Ke Cao

a Qingdao Institute of Marine Geology, Qingdao 266071, China

b Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266061, China

ABSTRACT

As an important part of an epidermic system, terrestrial deposits can provide a good record of major geological events in the Cretaceous epidemic system. This article is a review of the geological background, paleogeography, paleoclimate, basin evolution and sedimentary characteristics in China through the Cretaceous period, in order to provide a comprehensive understanding for interested researchers. During the Berriasian-Hauterivian age, red-mainly fluvial and shallow lacustrine deposition developed under arid and semi-arid climates in westen China when eastern China had been occupied by the “East Plateau”. During the Barremian-Albian, age coal-bearing depositions occurred to the north of the Yanshan Mountain under the wet and warm climate. However, mainly red fluvial and shallow lacustrine depositions prevailed in most of the south to the Yanshan Mountain except basins where seawater could enter and caused mostly green depositions. During the Cenomanian-Santonian age, high land uplift took place in northwestern China. Mainly red deposition with developed alluvial plains occupied southwestern China and South China when the Songliao Basin was filled by black deep lacustrine mud shale caused by transgression. Mainly red deposition under an arid and semi-arid climate occupied all basins in China during the Campanian-Maastrichtian age.

Keywords:

Cretaceous

Basin

Terrestrial deposits

1. Introduction

Cretaceous is considered a research model for Earth System Science (ESS) by international scholars. Many important geological events occurred during this period,including massive volcanic activity (Larson RL, 1991; Kaiho K and Saito S, 1994), oceanic anoxic events and black shale(Schlanger SQ, Jenkyns HC, 1976), oceanic red beds and oxic process (Wang CS et al., 2005; Hu XM et al., 2005),significant radiation and replacement (Leckie RM et al., 2002)of biota and so on, which may have causeed major disturbances in the epidermic system during that period (Ma et al., 2003). These geological events were mostly identified from in-depth research on ocean sediments, while research on their geological responses on land has attracted a great deal of attention in recent years. It is of vital importance to describe any change in the Cretaceous epidermic system completely and accurately as well as explore its properties and mechanisms.

During the Cretaceous age, and influenced by high global sea levels, large land exposures occurred in East Asia, and China presented the broadest distribution of terrestrial Cretaceous with the most complete horizons. For decades,extensive studies have been carried out on Cretaceous stratigraphic classification and correlation (Luo YD, Yu YW,2004; Zhang N, 2009), sedimentary environments (Jia JH,2009; Zhang H et al., 2008), biota (Zheng SL et al., 2004),paleo-geographic evolution ( Chen PJ, 1987; Wan XQ et al.,2007), and the coal accumulation and oil generation rules(Feng ZQ et al., 2010) of different terrestrial basins. A large number of important conclusions have been achieved,providing a solid foundation for subsequent Cretaceous researches.

Based on previous studies, and the latest stratigraphic correlation achievements, the spatiotemporal distribution characteristics of Cretaceous terrestrial deposits and basin filling sequences were discussed in detail. On this basis, the study preliminarily presented the Cretaceous paleogeographic outline in China, and also explored the relationship between sedimentary characteristics and tectonics as well as the climate. These comprehensive descriptions are expected to facilitate future researches.

2. Geological background

2.1. Tectonic setting

During the Jurassic-Cretaceous era (165–83 Ma), a multidirectional convergence effect occurred on the Pacific Plate, Lhasa-Cimmerian Plate and the Siberian Plate around the North China Plate, resulting in the geological characteristics dominated by intra-continental deformation and orogeny (Dong SW et al., 2007, 2009). This activity is called“Yanshanian Movement” in China, not only embuing the Cretaceous with the characteristics of a massive lithospheric extension, normal fault and intra-continental rift effect (Gilder SA et al., 1991), volcanic activities, the formation of an extensional basin (Ren JY et al., 2002; Lin W et al., 2006) and metamorphic core complex (Liu JL et al., 2005), and midlarge scale mineralization and accumulation, but also inducing a series of major geological events such as climate change and biological replacement.

During the Late Jurassic-early Early Cretaceous (165–135 Ma), Okhotsk at the northern margin of East Asia gradually closed due to the southward effect of the Siberian Plate (Yin A, Nie S, 1996; Yang Z et al., 1998), resulting in the formation of the orogenic belt a great distance from the plate margin and accompanying fold-thrust belts (Meng QR et al.,2003). The subduction of the Izanagi Plate is along the direction approximately perpendicular to the northwest,leading to the whole of East China under the extrusion environment (Okada H, 2000). As a result, the crustal lithosphere was thickening in East China, and also substantially thickening on the North China Plate. Meanwhile,the “East Plateau” formed during this period (Zhang SM et al., 2001).

During the late Early Cretaceous (135–100 Ma), the northwestward movement of the Izanagi Plate gradually changed into northward, where the border type was also transited from a subduction boundary to a transform boundary(Okada H, 2000). Moreover, the tectonic environment of Eastern China was converted from an extrusion to an extension, which resulted in the collapse and thinning of the lithosphere with North China as the center as well as craton destruction (Wu FY et al., 2008; Zhu RX et al., 2012). It was considered by Zhang Q et al. (2008) that the direct impact of the lithospheric thinning process on the shallow crust included the wide distribution of the rift basin system in East Asia as well as the development of 130–100 Ma volcanic rocks (Mao JW et al., 2003) and 135–110 Ma magmatism (Chen PJ et al.,2003) in Eastern China. The extension and thinning process during this period is regarded as the after effects of compressional orogeny. In the meantime, the strike-slip process of the Tan-Lu Fault in Eastern China resulted in a series of pull-apart basins on both sides during this period.

During the early Late Cretaceous, the Kohistan-Dras Arc collided with Lhasa Block, causing the large-scale uplift of Qinghai-Tibet areas and Northwest China. The northwestward oblique subduction took place on the Izanagi Plate, when the Kula Plate appeared on the southern Izanagi Plate. The Izanagi Plate affected the central and northern parts of Eastern China, while the southeast region was controlled by the Kula Plate and the Pacific Plate. Eastern China was exposed to the extrusion environment again. In the late period of the Late Cretaceous era, a new Pacific Plate was formed with oblique subduction towards the East Asia Continent, but the velocity was largely reduced as compared with the early Late Cretaceous.

2.2. Paleogeography

Previous paleomagnetic data showed that the North China plate, the Yangtze plate and the Korean plate formed a single block beginning in the Late Jurassic period (Gilder SA and Courtillot V, 1997). According to the paleo-geographic map developed by Wang HZ et al. (1985), it is shown that the nearly SN-trending Daxing’anling-Taihang Mountains-Huang ying Mountains and Helan Mountains-Yinshan Mountains as well as the nearly EW-trending Qiliang Mountains-Qinling-Dabie Mountains and Yinshan Mountains-Yanshan Mountains were formed in the Cretaceous period, when the Paleo-Qinghai-Tibet Plateau, Yunnan-Guizhou Plateau, West Sichuan Plateau and Kunlun Mountains already existed. The major plateaus or mountains, which have disappeared but with profound influence, are described in this study.

2.3. Paleoclimate

The global distribution map of the paleo-climate zones was restored under the use of climate sensitive sediments by Chumakov NM (1995) and Boucot AJ et al. (2013). It is shown that the Cretaceous era in China was dominated by an arid-semi-arid climatic environment, but only in the late Early Cretaceous, warm climates prevailed in the Northeastern stratum area. The same conclusions have been reached through statistics in this study.

3. Stratigraphic correlation and division

Based on previous systematical regional geological surveys and stratigraphic reappraisals, massive newlypublished biostratigraphic, isotope chronostratigraphic and magnetostratigraphic data (Cao K, 2013) were used to revise China’s Cretaceous terrestrial stratigraphic correlation scheme(Fig. 1), and division was also carried out (Fig. 2).

Fig. 1.Cretaceous terrestrial stratigraphic correlation in China (modified from Cao K, 2013). Basins code descriptionreferring to Fig. 4.

Fig. 2.Schematic diagram of the terrestrial Cretaceous stratigraphic area in China. The base map is the early Cretaceous basin distribution diagram. Basin codes correspond to Fig. 1.

Biostratigraphic, isotope chronostratigraphic, magnetostratigraphic data were used to revise the Cretaceous terrestrial stratigraphic correlation scheme of China. Biostratigraphic data including pollen (He CQ et al., 2004; Li MY et al., 2005;Li WB et al., 2001; Liang SJ et al., 2006; Li CB et al., 2007;Huang P et al., 2008; Zheng YL et al., 2005; Wan CB et al.,2004; Wu BW et al., 2007; Si SY et al., 2001b; Jiang XD et al., 2006, 2007), conchostracans (Chen PJ, 1997; Li CB et al.,2007) and charophytes (Wang QG et al., 2003; Fu JH et al.,1997; Wu JH et al., 1999; Peng WS et al., 2003; Yang JL et al., 2008). Isotope chronostratigraphic data mainly distribute in eastern China, including northeasten China (Zhang H et al.,2008; Ding RX et al., 2007; Shu P et al., 2007; Wang PJ et al.,2009), northern Hebei and western Liaoning province (Zhang H et al., 2008; Cope TC, 2003; Zhu RX et al., 2001; Wang QL, 2008; Zhang H et al., 2008), Shandong province (Ling et al., 2006; Tang et al., 2008), Anhui province (Wu HG et al.,2002; Wang QF et al., 2003; Niu ML et al., 2001; Yan J et al.,2009; Yu Y et al., 2009;Hou et al., 2010), southeastern China(Wu JH et al., 1999; Wang Y et al., 2002; Zhang JJ et al.,1999; Zhang WL et al., 2007; Luo YD et al., 2004; Li XH et al., 2011).

The distribution characteristics of terrestrial Cretaceous strata in China obviously shows as following:

(i) In the early period of the Early Cretaceous era(Berriasian-Hauterivian), a huge unconformity surface existed between the Jurassic and Cretaceous eras, and continuous strata only occurred in North Hebei-West Liaoning. The strata in this period was missing in Northeast China and North China. Meanwhile, Hauterivian the volcanic-sedimentary rock series developed in several fault basins of South China, but commonly there was a lack of Berriasian-Valanginian strata.

(ii) In the late Early Cretaceous (Barremian-Albian), the strata in this period was well developed in China and even in East Asia, shows as continuous strata.

(iii) In the early Late Cretaceous (Cenomanian-Santonian), the strata was missing in Northwest China and Northeast China (except the Songliao Basin).

(vi) In the late period of the Late Cretaceous (Campanian-Maastrichtian), deposits occurred in Northwest China and Northeast China again, while the strata was missing in the area to the east of the Ganzhou-Hangzhou Fault.

4. Basin evolution and sedimentary characteristics

4.1. Berriasian-Hauterivian

Tuchengzi Formation sedimentary rocks and Zhangjiakou Formation volcanic rocks occurred in northern Hebei and the western Liaoning basin group. Tuchengzi Formation that prevail mainly consisted of an alluvial-fan conglomerate, and shore-shallow lacustrine-fluvial sand shale, which was characterized by “reversed cutting strata”, indicating the basin was formed in the background of extrusion, which was completely consistent with the tectonic settings reflected by regional tectonic stress fields (Dong SW et al., 2009),Tiaojishan Formation volcanic rocks (Li WP et al., 2004) and the thrust nappe system developed in this period (Sun LX et al., 2007). It was speculated that the basin in this period had a certain altitude (Fig. 3).

Fig. 3.The main basin sedimentary sequence comparison chart in Cretaceous, China (with no scale, the color in the Fig.3 represents the main color of the stratum).

Zhangjiakou Formation volcanic rocks (Niu BG et al.,2004; Zhang H et al., 2008) and Shangkuli Formation (Xu MJ et al., 2011) in the western basin group were the product of basin rifting, dominated by volcanic rocks, partially mixed with local volcanic lacustrine sediments formed in the break of volcanic eruption.

Till late Hauterivian (about 135 Ma), the subduction rate and angle of the Izanagi Plate towards the NW direction were reduced (21.1 cm/y). The North Hebei-Yanshan Basin in the East of China (Niu BG et al., 2004), Zhejiang-Fujian region,the middle and lower reaches of the Yangtze River, and South Jiangxi started to transform from extrusion to extension environments, thus forming a series of fault basins with volcanic eruptions. These volcanic rocks show bi-model characteristics of rhyolite-basalt successive eruptions, proving the middle and lower reaches of the Yangtze River were converted to an extensional tectonic setting (Xie GQ et al.,2006).

Multiple large-scale sedimentary basins developed in the northwest and southwest stratigraphic areas, including the Junggar Basin, Turpan-Hami Basin, Tarim Basin, Qaidam Basin, Ordos Basin and the Sichuan-Yunnan Paleo-lacustrine Basin. These basins showed the same nature with the flexural basin (Fig. 4a). They have similar sedimentary characteristics,i.e., dominated by red sandstone and mudstone, while interlayered by greyish-white, grey-green and other particolor layers. A set of alluvial-fan conglomerate reservoirs were generally developed at the bottom with a considerable thickness and evolving to fluvial and shore-shallow lacustrine sediments upwards.

4.2. Barremian-Albian

Rift basins widely developed during this period. Due to elevation decline in the northeast stratigraphic area, the north warm wet climate zone moved southwards. However, the elevation of the Yanshan Mountains might reach 5000 m (Xia et al., 2012) during this period, limiting the southern margins warm wet climate zone. As a result, the northeast stratigraphic area was characterized by two sets of coal-bearing volcanicsedimentary sequences. Sedimentary rocks were dominated by black and yellow fan delta-shore-braided fluvial sediments with a coal bed. Dinosaur fossils were mainly distributed in rift basins of the northeast stratigraphic area, basically consistent with the distribution of coal-bearing strata.

The North China stratigraphic area was dominated by alluvial fan-fluvial–shore-shallow lacustrine sediments, and different from the northeast stratigraphic area, i.e., the coal seam was not developed. In addition, semi-deep and deep lacustrine sediments occurred in the Jiaolei Basin and Hefei Basin, which might be associated with the strike-slip activities of Tan-Lu Fault. As a result, these basins had the characteristics of a strike-slip basin and rift basin simultan eously.

The southeast stratigraphic area mainly consisted of intermont basins controlled by a fault with smaller basin areas and two sets of volcanic-sedimentary sequences. Sediments were dominated by green and grey-green alluvial fan conglomerates, sandstone, shore-shallow lacustrine sandstone and mudstone, while semi-deep and deep lacustrine stratigraphic mudstones developed in individual basins (Fig. 3).

Fig. 4.Cretaceous terrestrial sedimentary basins in China. The main faults were from Wan TF (2012). The basins were prototype basins recovered by former researchers (Li YQ et al., 2016; Feng ZQ et al., 2010). The sea boundary was concluded from the distribution of marine strata. a–Berriasian-Hauterivian; b–Barremian-Albian; c–Cenomanian-Santonian; d–Campanian-Maastrichtian Mountain: M1–Da Hinggan mountain; M2–Yinshan-Yanshan mountain; M3–Taihang mountain; M4–Qinling-Dabie mountain; M5–Huaying mountain; M6–Helan mountain; M7–Liupan mountain; M8–Qilian mountain; M9–Tianshan mountain; M10–Sulu orogenic belt. Fault: F1–Tan-Lu fault belt; F2–Altun fault; F3–Jinshajiang-Red river fault; F4–Longmen mountain fault; F5–Ganzhou-Hangzhou fault; F6–Zhenghe-Dapu fault; F7–Bangong-Nujiang Suture. Basin: BH–Bohai bay basin; BHH–North South Sea basin; BS–Baisha basin; CD–Qaidam basin; CS–Chaoshan Basin; CX–Chuxiong basin; DH–East China Sea basin; EE–Ordos basin; EL–Erlian basin; GH–Genhe basin; HF–Hefei basin; SB–Subei basin; HL–Hailaer basin; HY–Hengyang basin; JH–Jianghan basin; JL–Jiaolai basin; JQ–Jinqu basin; JY–Jiayin basin; LB–Labudalin basin; LP– Lanping-Simao basin; MH–Mohe basin; NH–South North China basin; NHH–South South Sea basin; NY–Nanyang basin; SC–Sichuan basin; SJ–Sanjiang basin; SL–Songliao basin; SW–Shiwan mountain basin; TH–Turpan-Hami basin; TL–Tarim basin; YE–Yingen-Ejinaqi basin; YM–Yuanma basin; ZG–Junggar basin; ZL–Zoulang basin.

Multiple small rift basins developed in the central-south stratigraphic area, where the basins were not mutually connected, but they were all dominated by the red alluvial fan,as well as shore-shallow lacustrine and shallow lacustrine sediments. Volcanic rocks developed at the bottom of the basins in the middle and lower reaches of the Yangtze River,characterized by the bi-model shape of the rhyolite-basalt successive eruption, validating the extensional tectonic environment in this area (Xie GQ et al., 2006).

Depression subsidence occurred to the flexural basins in the southwest and northwest stratigraphic areas successively,and mainly consisted of red alluvial fan conglomerate as well as sandstone-shore-shallow lacustrine sandstone and siltstone.Desert sediments developed in the Ordos Basin, the southern Sichuan Basin and the Tarim Basin (Jiang XS et al., 2000).The Early Cretaceous morphology and sedimentary paleogeography of the Ordos Basin were discussed in detail by Zhang H et al. (2008). It was considered that the area surrounding the Ordos Basin was dominated by alluvial fan(debris flow) conglomerate and glutenite. Meanwhile, an extensive range of desert sediments developed between the distal alluvial fan and lake, mainly comprised of aeolian sand dunes and inter-dunal sediments. In addition, the intermittent fluvial sediments and desert lacustrine sediments might be developed in certain regions (Fig. 4b).

It is necessary to point out that evidence of massive marine interlayers have been found in the rift basins of Eastern China, such as in the Sanjiang Basin (Zhu YH et al.,2003), the Jiaolai Basin (Zhang SM et al., 2001) and the Zhejiang-Fujian region (Hu G et al., 2012). Although these interlayers accounted for a small proportion in the strata,which might make important influences on the evolutionary processes of these basins, and necessitate added concerns.

4.3. Cenomanian-Santonian

Deposition occurred only in the Songliao Basin within the northeast stratigraphic area. In the period of the Quantou Formation, the Songliao Basin was transited from the rift to the depression, and mainly comprised of red meandering river sediments, where the shallow lacustrine was not developed.The delta-front sediments with a small thickness occurred at the top of the Quantou Formation, representing the late period of the Quantou Formation, when the basin began to subside(Wang GD et al., 2009). The Qingshankou Formation was a product of the first large-scale lacustrine transgression in the Songliao Basin, dominated by deep lacustrine, semi-deep lacustrine-deep lacustrine green and grey-green mudstones,and interlayered with marl, ostracod limestone and so on. Its formation might have a relation to the transgression induced by global sea level rise (Xi PD et al., 2011). Shallow lacustrine, semi-deep lacustrine and delta sediments were identified from the Yaojia Formation by Cheng RH et al.(2009). The sedimentary environment of the Yaojia Formation was basically dominated by shallow lacustrine with river inflow. Deep lacustrine mudstones developed in Member 1 of the Nenjiang Formation; Member 2 of the Nenjiang Formation was dominated by semi-deep and deep lacustrine mudstones, where the cycle consisting of silty mudstones, argillaceous siltstones and silty sandstones was developed at the top. As the second set of major source rocks,this formation was the sedimentary product of massive lacustrine transgression in the Songliao Basin (Fig. 3).

A set of red-mainly alluvial fan, fluvial and shore-shallow lacustrine sediments developed in other basins, located in North China and South China. The widely developed alluvial plains provided enough space, food and water for dinosaur living and survival, where dinosaur fossils were widely distributed.

The Sichuan Basin, Xichang Basin and Chuxiong Basin in the southwest stratigraphic area were dominated by fan delta red conglomerate, sand and mudstone as well as fluvial sand and mudstone. In the meantime, a wide range of desert sedimentary systems were developed in the southern Sichuan Basin (Jiang XS et al., 2000), dominated by the desert lacustrine sedimentary system of the Wotoushan Formation at the lower part and aeolian dune sediments in the Daerdang Formation, also suggesting the arid environment in the southern Sichuan Basin.

In the Campanian-Santonian era, a set of red alluvial fan conglomerates with a huge thickness was developed in the Zhejiang-Fujian intermont basin to the west of the Zhenghe-Dapu Fault and the eastern Jiangxi respectively. However, the western Jiangxi, Hunan, Hubei and other regions were dominated by alluvial fan-fluvial sediments. The distribution of sediments indicate the re-uplift of the east to the Zhenghe-Dapu Fault (Fig. 4c).

4.4. Campanian-Maastrichtian

In the early Campanian, the northeast stratigraphic area experienced a brief tectonic inversion. There was an obvious unconformity surface between Member 2 and Member 3 of the Nenjiang Formation, Songliao Basin, and also a significant change in the basin provenance direction (Zhao B et al., 2012). Since then, depression has occurred widely in this area, and the sediments were deposited simultaneously,dominated by red alluvial fan and fluvial sediments with the development of the alluvial plain. At the end of the sedimentary period in the Nenjiang Formation, tectonic inversion recurred in this area. With the exception of the Songliao Basin, sediments were not deposited in other regions. The Songliao Basin began to enter the shrinking period, dominated by red fluvial, shore-shallow lacustrine sandstone and mudstone. In the meantime, the Songliao Basin was a shallow basin with a gentle terrain, low structural amplitude, small allowable space and frequent lake-level fluctuation (Fig. 3) (Han JH et al., 2009).

Deposition reoccurred in the northwest stratigraphic area.A set of red fan delta, braided lacustrine, shore-shallow lacustrine sediments was mainly developed in the Tarim Basin, Junggar Basin, Turpan-Hami Basin and the Xining-Minhe Basin (Fig. 4d). It should be pointed out that marine calcareous nannofossil assemblages were found in the Kuqa area by Su X et al. (2003), proving the influence of transgression on this area in the late period of the Late Cretaceous.

The North China stratigraphic area, the central-south stratigraphic area and the southwest stratigraphic area were dominated by red alluvial fan, fluvial and shallow lacustrine sand shale. In these areas, the alluvial plain developed, and dinosaur fossils were commonly seen.

5. Discussion

5.1. Berriasian-Hauterivian

The geomorphologic pattern of “high in the east and low in the west” formed due to the uplift of the plateau-mountain system (Okada H, 2000) at the boundary of the East Asian continent. Sedimentary basins mainly developed in the northwest and southwest stratigraphic areas. Most of them show the nature of the flexural basin (Okada H, 2000). There is no volcanic activity in these basins, where red-mainly lacustrine sediments are dominant with the development of alluvial fan-fluvial-delta-shore-shallow lacustrine or fan delta and shore-shallow lacustrine sedimentary sequences. Arid and semi-arid climates (Chumakov NM, 1995; Boucot AJ et al.,2013) prevailed in the early Early Cretaceous with deposition of desert sediments (Jiang XS et al., 2008), gypsum interlayers (Xiang F et al., 2009) and calcareous concretion(Fig. 5) (Li XH et al., 2013).

5.2. Barremian-Albian

The widly distributing rift basin system on the wide plains occurred in East Asia during this period. The Yanshan Mountains, rising between the Chaobai River on the west and the Shanhai Pass on the east divide the natural features of China’s landscape into widely varying terrain, and topography. Coal-bearing deposition developed in rift basins with a wet and warm climate in the north and an arid and semi-arid climate in the south. Red-mainly lacustrine sediments with desert sediments (Jiang XS et al., 2008), gypsum interlayers(Xiang F et al., 2009) and calcareous concretion (Li XH et al.,2013) developed in northwestern and southwestern China(Fig. 6). However, green-mainly lacustrine deposition developed in rift basins in North China and southeastern China, where sea water entered intermittently (Hu G et al.,2012).

5.3. Cenomanian-Santonian

The geomorphologic pattern changed into “high in the west and low in the east” through the Cenomanian to the Santonian era. An arid and semi-arid climate (Chumakov NM,1995; Boucot AJ et al., 2013) prevailed throughout China.Red-mainly alluvial fan, fluvial and shore-shallow lacustrine sediments developed all over China except within the Songliao Basin in eastern China, where black deep lacustrine mud shale occurred due to transgression (Feng ZQ et al.,2010). An event worth noting occurred in southern China is that more gypsum interlayers occurred after the uplift of the southeastern coastal mountains (Fig. 7).

5.4. Campanian-Maastrichtian

It was similar to the Cenomanian-Santonian era in climate and deposition and three main differences were displayed(Fig. 8). Firstly, the Songliao basin tended to become a depression basin and gradually entered the shrinking period,where red-mainly fluvial deposition developed. Secondly,red-mainly fluvial deposition occurred in basins in the northwestern stratum area and the northeastern stratum area again, but within a limited sedimentary range. Thirdly, the western margin of the southeastern coastal mountains reached the Ganzhou-Hangzhou Fault and the range of basins in South China enlarged.

Fig. 5.Cretaceous sedimentary palaeogeography evolution (Berriasian-Hauterivian)

Fig. 6.Cretaceous sedimentary palaeogeography evolution (Barremian-Albian)

Fig. 7.Cretaceous sedimentary palaeogeography (Cenomanian-Santonian)

Fig. 8.Cretaceous sedimentary palaeogeography (Campanian-Maastrichtian)

6. Research prospect

In spite of our geologists’ efforts, especially from SKI and SKII wells drilled, the research on Cretaceous in China especially those in connection with the continental has made considerable progress, and the following points in connection with future study need attention.

6.1. Continuity of continental sedimentary strata

Except for the Early Cretaceous strata in the Songliao Basin and other rift basins, continuous sedimentary strata are not common. Fluvial and lacustrine facies strata represented by Cretaceous red beds might be event deposits, with different scale discontinuities. However, the recognition of such smallscale unconformities has not attracted enough attention in previous studies and has even been considered to be continuous. However, it is difficult to deepen the study of large sedimentary discontinuities which can be identified.There is no mature research precedent on the duration,formation mechanism, tectonic and climatic significance of these sedimentary discontinuities. Therefore, in order to establish a precise continental Cretaceous sedimentary stratigraphic framework, in addition to obtaining enough paleontological and chronological data, strata studies of sedimentology, mineralogy and paleontology in different basins are indispensable, and paleoclimatology research based on this is credible.

6.2. Extensive comparison of Cretaceous strata in the East Asian continental margin

Although IGCP had supported several international Cretaceous stratigraphic correlation projects, stratigraphic correlation on the continental margin of East Asia is still quite limited, and most of these studies focus on paleobiostratigraphy rather than sedimentology. China, Japan and South Korea are also the main participating countries, and the Cretaceous strata in Southeast Asia had not been systematically studied. In addition, the Mesozoic strata in the marine sedimentary basins located on the continental shelf of China have not been used as the target strata for exploration for a long time, which causes a lack of systematic stratigraphic data. The result is that the sedimentary basins in eastern China that we had seen were only basin systems at the far end of the subduction zone, and the layers closer to the subduction zone contain more information. Therefore, on the basis of speeding up the exploration of Cretaceous sedimentary basins in China marine sedimentary basins,extensive international comparative studies, the establishment of the Cretaceous stratigraphic framework on the west coast of the Pacific Ocean, the exploration of Cretaceous tectonic movement and basin evolution, and the formation of systematic source-sink models are the solutions to major geological problems of the Cretaceous.

6.3. Resource and environmental effects in Cretaceous

Besides oil and gas, sandstone-type uranium deposits,potassium salts, gypsum and other mineral resources are developed in the continental Cretaceous basins in China.What are the enrichment and formation mechanisms of these resources? What are the relationships between their formation and tectonics, sedimentation and climate change? Answering these questions will not only help to promote future mineral resource exploration, but also promote the study of continental Cretaceous in China.

7. Conclusions

Extensive data collection and stratigraphic correlation had been carried out in this artical, which show thatred-mainly fluvial and shallow lacustrine deposition developed under arid and semi-arid climate in westen China when eastern China had been occubied by “East Plateau ” through Berriasian-Hauterivian.During Barremian-Albian, coal-bearing deposition occurred to the north of Yanshan Mountain under wet and warm climate. However, red-mainly fluvial and shallow lacustrine depositions were prevailing in most of south to Yanshan Mountain except basins where seawater could enter and caused green-mainly deposition. During Cenomanian-Santonian, high land uplift in northwestern China. Red-mainly deposition with developed alluvial plains occupied southwestern China and South China when Songliao Basin was filled by black deep lacustrine mud shale caused by transgression. Red-mainly deposition under arid and semi-arid climate occupied all basins in China during Campanian-Maastrichtian.

Acknowledgment

This research was financially supported by the National Key Project for Basic Research of China (2012CB822003),the National Natural Science Foundation of China (41402105)and the Natural Science Foundation of Shandong province(ZR2014DQ003)， China Geological Survey Project(DD20160145). The revision form anonymous reviewers and Dr. Yan Yang have greatly approved this manuscript, the author would like to express sincerely thanks to them.