1 Introduction
2 Geological setting
3 Methods
3.1 Materials
3.2 Research methods
![](https://academic.hep.com.cn//article\2021\2095-0195/2095-0195-15-4-909/thumbnail/fes-21932-ct-fig3.jpg)
Fig.3 Pollen panel of the Shahejie Formation in the Chezhen Depression. Ang. = Angiospermae, Gym. = Gymnospermae, Lil. = Liliacidites, Che. = Chenopodiaceae, Tro. = Trochodendraceae, Rut. = Rutaceae, Nys. = Nyssapollenites, Pel. = Peltandripites, Lam. = Lamiaceae, Sap. = Sapindaceaepiles, Fag. = Faguspollenites, Rho. = Rhoipites, Mel. = Meliaceae, Mag. = Magnolipollis, Hyd. = Hydrocharitaceae, Liq. = Liquidambarpollenites, Ulm. = Ulmipollenites, Que. = Quercoidites, Cor. = Corylus, Bet. = Betulaceae, Aln. = Alnipollenites, Bets. = Betulaepollenites, Jug. = Juglanspollenites, Sal. = Salixipollenites, Car. = Caryapollenites, Pla. = Platycaryapollenites, Tax. = Taxodiaceae, Eph. = Ephedripites, Tsu. = Tsugaepollenites, Abi. = Abies, A.P. = Abietineaepollenites and Pinuspollenites, Ced. = Cedripites, Pic. = Picea, Pin. = Pinaceae, Pod. = Podocarpidites, Pol. = Polypodiaceae. |
Tab.1 Climatic parameters of the nearest living relatives of the studied pollen |
Fossil Spore-pollen | nearest living relative | MAT/℃ | CMT/℃ | WMT/℃ | MAP/ mm | WMP/ mm | DMP/ mm |
---|---|---|---|---|---|---|---|
Liquidambarpollenites | Liquidambar | 11.5‒24.6 | -1‒23.8 | 23‒29.3 | 619‒1823 | 109‒340 | 2‒72 |
Lamiaceae | Elsholtzia | 2.2‒15.1 | -16.1‒2.0 | 18.6‒28.0 | 332‒1164 | 215‒488 | 8‒53 |
Meliaceae | Melia | 2.9‒24.8 | -8.6‒20.1 | 10.6‒30.1 | 465‒2993 | 251‒1428 | 10‒547 |
Ulmipollenites | Ulmus | -5.8‒21.6 | -29.8‒13.2 | 8.3‒29.4 | 21‒1770 | 15‒959 | 0‒228 |
Quercoidites | Quercus | 0‒27 | -22.7‒25.9 | 13.7‒28.3 | 201‒3905 | 33‒610 | 5‒180 |
Corylus | Corylus | -4.9‒24 | -32.4‒16.7 | 12.9‒29.4 | 389‒1682 | 45‒343 | 3‒73 |
Juglanspollenites | Juglandaceae | 0‒27.5 | -22.7‒25 | 13.7‒31.2 | 210‒2617 | 44‒582 | 1‒114 |
Rhoipites | Anacardiaceae | 3.4‒27.7 | -12.9‒27 | 18.7‒28.1 | 130‒3151 | 17‒389 | 0‒165 |
Alnipollenites | Alnus | -13.3‒27.4 | -40.9‒25.6 | 12‒38.6 | 41‒2559 | 8‒353 | 0‒135 |
Taxodiaceae | Cunninghamia | 2.0‒24.7 | -7.2‒19.8 | 9.9‒30.1 | 626‒2435 | 299‒1428 | 15‒259 |
Ephedripites | Ephedraceae | 8.1‒27.6 | -0.1‒25 | 12.5‒33.7 | 30‒1741 | 5‒262 | 1‒48 |
Abietineaepollenites | Pinus | -9.2‒25.5 | -36.8‒21.4 | 7.1‒32.9 | 180‒1741 | 28‒293 | 0‒94 |
Pinuspollenites | Pinus | -9.2‒25.5 | -36.8‒21.4 | 7.1‒32.9 | 180‒1741 | 28‒293 | 0‒94 |
Piceapollis | Picea | -8.9‒21.7 | -28.6‒15.6 | 13.8‒31.6 | 235‒1958 | 36‒323 | 8‒83 |
Podocarpidites | Podocarpus | 11‒27.7 | 1.7‒27 | 15.1‒28.8 | 652‒3151 | 68‒448 | 16‒165 |
Betulaceoipollenites | Betula | -12.4‒25.8 | -26.8‒21.1 | 3.9‒28.7 | 110‒2559 | 23‒353 | 3‒135 |
3.2.1 Pollen climate analysis
Tab.2 Quantitative classification of the climate indicator significance of pollen. The subscript med represents the median of the interval |
Climate Indicator Type | Division Basis | Description | Fossil Pollen |
---|---|---|---|
Hot Climate Group | MATmed>15℃, CMTmed>5℃ | Pollen parent plants are mainly distributed in tropical and subtropical regions, and a few can reach warm temperate zones. | Liquidambarpollenites, Ephedripites, Podocarpidites, Rhoipites |
Warm Climate Group | 10℃<MATmed<15℃, 0℃<CMTmed<5℃ | Pollen parent plants are mainly distributed in warm temperatures, and a few can reach cold temperate or subtropical zones. | Quercoidites, Ulmipollenites, Juglanspollenites |
Cold Climate Group | MATmed<10℃, CMTmed<0℃ | Pollen parent plants are widely distributed in the cold temperate zone, warm temperate zone, subtropical and even tropical zone. Compared with the heat-loving group and the temperature-loving group, its cold tolerance is generally stronger and can be adapted to harsh environments. | Corylus, Alnipollenites, Piceapollis, Pinuspollenites, Abietineaepollenites, Betulaceoipollenites |
Xerophytic Group | MAPmed<1200 mm, DMPmed<100 mm | Pollen parent plants are adapted to arid and water-deficient terrestrial environments, such as deserts or dry grasslands with sparse rainfall, with strong drought tolerance, well-developed root systems, and small and thick leaves. | Piceapollis, Alnipollenites, Pinuspollenites, Abietineaepollenites, Ephedripites |
Wet Group | MAPmed>1200 mm, WMPmed>200 mm | Pollen parent plants are wet, marsh, or aquatic plants. | Liquidambarpollenites, Quercoidites, Juglanspollenites, Rhoipites, Podocarpidites |
![](https://academic.hep.com.cn//article\2021\2095-0195/2095-0195-15-4-909/thumbnail/fes-21932-ct-fig4.jpg)
Fig.4 (a) Percentage of each group of temperature indicators; (b) percentage of each group of humidity indicators; T: evolution of the temperature of the Shahejie Formation in the Chezhen Depression; H: evolution of the humidity of the Shahejie Formation in the Chezhen Depression. |
3.2.2 Coexistence analysis
![](https://academic.hep.com.cn//article\2021\2095-0195/2095-0195-15-4-909/thumbnail/fes-21932-ct-fig5.jpg)
Fig.5 Ten zones based on 12 pollen taxa in the Shahejie Formation in the Chezhen Depression. Ang. = Angiospermae, Gym. = Gymnospermae, Liq. = Liquidambarpollenites, Lam. = Lamiaceae, Mel. = Meliaceae, Ulm. = Ulmipollenites, Que. = Quercoidites, Cor. = Corylus, Jug. = Juglanspollenites, Aln. = Alnipollenites, Tax. = Taxodiaceae, Eph. = Ephedripites, A.P. = Abietineaepollenites and Pinuspollenites. |
![](https://academic.hep.com.cn//article\2021\2095-0195/2095-0195-15-4-909/thumbnail/fes-21932-ct-fig6.jpg)
Fig.6 The principle of climatic parameter restoration in the R1 zone. The orange area is the coexistence interval of the reference pollen climate parameters. (a) Coexistence interval determination of the MAT; (b) coexistence interval determination of the CMT; (c) coexistence interval determination of the WMT; (d) coexistence interval determination of the MAP; (e) coexistence interval determination of the WMP; (f) coexistence interval determination of the DMP. Li. = Liquidambarpollenites, La. = Lamiaceae, Ul. = Ulmipollenites, Qu. = Quercoidites, Co. = Corylus, Ju. = Juglanspollenites, A.P. = Abietineaepollenites and Pinuspollenites. |
Tab.3 Climatic parameters for each pollen zone and the entire Shahejie Formation |
Zone | MAT/℃ | CMT/℃ | WMT/℃ | MAP/mm | WMP/mm | LMP/mm |
---|---|---|---|---|---|---|
R1 | 11.5‒15.1 | -1‒2 | 23‒28 | 619‒1164 | 215‒293 | 8‒53 |
R2 | 2.2‒15.1 | -16.1‒2 | 18.6‒28 | 389‒1164 | 215‒293 | 8‒53 |
R3 | 2.9‒15.1 | -7.2‒2 | 18.6‒28 | 626‒1164 | 251‒343 | 10‒53 |
R4 | 2.9‒21.6 | -8.6‒13.2 | 13.7‒28.3 | 465‒1682 | 251‒343 | 10‒73 |
R5 | 8.1‒21.6 | -0.1‒13.2 | 13.7‒28.3 | 465‒1682 | 251‒262 | 10‒48 |
R6 | 11.5‒15.1 | -1‒2 | 23‒28 | 619‒1164 | 251‒293 | 10‒53 |
R7 | 2‒21.6 | -7.2‒13.2 | 13.7‒28.3 | 626‒1770 | 299‒353 | 15‒135 |
R8 | 2‒21.6 | -7.2‒13.2 | 13.7‒28.3 | 626‒1682 | 299‒343 | 15‒73 |
R9 | 2.9‒15.1 | -0.1‒2 | 18.6‒28 | 465‒1164 | 251‒262 | 10‒48 |
R10 | 0‒21.6 | -22.7‒13.2 | 13.7‒28.3 | 389‒1682 | 45‒293 | 5‒73 |
Entirety | 8.1‒15.1 | -0.1‒2 | 18.6‒28 | 389‒1164 | 215‒262 | 8‒48 |