Introduction

The geochemical composition of clastic sediments has been widely used to decipher the provenance (Madhavaraju and Lee 2010; Migani et al. 2015; Odoma et al. 2015), to evaluate the weathering history of the source area (Zaid 2013; Rahman et al. 2014), and to infer the tectonic settings (Roser and Korsch 1986; Armstrong-Altrin 2015). The geochemical characteristics of clastic sediments are controlled by several factors, such as the source rock composition, weathering intensity, sedimentation and post-depositional diagenesis (Nesbitt and Young 1982; McLennan 1989). Recent studies (Armstrong-Altrin et al. 2014; Zhang et al. 2014) indicated that trace elements like Y, Sc, Th, Zr, Hf, Cr, Co and rare earth elements (REE) are only negligible affected by chemical weathering, denudation, and aggradation. Therefore, these elements can be used to in provenance studies and to determine the tectonic settings of sedimentary basins (Cullers et al. 1987; Condie et al. 1992; Holail and Moghazi 1998; McCann 1998). However, because of multiple factors controlling the geochemical characteristics of sedimentary rocks, combined petrological and geochemical analyses should be applied to reveal the provenance and tectonic setting of a sedimentary basin (Hanson et al. 2001; Zhang et al. 2012; Xu et al. 2013a, b).

The Laoheishan basin is located in the eastern Heilongjiang Province, northeast China (Fig. 1), and contains abundant coal and oil shale resources. Previous studies were focused only on the calculation of coal resources, the provenance and tectonic setting of clastic sediments has not been studied. In this study, the petrological and geochemical analyses are carried out on the clastic sediments of the Muling Formation to infer paleoweathering, source rock characteristics, and tectonic setting.

Fig. 1
figure 1

a Sketch map showing the geotectonic of China (Lv et al. 2015), b tectonic units of northeast China showing the position of the Xingkai massif (Wu et al. 2007; Xu et al. 2012), c geological map of the Laoheishan basin and the sampling location, d profiles of the Laoheishan basin showing the basin structure

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Geological setting

Northeast China is formed by several micro-continental blocks separated by major faults. The micro-continental blocks are (from NW to SE) the Erguna, Xing’an, Songliao, Jiamusi and Xingkai blocks (Fig. 1a, b) (Wu et al. 2007).

The Laoheishan basin is situated in the Xingkai Block composed of Precambrian metamorphic basement, partly covered by carbonate, clastic and volcanic rocks of Paleozoic and Mesozoic age (Shi 2006; Xu et al. 2012). The basin covers an area of approximately 400 km2. Outcrops of the Cretaceous basin fill are very rare and occur only in northwestern part of the basin (Fig. 1c). The central and southeastern parts of the basin are covered by extensive and thick basalt layers of the Tertiary Chuandishan Formation (Fig. 1c, d).

The Lower Cretaceous basin fill is about 400 m thick and dips southeastwards with less than 5°. It comprises the Muling Formation and the overlying Dongshan Formation. The Muling Formation is subdivided into two members. The lower member is composed of conglomerate with interbedded sandstone and mudstone (K1ml1). In contrast, the upper member (K1ml2) consists of mudstone, sandstone and limited conglomerate, with several coal and oil shale layers (Fig. 2).

Fig. 2
figure 2

Stratigraphic division of the Laoheishan basin

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Samples and analytical methods

Samples for the study were collected from the new-drilled well NY1, which located in the basin center (Fig. 1c) with large thickness of K1ml (total thickness 277.22 m). The samples were taken in Klml2 (total thickness 263.46 m), from 121 to 372.8 m interval and the sample location was indicated in Fig. 3. Twenty-four sandstone samples have been selected for petrographic study (Fig. 3; Table 1) and 8 fine-grained sediments (Fig. 3; Table 2) were analyzed for the mineral composition. Additionally, 11 (Fig. 3; Table 3) and 35 fine-grained sediments (Fig. 3; Tables 4 and 5) have been selected for major elements, trace and rare earth elements analyses, respectively. For mineral composition and geochemical analyses, samples were ground in an agate mortar and stored in the glass capillary to prevent oxidation prior to analysis.

Fig. 3
figure 3

Lithologic log of well NY-1, visualizing sampling depth and principal investigations performed

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Table 1 Modal point-count data of sandstone samples from the Laoheishan basin
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Table 2 Mineralogy of the samples from the Laoheishan basin as determined by XRD
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Table 3 Major element concentrations of the samples from the Laoheishan basin as determined by XRF
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Table 4 Trace element concentrations of the samples from the Laoheishan basin as determined by HR-ICP-MS
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Table 5 Rare earth element concentrations of the samples from the Laoheishan basin as determined by HR-ICP-MS
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For petrographic investigations, 24 thin sections were prepared following the procedure by Camuti and McGuire (1999). The point counts were done using Dickinson (Dickinson, 1985) and standard methods. In each section, we used the 300-grain-count practice originally from Dryden (1931), for total quartz [Q = monocrystalline quartz (Qm) + polycrystalline quartz (Qp)], total feldspar [F = K-feldspar (K) + plagioclase feldspar (P)] and total lithic fragments [L = volcanic (Lv) + sedimentary (Ls) + metamorphic (Lm) rock fragments] (Dickinson 1970; Ingersoll et al. 1984), the results were presented in Table 1. The mathematical background for point-counting statistics is shown in Howarth (1998), and the statistical error is ±5 vol%. The practical procedures are given in Howarth and French (1998).

X-ray diffraction analyses were conducted on a Philips PW 1830/40 device using CuKα-radiation (1.54 Å, 35 kV, 35 mA). Scans with a step size of 0.02。were run between 2 and 67。2θ in the air-dry state (random powder mount and oriented powder mount) and between 2 and 45。2θ in the ethylene- glycoliated state and after heating to 350 and 550。C. Qualitative processing was done using the dataset of Brindley and Brown (1980) and Moore and Reynolds (1997). Quantitative interpretation was carried out using the methods described by Schultz (1964).

The major element compound content was determined using a Philips PW2404 X-ray fluorescence (XRF) spectrometer. Powdered samples were heated to 110。C for 6 h followed by heating in a muffle furnace at 1000。C for two hours to determine LOI (loss on ignition). Lithium tetraborate was mixed with the samples and heated to 1000。C to form a fused samples for XRF analysis. An international reference standard material (JB-2) was used to check the accuracy that was better than ±5 % and the precision of the measurement based on duplicate was within the acceptable limit. The results are reported in Table 3, CIA refers to the chemical index of alteration, which proposed by Nesbitt and Young (1982), defined as CIA = 100 × Al2O3 / (Al2O3 + CaO* + Na2O + K2O), and CaO* refers only to the CaO in siliceous minerals. ICV refers to the index of chemical variability, proposed by Cox et al. (1995), defined as ICV = (Fe2O3 + K2O + Na2O + CaO + MgO + MnO + TiO2)/Al2O3.

Trace and rare earth elements were determined from solutions prepared by homogenized samples powder dissolved in reagent grade HF: HNO3 acid mixture in screwtop vessels. A test portion (0.05 g) of samples was added to 25 ml pressure decomposition vessels. Matrix matching international certified reference materials MAG-1 (marine mud, United States) and GSR-4 (sandstone sediment, China) along with couple of procedural blanks were also prepared with the sample batch by adopting the same protocol described above to negate errors due to reagent and handling. Solutions were analyzed by high resolution inductively coupled plasma mass spectrometer (HR-ICP-MS) (Thermo Scientific X-Series). The MAG-1 was used for calibration. The analytical precision for all the elements was estimated to be <5 % based on duplicate analyses of samples and standards. The results are reported in Tables 4 and 5.

Results

Petrography

The sandstones from the lower Cretaceous Muling Formation comprise three components: framework gains, cements, and pores. Most of the framework grains are medium sorted, sub-angular to sub-round in shape and are texturally moderately mature (Armstrong-Altrin et al. 2015b), mainly composed of quartz (Q), feldspar (F) and rock fragments (L), with a few heavy minerals and matrix (Table 1). The average ratio of Q-F-L is Q63-F22-L15, indicate the compositionally moderately mature.

Quartz is the most abundant grain component in the sandstones and can be subdivided into two groups: monocrystalline quartz (Qm) and polycrystalline quartz (Qp) (Table 1; Fig. 4a, b). Qm contains nonundulose and undulose grains, indicating low-grade metamorphism (Basu et al. 1975); and most Qp grains consist of more than three crystals of two types: 1) more than five elongated irregular crystals with crenulated intercrystal boundaries (Fig. 4a); 2) five or more crystals with straight to slightly curved inter-crystals boundaries (Fig. 4b). The first type indicating a metamorphic origin (Asiedu et al. 2000) is less in the study area, whereas the second type is predominant, indicating an igneous origin (Tucker 2009).

Fig. 4
figure 4

Photomicrographs of the Muling Formation sandstone samples (cross-polarized light): a Qp grains belonging to metamorphic rock fragments, along with K-feldspar (Kf), Qm, biotite (Bio) grains and carbonate cement (Cc); b Qp grain belonging to igneous rock fragment, Qm and biotite (Bio) grain; c acid igneous rock fragment (Lv, probably granite fragment) and Qm grains; d intermediate igneous rock fragment (Lv, probably andesite fragment) along with plagioclase (Pl) and Qm grains

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Feldspar in the sandstones mainly comprise alkali feldspar (Fig. 4a) and plagioclase (Fig. 4d). Most feldspar grains are unaltered, although some grains are altered to sericite. Orthoclase is common in alkali feldspar, whereas microcline is very rare.

Lithic fragments in the sandstones include volcanic (Lv), sedimentary (Ls) and metamorphic (Lm) rock fragments. Volcanic rock fragments comprise felsic igneous rock (such as granite, Fig. 4c) and intermediate igneous rock (such as andesite, Fig. 4d); metamorphic rock fragments mainly consist of Qp; sedimentary fragments include sandstone and mudstone. The lithic fragments in the sandstones are predominantly Lv, indicating that the Muling Formation are mainly derived from igneous rock sources.

A limited content of heavy minerals is observed (<2 % on average) in the sandstones, including zircon, rutile and tourmaline. The matrix of the sandstones consist of clay minerals, carbonate, and communited lithic fragments. However, the existence of pseudomatrices makes it difficult to distinguish the primary and the epigenetic matrix (Dickinson 1970). Hence, the percentage of matrix may be overestimated.

The diagenesis of sandstones comprise compaction and cementation processes, the characteristics are as follows: 1) contact relation between detrital grains includes point and line contacts (Fig. 4); and 2) compaction deformation occurred in plastic grains (such as biotite) (Fig. 4b). The cementation mainly consist of carbonate cementation, usually formed in the primary porosity (Fig 4a).

Mineralogy

The XRD study indicates that the fine-grained sediments of K1ml2 mainly consist of clay minerals and detrital minerals with little other minerals (Table 2). The clay minerals on average comprise smectite (10 %), I/S mixed layers (15 %), illite (8 %), kaolinite (19 %) and chlorite (8 %). The detrital minerals comprise quartz (32 %), K-feldspar (3 %) and plagioclase (6 %), whereas the content of other mineral is very low (calcite <1 %).

Geochemistry

Major elements

Major elements concentrations in sedimentary rocks are controlled by several factors, one of the most important factors is the mineral composition (Zhang et al. 2014). For example, the K2O/Na2O ratio of sedimentary rocks is controlled by the relative proportion of K-feldspar to plagioclase, and the content of SiO2 is controlled by the abundance of quartz. Furthermore, weathering can also influence the major elements concentrations in sedimentary rocks. For instance, Na in weathered crust could be carried away more easily than K, causing a strong deficit of Na and an abnormally high K2O/Na2O ratio; and the SiO2 content may increase abruptly through a hydrothermal or surface weathering process (Cullers et al. 1987). The K2O/Na2O ratio of fine-grained sediments from the Muling Formation ranges from 0.22 to 1.18, with an average of 0.74 (Table 3), lower than the upper continental crust (UCC = 0.9), indicating these samples are affected by weathering. The medium content of SiO2 (38 ~ 63 %, with an average of 55 %) indicates medium mineral maturity and medium content of quartz and/or Si-rich minerals (Zhang et al. 2014). The relatively high ferromagnesian element concentrations (such as TiO2, Fe2O3, and MgO) indicate some influence from basic rocks. The high Al2O3 content (13.4 ~ 24.8 %, with an average of 18.7 %) is probably related to the high content of aluminum-rich minerals, such as clay minerals, feldspar and mica.

Trace elements

The selected trace elements are discussed as three groups, i.e. transition trace elements (TTE: Co, Ni, V, Cr), large ion lithophile elements (LILE: Sr, Rb, Ba) and high field strength elements (HFS: Th, Sc, Nb, Ta, Zr, Hf, Y, U). Table 4 lists the selected trace elements concentrations, the distribution pattern of these elements are presented in Fig. 5.

Fig. 5
figure 5

UCC-normalized selected trace elements diagram of samples from the Laoheishan basin (UCC data from Taylor and McLennan 1985)

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The TTE in fine-grained sediments are enriched relative to the upper continental crust (UCC), indicating a cryptic mafic or ultramafic component carried in the clay fractions of the sediments (Hossain et al. 2010). The LILE are depleted relative to the UCC. Among these, Rb shows the greatest depletion (Fig. 5). Because Rb is incorporated into clay during chemical weathering (Nesbitt and Young 1982), so it indicates strong chemical weathering in the source area. The HFS are similar to the UCC, suggesting the source rocks are probably derived from the UCC (McLennan et al. 1995).

Rare earth elements

The REE contents of the fine-grained sediments from the Muling Formation are presented in Table 5. The REE contents range from 65.99 to 336.81 μg/g, with an average of 171.65 μg/g, similar to the UCC (ΣREE = 146.4 μg/g), indicating a probably felsic source from the UCC (Taylor and McLennan 1985), and probably influenced by some intermediate rock sources. Of these, the total light rare earth elements (ΣLREE, include La to Eu) and total heavy rare earth elements (ΣHREE, include Gd to Lu) are 55.65–301.49 ppm and 8.03–36.08 ppm, respectively. The ΣLREE/ΣHREE ratio ranges from 3.19 to 13.44 with an average of 7.68 (Table 5). The chondrite normalized REE patterns (Fig. 6) show LREE enrichment and relatively flat HREE. The medium (La/Yb)N value (2.55–19.02, avg. 8.44) indicates the medium extent of fractionation between LREEs and HREEs, consistent with the medium ΣLREE/ΣHREE ratio. Eu anomaly (δEu) value varies between 0.40 and 0.81, with an average of 0.63, reveals a negative Eu anomaly.

Fig. 6
figure 6

Chondrite-normalized REE distributions of samples from the Laoheishan basin (Chondrite data from Taylor and McLennan 1985)

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Discussion

Weathering and sediment maturity

During the weathering process, stable cations (such as Al3+ and Ti4+) are sorted in stable weathering products, whereas the unstable cations (such as Na+, Ca2+ and K+) tend to be lost (Fedo and Nesbtit 1995). Such elemental enrichment and loss commonly depend on the intensity of chemical weathering (Condie et al. 1992). In order to quantify the degree of weathering, Nesbitt and Young (1982) proposed the Chemical Index of Alteration (CIA). The Al2O3-(Na2O + CaO*)-K2O ternary diagram (Fig. 7) shows that the CIA of K1ml2 samples range from 69 to 90 with an average of 78, suggesting strong chemical weathering.

Fig. 7
figure 7

Al2O3-(Na2O + CaO*)-K2O ternary diagram of samples from the Laoheishan basin, showing the weathering status of its source rocks (after Condie et al. 1992)

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The index of chemical variability (ICV; Cox et al. 1995) is a measure to identify the compositional maturity of sediments, which has successfully applied in many studies (Armstrong-Altrin et al. 2015a, b). Typical rock forming minerals like feldspars, amphiboles, and pyroxenes have ICV values of >1, whereas alteration products such as kaolinite, illite, and muscovite have ICV values <1 (Cox et al. 1995; Cullers and Podkovyrov 2000). The ICV values of K1ml2 samples range from 0.28 to 0.63 with an average of 0.47, indicating the samples are geochemically moderately mature and may derive from a strong weathered source.

Provenance

The sedimentary source regions

The sandstones from the Muling Formation show medium to high quartz content, relatively low contents of feldspar and lithic fragments (Table 1), medium sorted, and sub-angular to sub-round in shape. These features are indicative of compositionally and texturally moderately mature. The types of lithic fragments in sandstones are similar to the basement surrounding the basin. Furthermore, in conglomerates at the K1ml1, much gravel has been found from the basement, i.e. dacite, acid tufflava, andesite, granite, rhyolite and tuff, etc., suggesting the felsic and intermediate igneous source rocks. Dickinson (1985) suggested that detrital modes of sandstone suites primarily reflect the different tectonic settings of provenance terranes. On the Q-F-L ternary diagram, most of the K1ml2 sandstones plot in the recycled orogeny field (Fig. 8).

Fig. 8
figure 8

Q-F-L ternary plots from the Muling Formation sandstone in the Laoheishan basin (Q = Quartz; F = feldspar; L = lithic rocks) (after Dickinson 1985)

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Type of the source rocks

Major and trace element concentrations of terrigenous sediments can give a reliable clue about the provenance of the source area (Armstrong-Altrin et al. 2015b; Odoma et al. 2015). Among major elements, Al2O3 and TiO2 are considered as immobile during weathering, transportation, and diagenesis. Hence, the Al2O3/TiO2 ratio can be used to infer the source rock composition (Zhou et al. 2015). According to Hayashi et al. (1997), the Al2O3/TiO2 ratios range from 3 to 8 represent mafic, 8–21 indicate intermediate and 21–70 for felsic igneous rocks. The Al2O3/TiO2 ratios of fine-grained samples from the K1ml2 vary between 17 and 32. The variation in Al2O3/TiO2 ratios indicate that K1ml2 samples are derived from felsic and intermediate igneous source rocks.

Trace elements such as Sc, Ni, Cr and Co tend to be enriched in mafic rocks, whereas La, Th, Hf, Zr and REE are richer in acidic rocks (Cullers and Podkovyrov 2000). The fine-grained sediments from K1ml2 show variable La/Sc ratio (0.81–7.68, avg. 3.04) and relatively constant Co/Th ratio (0.14–4.96, avg. 0.97), which plot mostly in felsic volcanic rock and andesite areas (Fig. 9a). Floyd and Leveridge (1987) established a discrimination diagram using the La/Th ratio vs. Hf to determine different sources and to further distinguish the andesite and basalt sources. The samples show relatively low La/Th ratio (<5.0) and Hf content (3.04–11.1, avg. 5.94), suggesting that they may have originated from felsic and intermediate source rocks (Fig. 9b). Thus, the geochemical analyses indicate that the source rocks of the K1ml are mainly derived from felsic and intermediate igneous rocks, probably felsic volcanic rock and andesite.

Fig. 9
figure 9

Source rock discrimination diagrams for the K1ml2 samples in the Laoheishan basin; a La/Sc vs. Co/Th (after Wronkiewicz and Condie 1987); b Hf vs. La/Th plot (after Floyd and Leveridge 1987)

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The location of source area

Several igneous rocks developed surrounding the Laoheishan basin, such as the northwestern granodiorite, the northeastern quartz diorite, the northern granite porphyry and the pyroxene diorite (Cheng et al. 2006; Zhao et al. 2009; Xu et al. 2013a, b). Previous studies indicated that the granodiorite from the northwest is strong REE fractionation ((La/Yb)N = 6.34–16.68) with a negative Eu anomaly (δEu = 0.53–0.74) (Zhao et al. 2009), similar to the K1ml2 samples (Fig. 10a). Similarly, the quartz diorite from the northeast also shows relatively strong REE fractionation ((La/Yb)N = 5.28–8.21) and a negative Eu anomaly (δEu = 0.63–0.82) (Zhao et al. 2009; Fig. 10b). However, the granite porphyry from the north reveals strong REE fractionation ((La/Yb)N = 8.29) with a weak positive Eu anomaly (δEu = 1.07) (Xu 2009; Fig. 10c), and the pyroxene diorite from the north suggests weak REE fractionation and a weak positive Eu anomaly (Zhao 2013; Fig. 10d), which are different from the studied samples.

Fig. 10
figure 10

Chondrite-normalised REE distribution patterns of the study area and granite surrounding the Laoheishan basin (Chondrite data from Taylor and McLennan 1985). The grey shaded zones represent the REE distribution of the K1ml2 samples. a Granodiorite in the northeastern basin, with data from Zhao et al. (2009); b Quartzdiorite in the northwestern basin, with data from Zhao et al. (2009); c Granite porphyry in the northern basin, with data from Xu (2009); d Pyroxene diorite in the northern basin, with data from Zhao (2013)

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Therefore the source rocks of the K1ml2 have strong genetic relationships with the granodiorite and quartz diorite from the northwest and the northeast, respectively. But have weak relationships with the granite porphyry and the pyroxene diorite from the north, suggesting the source rocks may contain granodiorite and quartz diorite, and probably derived from the northwest and the northeast areas.

Tectonic setting

The distinctive elemental compositions of siliciclastic rocks in various tectonic environments have been widely used to indicate the tectonic setting of their respective sedimentary basins (Bhatia 1983; Bhatia and Crook 1986). Recently, based on the geochemical composition of Neogene-Quaternary sediments, Verma and Armstrong-Altrin (2013) proposed two discriminant-function-based major-element diagrams for the tectonic discrimination of siliciclastic sediments for high-silica [(SiO2) adj = 63–95 %] and low-silica [(SiO2) adj = 35–63 %] types, from three main tectonic settings: island or continental arc, continental rift and collision. In addition, these diagrams are already evaluated by some researchers (Nagarajan et al. 2015; Verma and Armstrong-Altrin 2016). In these high silica and low silica multi-dimensional diagrams, the K1ml2 samples are plotted in the collision and continental rift fields (Fig. 11a, b).

Fig. 11
figure 11

Discriminant-function multi-dimensional diagram for high-silica (a) and low-silica (b) clastic sediments (Verma and Armstrong-Altrin 2013). The subscript m1 in DF1 and DF2 represents the high-silica diagram based on loge-ratios of major elements. The discriminant function equations are: (1) DF1(Arc-Rift-Col)m1 = (0.263 × ln(TiO2/SiO2)adj) + (0.604 × ln(Al2O3/SiO2)adj) + (1.725 × ln(Fe2O3 t/SiO2)adj) + (0.660 × ln(MnO/SiO2)adj) + (2.191 × ln(MgO/SiO2)adj) + (0.144 × ln(CaO/SiO2)adj) + (−1.304 × ln(Na2O/SiO2)adj) + (0.054 × ln(K2O/SiO2)adj) + (−0.330 × ln(P2O5/SiO2)adj) + 1.588; (2) DF2(Arc-Rift-Col)m1 = (1.196 × ln(TiO2/SiO2)adj) + (1.604 × ln(Al2O3/SiO2)adj) + (0.303 × ln(Fe2O3 t/SiO2)adj) + (0.436 × ln(MnO/SiO2)adj) + (0.838 × ln(MgO/SiO2)adj) + (−0.407 × ln(CaO/SiO2)adj) + (1.021 × ln(Na2O/SiO2)adj) + (−1.706 × ln(K2O/SiO2)adj) + (−0.126 × ln(P2O5/SiO2)adj) - 1.068; The subscript m2 in DF1 and DF2 represents the low-silica diagram based on loge-ratios of major elements. The discriminant function equations are: (1) DF1(Arc-Rift-Col)m2 = (0.608 × ln(TiO2/SiO2)adj) + (−1.854 × ln(Al2O3/SiO2)adj) + (0.299 × ln(Fe2O3 t/SiO2)adj) + (−0.550 × ln(MnO/SiO2)adj) + (0.120 × ln(MgO/SiO2)adj) + (0.194 × ln(CaO/SiO2)adj) + (−1.510 × ln(Na2O/SiO2)adj) + (1.941 × ln(K2O/SiO2)adj) + (0.003 × ln(P2O5/SiO2)adj) - 0.294; (2) DF2(Arc-Rift-Col)m2 = (−0.554 × ln(TiO2/SiO2)adj) + (−0.995 × ln(Al2O3/SiO2)adj) + (1.765 × ln(Fe2O3 t/SiO2)adj) + (−1.391 × ln(MnO/SiO2)adj) + (−1.034 × ln(MgO/SiO2)adj) + (0.225 × ln(CaO/SiO2)adj) + (0.713 × ln(Na2O/SiO2)adj) + (0.330 × ln(K2O/SiO2)adj) + (0.637 × ln(P2O5/SiO2)adj) - 3.631

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The previous studies indicated that at the end of the Late Jurassic (~160 Ma), the lithosphere was affected by the early collision orogeny and intracontinental compressive deformation in the region of northeast (NE) China, caused a strong crustal shortening and thickening, and increased the lithosphere thickness (Cheng et al. 2006; Xu et al. 2012; Luo et al. 2014). At the middle stage of the early Cretaceous (120–130 Ma), the rapidly oblique subduction of the Paleo-Pacific plate beneath the Eurasian continent, caused the compressed and left-lateral strike-slip shearing environment in the eastern margin of the Eurasian continent (Zhou et al. 2009; Sun et al. 2010), agitated the upwelling of asthenosphere, and caused the lithospheric mantle and part of the lower crust to submergence into the asthenosphere mantle through delamination. Meanwhile the lithosphere intense thinning made asthenosphere mantle directly contact with the crust, and resulted in the large-scale magmatism and widespread development of extensional structures in the Mesozoic (Zhao et al. 2009; Liu et al. 2014). On the basis of Mesozoic volcanic rocks in NE China, Xu et al. (2013a, b) suggested the existence of late Early Cretaceous (106 ~ 133 Ma, peak age ~115 Ma) calc-alkaline volcanic rocks in the eastern Heilongjiang–Jilin provinces indicated an active continental margin setting, and the coeval bimodal volcanic rocks in the Great Xing’an Range and the Songliao Basin suggested an intracontinental extensional environment related to the low-angle subduction of the Paleo-Pacific Plate beneath the Eurasian continent. Thus, the previous studies (Sun et al. 2010; Xu et al. 2013a, b; Liu et al. 2014; Luo et al. 2014) indicated that during the late early Cretaceous, collision and continental rift settings developed in the NE China. The Laoheishan basin located in the eastern Heilongjiang Province (Fig. 1), combined with the results obtained from the discrimination diagrams, there is a high probability that clastic sediments of the K1ml2 were derived from the collision system, and however, there were possibilities that they may comprise sediments derived from the continental rift system.

Conclusions

Sedimentary rocks collected from the lower Cretaceous Muling Formation (K1ml) in the Laoheishan basin, northeast China are investigated the petrography, mineralogy and geochemistry to reveal the weathering intensity, provenance and tectonic setting.

Sandstones from the K1ml2 have high quartz, medium feldspar and low lithic fragments contents. Lithic fragments are predominantly volcanic clasts. Much gravel has been found from the basement in K1ml1 conglomerates. Petrological observation reveals that the sandstones are derived from the surrounding basement and recycled orogeny sources.

Petrography and geochemistry (Al2O3/TiO2, Co/Th, La/Sc, La/Th, Hf) results reveal that the source rocks are mainly felsic and intermediate igneous rocks, probably felsic volcanic rock and andesite. The strong genetic relationship with the igneous rocks from the northwest and northeast indicate the sediments have been derived from this area. The chemical weathering index (CIA) and index of chemical variability (ICV) suggest an intensive weathering in the source region of the sediments.

The multidimensional tectonic discrimination diagrams indicate that the source rocks of K1ml are predominantly derived from the collision system. However, they may also comprise sediments derived from the continental rift system. These results are consistent with the geology of the study area.