摘要
海参1井伊敏组孢粉化石异常丰富,自下而上可以划分出3个孢粉组合:Impardecispora-Cyathidites-Clavatipollenites组合,Stereisporites-Deltoidospora-Asteropollis组合,Appendicisporites-Asteropollis-Tricolpites组合,分别分布于伊敏组一段、二段和三段,组合特征明显,是海拉尔盆地乌尔逊凹陷划分伊敏组与大磨拐河组的重要生物依据之一,更是伊敏组内三段划分和井间对比的生物依据之一。3个孢粉组合中见有属种繁多的海金沙科孢子及其他繁盛于早白垩世中晚期的孢子花粉,结合在绝大多数样品中发现的早期被子植物花粉的情况分析,推测含这3个孢粉组合的伊敏组地质时代为早白垩世巴列姆期—早阿尔必期(Barremian—Early Albian)。
Abundant pollen and spores are found in the Yimin Formation of the Hailaer Basin for the first time. They can be divided into three assemblages from bottom to top. The first is the Impardecispora-Cyathidites-Clavatipollenites assemblage, which occurs in lowest part of the Yimin Formation. This assemblage is characterized by abundant fern spores （ranging from 60. 9% to 85. 36%）, followed by gymnosperm pollen（ranging from 13.82% to 38. 4%） and angiosperm pollen（ranging from 0.7% to 0.8%）. Fern spores are dominated by Cicatricosisporites australiensis （11.9-27.2%）, Cyathidites minor （0.81- 11.2 % ）, Cicatricosisporites minutaetriatus （0-9. 80%）, Impardecispora purveruleta （0.7-13.82 % ） and Pilosisporites verus （0-13.82%）, other important fern spores include Impardecispora trioreticulosa （0-0.7%）, Leptolepidites verrucatus （0 1. 4%）, Appendicisporites auriflerus （0-0.7%）, Cicatricosisporites minor（0-1. 4%）, Fixisporites tortus（0-0. 7%）, Foraminisporites wonthaggiensis（0- 1. 62%）, Aequitriradites ornatus（0-1.4）, A. reticulates（0-1. 4%）, A. spinulosus（0- 0.7%）, A. verrucosus（0- 0.81%）, Couperisporites complexus（ 0-0. 7%）, Triporoletes reticulatus（ 0-4. 87 % ）. Gymnosperm pollens are dominated by the genus of Piceaepollenites, including P. altus （0-6.3 %）, P. prologatus （0-0. 7 %）, and P. sp. （0-7. 31%）. Other common gymnosperm pollens include Pseudopicea variabiliformis（0- 13.2%）, Cycadopites nitidus （1. 4-3. 25 %）, Jiaohepollis c f. verus （1.4-0.81% ）, and J. verus （0- 1.4%）. Clavatipollenites hughesii（0. 7-0.81% ） is the only angiosperm pollen, which is numerically rare but has important biostratigraphic significance. The second assemblage is the Stereisporites-Deltoidospora-Asteropollis assemblage, which occurs in middle part of the Yimin Formation. Again, fern spores are the most abundant（44.4-77.8%）, followed by gymnosperm pollens（21. 0-55. 0%） and angiosperm pollens （0. 6-1.5%）. Among recovered fern spores, Laevigatosporites ovatuo is the most abundant（9.6 25.6 %）. Other common fern spores are Deltoidospora hallii （ 6.6- 14.5 % ）, Cicatricosisporites australiensis （ 1.2- 12.6 % ）, C. minor （0.6- 11.5 % ）,. and Stereisporites antiquasporites （1. 2-10. 2%）. Other important fern fossils include Impardecispora apiverrucata （0-1.2 % ）, I. cavernosa （0-0. 6 % ）, I. Tribotrys （0-0.6 % ）, Leptolepidites verrucotus （0 0.6%）, Pilosisporites brevipapillosus（0-0. 6%）, P. setiferus（0- 1.5%）, P. trichopapillosus（0-0. 6%）, Cicatricosisporites minutaestriatus （0- 1.2 % ）, Appendicisporites cf. potomacensis （0-0.6 % ）, A. tricornitatus（0-0. 6%）, Fixisporites tortus （0-1.2%）, Crybelosporites minor（0. 5-0.6%）, Triporoletes involuratus （0-0.6 % ）, T. reticulatus （0.5-2.4 % ）, T. singularis （0.5-0.6 % ）, Aequitriradites echinatus （0- 0.6%）, A. verrucosus（0-1.0%）, and Shizosporis reticulatus（0-0. 6%）. Among Gymnosperm pollens, Pinuspollenites minutus（0. 6-9.6 %） is the most abundant species, followed by Abietineaepollenites enodatus （2.4- 9.0 % ） and Pinuspollenites enodatus （2.4-7. 8 % ）. In addition Cycadopites nitidus （2.4-4.2 % ）, C. giganteus （0.6-1.2%）, Podocarpidites arquatus （0.6-3.0%）, P. ornatus（0. 6-0. 0%）, P. multesimues （0.5- 0. 6 % ） and Jiaohepollis annulatus （0. 6- 1.2 % ） are also common. Tricolpopollenites sp. （0-0. 5%） is found as the only angiosperm pollen. Asteropollis sp. （0. 6-1.5%） is more abundant than that in the lowest part of the Yimin Formation.
The third assemblage is the Appendicisporites-Asteropollis-Tricolpites assemblage, which occurs in upper part of the Yimin Formation. This assemblage characterized by a fern spore percentage of 36.53- 65.05%, gymnosperm pollen percentage of 33.01-58.71%, and angiosperm pollen percentage of 1.94- 5.5%, Cyathidites minor is the most abundant fern spore species（4.0-20. 39%）. The genus Cicatricosisporites genus is also variably abundant, including Cicatricosisporites augustus（ 0. 5-4.85%）, C. ewiloides （0-0. 5%）, C. mediostriatus （ 0-0. 79%）, C. minor （ 0-0. 97%）, C. minutaestriatus （ 0-1. 94%）, C. pacificus （0-1.5%）, C. potomacensis （0-0.79%）, C. pseudoaurifer （0-1. 59%）, C. venutes （0- 0. 97%）, C. and sp. （0-5.0%）. Other common members include Deltoidospora hallii（0-7.14%）, Plicifera delicata （ 0. 79-3. 0%）, Granulatisporites sp. （ 0-3. 88 % ）, Concavissimisporites minimus （ 0- 2.38 % ）, C. punctatus （0-3.88 % ）, Appendicisporites sp. （0. 97-3.0 %）, Lygodiumsporites subsimplew （0-1. 94%）, Impardecispora minor （0-0.79%）, Pilosisporites trichopapillosus （0-0. 5%）, P. verus （0. 79-2.0%）, Klukisporites pseudoreticulatus （0-0. 79%）, Appendicisporites crimensis （0-0. 97%）, A. potomacensis （0-0. 5%）, A. tricornitatus （0-0. 97%）, Foraminisporites asymmetricus （0-0. 5%）, Cooksonites sp. （0-0. 5 % ）, Triporoletes reticulatus （0-0. 79 % ）, T. radiatus （ 0- 0. 5 % ）, Aequitriradites verrucosus （0-0.5%）,A. sp. （0-0. 97%）,Trilobosporites sp. （0-1.94%）,Schizaeoisporites certus（0- 0.5%）, S. evidensis（0-1.5%）, and Schizosporis parvus（0-0. 79%）. The most abundant gymnosperm pollens are represented by the genera Tawodiaceaepollenites and InaperturopoUenites, including Tawodiaceaepollenites hiatus（0.97-11.91%）, T. sp. （0-19.42%）, and Inaperturopollenites dubius（4.5- 14.29 % ）. Other gymnosperm pollens include PinuspoUenites sp. （0. 97-5.0%）, Cedripites cretaceus（0- 5.0%）, C. sp. （0-10.5%）, Spheri pollenites psilatus （ O- 10. 0%）, S. scabratus （ 0- 7.14 % ） , Exesipollenites tumulus（0-0. 97%）. Angiosperm pollens are more abundant than in the second assemblage, ineluding Clavatipollenites hughesii（0-0. 97 %）, C. sp. （0-1.0%）, Asteropollis asteroides（0. 97-3.97%）, Tricolpites sp. （0-0.5%）, and Tricolporoidites sp. （0-0.5%）.
The characteristics of the above-mentioned three assemblages provide an important basis for the biostratigraphie differentiation of the Yimin Formation from the Damoguaihe Formation and the subdivision and correlation of the three parts of the Yimin Formation. Based on the palynologieal data, the Yimin Formation is inferred as Barremian to early Albian iin age, because of the abundance of lygodiaeean spores and other pollens and spores characteristic of middle and late Early Cretaceous.
出处
《地层学杂志》
CSCD
北大核心
2007年第1期23-34,共12页
Journal of Stratigraphy
基金
国家自然科学基金(No49894190)
大庆油田有限责任公司科技攻关基金(批准号:QR/AO/4-2-01)资助项目
关键词
海拉尔盆地
内蒙古
孢粉组合
早白垩世
伊敏组
被子植物花粉
Hailaer Basin, Inner Mongolia, pollen and spore assemblages, Early Cretaceous, Yimin Formation, angiosperm pollen
