Figure
1.
Sketch geological and index map showing the samples'location in Huimin depression.The filled circles show the location of the selected samples.
| Citation: | Jin-liang ZHANG, Xin ZHANG. Composition and Provenance of Sandstones and Siltstones in Paleogene, Huimin Depression, Bohai Bay Basin, Eastern China. Journal of Earth Science, 2008, 19(3): 252-270.
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This study was conducted to distinguish the compositions and provenance of sandstones and siltstones in the E
The quartz-feldspar-lithic fragment (QFL) of sandstones has been used to infer provenance and tectonic environments (Dickinson, 1985; Ingersoll et al., 1984; Dickinson and Suczek, 1979).Major and trace element compositions or ratios and the isotopic composition of sandstones also have been used to further constrain provenance (Cullers, 2000, 1994b; Cullers and Berendsen, 1998; McLennan et al., 1993, 1990; McLennan and Taylor, 1991; Wronkiewicz and Condie, 1990; Roser and Korsch, 1988, 1986; Bhatia and Crook, 1986; van de Kamp and Leake, 1985; Bhatia, 1983).For example, A-CN-K plots (molar ratios of Al2O3- (Na2O+CaO) -K2O) have been used to estimate the alkali feldspar to plagioclase ratios of source rocks and the extent of K-metasomatism of associated siltstones (Fedo et al., 1997a, b, 1995).Also trace element ratios such as Th/Sc and Eu/Eu*have been used to distinguish sandstones derived from different source rocks and to infer tectonic setting (McLennan et al., 1993).
The major element, trace element, and isotopic compositions of sandstones and siltstones, however, have been important in determining provenance and tectonic setting in some cases (Cullers, 2000, 1995, 1994a, b; Mongelli et al., 1996; Cox et al., 1995; Condie and Wronkiewicz, 1990; Bhatia, 1985; Allegre and Rousseau, 1984; McLennan et al., 1983; Bavinton and Taylor, 1980).For instance, index of mass percent (%) variability (ICV= (Fe2O3+K2O+Na2O+CaO+MgO+TiO2) /Al2O3) can be used to assess whether or not a given sequence of sandstones or siltstones represents first cycle sediment or if they were derived from recycling if diagenesis does not alter the amount of K2O, Na2O, or CaO (Cullers and Podkovyrov, 2000; Cox et al., 1995).Ratios of trace elements in sandstones and siltstones those are concentrated in silicic source rocks (La and Th) relative to those that are concentrated in basic rocks (Co, Cr, Ni) may be used to determine the relative amount of silicic to basic rock input from the source.Also the Eu anomaly (Eu/Eu*), the La/Lu ratios, and three component trace element plots (e.g., La-Th-Sc) may also be used to determine the provenance of the sandstones and siltstones as most basic rocks, which contain no negative Eu anomaly and often contain low La/Lu ratios, whereas more silicic rocks are more likely to contain a negative Eu anomaly and often have high La/Lu ratios.
In the current study, the provenance of sandstones and siltstones in the Ek1–Es3 members of Paleogene will be compared with that in Huimin depression of Bohai Bay basin using the above methods.In addition, the relative contents of primary and recycled material in the terrigenous sedimentary rocks will be estimated.
The Huimin depression is located in the south of the Jiyang ebbing of the Bohai Bay basin (Zhang L.e al., 2007).It covers approximately 250 km2 with a nearly E-W strike and the depression is divided into Zizhen sub-sag in the north, Linnan sub-sag in the south, Lizezhen sub-sag in the east and Yangxin sub-sag in the northeast (Jiang et al., 1999).It is bounded on the north by the Ningjin embossment and the Wuli embossment in the Chengning uplift, and on the south by the Luxi uplift.On the west it has a transitional relation to the Xinxian depression in the Linqing large depression.And on the east there is the Linfanjia embossment (Fig. 1).
The Paleogene consists of three formations in Huimin depression, namely, Kongdian Formation Shahejie Formation, and Dongying Formation (abbreviated as Ek, Es, Ed, respectively) from the lower to the upper (Dai, 1999).The Kongdian Formation is thicker which has been revealed by drilling and is subdivided into three members; they are the first member Ek1, the second member Ek2, and the third member Ek3 from the upper to the lower (Fig. 2).Terminal fan sediment develops in the Huimin depression in Ek1member.The provenance comes from the northern uplift and southern uplift.The lithologic associations are mainly red siltstone and fine sandstone.The Shahejie Formation is subdivided into four members; they are the first member Es1), the second member Es2, the third member Es3, and the fourth member Es4 from the upper to the lower.Delta beach bar, and braided fan sediments develop in Es4member.The provenance comes from the northern southwestern, and southern uplifts.The lithologic associations are mainly siltstone, fine sandstone and medium sandstone.Delta and turbidite sediments develop in Es3member (Zhang and Liu, 2001).The provenance comes from the northern, western, and southern uplifts (Yang, 2000).The lithologic associations are mainly siltstones, fine sandstones and coarse sandstones.
The central uplift zone was not formed until the deposition of Es4 when deep to semi-deep lake black sandstones were deposited.Accompanying the Linyi fault activity, the uplift began to form and extended eastward (Dai, 1999).Meanwhile, the lake gradually retreated eastward and large-scale prograding fluvial-deltaic system was built up from the west to the east along the uplift zone.The faulting and the lake level tended to be descendent and stable in the Es3, and the mid-to low-energy shore to shallow lake shoal was formed on the underlying preexisting fluvial-deltaic deposits.
The sandstones and siltstones were sampled in different parts of the Huimin depression (Fig. 1).The mineralogical analysis was carried out using petrographic microscopes and X-ray diffractometry (Table 1).Major elements were determined by the X-ray fluorescence method using a PW1400spectrometer.The trace elements were determined by ICP-MS.The accuracy of the analyses with respect to the certified values of the standard materials is within8% (Table 2).The analyses were carried out at the Yichang Geological Institute, Hubei Province, China.The modal composition of the rocks was studied following the Gazzi-Dickenson point-count method, as illustrated by Ingersoll et al. (1984), which was supplemented by computer software designed to calculate modal composition of sedimentary rocks from major element chemical analysis results (Cohen and Ward, 1991).
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Mineralogy has been determined on representative siltstones and fine to coarse sandstones (Table 1).They are mostly arkosic with quartz, feldspar, and clay minerals.There is little carbonatite in these rocks.The Ek1 member contains higher quartz contents than Es4 and Es3 members (Fig. 3a).Moreover, the sandstones and siltstones have a higher quartz/total feldspar ratio than those in granitoids or granite gneisses (Fig. 3b).This suggests that detritus in the Ek1–Es3 members was weathered enough to remove more of the feldspar from the original granitoid sources or that it was derived from recycled sedimentary rocks (Suttner and Dutta, 1986).The alkali feldspar to plagioclase ratios increase from the Es3 member to the Es4 member to the Ek1 member suggesting differences in degree of weathering or source rock composition.If the sandstones and siltstones have high quartz contents due to more weathering, then the greater abundance of plagioclase relative to alkali feldspar in the Ek1 member may be because of source rock composition as plagioclase generally weathers more readily than alkali feldspar (Nesbitt and Markovics, 1997).This interpretation will be seen to be consistent with the chemical index of weathering of these units as discussed later in the article.
The element contents of each sample are given in Table 2, and the average and standard deviation of the elemental compositions in each member are provided in Table 3.The average of thee lemental concentrations is compared from different members in Fig. 4, and the variation ranges are given in the figure.The averages of the elemental contents have been taken to the log10 to compare them statistically in order to avoid the constant sum problem (Cardenas et al., 1996).This procedure converts the original data of constant sums to continuous variables that can range up to infinity.The log of compositions of SiO2, Fe2O3T, Na2O, Sr, and Cr is significantly lower in the Es4 member than those of the Es3 member (Fig. 4a).The log of compositions of Al2O3, K2O, CaO, MgO, Sc, Th, and most of the REE is significantly higher in the Es4member than those of the Es3 member.This difference must at least partially be due to the higher quartz and feldspar contents (concentrating Si, Na, and diluting many other elements) relative to clay (concentrating Al2O3, K2O) and carbonate rock minerals (concentrating Ca, Mg) in the Es3 member than those in the Es4 member.Also the Eu/Eu*of the sandstones and siltstones in Es3 member is higher than that in the Es4 member, presumably because of higher amounts of feldspar (high Eu/Eu*) and lower amounts of carbonate rock minerals and clay minerals (low Eu/Eu*) in the Es3 relative to the Es4 member.
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The log of compositions of SiO2, K2O, Ba, and Cr is significantly higher in the Ek1 member than those in the Es4 member (Fig. 4b).The log of compositions of Al2O3, Fe2O3T, CaO, MgO, Sr, Sc, Th and most of the REE is significantly lower in the Ek1member than that in the Es4 member.The higher quartz and feldspar contents relative to clay, carbonate rock minerals, and ferromagnesian minerals (concentrating Fe, Mg) in the Ek1 member than those in the Es4 member might cause this difference.The Eu/Eu*values of the sandstones and siltstones in Es4and Ek1 members are not significantly different.
The log of compositions of Al2O3, Fe2O3T, CaO, MgO, TiO2, Sr, Sc, and Th of the siltstones to fine sandstones is significantly lower in the Ek1member relative to the Es3 member (Fig. 4c).These are likely due to depletion in biotite or other ferromagnesian minerals and carbonatite in the former than the latter The log of compositions of SiO2, K2O, and Ba are is significantly higher, which suggests these higher quartz and feldspar contents in the Ek1 member than those in the Es3 member.Elemental ratios of the source rock composition, such as REE, (La/Lu) cn, La/Cr, and Th/Sc are not significantly different in the sandstones and siltstones, suggesting a similar provenance signature in the Ek1–Es3 members.
Variation in major element compositions due to mineralogical differences can be illustrated in plots of elemental contents (Fig. 4).The sandstones and siltstones of the Ek1 member have the largest compositional difference of any of the units.The sandstones of the Ek1 member have the highest SiO2relative to Al2O3 content compared to those of the Es3member and Es4 member (Fig. 5).The high SiO2/Al2O3 ratios of the sandstones and siltstones in the Ek1 member are likely for the enriched Si-rich quartz relative to Al-rich feldspar and clay minerals like kaolinite or illite.The high quartz content relative to other minerals in the sandstones of the Ek1 member would produce high SiO2/Al2O3 ratios.The sandstones and siltstones of the Es4 member have the lowest SiO2relative to Al2O3 content, consistent with enrichment in calcite or Fe-rich minerals.The samples with the lowest SiO2 and Al2O3 also contain the highest Ca O and LOI, consistent with calcite must be the most likely reason for this elemental correlation.The siltstones from the Es4 member have the lowest SiO2/Al2O3 ratios.This is likely because of more Al-rich clay minerals and feldspar and less quartz in the siltstones of the Es4 member compared to those of Es3 member and Ek1 member.The SiO2/Al2O3 ratios of the sandstones and siltstones, however, are intermediate between those of the other members This suggests that there is an intermediate amount of quartz relative to feldspar in the Es4 member compared to the Es3 member and Ek1 member as observed.
The SiO2 concentrations of the sandstones are higher than those of the siltstones.This result is likely due to the abundant quartz and lower fine-grained content in the sandstones relative to the siltstones (Zhang and Zhang, 2007; Zhang X. et al., 2007).The SiO2 and Al2O3 concentrations of the sandstones overlap those of the siltstones at lower SiO2 and higher Al2O3 values.This relationship is most likely because of the high SiO2 content of the feldspars in the sandstones and the high Al2O3 content in the clay minerals in the abundant ground mass and sedimentary rock fragments in the siltstones.Siltstones contain the highest Al2O3 and lowest Si O2concentrations presumably because of their higher illite, muscovite, and chlorite, and their lower amounts of quartz compared with the sandstones.The TiO2, Al2O3, Fe2O3T, Na2O, and Eu/Eu*values are higher in the siltstones than those in the sandstones.An inverse correlation of SiO2 and Al2O3 is illustrated in Fig. 5.This relationship may partially be because of dilution by quartz in the sandstones and siltstones.Differences in the trace elements because of possible source rock differences will be given in the discussion section.
The samples from the three members have relatively constant SiO2/Al2O3 ratios and vary in the inverse correlation (Fig. 5).This suggests that much of the chemical variation is because of dilution of minerals with more SiO2 and Al2O3, consistent with deficiency in calcite or Fe-rich minerals.
In the Fe2O3 vs.Al2O3 plot, there is a lot of variation of rocks in the three members between calcite-quartz, hematite-magnetite, and layer silicate clay minerals and biotite-feldspar end members, suggesting that much of the variation in this plot is because of variation in these minerals (Fig. 6).
According to the diagrams of Pettijohn et al. (1972) and Herron (1988), the rocks are classified mainly into litharenite and arkose (Fig. 7).Only few samples from the Ek1 member are classified as subarkose (Fig. 7b).Noteworthy is the generally good agreement between the two classification schemes, even if elements with different geochemical behaviors are used.The difference in mobility of Na and K during diagenesis seems to have strongly influenced sandstones and siltstones analyzed, as shown in the data of Table 2 and the clustering in Fig. 7.
The molar ratios of Al2O3- (CaO*+Na2O) -K2O may be plotted in triangular A-CN-K diagram to distinguish chemical weathering, K-metasomatism, and source rock compositions (Fedo et al., 1997a, b, 1995).The Ca O included in the carbonate minerals and apatite can be subtracted from the total CaO content before plotting the molar ratios to give the Ca O*.Here, we subtracted the Ca O in apatite assuming all the P2O5 was present in apatite and dolomite since CO2 in the rocks was determined.
Clay minerals formed from plagioclase-alkali feldspar rocks as predicted from kinetic leach rates should plot along lines parallel to the CN side of A-CN-K diagram (Fig. 8a, dashed line; Fedo et al., 1997a, b, 1995).For example, tonalite should plot on the plagioclase side of the feldspar join so clay minerals formed from the rock should plot along the dashed line if no other process affects the samples.Thus, clay-rich sandstones and siltstones may be extrapolated back to the plagioclase-alkali feldspar line to suggest the plagioclase/alkali feldspar ratio in the original rock.The K-metasomatism of weathered rocks originally containing kaolinite can produce illite resulting in a trend at right angles to the A-K joint (solid line, Fig. 8).The average alkali feldspar to plagioclase ratio of the source after K-metasomatism may still be estimated (bottom left of the solid line, Fig. 8).
Sandstones may have two extreme paths of K-metasomatism (Fedo et al., 1995).In one path, the Al-rich minerals like kaolinite may be converted to illite so that the samples change to K-rich compositions much like that described for the sandstones and siltstones.In the second process, plagioclase may be converted to authegenic alkali feldspar to move the composition of the sandstone to more K-rich composition.In our samples, alkali feldspar has not petrographically replaced plagioclase, but illite has replaced feldspar and thus, perhaps the original kaolinite in the feldspar.Thus, the sandstones may have had some K-enrichment just like the siltstones.
Also the sandstones contain abundant illite in the matrix and fragments so they may have K-enrichment.The sandstones and associated siltstones produce data that lie along a fairly tight cluster at right angles to the A-K joint (Fig. 8), suggesting that the samples were affected by metasomatism.In addition, the siltstone were affected more intensely than the sandstones.Aregression line through the points can be extended back to the plagioclase-alkali feldspar joint (solid line).The intersection suggests a high plagioclase to alkali feldspar ratio in the source such as ganite, tonalite, or granodiorite (Fig. 8).The ranges of regression lines in an A-CN-K diagram (solid lines) for sandstones and siltstones in Ek1 member appear at a higher ratio of alkali feldspar/plagioclase than in the Es3 and Es4members.The high amount of quartz relative to feldspar and lithic rock fragments in the sandstones and siltstones suggests that they may have had significant chemical weathering of a granitoid source or diagenetic alteration to form the sandstones.In addition, the sandstones and siltstones in Ek1 member have higher alkali feldspar/plagioclase ratios than the sandstones and siltstones in Es4 and Es3 members.Thus, the modal results, like the A-CN-K diagrams, suggest that the sandstones and siltstones in Ek1member could have been derived from more granite or granodiorite (Fig. 8b) and the sandstones and siltstones in Es4 and Es3 members could have been derived from more tonalites or granodiorites (Fig. 8a).Most notably the sandstones and siltstones were not likely derived from any significant amount of basalts.
Various indices of weathering have been proposed based on different mass percent (%) of mobile element oxides (Na2O, CaO, MgO, K2O) relative to immobile element oxides, Al2O3, ZrO2, and TiO2 (Chittleborough, 1991).For example, the chemical index of weathering (CIW=[Al2O3/ (Al2O3+CaO+Na2O) ]×100) or chemical index of alteration (CIA=[Al 2O3/ (Al2O3+CaO+Na2O+K2O) ]×100) has often been used as weathering indices with higher values suggesting more intense chemical weathering (Chittleborough, 1991; Harnois, 1988; Nesbitt and Young, 1982).Unfortunately, samples that vary a lot in CaO due to variation in calcite, such as carbonatites observed in this study, may suggest misleading conclusions if the CIW and CIA are used to infer the degree of weathering.Thus, in this study CaO will be left out of the chemical index of weathering CIW, so that CIW=[Al 2O3/ (Al2O3+Na2O) ]×100.
The CIWs of the siltstones of the Ek1 member are significantly higher than those from the Es3 member and Es4 member.The CIWs of the sandstones of the Es3 member are significantly lower than those of the other two members.This suggests that the intensity or duration of weathering of the siltstones and sandstones decreased in order of Ek1 member > Es4 member > Es3member.Also the quartz-rich nature of sandstones and siltstones from the Ek1 member relative to those from the Es4 member and Es3 member is consistent with more intense weathering of the Ek1 member source rocks.
As discussed previously, the plagioclase/alkali feldspar ratio in each member of sandstones may have implications as to the degree of weathering or to source rock.If the source rocks of the Es4 member and Es3 member had similar ratios of plagioclase/alkali feldspar, then the higher plagioclase/alkali feldspar ratio observed in the Es3 member relative to the Es4member would also suggest more intense weathering of the sandstones of the Es4 member than those from the Es3 member.The higher quartz component of the Ek1 member than the other two members suggests more intense weathering of the Ek1 member than the other members.
Also the chemical index of alteration (CIA) of the rocks may be read directly off the vertical axis of the A-CN-K diagram (Fedo et al., 1995; Nesbitt and Young, 1982).For example, unweathered rocks have CIAs of approximately 50, and an unmetasomatised siltstones plotting at the upper end of the dashed line would have a CIA of approximately 80.The K-metasomatism also lowers the CIA's of the samples.The original CIAs of the samples may be reconstructed back to the sample compositions prior to metasomatism (solid line back to the dashed line parallel to the A-K boundary in Fig. 8, Fedo et al., 1995).The present CIAs of the sandstones and siltstones associated with the wacke range from 60.4to 70.2.In addition, the siltstones have higher CIAs than those of sandstones.The CIAs extended back to the composition prior to metasomatism range from 75to 85 approximately (Fig. 8).This suggests that intense weathering produced these sandstones and siltstones.The CIAs decrease in the order of Ek1member > Es4member > Es3 member.This is consistent with the values of CIW.
The index of compositional variability[ICV= (Fe2O3+K2O+Na2O+CaO+MgO+TiO2) /Al2O3]may be used to assess the original composition of sandstones and siltstones (Cox et al., 1995).The nonclay minerals in the original rocks have higher values of ICVs than the clay minerals.The ICVs of constituent minerals increase, for instance, in the order of kaolinite (~0.03–0.05), montmorillionite (~0.15–0.3), muscovite-illite (~0.3), plagioclase (~0.6), alkali felds-par (~0.8–1), biotite (~8), and amphibole-pyroxene (~10–100) (Cox et al., 1995).Therefore, in relatively unaltered sandstones and siltstones composed mostly of feldspar, pyroxene, amphibole, or biotite with less abundant clay minerals, ICVs should tend to be greater than one.Such sandstones and siltstones are usually deposited as first cycle deposits in technically active areas (Pettijohn et al., 1987; van de Kamp and Leake, 1985).Sandstones and siltstones with abundant clay minerals tend to have ICVs less than one and form in areas of minimal uplift and are associated with extensive chemical weathering (Cox et al., 1995).Sands deposited in such areas approach a quartz arenite in composition.First cycle terrigenous sediment formed during intense chemical weathering or with long residence times in soils, however, may also become intensely weathered (Johnsson, 2000, 1993; Johnsson et al., 1988; Barshad, 1966) and thus form ICVs less than one.Thus, sandstones and siltstones with ICVs greater than one are most likely first cycle sediments, and those with ICVs less than one may be recycled or intensely weathered first cycle sediment.The ICVs of the sandstones and siltstones of the Ek1 member to Es3member have been calculated using corrected K2Ovalues obtained from the CIAs in the A-CN-Kdiagrams (Fig. 8).The variation in K2O before and after metasomatism, however, produces very few changes in the ICV value.Samples with carbonate minerals have been excluded before calculating.Many of the sandstones and siltstones have ICVs that average close to one but range from 0.705 to 1.253 (Table 2).Thus, some sandstones and siltstones thus likely have some first cycle materials.The high CIAs estimated for the unmetasomatised sandstones and siltstones of Ek1 member to Es3 member and the high percentage of quartz relative to other minerals in all sandstones suggest relatively intense weathering of any first cycle sediment.The ICVs decrease in the order of Es3 member > Es4 member > Ek1member.This suggests that the intensity or duration of weathering of the siltstones and sandstones decreased in order of Ek1member > Es4 member > Es3 member.
As mentioned in the result section, elemental ratios that are critical in determining the composition of the provenance are significantly different between the sandstones and siltstones of Ek1, Es4, and Es3members.The log of the (La/Lu) cn, La/Sc, and Th/Sc, ratios is significantly lower and the log of the Eu/Eu*is significantly higher of sandstones and siltstones in Es4 and Es3 members than those in Ek1 member.The log of elemental ratios converts constant sum data (in which the sum of all analyzed elements must add to100%) to a set of continuous variables that can range to infinity.Therefore, log-transformed data can be compared using parametric tests (Cardenas et al., 1996).This suggests that the sandstones and siltstones of Es4 and Es3 members may have received more input from an intermediate rock like granodiorite or tonalite, whereas, those of Ek1 member received more input from more silicic rocks like granite.This is consistent with the higher percentage of plagioclase observed in Es4 and Es3 members than those in Ek1member.
This possible input from granodiorite is illustrated in the La-Th-Sc diagram (Fig. 9).The sandstones and siltstones in Es3 and Es4 members extend more toward the hypothesized granite and grandiorite-tonalite (intermediate) composition, but those in the Ek1 member extend more toward the hypothesized granite composition.The compositions of basalts are also plotted in Fig. 9.The composition of basalt does not quite fall in line with the extended range of composition of the sandstones and siltstones.This is consistent with the hypothesis that basalts did not contribute to the composition of the sandstones and siltstones.Thus, intermediate mixing between these two extremes could have formed sandstones and siltstones derived from a provenance of granite and granodiorite-tonalite.Plots of various elemental ratios of sandstones and siltstones are also consistent with the range of their compositions being formed by mixing of granite and granodiorite end members but not from basalt (e.g., Fig. 9).The Eu/Eu*and Th/Sc ratios of sandstones and siltstones plot along a linear trend.The range of compositions of the sandstones and siltstones could be formed by a mix of a granite source with an Eu/Eu*=0.5 and Th/Sc=1.18 and granodiorite-tonalite with an Eu/Eu*=0.7 and Th/Sc=0.5.Again, note that a basaltic source does not fall in line with the linear trend of the plotted sandstones and siltstones, thus, suggesting that basalts are not the significant source of the sedimentary rocks (Fig. 10).
The log of the elemental ratios between the Es3–Es4 members and Ek1 member is not significantly different in most cases.Still the log of the Eu/Eu*of the Ek1 member is significantly lower and the La/Sc and Th/Sc ratios are significantly higher than the values obtained for the Es3 and Es4 members.Sandstones are less likely to represent the Eu/Eu*and Th/Sc ratios in the source than siltstones (Cullers, 1994a, 1988; Cullers et al., 1988).The siltstones of Es3 and Es4 members, however, mostly plot closer to the hypothesized granodiorite-tonalite composition than the siltstones of Ek1 member in the La-Th-Sc plots (Fig. 9).This relationship also suggests more input of granodiorite to tonalite into the sandstones of Es3 and Es4 members relative to those of the Ek1member.Of course, a source dominated by granite in the sandstones and siltstones of Ek1 member is consistent with the abundant quartz and alkali feldspar observed in the petrography of the Ek1 member.The abundant quartz and higher plagioclase/alkali feldspar ratios observed in the Es3 and Es4 members support a granodiorite to tonalite source.
The source rock of sandstones and siltstones in the Ek1–Es3 members is illustrated in the La/Yb-ΣREE diagram (Fig. 11).The ranges of basalt, granitic rock, calcic mudstone, chondrites, kimberlite, and carbonate are plotted in Fig. 11 (Allegre and Minster, 1978).The compositions of our samples fall in line with the range of composition of the granitic rocks.This is consistent with the hypothesis that the sandstones and siltstones are derived from granitic rocks.Thus, sandstones and siltstones in the Ek1–Es3 members derived from a provenance of granite and granodiorite-tonalite could have been formed by intermediate mixing between these end members.
(1) The quartz/feldspar ratios of the Es3 member and Es4 member are approximately the same as most granitoids and are higher than those observed in the Ek1 member.In addition, the alkali feldspar/plagioclase ratios decrease from the Ek1 member to the Es4 member to the Es3 member.The CIWs decrease in the same order.This observation suggests a more alkali feldspar-rich granitoid source and more intense weathering for the sandstones in the Ek1member than in the Es4 member and Es3 member.
(2) Variation in the elemental composition of the samples may be explained by the observed variation in mineralogy of the samples.For example, high SiO2content of the Ek1 member sandstones are because of enrichment in quartz relative to other minerals; the high Al2O3 content of the Es4 member are due to enriched Al-rich clay minerals relative to quartz.Also the positive correlation in SiO2 and Al2O3 within the Ek1–Es3 member sandstones suggests that Al-and Si-rich minerals like quartz, feldspar, and clay mineral lead to varied dilution of SiO2 and Al2O3.
(3) Plots of sandstone and siltstone compositions in an A-CN-K diagram suggest that they were altered by K-metasomatism.Extrapolation of the composition of the sandstones and siltstones backs to the alkali feldspar-plagioclase line, which suggests that the sources of the fine-grained rocks were derived from a source with more plagioclase than alkali feldspar.Nevertheless, the range of the composition of the extrapolation appears to plot at higher alkali feldspar to plagioclase ratios from Ek1 member than the sandstones and siltstones from Es4 and Es3 members.Thus, this is consistent with the granite source determined.The sandstones and siltstones could be derived from a mix of two end-member granitoids, one is a granite and the other a granodiorite-tonalite petrographically for the arenites.
(4) The high CIWs suggest that the weathering was intense and decreases in the order of Ek1member > Es4 member > Es3member.The high CIAs (75–85) estimated for the sandstones and siltstones because of metasomatism suggest that intense weathering was probable.The high ICVs of some sandstones and siltstones suggest that they contain much first cycle material.Some sandstones and siltstones have lower ICVs that suggest they contain recycled sediment or that weathering of the first cycle material was intense.
(5) Elemental ratios of these sedimentary rocks like (La/Lu) cn, Th/Sc, La/Sc, Th/Cr, La/Cr, La/Yb, and Eu/Eu*are consistent with their derivation mostly from granitoids as suggested by the petrography of the sandstones.These elemental ratios plot in well-defined trends.For example, the Th/Sc ratios of sandstones and siltstones from Ek1 member are higher than those from the Es4 and Es3 members, and the Eu/Eu*values of the Ek1 member are lower than those from the Es4 and Es3 members.This suggests that the Ek1 member was derived from a granitoid source formed by more fractional crystallization of feldspar or a lesser degree of melting from a feldspar-rich source than the granitoids weathered to produce the Es4 member and Es3 member.
ACKNOWLEDGMENT: The authors thank the researchers of Yichang Geological Institute for the analytical assistance.| Allegre, C. J., Minster, J. F., 1978. Quantitative Models of Trace Elements Behavior in Magmatic Processes. Earth and Planetary Science Letters, 38: 1–25. doi: 10.1016/0012-821X(78)90123-1 |
| Allegre, C. J., Rousseau, D., 1984. The Growth of the Continent through Geological Time Studied by Nd Isotope Analyses of Shales. Earth and Planetary Science Letters, 67: 19–34. doi: 10.1016/0012-821X(84)90035-9 |
| Barshad, I., 1966. The Effect of a Variation in Precipitation on the Nature of Clay Mineral Formation in Soils from Acid and Basic Igneous Rocks. In: Proc. Int. Clay Conf., Israel Program Sci. Translations, Jerusalem. 167–173. |
| Bavinton, O. A., Taylor, S. R., 1980. Rare-Earth Element Geochemistry of Archean Metasedimentary Rocks from Kambalda, Western Australia. Geochimica et Cosmochimica Acta, 44: 639–648. doi: 10.1016/0016-7037(80)90154-4 |
| Bhatia, M. R., 1983. Plate Tectonics and Geochemical Composition of Sandstones. Journal of Geology, 91: 611–627. doi: 10.1086/628815 |
| Bhatia, M. R., 1985. Rare Earth Element Geochemistry of Australian Paleozoic Graywackes and Mudrocks: Provenance and Tectonic Control. Sedimentary Geology, 45: 97–113. doi: 10.1016/0037-0738(85)90025-9 |
| Bhatia, M. R., Crook, K. A. W., 1986. Trace Element Characteristics of Graywackes and Tectonic Setting Discrimination of Sedimentary Basins. Contributions to Mineralogy and Petrology, 92: 181–193. doi: 10.1007/BF00375292 |
| Cardenas, A. A., Girty, G. H., Hanson, A. D., et al., 1996. Assessing Differences in Composition between Low Metamorphic Grade Mudstones and High-Grade SchistsUsing Log Ratio Techniques. Journal of Geology, 104: 279–293. doi: 10.1086/629825 |
| Chittleborough, D. J., 1991. Indices of Weathering for Soils and Palaeosols Formed on Silicate Rocks. Australian Journal of Earth Sciences, 38: 115–120. doi: 10.1080/08120099108727959 |
| Cohen, D., Ward, C. R., 1991. SEDNORM––A Program to Calculate a Normative Mineralogy for Sedimentary Rocks Based on Chemical Analyses. Computers & Geosciences, 17: 1235–1253. |
| Condie, K. C., Wronkiewicz, D. J., 1990. The Cr/Th Ratio in Precambrian Pelites from the Kaapvaal Craton as an Index of Craton Evolution. Earth and Planetary Science Letters, 97: 256–267. doi: 10.1016/0012-821X(90)90046-Z |
| Cox, R., Lowe, D. R., Cullers, R. L., 1995. The Influence of Sediment Recycling and Basement Composition on Evolution of Mudrock Chemistry in Southwestern United States. Geochimica et Cosmochimica Acta, 59: 2919–2940. doi: 10.1016/0016-7037(95)00185-9 |
| Cullers, R. L., 1988. Mineralogical and Chemical Changes of Soil and Stream Sediment Formed by Intense Weathering of the Danberg Granite, Georgia, USA. Lithos, 21: 301–314. doi: 10.1016/0024-4937(88)90035-7 |
| Cullers, R. L., 1994a. The Chemical Signature of Source Rocks in Size Fractions of Holocene Stream Sediment Derived from Metamorphic Rocks in the Wet Mountains Region, Colorado, USA. Chemical Geology, 113: 327–343. doi: 10.1016/0009-2541(94)90074-4 |
| Cullers, R. L., 1994b. The Controls on the Major and Trace Element Variation of Shales, Siltstones, and Sandstones of Pennsylvanian–Permian Age from Uplifted Continental Blocks in Colorado to Platform Sediment in Kansas, USA. Geochimica et Cosmochimica Acta, 58: 4955–4972. doi: 10.1016/0016-7037(94)90224-0 |
| Cullers, R. L., 1995. The Controls on the Major- and Trace-Element Evolution of Shales, Siltstones, and Sandstones of Ordovician to Tertiary Age in the Wet Mountains Region, Colorado, USA. Chemical Geology, 123: 107–131. doi: 10.1016/0009-2541(95)00050-V |
| Cullers, R. L., 2000. The Geochemistry of Shales, Siltstones, and Sandstones of Pennsylvanian–Permian Age, Colorado, USA: Implications for Provenance and Metamorphic Studies. Lithos, 51: 181–203. doi: 10.1016/S0024-4937(99)00063-8 |
| Cullers, R. L., Basu, A., Suttner, L. J., 1988. Geochemical Signature of Provenance in Sand-Size Material in Soils and Stream Sediments near the Tobacco Root Batholith, Montana, USA. Chemical Geology, 70: 335–348. doi: 10.1016/0009-2541(88)90123-4 |
| Cullers, R. L., Berendsen, P., 1998. The Provenance and Chemical Variation of Sandstones Associated with the Mid-Continent Rift System, USA. European Journal ofMineralogy, 10: 987–1002. doi: 10.1127/ejm/10/5/0987 |
| Cullers, R. L., Podkovyrov, V. N., 2000. Geochemistry of the Mesoproterozoic Lakhanda Sandstones in Southeastern Yakutia, Russia: Implications for Mineralogical and Provenance Control, and Recycling. Precambrian Research, 104: 77–93. doi: 10.1016/S0301-9268(00)00090-5 |
| Dai, J. S., 1999. Tectonic Evolution of the Kongdian Formation—Sha-Ⅳ Member in the Huimin Depression and the Dongying Depression. Scientia Geologica Sinica, 8 (2): 177–184. |
| Dickinson, W. R., 1985. Interpreting Provenance Relations from Detrital Modes of Sandstones. NATO ASI Series, Series C: Mathematical and Physical Sciences, 148: 333–361. |
| Dickinson, W. R., Suczek, C. A., 1979. Plate Tectonics and Sandstone Compositions. AAPG Bulletin, 63: 2164–2182. |
| Fedo, C. M., Nesbitt, H. W., Young, G. M., 1995. Unraveling the Effects of Potassium Metasomatism in Sedimentary Rocks and Paleosols, with Implications for Paleoweathering Conditions and Provenance. Geology, 23: 921–924. |
| Fedo, C. M., Young, G. M., Nesbitt, H. W., 1997a. Paleoclimatic Control on the Composition of the Paleoproterozoic Serpent Formation, Huronian Supergroup, Canada: A Greenhouse to Icehouse Transition. Precambrian Research, 86: 201–223. doi: 10.1016/S0301-9268(97)00049-1 |
| Fedo, C. M., Young, G. M., Nesbitt, H. W., et al., 1997b. Potassic and Sodic Metasomatism in the Southern Province of the Canadian Shield: Evidence from the Paleoproterozoic Serpent Formation, Huronian Supergroup, Canada. Precambrian Research, 84: 17–36. doi: 10.1016/S0301-9268(96)00058-7 |
| Harnois, L., 1988. The CIW Index: A New Chemical Index of Weathering. Sedimentary Geology, 55: 319–322. doi: 10.1016/0037-0738(88)90137-6 |
| Herron, M. M., 1988. Geochemical Classification of Terrigenous Sands and Shales from Core or Log Data. Journal of Sedimentary Petrology, 58: 820–829. |
| Ingersoll, R. V., Fullard, T. F., Ford, R. L., et al., 1984. The Effect of Grain Size on Detrital Modes: A Test of the Gazzi-Dickinson Point Counting Method. Journal of Sedimentary Petrology, 54: 103–116. |
| Jiang, Z. X., Cao, Y. C., Yang, J. P., 1999. Sedimentary Characters and Depositional Models of the Upper Sha-Ⅲ Member of the Oligocene Shahejie Formation in the Central Uplift Zone, Huimin Depression, China. Scientia Geologica Sinica, 8 (2): 169–176. |
| Johnsson, M. J., 1993. The System Controlling theComposition of Clastic Sediments. In: Johnsson, M. J., Basu, A., eds., Processes Controlling the Composition of Clastic Sediments. Special Paper—Geololgical Society of American, 284: 1–19. |
| Johnsson, M. J., 2000. Tectonic Assembly of East-Central Alaska: Evidence from Cretaceous–Tertiary Sandstones of the Kandik River Terrane. Geological Society of America Bulletin, 112: 1023–1042. doi: 10.1130/0016-7606(2000)112<1023:TAOEAE>2.0.CO;2 |
| Johnsson, M. J., Stallard, R. F., Meade, R. H., 1988. First-Cycle Quartz Arenites in the Orinoco River Basin, Venezuela and Colombia. Journal of Geology, 96: 263–277. doi: 10.1086/629219 |
| McLennan, S. M., Hemming, S., McDaniel, D. K., et al., 1993. Geochemical Approaches to Sedimentation, Provenance, and Tectonics. In: Johnson, M. J., Basu, A., eds., Processes Controlling the Composition of Clastic Sediments. Special Paper—Geological Society of America, 284: 21–40. |
| McLennan, S. M., Taylor, S. R., 1991. Sedimentary Rocks and Crustal Evolution: Tectonic Setting and Secular Trends. Journal of Geology, 99: 1–21. doi: 10.1086/629470 |
| McLennan, S. M., Taylor, S. R., Eriksson, K. A., 1983. Geochemistry of Archean Shales from the Pilbara Supergroup, Western Australia. Geochimica et Cosmochimica Acta, 47: 1211–1222. doi: 10.1016/0016-7037(83)90063-7 |
| McLennan, S. M., Taylor, S. R., McCulloch, M. T., et al., 1990. Geochemistry and Nd-Sr Isotopic Composition of Deepsea Turbidites: Crustal Evolution and Plate Tectonic Associations. Geochimica et Cosmochimica Acta, 54: 2014–2050. |
| Mongelli, G., Cullers, R. L., Muelheisen, S., 1996. Geochemistry of Late Cretaceous–Oligocene Shales from the Varicolori Formation, Southern Apennienes, Italy: Implications for Mineralogy, Grain-Size Control and Provenance. European Journal of Mineralogy, 8: 733–754. doi: 10.1127/ejm/8/4/0733 |
| Nesbitt, H. W., Markovics, G., 1997. Weathering of Granodioritic Crust, Long-Term Storage of Elements in Weathering Profiles, and Petrogenesis of Siliciclastic Sediments. Geochimica et Cosmochimica Acta, 61: 1653–1670. doi: 10.1016/S0016-7037(97)00031-8 |
| Nesbitt, H. W., Young, G. M., 1982. Early Proterozoic Climates and Plate Motions Inferred from Major Elemental Chemistry of Lutites. Nature, 299: 715–717. doi: 10.1038/299715a0 |
| Pettijohn, F. J., Potter, P. E., Siever, R., 1972. Sand and Sandstone. Springer-Verlag, New York. 618. |
| Pettijohn, F. J., Potter, P. E., Siever, R., 1987. Sand andSandstone. Springer, New York. |
| Roser, B. P., Korsch, R. J., 1986. Determination of Tectonic Setting of Sandstone-Mudstone Suites Using SiO2 Content and K2O/Na2O Ratio. Journal of Geology, 94: 635–650. doi: 10.1086/629071 |
| Roser, B. P., Korsch, R. J., 1988. Provenance Signatures of Sandstone-Mudstone Suites Determined Using Discriminant Function Analysis of Major-Element Data. Chemical Geology, 67: 119–139. doi: 10.1016/0009-2541(88)90010-1 |
| Suttner, L. J., Dutta, P. K., 1986. Alluvial Sandstone Composition and Paleoclimate: I, Framework Mineralogy. Journal of Sedimentary Petrology, 56: 329–345. |
| van de Kamp, P. C., Leake, B. E., 1985. Petrography and Geochemistry of Feldspathic and Mafic Sediments of the Northeastern Pacific Margin. Transactions of the Royal Society of Edinburgh: Earth Sciences, 76: 411–449. doi: 10.1017/S0263593300010646 |
| Wronkiewicz, D. J., Condie, K. C., 1990. Geochemistry and Mineralogy of Sediments from the Ventersdorp and Transvaal Supergroups, South Africa: Cratonic Evolution during the Early Proterozoic. Geochimica etCosmochimica Acta, 54: 343–354. doi: 10.1016/0016-7037(90)90323-D |
| Yang, J. P., 2000. Storm Deposits in the Upper Sha-3 Member of Eogene System in Western Central Uplift Belt of Huimin Depression. Journal of the University of Petroleum, China, 24 (1): 26–29 (in Chinese with English Abstract). |
| Zhang, L., Zhu, X. M., Zhong, D. K., et al., 2007. Vertical Distribution of Secondary Pores in Paleogene Sandstones in Huimin Depression and Its Genesis Analysis. Earth Science—Journal of China University of Geosciences, 32 (2): 253–259 (in Chinese with English Abstract). |
| Zhang, X., Zhang, J. L., 2007. Sedimento-geochemical Features of Sandstones from the Fourth Member, Shahejie Formation in the Southern Slope of Dongying Sag. Chinese Journal of Geology, 42 (2): 303–318 (in Chinese with English Abstract). |
| Zhang, X., Zhang, J. L., Qin, L. J., 2007. Petrological Characteristics and Provenance Analysis of Sandstones in the Kepingtage Formation of Silurian in the Tarim Basin. Journal of Mineralogy and Petrology, 27 (3): 106–115 (in Chinese with English Abstract). |
| Zhang, Y., Liu, Y. Q., 2001. The Evolution of Palaeogene Delta Depositional Systems and Sand Bodies in the Western Huimin Depression, Shandong Province. Geological Review, 47 (3): 322–328 (in Chinese with English Abstract). |
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Jin-liang ZHANG, Xin ZHANG. Composition and Provenance of Sandstones and Siltstones in Paleogene, Huimin Depression, Bohai Bay Basin, Eastern China. Journal of Earth Science, 2008, 19(3): 252-270.
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