Different genetic types of meter-scale cyclic sequences in stratigraphic records result from episodic accumulation of strata related to Milankovitch cycles. The distinctive fabric natures of facies succession result from the sedimentation governed by different sediment sources and sedimentary dynamic conditions in different paleogeographical backgrounds, corresponding to high-frequency sea-level changes. Naturally, this is the fundamental criterion for the classification of genetic types of meter-scale cyclic sequences. The widespread development in stratigraphic records and the regular vertical stacking patterns in long-term sequences, the evolution characters of earth history and the genetic types reflected by specific fabric natures of facies successions in different paleogeographical settings, all that show meter-scale cyclic sequences are not only the elementary working units in stratigraphy and sedimentology, but also the replenishment and extension of parasequence of sequence stratigraphy. Two genetic kinds of facies succession for meter-scale cyclic sequence in neritic-facies strata of carbonate and clastic rocks, are normal grading succession mainly formed by tidal sedimentation and inverse grading succession chiefly made by wave sedimentation, and both of them constitute generally shallowing upward succession, the thickness of which ranges from several tens of centimeters to several meters. The classification of genetic types of meter-scale cyclic sequence could be made in terms of the fabric natures of facies succession, and carbonate meter-scale cyclic sequences could be divided into four types: L-M type, deep-water asymmetrical type, subtidal type and peritidal type. Clastic meter-scale cyclic sequences could be grouped into two types: tidal-dynamic type and wave-dynamic type. The boundaries of meter-scale cyclic sequences are marked by instantaneous punctuated surface formed by non-deposition resulting from high-frequency level changes, which include instantaneous exposed punctuated surface, drowned punctuated surface as well as their relative surface. The development of instantaneous punctuated surface used as the boundary of meter-scale cyclic sequence brings about the limitations of Walter's Law on the explanation of facies distribution in time and space, and reaffirm the importance of Sander's Rule on analysis of stratigraphic records. These non-continuous surface could be traced for long distance and some could be correlative within same basin range. The study of meter-scale cyclic sequences and their regularly vertical stacking patterns in long-term sequences indicate that the research into cyclicity of stratigraphic records is a useful way to get more regularity from stratigraphic records that are frequently complex as well as non-integrated.
Meter-scale cyclic sequences, similar to meter-scale cycles defined by Anderson and Goodwin (1990), refer to fundamental units of stratigraphic accumulation that could be discerned directly in outcrop. As the fundamental working units in stratigraphic records, meter-scale cyclic sequences result from punctuated-aggradational process governed by allocyclic mechanisms related to Milankovitch cycle (Mei, 1995, 1993; Schwarzacher, 1993; Osleger, 1991; Masseti et al., 1991). Used as the basic tokens of sedimentary rhythms, they are similar to microsequence (Wang and Shi, 1998), also similar to other terminology such as high-frequency sequences (Mitchum and Von Wagoner, 1991), parasequences of sequence stratigraphy (Wilgus et al, 1988) and cyclic fundamental sequences of lithostratigraphy (Wei et al, 1991). In rhythmically spectrum meter-scale cyclic sequences belong to cyclic sequences of Milankovitch band (Fischer and Bottjier, 1991). In stratigraphic records, one single meter-scale cyclic sequence could be divided into five seventh-order rhythmites occasionally, and four meter-scale cyclic sequences could be grouped into one fifth-order parasequence set, so meter-scale cyclic sequence may be defined as a sixth-order parasequence. Therefore, the seventh-order rhythmites, meter-scale cyclic sequences and fifth-order parasequence sets are correlated in origin with procession of equinox cycles, short eccentricity cycles and long eccentricity cycles, respectively. All of these natures indicate that meter-scale cyclic sequence could be used as stratigraphical elementary working units with equal time intervals (Mei et al., 1998; Schwarzacher, 1993; Goldhammer et al., 1990). The distinctive facies succession of meter-scale cyclic sequences are the results of different sedimentary sources and dynamics in different paleogeographical backgrounds in cyclic changes of sedimentary environment controlled by Milankovitch cycles, a basis for classification of the genetic types of meter-scale cyclic sequences.
GENETIC TYPES OF CARBONATE METER-SCALE CYCLIC SEQUENCE
Normal sedimentary process such as tidal-flat progradation, horizontal migration of tidal island, progradation of carbonate sand-body, vertical aggradation of subtidal sediment (reef or grain beach) and so on, could make the sediment of platform carbonate build up to sea-level or above it, resulting in formation of shallowing upward succession from subtidal to supratidal. The changing process of sedimentary environment caused by high-frequency sea-level changes could generate evident brands of sedimentation and diagenesis in carbonate rock. With the deepening of environment governed by sea-level rising, subtidal environment could be widespread in platform and the restricted tidal-flat is only limited to narrow region closed to seashore. On the contrary, the shallowing process of sedimentary environment resulting from sea-level falling could lead to carbonate platform that has turned shallow or exposed over water surface, which may generate particular sediments and sedimentation such as evaporate precipitation of sebkha in arid climate, calcretes and vadose pesolits formed by soil formation in semiarid climate, karstification generated in humid climate. The sensitive response of carbonate sedimentation to high-frequency sea-level changes is to generate the regular shallowing upward succession, a general character of meter-scale cyclic sequence. Many geologists are very interested in the study of carbonate meter-scale cyclic sequence, for example, the systematic depiction of L-M carbonate couplets by Einsele and Seilacher (1982), the study of peritidal carbonate cycles by Read (1985), the comprehensive research into subtidal carbonate cycles by Osleger (1991), the overall introduction of deep-water asymmetrical carbonate cycles by Masetti et al. (1991), all of which are the bases that group carbonate meter-scale cyclic sequences into four genetic types (Fig. 1, Mei, 1995, 1993).
Figure
1.
Genetic types of carbonate meter-scale cyclic sequences and their changing spectrum of sedimentary environment ramp platform (A), rimmed-shelf platform (B). 1. thin-bedded dolostone; 2. grain micrite; 3. grain limestone; 4. bioclastic limestone; 5. micrites with burrow; 6. marl; 7. low-stand breccias. (1). sea-level; (2). normal wave base; (3). storm wave base. a. peritidal type of carbonate meter-scale cyclic sequence; b. subtidal type; c. deep-water asymmetrical type; d. L-M type.
The first type is called L-M type composed of marl and limestone, whose denomination is made by selection the head characters of limestone and marl. This type mainly develops in deep-water setting, characteristic of inverse grading succession of marl-limestone (c of Fig. 1).
The second type is called deep-water asymmetrical type (d1 and d2 of Fig. 1), chiefly developing in margin and slope setting of rimmed-shelf carbonate platform, whose facies-succession fabric is similar to that of L-M type, with the distinctive low-stand breccia caps frequently developed on top of this type of meter-scale cyclic sequence.
The third type refers to subtidal type, characterized by upward shallowing of sedimentary environment, upward coursing of depositional grains and upward thickening of rock beds (b1, b2 and b3 of Fig. 1). This type of carbonate meter-scale cyclic sequences mainly in subtidal neritic environment whose boundaries are marked by instantaneous drowned punctuated surface. Peritidal type of carbonate meter-scale cyclic sequences belongs to the fourth type (al, a2 and a3 of Fig. 1), which principally developed in interior part of carbonate platform, marked by tidal sedimentation. The essential natures of this type include upward shallowing of sedimentary environment; upward thinning of rock beds and upward fining of sedimentary grains, making up an inverse grading succession. The top of this type frequently developed on the tidal flat dolostones, karst breccias, paleosoil beds etc., indicating that its boundaries belong to instantaneous exposed punctuated surface.
According to facies-succession fabric natures, carbonate meter-scale cyclic sequences could be generally grouped into two types, one type constituted by inverse grading succession (including L-M type, deep-water asymmetrical type and subtidal type) developed on instantaneous drowned punctuated surface, the other type is characteristic of normal grading succession peritidal type developed on instantaneous exposed punctuated surface. The former occurs in depositional background near normal wave base and in deeper environment, where deepening effect of environment is caused by high-frequency sea-level rise including the generation of instantaneous inundated event and the deposition of pelagic or semipelagic sediments. The normal neritic sediments deposited in shallowing process of sedimentary environment governed by high-frequency sea-level fall. Consequently, the inverse grading succession is produced. The latter occurs principally in neritic settings above normal wave base. The normal neritic sediments deposited in deepening process of sedimentary environment corresponding to high-frequency sea-level rising and to restricted tidal-flat sediments. The similar materials deposited in shallowing process of sedimentary environment resulting from high-frequency sea-level fall, ultimately resulting in the normal grading succession. The peritidal type of carbonate meter-scale cyclic sequences is characterized by normal grading succession, on the top of which many exposed marks constitute a special cap that indicates boundary of exposed punctuated surface, including the dolomitization and karstification in humid climate, dolostones produced by infiltration-reflux dolomitization and gypsum-salt caps in arid climate, and the paleosoil beds in both type climates. In shallower environment such as the interior of epicontinental carbonate platform, develop the meter-scale cyclic sequences belonging to peritidal type composed of special succession of "open platform facies, grain micrites-tidal flat dolostones-lagoon facies, gypsum and salts". For example, those developed in Ordovician Majiagou Formation in North China could represent this type.
There is a regular vertical stacking pattern of carbonate meter-scale cyclic sequences in long-term sequence, in long-term sea-level rise, meter-scale cyclic sequences constitute a succession of obvious drowned beats or nonobvious exposed beats, with those superimposed in long-term sea-level fall making up a succession marked by evident exposed beats or nonobvious drowned beats. For example, four third-order sequences discerned in late Cambrian of the northern part of North China (Fig. 2) are composed of the regular vertical stacking patterns of carbonate meter-scale cyclic sequences, i. e., the L-M type at the bottom and subtidal type do in upper part of third-order sequences, representing the stacking patterns of drowned beats from obvious to nonobvious and from the bottom to the top. A lot of research results, such as the study of Triassic cyclicity in Europe by Goldhammer et al. (1990) and that of Cambrian and Ordovician in North America by Osleger and Read (1991), show the similar pattern.
Figure
2.
Regular vertical stacking patterns of carbonate meter-scale cyclic sequences in long-term sequences, an example from late Cambrian in North China. 1 to 4 represent four third-order sequences. DR refers to deep ramp; MR means middle ramp; SR indicates shallow ramp; TF express tidal flat. It could be pay attention to that the biostratigraphic stage boundaries are always lagged to those of environment changing represented by sequence boundaries of third-order sequences, exampled from the Xishan Section of Beijing. (1). oolitic limestone; (2). bioherm limestone; (3). limestone with burrows and bioturbites; (4). storm calcirudites; (5). muddy micrites; (6). micrites with storm rhythms; (7). marls. G expresses the strata that develop glauconites.
GENETIC TYPES OF CLASTIC METER-SCALE CYCLIC SEQUENCE
According to the fabric natures of facies succession, two types of clastic meter-scale cyclic sequences are discerned in terrigeneous clastic strata, of both the tidal dynamic type and the wave dynamic type. Similar to carbonate meter-scale cyclic sequences, they are the products of autocyclic sedimentation controlled by allocyclic mechanisms.
As shown in (A) of Fig. 3, several lithofacies units chiefly develop in terrigeneous clastic rocks of tidal dynamic background.
Figure
3.
Genetic types of clastic meter-scale cyclic sequence. (A) refers to tidal dynamic type; (B) represents wave dynamic type. Lithofacies units are indicated by a, b, c and d respectively, more detail description could be seen in the text. 1. mud crack; 2. ripple mark; 3. wave tidal bedding; 4. leuticular tidal bedding; 5. vein tidal bedding; 6. cross bedding; 7. scouring surfaces; 8. sandy shale; 9. muddy sandstone; 10. sandstone; 11. Skolithus; 12. horizontal laminae; 13. storm shell coacervates; 14. calcareous muddy shale.
a. Subtidal high-energy sandstone characteristic of the development of large-size cross beddings and scouring surfaces with a high maturity of content and texture belong to the deposits of high-energy upheaval neritic environment.
b. Subtidal flat sandstone with cross bedding and vein tid-HJal bedding.
c. Intertidal flat muddy sandstone with wave tidal beddings, wave cross bedding and ripple marks.
d. Supratidal flat sandy shales with lenticular tidal beddings, mud cracks and horizontal laminae.
Many kinds of clastic meter-scale cyclic sequences belong to tidal dynamic type superimposed by these lithofacies units with elementary natures including the upward shallowing of sedimentary environment, upward thinning of rock beds, upward finning of sedimentary grains, their boundaries are marked by instantaneous exposed punctuated surface and its relative surface. In stratigraphic records, the meter-scale cyclic sequences constituted by integrated lithofacies succession such as the succession of "babcd" shown in (A) of Fig. 3 are very seldom, but those composed of two to three units as "ab, abe, ac, be, bcd, bd, cd" as shown in (A) of Fig. 3 are common.
In neritic environment mainly marked by wave sedimentation, chiefly develop following lithofacies ((B) of Fig. 3).
a. Shelf facies muddy shales with horizontal laminae and storm shell coacervates.
b. Distal shoreface-facies sandy mudstones with rare cross bedding and horizontal laminae, which are the products of weak turbulent environment near wave base.
c. Near shoreface-facies muddy sandstone with wave cross bedding and ripple marks, which is formed in secondary turbulent environment above the storm wave base and under the normal wave base.
d. Shoreface-facies sandstone with cross beddings, scouring surface and trace fossils such as Skolithus etc., which deposited in turbulent neritic environment.
Meter-scale cyclic sequences of wave dynamic type are orderly stacked by these lithofacies units. Their general characters include the upward shallowing of sedimentary environment, the upward thickening of rock beds and the upward coarsening of sedimentary grains. Their boundaries are marked by instantaneous drowned punctuated surface. Tidal dynamic type of meter-scale cyclic sequence is characteristic of normal grading succession, as the wave type is marked by inverse grading succession (Arnott, 1995). Meter-scale cyclic sequences of the wave dynamic type constituting by intact succession such as "abcd", as shown in (B) of Fig. 3 are seldom, the common are those composed of two to three lithofacies units.
The regular vertical stacking patterns of clastic meter-scale cyclic sequences in long-term sequences include several forms as follow.
The first form, third-order sequence, is constituted by tidal dynamic types as well as wave dynamic types. The wave dynamic types are chiefly superimposed in rising period of third-order sea-level changes, but the tidal dynamic types mainly developed in third-order sea-level falling period. Therefore occurs the succession of drowned beats in lower part and exposed beats in upper part of third-order sequence.
The second form, third-order sequence, is composed of wave dynamic types. In the rising period of third-order sea-level cycle, the superimposed lower part units (shelf shales) of meter-scale cyclic sequence are thicker. In the falling period of third-order sea-level changes the upper part unit (shoreface-facies sandstone) of meter-scale cyclic sequences is thicker, which constitutes the succession of third-order sequences marked by more nonobvious features of drowned beats from the bottom to the top.
The third form refers to the tidal dynamic types of clastic meter-scale cyclic sequences constituting the third-order sequence. Subtidal high-energy sandstone and subtidal flat sandstone of meter-scale cyclic sequences developing in the rising period of third-order sea-level cycles are thicker. In third-order falling period of sea-level changes, the supratidal sandy shale units of meter-scale cyclic sequences are thicker, consequently, constituting the particular succession of third-order sequence where the exposed beats become more and more evident from the bottom to top.
In the middle Proterozoic Dahongyu Formation of the Xinglong County, Hebei Province, three third-order sequences constituting meter-scale cyclic sequences in the tidal dynamic type could be discerned (Fig. 4). Thicker subtidal high-energy sandstones of clastic meter-scale cyclic sequences occurs in the rising period of third-order sea level cycles and thicker supratidal sandy shales deposited in the falling period of third-order sea-level changes, indicating that the successions of third-order sequences are characterized by the exposed beats more and more evident from the bottom to the top, a typical example of the third form described in foregoing context. Such examples like the Dahongyu Formation are too many to enumerate.
Figure
4.
Regular vertical stacking patterns of meter-scale cyclic sequences belong to the dynamic type in third-order sequences, an example from the middle Proterozoic Dahongyu Formation in Xinglong County of Hebei Province. The lithologic marks are same to Fig. 3. (1). supratidal flat; (2). intertidal flat; (3). subtidal flat; (4). high-energy subtidal zone. The curve refers to that of paleodepth changes.
GENETIC TYPES OF METER-SCALE CYCLIC SEQUENCES CONSTITUTED BY ALTERNATING LAYERS OF CLASTIC AND CARBONATE ROCKS
It is difficult to discern the meter-scale cyclic sequences in strata of alternating layers of clastic and carbonate rocks, which is caused by the difficult determination of stacking relation between lithofacies units. Actually, two types could be formed in response to the changing process of sedimentary environment governed by high-frequency sea-level cycles (Fig. 5), a product of different injection mechanisms of clastic sediments into depositional area from terrigenous formed by different dynamic conditions.
Figure
5.
Types of meter-scale cyclic sequences constituted by the alternating layers of clastic and carbonate rocks. (A) represents the type of clastic-carbonate succession; (B) expresses the type of carbonate-clastic succession. (1) to (4) indicate the single meter-scale cyclic sequence. 1. limestone; 2. dolostone; 3. muddy sandstone; 4. bioclastics; 5. glauconites.
The first type is characterized by the succession of "clastic rocks-carbonate rocks". The lower part unit constituted by clastic rocks generated by the injection mechanism of clastic sediments resulted from the reflux of wave and tide as well as storm current to depositional area from terrigenous in the rising period of high-frequency sea-level changes. In falling period of high-frequency sea-level cycles, the coast line is shrunk back to sea from terrigenous and the clastic sediments injected to depositional area is reduced, so sedimentary environment become clean. In the end, the upper part unit composed of carbonate rocks is formed ((A) of Fig. 5).
The second type consists of the succession of "carbonate rocks-clastic rocks". In the deepening process of sedimentary environment, a response to the rising of high-frequency sea-level cycles, the strength of river sedimentation becomes weak and sedimentary environment becomes clean, so the lower carbonate rock units of meter-scale cyclic sequences are formed, which is the result of the decreasing of clastic sediments injected into deposition area transported by river current. In the shallowing process of sedimentary environment generated by the fall of high-frequency sea-level changes, the strength of river sedimentation becomes strong and the sedimentary environment becomes muddy. It was caused by the increase of clastic sediments injected into depositional area transported by river current. Consequently, the upper clastic rock units of meter-scale cyclic sequences deposited ((B) of Fig. 5).
In meter-scale cyclic sequences of clastic-carbonate succession, the lower clastic rock units often contain glauconites and the upper carbonate rock units are frequently dolomitized. In those of carbonate-clastic succession, more shallowing marks such as mudcracks develop in the upper clastic rock units, and more bioclastics or shells and other grains in lower carbonate rock units.
EARTH-HISTORY EVOLUTIONARY NATURE OF METER-SCALE CYCLIC SEQUENCES AND THEIR CHRONOS-TRATIGRAPHICAL MEANINGS
Since 1895 of Gilbert's time, many geologists have made fruitful researches into the cyclicity of stratigraphic records. The regular alternation indicated by various types of meter-scale cyclic sequences are the products of autocyclic sedimentation that is genetically related to high-frequency cycles governed by orbital force, which progressively become the common understandings (Mei et al., 1997; Schwarzacher, 1993; Fischer and Bottjier, 1991; Osleger and Read, 1991). In earth-history period of ice-house such as Carboniferous and Sinian, high-frequency sea-level changes of glacial type governed by orbital force are marked by fast velocity and large scope resulted from the development of polar glacial sheets, so occur meter-scale cyclic sequences characteristic of the abrupt facies-changes and the discontinue facies zones. Meter-scale cyclic sequences developing in the lower part of the Carboniferous Benxi Formation is in the southern Liaoning Province and Sinian Dengying Formation in the Three Gorge region of the Yangtze River could represent their elementary natures in icehouse period (Fig. 6).
Figure
6.
Fancies-succession natures of meter-scale cyclic sequences developed in icehouse period of earth history. (A) represents meter-scale cyclic sequences developed in Carboniferous Benxi Formation of southern Liaoning Province; (B) expresses those developed in Sinian Dengying Formation in the Three Gorges of the Yangtze River. 1. karst breccias; 2. ferruginous residues belong to laterite type; 3. pasammitic-bioclastic limestone; 4. stromatolitic and algal clastic dolostone; 5. grain-bearing lime-dolostones; 6. boundaries of meter-scale cyclic sequences; 7. curve of relative sea-level change.
In greenhouse period of earth history, high-frequency sea-level changes characterized by the small scope and the slow velocity resulted in meter-scale cyclic sequences marked by the changing continuity of facies zones. Those developing in the Ordovician Majiagou Formation and middle Proterozoic Wumi-shan Formation in North China platform could express the fundamental characters (Fig. 7).
Figure
7.
Facies-succession fabric of meter-scale cyclic sequences developed in greenhouse period of earth history. (A) represents meter-scale cyclic sequences developed in Ordovician Majiagou Formation of North China; (B) expresses those developed in Wumishan Formation of middle Proterozoic in North China. l. evaporite-solution breccias; 2. rock salt; 3. micritic dolostone; 4. chert micritic dolostone; 5. dolomitic parkstone; 6. packstone; 7. paleosoil layer; 8. dolomitic mudstone; 9. muddy dolostone; 10. silicated stromatolitic dolostone; 11. stromatolitic bioherms and biostrome; 12. boundaries of meter-scale cyclic sequences; 13. relative sea-level changes.
In stratigraphical records, three to five orderly stacked meter-scale cyclic sequences may form one fifth-order parasequence set universally. Occasionally, five seventh-order rhythmites are also recognized in some single meter-scale cyclic sequence. Therefore, the seventh-order rhythmites, meter-scale cyclic sequences and the fifth-order parasequence sets are correlated in origin with precession of equinox cycles, short eccentricity cycles and long eccentricity cycles, respectively. These regularly vertical stacking patterns, imagnery, are called the natures of the Milankovitch cycles in stratigraphic records (Schwarzacher, 1993; Goldhammer et al., 1990), which become a tool to estimate the absolute time limit of strata accumulation. For example, sixty to eighty meter-scale cyclic sequences of carbonate subtidal type and L-M type are discerned in the Cambrian Zhangxia Formation of North China (Mei et al., 1997, 1994), their orderly stacking relation of 1∶4 shows the formation of time-limit of single meter-scale cyclic sequence is about 0.1 Ma, genetically related to short eccentricity cycles. This further indicates the time-span of Zhangxia Formation is from 6 Ma to 8 Ma. The chronostratigraphical meanings of the meter-scale cyclic sequences provide a useful way to estimate the absolute time limits of strata accumulation, a hot spot of cyclostratigraphy today (Mei and Mei. 1997).
CONCLUSlON
As the basic working units of stratigraphy and sedimentology, meter-scale cyclic-sequences are constituted by orderly vertical stacking patterns of lithofacies and may be used as the tokens to describe the cyclicity related to high-frequency sea-level cycles governed by the orbital elements of our planet. It is important to make a reasonable classification of genetical types of meter-scale cyclic sequences in terms of the fabric natures of lithofacies succession. Directed at the complexity and non-integrity of stratigraphic records, the study of cyclicity indicated by meter-scale cyclic sequences and their regular vertical stacking patterns in long-term sequences could provide a useful way to get more regularity. The regularity of cyclicity expressed by meter-scale cyclic sequences includes three categories: sequence of rock types, thickness of the cycle and finally time interval represented by the cycle. Many best features of meter-scale cyclic sequences such as the regular vertical stacking patterns in long-term sequence, the fabric natures of lithofacies, the chronostratigraphical meanings, the sophisticate but regular forming mechanism and so on, all show that meter-scale cyclic sequences are not only equal to parasequence of sequence stratigraphy but is the extension and the replenish of parasequence.
Anderson E J, Goodwin P W, 1990. The Significance of Meter Scale Allocycles in the Quest for a Fundamental Stratigraphic Unit. Journal of Geological Society, 147: 507-518 doi: 10.1144/gsjgs.147.3.0507
Arnott R W C, 1995. The Parasequence Definition is Transgressive Deposit Inadequately Addressed? Journal of Sedimentary Research, 55 (1): 1-6
Einsele G, Seilacher A, 1982. Cyclic and Event Stratificalion. Springen Verlag. 1-306
Fischer A G, Bottjier D J, 1991. Orbital Forcing and Sedimentary Sequences. Journal of Sedimentary Petrology, 61 (7): 1063-1069
Goldhammer R K, Dunn P A, Hardie L A, 1990. Depositional Cycles, Composite Sea-Level Changes, and Cycle Stacking Patterns of the Hierarchy of Stratigraphie Forcing: Examples from Alpine Triassic Platform Carbonates. Geo Soc Am Bull, 102 (5): 535-562 doi: 10.1130/0016-7606(1990)102<0535:DCCSLC>2.3.CO;2
Masetti D, Nero C, Bosllinni A, 1991. Deep-Water Asymmetrical Cycles and Progradation of Arbonate Platform Governed by High Frequency Osillations (Triassic of the Dolomites, Italy). Geology, 19: 336-339
Mei M, 1993. Genetic Types and Mechanisms of the Carbonate Rock Meter Scale Cyclic Sequences. Lithofacies and Paleogeography, 13 (6): 34-43 (in Chinese with English Abstract)
Mei M, 1995. Carbonate Cycles and Sequences. Guiyang: Guizhou Science and Technology Press. 1-227 (in Chinese)
Mei M, Luo G, Su D, 1994. Carbonate Allogenic Cyelic Sequence of Composite Sea-Level Change-Example from the Zhangxia Formation of Middle Cambrian in Western Hill of Beijing. Journal of Guilin College of Geology, 14 (2): 145-153 (in Chinese with English Abstract)
Mei M, Ma Y, Zhou P, et al, 1988. Introduction of Carbonate Sedimentology. Beijing: Seismic Publishing House. 1-306 (in Chinese)
Mei M, Ma Y, Mei S, et al, 1997. Frame work of Cambrian Sedimentary Sequence and Evolution of Carbonate Platform in Nort h-China. Geosciences, 11 (3): 275-282 (in Chinese with English Abstract)
Mei M, Mei S, 1997. Cyclic-Sequence of Composite Sea Level Change Developed in Zhangxia Formation of Middle-Cambrian in North-China. Acta Sedimentologica Sinica, 15 (4): 5-10 (in Chinese with English Abstract)
Mitchum R M, Van Wagoner J C, 1991. High Frequency Sequences and Their Stacking Pattern: Sequence Stratigraphic Evidence of High Frequency Eustatic Cycles. Sedimentary Geology, 70: 131-160.
Osleger D A, 1991. Subtidal Carbonate Cycles: Implications for Allocyclic Versus Autocyelie Controls. Geology, 19: 917-920
Osleger D A, Read J F, 1991. Relation of Ecstasy and Stacking Patterns of Meter Scale Carbonate Cycles, Late Cambrian. USA Journal of Sedimentary Petrology, 61: 1225-1252
Read J F, 1985. Carbonate Platform Facies Models. Am Assoc Petro Geo Bull, 69: 1-21
Schwarzacher W, 1993. Cyelostratigraphy and the Milankovitch Theory. Amsterdam: Elsiver. 1-255
Wang H, Shi X, 1998. Hierarchy of Depositional Sequences and Eustastic Cycles-Discussion on the Mechanism of Sedimentary Cycles. Geosciences, 12 (1): 1-16 (in Chinese with English Abstract)
Wei J, Lu C, Xu H, et al, 1991. A Guide to the Method of the 1: 50 000 Regional Geological Survey in Sedimentary Rock Areas. Wuhan: China U niversity of Geosciences Press. 1-158 (in Chinese)
Vail P R, Mitchuxn R M, Thompson I S, 1997. Seismic Stratigraphy and Global Changes of Sea Level, Part 3: Relative Changes of Sea Level from Coastal Onlap. In: Payton C E, ed. Seismic Stratigraphy-Applications to Hydrocarbon Ex ploration. AAPG Memoir, 26: 63-97
Wilgus C K, Hasting B S, Kedall C G S T, et al, 1988. Sea-Level Change: An Integrated Approach. SEP M Special Publication, 42: 1-288
Figure 1. Genetic types of carbonate meter-scale cyclic sequences and their changing spectrum of sedimentary environment ramp platform (A), rimmed-shelf platform (B). 1. thin-bedded dolostone; 2. grain micrite; 3. grain limestone; 4. bioclastic limestone; 5. micrites with burrow; 6. marl; 7. low-stand breccias. (1). sea-level; (2). normal wave base; (3). storm wave base. a. peritidal type of carbonate meter-scale cyclic sequence; b. subtidal type; c. deep-water asymmetrical type; d. L-M type.
Figure 2. Regular vertical stacking patterns of carbonate meter-scale cyclic sequences in long-term sequences, an example from late Cambrian in North China. 1 to 4 represent four third-order sequences. DR refers to deep ramp; MR means middle ramp; SR indicates shallow ramp; TF express tidal flat. It could be pay attention to that the biostratigraphic stage boundaries are always lagged to those of environment changing represented by sequence boundaries of third-order sequences, exampled from the Xishan Section of Beijing. (1). oolitic limestone; (2). bioherm limestone; (3). limestone with burrows and bioturbites; (4). storm calcirudites; (5). muddy micrites; (6). micrites with storm rhythms; (7). marls. G expresses the strata that develop glauconites.
Figure 3. Genetic types of clastic meter-scale cyclic sequence. (A) refers to tidal dynamic type; (B) represents wave dynamic type. Lithofacies units are indicated by a, b, c and d respectively, more detail description could be seen in the text. 1. mud crack; 2. ripple mark; 3. wave tidal bedding; 4. leuticular tidal bedding; 5. vein tidal bedding; 6. cross bedding; 7. scouring surfaces; 8. sandy shale; 9. muddy sandstone; 10. sandstone; 11. Skolithus; 12. horizontal laminae; 13. storm shell coacervates; 14. calcareous muddy shale.
Figure 4. Regular vertical stacking patterns of meter-scale cyclic sequences belong to the dynamic type in third-order sequences, an example from the middle Proterozoic Dahongyu Formation in Xinglong County of Hebei Province. The lithologic marks are same to Fig. 3. (1). supratidal flat; (2). intertidal flat; (3). subtidal flat; (4). high-energy subtidal zone. The curve refers to that of paleodepth changes.
Figure 5. Types of meter-scale cyclic sequences constituted by the alternating layers of clastic and carbonate rocks. (A) represents the type of clastic-carbonate succession; (B) expresses the type of carbonate-clastic succession. (1) to (4) indicate the single meter-scale cyclic sequence. 1. limestone; 2. dolostone; 3. muddy sandstone; 4. bioclastics; 5. glauconites.
Figure 6. Fancies-succession natures of meter-scale cyclic sequences developed in icehouse period of earth history. (A) represents meter-scale cyclic sequences developed in Carboniferous Benxi Formation of southern Liaoning Province; (B) expresses those developed in Sinian Dengying Formation in the Three Gorges of the Yangtze River. 1. karst breccias; 2. ferruginous residues belong to laterite type; 3. pasammitic-bioclastic limestone; 4. stromatolitic and algal clastic dolostone; 5. grain-bearing lime-dolostones; 6. boundaries of meter-scale cyclic sequences; 7. curve of relative sea-level change.
Figure 7. Facies-succession fabric of meter-scale cyclic sequences developed in greenhouse period of earth history. (A) represents meter-scale cyclic sequences developed in Ordovician Majiagou Formation of North China; (B) expresses those developed in Wumishan Formation of middle Proterozoic in North China. l. evaporite-solution breccias; 2. rock salt; 3. micritic dolostone; 4. chert micritic dolostone; 5. dolomitic parkstone; 6. packstone; 7. paleosoil layer; 8. dolomitic mudstone; 9. muddy dolostone; 10. silicated stromatolitic dolostone; 11. stromatolitic bioherms and biostrome; 12. boundaries of meter-scale cyclic sequences; 13. relative sea-level changes.
DownLoad:
DownLoad:
