined with gas chromatography–flame ionization detector and High-performance liquid chromatography analysis. Results showed that total petroleum hydrocarbon varied from 21700 to 1503100 ng/g wet wt., Argyrops Spinifer showed the highest level of TPH in the muscle tissue followed by Euthynnus affinis 1459800 ng/g wet wt. These data are very important for coming pollution monitoring program to the Suez Gulf. Polycyclic aromatic hydrocarbons (16 PAHs) varied between 81.499 and 5895.608 ng/g wet wt. The diagnostic indices used showed that the hydrocarbons in the area were from both biogenic and anthropogenic sources. Hence, there is need for adequate regulation and control of all activities contributing to the levels of petroleum hydrocarbon in the marine environment for the safety of human, and fish species lives in the area. [ABSTRACT FROM AUTHOR]

Oil hydrocarbon fingerprints derived from polycyclic aromatic and aliphatic hydrocarbon were analyzed in marine organisms of various aquatic species muscles collected from 10 different sites along Suez Gulf, Egypt. All samples were analyzed for n-alkanes (C15–C37) and polycyclic aromatic hydrocarbons (EPA list of PAHs). n-Alkanes in ten aquatic species were found to be in the range of 11.391–96.747 ng/g wet weight with a mean value of 60.755 ng/g wet weights. Different indices were calculated for the n-alkanes to assess their sources as carbon preference index (CPI), average chain length (ACL), terrigenous/aquatic ratio (TAR), natural n-alkane ratio (NAR) and proxy ratio (Paq). Most of the various species of n-alkanes were discovered to be from natural sources. Polycyclic aromatic hydrocarbons (PAHs) varied between 81.499 and 5895.608 ng/g wet weight with an average of 2521.126 ng/g wet weight. The contents of ƩPAHs were the highest in the tissues. The carcinogenic risks for humans from residual ƩPAHs in the various fish tissues higher than10−5. [ABSTRACT FROM AUTHOR]

This study represents the concentrations of 16 PAHs in a commercial aquatic species Sauridaund squamis;Euthynnus affinis; Rhabdosargus haffara; Argyrops Spinifer; Nemipterus Japonicus, Oreochromis Niloticus; Trachurus Indicus; Peneus Japonicas; Scomber Japonicus; and Pomadasys Stridens, which were collected from the coastal area of the Suez Gulf waters. The analyses of polycyclic aromatic hydrocarbons (PAHs) were determined using HPLC to identify the sources of PAHs. The results revealed that low molecular weight of PAHs were more than high molecular weight in aquatic species, Benzo (a)Anthracene/(Benzo (a) Anthracene + Chrysene) BaA/(BaA + Chr), Indeno (1,2,3-cd) pyrene/(Indeno (1,2,3-cd) pyrene + Benzo (ghi) perylene) IP/(IP + BP) and Fluoranthene/Pyrene (Fl/Pyr), they reflected that the PAHs sources in aquatic species are petrogenic as a main sources, pyrogenic sources. The study area was generally contaminated with hydrocarbons and continuous consumption of food from this area may pose public health hazards. [ABSTRACT FROM AUTHOR]

Late Jurassic Madbi shale samples from Al-Qarn-01 well in the NW Say'un-Masila Basin, Eastern Yemen are analyzed using conventional geochemical data such as total organic carbon (TOC) content and Rock-Eval pyrolysis. The results in this study are used to evaluate the gas resource potentiality in the basin. The analyzed shales have high TOC content between 1.00% and 3.12%, and their HIs range from 77 to 177 mg HC/g TOC. These values indicate that the investigated Madbi shale intervals contain Type III kerogen and are considered to be very good gas-source rocks. Furthermore, the relatively high Rock-Eval pyrolysis Tmax (447–459 °C) and PI (0.09–0.44) values indicate mainly peak to late mature oil window. [ABSTRACT FROM AUTHOR]

This study aims to evaluate source rock formations (Kareem and Rudeis) through quantitative and qualitative analysis of pyrolysis data from 44 ditch samples from three wells (Elkhaligue-1, Kareem-1, and El Ayune-1) at different depths in the central Gulf of Suez. From these data we concluded that Kareem and Rudeis formations are fair to good source rocks and have a generating potential fair to good to generate both oil and gas generated from mixed type II kerogene deposited under anoxic conditions, also they considered as fair to good oil sources. Both formations are mature and this conclusion is confirms by the burial histories of the three wells where Kareem Formation reached the early stage of generation at time ranges from 6 to 1.5 m.y while Rudeis Formation reached the oil window at time ranges from 18 to 6.6 m.y which considered a very good timing for excellent preservation efficiency of the hydrocarbons generated. [ABSTRACT FROM AUTHOR]

This study reports the concentrations of 16 PAHs in 10 of Aquatic Species samples collected along the Gulf of Suez, Eygpt, between 2016 and 2018. Among 10 species of fish investigated, Argyrops Spinifer; Pomadasys Stridens; Euthynnus affinis; Scomber Japonicus; Peneus Japonicas, detected the maximum concentration of PAHs followed by Nemipterus Japonicus; Oreochromis Niloticus; Trachurus Indicus; Rhabdosargus haffara; Sauridaundo squamis. The lower-molecular-weight PAHs were detected at highest levels. Estimated intakes of PAHs by fish consumption for the general population were ranged between 4.482 and 317.148 ng/kg bodyweight/day. Argyrops Spinifer contributed to the highest intakes of PAHs. The toxic equivalents (TEQs) of PAHs were calculated using a TEQ proposed in literature, and the intake ranged from 27.067 to 8951.220 pg TEQ/kg bodyweight/d. The estimated excess cancer risk value (5.40 × 10−5-3.91 × 10−3) from fish consumption for the general population exceeded the guideline value (1.0 × 10−6) for potential cancer risk. [ABSTRACT FROM AUTHOR]

Effect of provenance of organic matter evaluated through the distribution of occurrence of triterpanes and steranes in surface sediments from coastal stations located in the Gulf of Suez Gulf. The samples have been studied in four coastal stations located in the Gulf of Suez namely: Al-Nasr Oil Company (NPC), West outlet of SOPC, Inlete of SOPC, and El-Sukhna of Loloha Beach. Saturated hydrocarbons were analyzed by gas chromatography-mass spectrometry, to assessing of organic content and maturity level of the sediments. The results showed that the hydrocarbons are originated mainly from predominance of petrogenic and biogenic hydrocarbons with high maturity level. [ABSTRACT FROM AUTHOR]

The objectives of this study are the correlation between the oil samples recovered from the Lower Cretaceous reservoirs and Lower and Upper Cretaceous source rocks. The investigated biomarkers of five oils indicated the oils were derived from mixed marine and terrigenous (lacustrine) organic matter and deposited under suboxic to anoxic conditions. These oils were also generated from source rocks of high thermal maturity at the peak oil window. So, based on the molecular indicators of organic source input,depositional environment and maturity parameters of oils and extracts, we can conclude that the oil recovered from Al Baraka oil field were derived from Lower Cretaceous source rocks especially KomOmbo (B) source rocks where it reached the oil window. Furthermore, we can indicate that the other lower Cretaceous formations as Abu Ballas Formation will have the opportunity to generate and expel oil at the deeper part of the basin as shown in the eastern part of the basin. [ABSTRACT FROM AUTHOR]

The pyrolysis and vitrinite reflectance estimations for fifteen shale rock tests and additionally, geochemical burial history, and gas chromatography - mass spectrometry parameters were talked about to explore the hydrocarbon generation and maturation level and time, type of hydrocarbon produced of rock units of Safir-1x well. The results assign that the Bahariya Formation is poor to great source rock to create oil and gas, with a lower thermal maturation degree than the Khatatba and Alam El Bueib formation. Alam El Bueib is viewed as good to excellent source rock for oil and gas age, having marginally high level of thermal maturation at oil window at around 40 million years. Khatatba formation achieved the oil and gas generation window at about 80 and 50 million years separately and considered excellent source rock. The molecular gas chromatography and mass spectrometry parameters demonstrated that the extracts of source rocks reflected that the Bahariya and Alam El Bueib extracts have a mixed sources formed under transitional conditions at low grad of thermal maturation. Khatatba source rock extracts originated from marine sources formed under reducing conditions at high grade of maturation. [ABSTRACT FROM AUTHOR]

The compositions of polycyclic aromatic hydrocarbons used as chemical markers for the identifying of different sources in the surface seawater of Alexandria coastal area. The quantitative analysis of polycyclic aromatic hydrocarbons (PAHs) showed a concentration ranged from 8970.939-1254756.00 ng/L, which exceed the maximum admissible concentrations of PAHs (200 ng/L) for the water standard of European Union. The calculated diagnostic ratios suggested that the sources of PAHs at the majority of the studied area are derived primarily from pyrogenic sources from incomplete fuel combustion of the boats and vehicle engines with lesser amounts of PAHs contributed from petrogenic sources. Some stations displayed mixed sources in comparison to many other studied marine systems, the PAHs concentrations detected at Alexandria area were considered be higher to pose health risks to aquatic bodies. [ABSTRACT FROM AUTHOR]

Characterization and correlation of crude oils from some wells in the North Western Desert, based on six crude oil samples, were studied by different analytical techniques, including API gravity, sulfur content, nickel and vanadium, bulk compositions and saturated fraction obtained from gas chromatography have been studied. The results show that the crude oils are normal to medium aromatic oils, with high API gravity and high sulfur content. V, Ni, V/Ni and V/(V + Ni) reflecting oils might be sourced from non-clastic source rocks, possibly carbonates, deposited under anoxic-suboxic conditions. Bulk compositions revealing that the crude oils were derived from marine organic sources. While, the paraffins and naphthenes percent indicates that the oils belong to paraffinic to naphthenic oil types, deposited in slightly anoxic to suboxic conditions and contained marine organic matter. Thermal maturity data showed that the oil samples were generated from mature source rocks. This indicates the studied oil samples are well correlated with each other, where they are similar in their oil type maturation and source depositional environments. [ABSTRACT FROM PUBLISHER]

In the present study, the geochemical analyses of API gravities, vanadium, nickel, sulfur, and bulk composition were performed on eight samples from productive wells in Gindi, South Deep Abu-gharadig, Abu-gharadig, Dahab-Merier, and Faghure basins locates in the North Western Desert. The results were used to describe the source organic matter input, depositional environment, assess the degree of thermal maturity, and to correlate between crude oils to determine the genetic relationship between hydrocarbon generation and their source rock for the studied oil samples. The results showed that a wide range of crude oil parameters exists in this data, indicating that a variety of oil types is represented. Crude oils range from unaltered to altered by vanadium, nickel, and sulfur concentrations, V/Ni and saturate fraction were used to classify the oils. Oils are classified into two groups. Group I contains oil samples from Gindi, South deep Abu-gharadig and Abu-gharadig, and Dahab-Merier that are generated from organic matter input deposited in marine environment under anoxic to suboxic conditions. Group II from Faghur basin possess high Pr/Ph ratios suggesting high contribution of terreginous organic matter deposited under relatively oxic conditions. [ABSTRACT FROM AUTHOR]

The present work deals with isopach, lithofacies changes, and source rock chracteristics of Khatatba and Alam El Bueib formations of some wells in North East Western Desert. Isopach and lithofacies changes showed that the thickness of Khatatba Formation increases toward the south western direction and decreases toward northern parts, and the sediments consisting of sandstone and shale facies indicate a shallow marine environment. Alam El-Bueib sediments increase toward the north direction, and argillaceous sandstone facies reflect terrestrial-to-shallow marine environment. The geochemical analysis showed that Khatatba Formation bears a mature source rock and has poor-to-good generating capability for both oil and gas and lie within the early generation window and oil window. Alam El Buieb Formation constitutes a mature source rock and has poor-to-good generating capability for both oil and gas. It can be stated that Khatatba and Alam El Buieb are the main source rock for hydrocarbon accumulations rich with organic sediments and could be considered as effective source rocks for generating hydrocarbons in the the studied wells. [ABSTRACT FROM PUBLISHER]

Poly-aromatic hydrocarbons (PAHs) were analyzed in sediments collected from the Suez Gulf to evaluate the composition, sources, and ecological risk assessment. The highest concentration of total PAHs is recorded in sediments collected from Inlet of Suez Oil Petroleum Company (SOPC), followed by east of the Outlet of SOPC and Outlet of SOPC. While lower concentrations of total PAHs are detected in Suez Beach west of the Outlet of SOPC, from Inlet of Al-Nasr Petroleum Company (NPC). The ratio of ∑LPAHs/∑HPAHs was <1, revealing their pyrogenic sources. The concentration levels of PAHs in the current study were compared to the effect range low (ERL) and the effect range medium (ERM) values for all investigated stations was below the ERL except for Inlet of SOPC. This finding indicated that PAHs in the surface sediments of the studied area have adverse biological effects, which may cause severe adverse biological and acute effects. The high levels of BaP equivalent (BaPE) values east of the Outlet of SOPC indicate that PAHs have relatively high toxicity among all sites. The toxic equivalent (TEQcarc) values of the sediment samples varied from 0.1883 to 1449.286 ng/g TEQ, with the mean value of 144.295 ng/g TEQ; the higher total TEQcarc values were found at 50 m east of the Outlet of SOPC: 1449.286 ng/g TEQ. [ABSTRACT FROM PUBLISHER]

The present work aims to using the application of GC, GC/MS, UV, and FT/IR spectroscopy organic matters extracted from sedimentary hydrocarbons from six coastal stations located in the Gulf of Suez and proposed to evaluate hydrocarbons in the sediments. The results the origins of hydrocarbons are multiple sources from terrestrial inputs, biogenic, and pyrolytic. Abundance of vascular plantnC23–nC33alkanes with a high odd-to-even predominance, pristane, and phytane besidenC29/nC17ratios and the presence of biogenic hopanes indicate the predominance of biogenic in combination with petrogenic hydrocarbons. FT-IR spectroscopic analysis indicates high concentrations of aliphatic hydrocarbons as well as mono- and polynuclear aromatic hydrocarbons are useful tool in organic geochemistry studies. UV analysis for organic matters incorporated in sediments reveals that oil pollutants have considerable amounts of aromatic compounds. [ABSTRACT FROM PUBLISHER]

The authors aimed to examine a multivariate statistical analysis approach for monitoring the hydrocarbon potentiality of source rocks in the North Western Desert to recognize the potentiality of source rocks and subsequently investigate the maturation level of the proven potential source formations for oil preservation. To achieve this aim, they applied multivariate statistics analysis (principle component analysis [PCA], cluster analysis, and correlation coefficient) and Rock-Eval pyrolysis analyses. The results showed that both PCA and cluster analyses have showed two types of source rocks. The first is classified as poor to fair source rock and immature to marginally mature source rock, the second is considered as fair to good source rock and mature to post mature source rock. PCA extracted two independent factors, which explained 81.87% of the total variance. The first type of source rock was responsible for 50% of the total variance and was best represented by variables TOC, S2, OI, and Ro, and the second one was responsible for 31.65% of the total variance and was represented by the HI variable. Pearson correlation coefficient showed a significant positive correlation between TOC and S2 or Ro. A positive correlation between S2 and HI or OI and also between OI and Rowas observed, while no significant correlation was noticed between HI and Ro. [ABSTRACT FROM PUBLISHER]

The semienclosed Suez Gulf records various signals of high anthropic pressures from surrounding regions and the industrialized Suez countries. The sedimentary hydrocarbons have been studied in six coastal stations located in the Gulf of Suez. Nonaromatic hydrocarbons were analyzed by GC/FID and GC/MS to assess organic content in surface sediments of Suez Gulf, Egypt, depending on alkane, terpane, and sterane biological marker indicators. The results showed that the hydrocarbons are originated frommultiple terrestrial inputs, biogenic and pyrolytic. Several ratios hydrocarbons indicated the predominance of petrogenic in combination with biogenic hydrocarbons. [ABSTRACT FROM AUTHOR]

Regression lines obtained from TOC versusS2graphs of organic rich samples were collected from Rahmi, West Bakr, Ras Gharib, and Esh El Melleha wells in the Gulf of Suez. By applying the hydrogen index values obtained fromS2versus TOC graph and mass balance calculations obtained from the results of Rock-Eval pyrolysis, the original hydrocarbon generative capacity and the amounts of the hydrocarbons generated are estimated. Calculation results indicate that the amounts of original hydrocarbons and the hydrocarbon generative capacities of the two methods are similar and correlated with the results of the Rock-Eval pyrolysis. This indicates that such calculations can be applied in the hydrocarbons evaluation of source rocks. [ABSTRACT FROM AUTHOR]

API gravity, sulfur content, gas chromatography, and gas chromatography-mass spectrometry analyses were carried out for eight oil samples collected from different wells in the Gulf of Suez. The results showed that two types of oils could be recognized: (a) heavy oils, which are oils from Zafarana, Rahmi, West Bakr, and Ras Gharib wells, are of low maturation and originated mainly from terrestrial organic sources; and (b) light oils, which are oils from Um El Yuser, Ras El Ush, Gemsa-SE, and Hurghada wells, have a high level of maturation and orginate mainly from marine organic sources. [ABSTRACT FROM AUTHOR]

The oil–source rock correlation between oils from Baharyia and Abu Roash “E” member from the EWD 19–1x oilfield and extracts of Kharita and Abu Roash “F” member from the Qarun 2-1 oilfield were carried out through the advanced gas chromatography–mass spectrometry analyses of four extracts and oil samples from the oilfields to characterize the depositional environments and to assess the thermal maturity of the respective source rocks. The results show that the oil sample from Bahariya reservoir originated from mixed organic matters and is more mature. The oil sample of Abu Roash “E” reservoir is originated from source rocks rich in marine derived organic matters with little input from mixed sources and is less mature. The extracts of Kharita formation and Abu Roash “F” Member originated mainly from mixed and marine organic sources, respectively. The oil–source correlation indicates that there is well correlation between oils from the Bahariya and Abu Roash “E” reservoirs and extracts of source rocks including Kharita formation and Abu Roash “F” member. [ABSTRACT FROM PUBLISHER]

Ten core samples representing the subsurface formation of Sidi Salem well No. 1, in the onshore Nile Delta, Egypt. The samples were subjected to comprehensive organic geochemical studies (such as rock-eval pyrolysis, gas chromatograph [GC] and gas chromatography-mass spectrometry [GC-MS]) aiming to evaluate potential source rocks, organic matters types, depositional environments, and maturation. The results revealed that the source rocks in the drilled sections are marginally mature to mature zone and have fair to good potential for generating oil and gas. These rocks are dominated by organic matter derived mainly from mixed organic matters (marine and terrestrial) with contributions from algae and bacteria deposited under anoxic to suboxic saline environments. [ABSTRACT FROM AUTHOR]

Different oil samples were collected from oil fields in the North Western Desert; namely, Meleiha, Razaak, and North Qarun fields. These oils were analyzed geochemically, including sulfur content, American Petroleum Institute (API) gravity, and gas chromatography The results showed that API gravity and sulfur content indicate that the crude oils have high mature level of marine origin. Distribution of n-alkanes (Carbon Preference Index [CPI], pr/ph, and isoprenoide/n-alkanes ratios) reflects that the oil samples originated mainly from marine organic sources deposited in a reducing environment. This indicates that the oil samples under investigation are well correlated with each other in the western part of the North Western Desert. [ABSTRACT FROM AUTHOR]

Crude oils together with extracts from the Middle Jurassic (Khatatba Formation), Barremian-Early Aptian Alam El Bueib Formation, and Early Albian Kharita Formation were collected from five wells (Ras Qattara-Zarif-5, Ras Qattara-Zarif-3, and Zarif-1, Zarif-2, SW Zarif-1) in the North Qattara Depression. Biomarkers (pristane/phytane, isoprenoids/n-alkanes, steranes, triterpanes, C29 steranes 20S/20S + 20R, C23 tricyclic/C30 hopane, Ts/Tm, C30 moretane/C30 hopane ratios, homohopane and gammacerane indices) of the saturated hydrocarbon fraction were analyzed in order to assess the source and maturity of the crude oils and the extracts. The results suggested that the oils from Khatatba and Alam El Bueib formations are mature, derived from source rocks containing marine and terrestrial organic matter, respectively. The source environments and maturity of the oil from the Khatatba Formation is similar to that of the Khatatba source rock extract. The oil from the Alam El Bueib formation differs from the extracts of the Alam El Bueib and Kharita formations. The Khatatba formation seems to be an effective source rock in the North Qattara Depression. [ABSTRACT FROM AUTHOR]

The organic geochemical and biomarker analyses of the Miocene source rocks of some wells in the onshore Nile Delta, suggested that the Abu Madi Formation has poor immature to marginally mature source rocks of Type III Kerogen deposited under the terrestrial environment. The Sidi Salem Formation has fair-to-good mature source rocks of producing mixed oil and gas, originating mainly from marine organic sources. The Moghra Formation has mature good source rocks for Type (II/III) kerogen, derived from organic matter and rich in both terrigeneous and marine sources. The geochemistry of condensates revealed that the Abu Madi and Moghra condensates originated from marine organic matters with little input from a terrestrial source, while Sidi Salem condensate was derived from more contribution of terrestrial organic matters. Abu Madi condensate is less mature than Sidi Salem and Moghra condensate. The geochemical thermal modeling of the Miocene source rocks indicates that the Abu Madi formations are in the early stages of hydrocarbon up until the present time, while Moghra and Sidi Salem formations are in the mature stage of hydrocarbon generation up until the present time. This indicates that the studied condensates have probably migrated from deeply buried source rocks which are at a higher level of maturity rather than from less mature source rocks in the study area. [ABSTRACT FROM AUTHOR]

Seven representative oil show samples from wells in the north and north central Sinai have been characterized by means of a variety of organic geochemical techniques (C 7 hydrocarbon and biomarker analyses), to illustrate origin, differences, and similarity among oils. These oils were obtained from Cretaceous and Jurassic reservoirs. The C 7 oil correlation star diagram (OCSD) suggests closely related oils, derived mainly from similar source rocks, while the C 7 oil transformation star diagram (OTSD) and C 7 light hydrocarbon analyses indicate a minor degree of transformation of some oils, as Misri-1, Halal-1, and Nakhl-1 oils were subjected to evaporative fractionation. Moreover, the studied oils show no sign of water washing and biodegradation. Molecular characteristics suggest pre-Tertiary shales and carbonate source rocks, deposited under a saline oxic environment, rich in terrigeneous organic sources with significant bacterial and algal input. Since the studied oils are of mixed marine and terrestrial origin, C 7 signature of these oils is not representative of their origin and should be supported by other geochemical evidence (e.g., biomarkers) to predict their origin. [ABSTRACT FROM AUTHOR]

Sixteen cutting and four core samples, in addition two crude oil samples are representative for the Miocene source rocks and reservoirs in some wells in the southern part of Gulf of Suez. These samples were subjected to advanced geochemical tools (pyrolysis, elemental analyses, gas chromatography, and gas chromatography-mass spectrometry). In addition, burial history model of the deepest well is recognized. The results showed that the Middle-Upper Miocene source rocks are immature, originated mainly from mixed organic sources, have poor to fair potentiality to produce oil, and did not reach the early stage of hydrocarbon generation until the present time. Lower Miocene source rocks are mature, derived from marine organic sources, have good potential to generate oil and gas, and entered the early stage of hydrocarbon generation and oil window till present time. The crude oil samples are mature, originated mainly from marine sources, and show good correlation with the Lower Miocene source rocks. Therefore, the Lower Miocene source rocks may be considered an effective source for oil generation in the southern part of Gulf of Suez. [ABSTRACT FROM AUTHOR]

Physical and specific geochemical analyses are used in detail for the petroleum geochemical studies to permit the correlation of six crude oil samples from Western Desert Egypt. Different analytical techniques, including liquid chromatographic separation, gas chromatography, and gas chromatography-mass spectrometry (GC-MS), were used to characterize the oil samples. The oils were identified using oil characterization parameters including specific gravity (°API), sulfur content, distribution of n-alkanes, carbon preference index (CPI), pristane/phytane ratio, isoprenoid/n-alkane ratios, and detailed biological marker analysis. All these parameters showed that the studied oil samples are correlated with each other, where they are similar in their oil type maturation and source depositional environments. [ABSTRACT FROM AUTHOR]

The results of the geochemical evaluation for eleven crude oil samples from some Meleiha oil fields revealed that, these oils have high specific gravity (°API), low sulfur content and rich in saturated hydrocarbons. Two oil classes were recognized. The first is carbonate oils of high maturity level, originated from marine origin. The second, deltaic oils of moderately level of maturation, derived mainly from terrigenous sources. Oil: source correlation for the productive oils and the extracts of the potential source beds revealed a genetic close relationship between oils and extracts of Khatatba and Alam El Bueib formations. This indicates that the source of the oils in the study area may be related to mixed sources of these formations. [ABSTRACT FROM AUTHOR]