南极半岛西摩岛始新世拉揭塞塔组Teredolites遗迹化石研究

doi:10.13745/j.esf.sf.2021.7.23

摘要/Abstract

摘要：

Teredolites遗迹化石是一类赋存于海相地层中的以木质基底为特征的钻孔遗迹组合,是由海相钻木类双壳动物(如船蛆、海笋等)寄生于漂浮或沉入海洋的树干中形成。Teredolites遗迹化石可指示浅海沉积环境,提供寄生木材的分类信息、古地理信息以及埋藏过程中的环境信息。本文研究了南极半岛西摩岛拉揭塞塔组顶部首次发现的一例Teredolites longissimus(Apectoichnus longissimus)遗迹化石,层位时代为晚始新世,根据木基底内保存的船蛆化石的发育特征和分布特征,确定本例为船蛆幼年群体对木基底的初期感染形成的钻孔遗迹。利用场发射扫描电镜(FESEM)和X射线能谱仪(EDS)对基底木化石和船蛆化石进行深入研究分析,将本例Teredolites遗迹化石的基底木化石定为裸子植物罗汉松科(Podocarpaceae)叶枝杉型木属未定种(Phyllocladoxylon sp.),证实了叶枝杉型木属在西摩岛上的分布延续至始新世晚期;船蛆化石内部赋存大量草莓状黄铁矿,其中粒径超过10 μm的草莓状黄铁矿占比达39.2%,最大粒径达到44 μm,粒径的统计和分析显示其形成于氧化水体沉积环境,证明始新世晚期南极半岛地区古海洋处于氧化海状态。

关键词: Teredolites, 西摩岛, 始新世, 拉揭塞塔组

Abstract:

The ichnogenus Teredolites, produced by wood-boring marine bivalves (Teredinidae or Pholadidae), describes trace assemblage of club-shaped borings in log-ground in marine strata. Teredolites are taphonomically indicative of shallow marine environments, thus they can provide valuable information on the taxonomy and distribution of wood substrates as well as the environmental setting during the burial. This article investigates the trace fossil Teredolites longissimus (Apectoichnus longissimus) discovered in the upper part of the La Meseta Formation of Seymour Island, Antarctic Peninsula. The age of this horizon is constrained in the Late Eocene and the development and distribution features of teredinid body fossils preserved in the wood substrate indicate an incipient stage of infestation. Wood substrate and teredinid body fossils were investigated thoroughly using field emission scanning electron microscope (FESEM) and energy dispersive X-ray spectrometer (EDS). The xylic substrate was identified as Phyllocladoxylon sp. of family Podocarpaceae, which confirmed the existence of Phyllocladoxylon had lasted until the Late Eocene in Seymour Island. Framboidal pyrite was discovered in abundance inside teredinid body fossils, 39.2% of the framboids were above 10 μm in grain size, and the maximum grain size reached 44 μm; the size distribution analysis indicated they were formed under oxic condition, suggesting the paleo-ocean in the Antarctic Peninsula area was oxic at the end of the Eocene.

Key words: Teredolites, Seymour Island, Eocene, La Meseta Formation

中图分类号:

Q91
P534.61

李若霜, 李全国. 南极半岛西摩岛始新世拉揭塞塔组Teredolites遗迹化石研究[J]. 地学前缘, 2022, 29(3): 381-391.

LI Ruoshuang, LI Quanguo. Characterization of the trace fossil Teredolites longissimus (Apectoichnus longissimus) from the Eocene La Meseta Formation, Seymour Island, Antarctic Peninsula[J]. Earth Science Frontiers, 2022, 29(3): 381-391.

图/表 10

图1 南极半岛西摩岛位置图

Fig.1 Location of Seymour Island, Antarctic Peninsula

图2 拉揭塞塔组岩性单元划分(根据文献[18]修改)

Fig.2 Lithologic units of the La Meseta Formation. Modified from Reference [18].

图3 拉揭塞塔组Teredolites遗迹化石野外采集点照片

Fig.3 Field photo of the Teredolites from the La Meseta Formation

图4 本文研究的拉揭塞塔组Teredolites遗迹化石照片 a—CUGB P2001-1 正面;b—CUGB P2001-1 背面;c—CUGB P2001-2 正面;d—CUGB P2001-2 侧面;图中箭头均指向采样点。

Fig.4 Photos of the studied Teredolites from the La Meseta Formation

图5 木化石场发射扫描电镜照片 a—管胞与单列纹孔;b—管胞双列纹孔对列;c—交叉场,右倾箭头指向交叉场内2个纹孔,左倾箭头指向交叉场内单个纹孔;d—木射线及交叉场,右倾箭头指向交叉场内2个纹孔,左倾箭头指向交叉场内单个纹孔。

Fig.5 SEM images of fossil wood from relic log-ground

图6 船蛆化石横截面能谱分析面分布图(a)和草莓状黄铁矿富集局部能谱分析面分布图(b)

Fig.6 Energy dispersive X-ray spectrometric analysis of the cross section of teredinid body fossil (a) and local framboidal pyrite aggregates (b)

图7 船蛆化石中赋存的草莓状黄铁矿场发射扫描电镜照片 a—多个莓体聚集产出;b—莓体粒径大小不一;c—单个莓体;d—五角十二面体微晶;e—八面体微晶;f—球状微晶。

Fig.7 SEM images of framboidal pyrite in teredinid body fossils

表1 草莓状黄铁矿粒径统计结果

Table 1 Statistical results of the size distribution of framboidal pyrite grains

样本	统计数量/个	平均粒径/μm	中间粒径/μm	最大粒径/μm	标准偏差/μm
草莓状黄铁矿	273	10.52	8.72	44	6.32

图8 草莓状黄铁矿粒径分布盒须图(a)和频率分布直方图(b)

Fig.8 Grain size box-and-whisker diagram (a) and histogram (b) of framboidal pyrite

图9 草莓状黄铁矿粒径平均值-标准偏差二元图解(a)和平均粒径对偏态系数的二元图解(b)(黑色实线引自文献[52],红色实线和虚线引自文献[53])

Fig.9 Mean-standard deviation (a) and mean-skewness (b) of the size distribution of framboidal pyrite grains. Adapted from [52-53].

参考文献 53

[1]	KELLY S, BROMLEY R G, et al. Ichnological nomenclature of clacate borings[J]. Palaeontology, 1984, 27(4): 793-807.
[2]	LEYMERIE M A. Suite de mémoire sur le terrain Crétacé du department de l’Aube[J]. Mémoires de la Société Géologique de France, 1842, 4: 291-364.
[3]	DONOVAN S K. A new ichnogenus for Teredolites longissimus Kelly and Bromley[J]. Swiss Journal of Palaeontology, 2018, 137(1): 95-98. DOI URL
[4]	DONOVAN S K, EWIN T A M. Substrate is a poor ichnotaxobase: a new demonstration[J]. Swiss Journal of Palaeontology, 2018, 137(1): 103-107. DOI URL
[5]	VILLEGAS-MARTÍN J, DE GIBERT J M, ROJAS-CONSUEGRA R, et al. Jurassic Teredolites from Cuba: new trace fossil evidence of early wood-boring behavior in bivalves[J]. Journal of South American Earth Sciences, 2012, 38: 123-128. DOI URL
[6]	SERRANO-BRAÑAS C I, ESPINOSA-CHÁVEZ B, MACCRACKEN S A. Teredolites trace fossils in log-grounds from the Cerro del Pueblo Formation (Upper Cretaceous) of the state of Coahuila, Mexico[J]. Journal of South American Earth Sciences, 2019, 95: 102316.
[7]	KUMAR K, SINGH H, RANA R S. IchnospeciesTeredolites longissimus and teredinid body fossils from the early Eocene of India: taphonomic and palaeoenvironmental implications[J]. Ichnos, 2011, 18(2): 57-71. DOI URL
[8]	PLINT A G, PICKERILL R K. Non-marine Teredolites from the middle Eocene of southern England[J]. Lethaia, 1985, 18(4): 341-347. DOI URL
[9]	GINGRAS M K, MACEACHERN J A, PICKERILL R K. Modern perspectives on the Teredolites ichnofacies: observations from Willapa Bay, Washington[J]. PALAIOS, 2004, 19(1): 79-88. DOI URL
[10]	常晓琳, 黄元耕, 陈中强, 等. 沉积地层中草莓状黄铁矿分析方法及其在古海洋学上的应用[J]. 沉积学报, 2020, 38(1): 150-165.
[11]	MACELLARI C E. Stratigraphy, sedimentology and paleoecology of Upper Cretaceous/Paleocene shelf-deltaic sediments of Seymour Island (Antarctic Peninsula)[M]// Geological Society of America memoirs. Boulder: Geological Society of America, 1988: 25-54.
[12]	ZINSMEISTER W J. Review of the Upper Cretaceous-Lower Tertiary sequence on Seymour Island, Antarctica[J]. Journal of the Geological Society, 1982, 139(6): 779-785. DOI URL
[13]	MARENSSI S A, NET L I, SANTILLANA S N. Provenance, environmental and paleogeographic controls on sandstone composition in an incised-valley system: the Eocene La Meseta Formation, Seymour Island, Antarctica[J]. Sedimentary Geology, 2002, 150(3/4): 301-321. DOI URL
[14]	POREBSKI S J. Shelf-valley compound fill produced by fault subsidence and eustatic sea-level changes, Eocene La Meseta Formation, Seymour Island, Antarctica[J]. Geology, 2000, 28(2): 147-150. DOI URL
[15]	MARENSSI S A, SANTILLANA S N, RINALDI C A. Stratigraphy of the La Meseta Formation (Eocene), Marambio (Seymour) Island, Antarctica[J]. Asociación Paleontológica Argentina, Publicación Especial, 1998, 5: 137-146.
[16]	ELLIOT D H. Tectonic setting and evolution of the James Ross Basin, northern Antarctic Peninsula[M]// Geological Society of America memoirs. Boulder: Geological Society of America, 1988: 541-556.
[17]	ELLIOT D H, TRAUTMAN T A. ower Tertiary strata on Seymour Island, Antarctic Peninsula[M]//CRADDOCK C. Antarctic geosciences. Madison: University of Wisconsin Press, 1982: 287-297.
[18]	SADLER P M. Geometry and stratification of uppermost Cretaceous and Paleogene units on Seymour Island, northern Antarctic Peninsula[M]// Geological Society of America memoirs. Boulder: Geological Society of America, 1988: 303-320.
[19]	HARWOOD D M. Cretaceous to Eocene Seymour Island siliceous microfossil biostratigraphy[C]// Workshop on Cenozoic geology of the Southern High Latitudes. Columbus: Ohio State University, 1985: 17-18.
[20]	ASKIN R A. Eocene-?earliest Oligocene terrestrial palynology of Seymour Island, Antarctica[M]// RICCI C A. The Antarctic Region: geological evolution and processes Terra Antarctica Publication. Siena, 1997: 993-996.
[21]	HALL S A. Cretaceous and Tertiary dinoflagellates from Seymour Island, Antarctica[J]. Nature, 1977, 267(5608): 239-241. DOI URL
[22]	DUTTON A L, LOHMANN K C, ZINSMEISTER W J. Stable isotope and minor element proxies for Eocene climate of Seymour Island, Antarctica[J]. Paleoceanography, 2002, 17(2): 6-13.
[23]	MARENSSI S A. Eustatically controlled sedimentation recorded by Eocene strata of the James Ross Basin, Antarctica[J]. Geological Society of London, Special Publications, 2006, 258(1): 125-133. DOI URL
[24]	STILWELL J D, ZINSMEISTER W J. Molluscan systematics and biostratigraphy:lower Tertiary La Meseta Formation, Seymour Island, Antartic Peninsula[M]. Washington, DC: American Geophysical Union, 1992.
[25]	MEYER D L, OJI T. Eocene crinoids from Seymour Island, Antarctic Peninsula: paleobiogeographic and paleoecologic implications[J]. Journal of Paleontology, 1993, 67(2): 250-257. DOI URL
[26]	DOKTOR M, GAŻDZICKI A, JERZMA ŃSKA A, et al. A plant-and-fish assemblage from the Eocene La Meseta Formation of Seymour Island (Antarctic Peninsula) and its environmental implications[J]. Palaeontologica Polonica, 1996, 55(55): 127-146.
[27]	FRANCIS J E. Growth rings in Cretaceous and Tertiary wood from Antarctica and their palaeoclimatic implications[J]. Palaeontology, 1986, 29: 665-684.
[28]	FELDMAN R M, WOODBURNE M O. Geology and paleontology of Seymour Island, Antarctic Peninsula[M]. Boulder: Geological Society of America, 1988.
[29]	WOODBURNE M O, ZINSMEISTER W J. Fossil land mammal from Antarctica[J]. Science, 1982, 218(4569): 284-286. DOI URL
[30]	FORDYCE R E. Origins and evolution of Antarctic marine mammals[J]. Geological Society of London, Special Publications, 1989, 47(1): 269-281. DOI URL
[31]	ENGELBRECHT A, MÖRS T, REGUERO M A, et al. Eocene squalomorph sharks (Chondrichthyes, Elasmobranchii) from Antarctica[J]. Journal of South American Earth Sciences, 2017, 78: 175-189. DOI URL
[32]	JADWISZCZAK P. Penguin response to the Eocene climate and ecosystem change in the northern Antarctic Peninsula region[J]. Polar Science, 2010, 4(2): 229-235. DOI URL
[33]	HOSPITALECHE C A, REGUERO E. Additional Pelagornithidae remains from Seymour Island, Antarctica[J]. Journal of South American Earth Sciences, 2020, 99: 102504. DOI URL
[34]	DINGLE R V, MARENSSI S A, LAVELLE M. High latitude Eocene climate deterioration: evidence from the northern Antarctic Peninsula[J]. Journal of South American Earth Sciences, 1998, 11(6): 571-579. DOI URL
[35]	IVANY L C, VAN SIMAEYS S, DOMACK E W, et al. Evidence for an earliest Oligocene ice sheet on the Antarctic Peninsula[J]. Geology, 2006, 34(5): 377-380. DOI URL
[36]	SAVRDA C E. Teredolites, wood substrates, and sea-level dynamics[J]. Geology, 1991, 19(9): 905-908. DOI URL
[37]	SAVRDA C E, COUNTS J, MCCORMICK O, et al. Log-grounds and Teredolites in transgressive deposits, Eocene Tallahatta Formation (Southern Alabama, USA)[J]. Ichnos, 2005, 12(1): 47-57. DOI URL
[38]	SAVRDA C E, OZALAS K, DEMKO T H, et al. Log-grounds and the ichnofossil Teredolites in transgressive deposits of the Clayton Formation (lower Paleocene), western Alabama[J]. PALAIOS, 1993, 8(4): 311-324. DOI URL
[39]	GOTHAN W. Fossile Hölzer aus dem Bathonian von Russisch-Polen[J]. Verhandlungen Russische-Kaiserlische Mineralogische Gesellschaft, 1906, 44: 435-458.
[40]	CANTRILL D J, POOLE I. Taxonomic turnover and abundance in Cretaceous to Tertiary wood floras of Antarctica: implications for changes in forest ecology[J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 2005, 215(3/4): 205-219. DOI URL
[41]	PHILIPPE M, BAMFORD M K. A key to morphogenera used for Mesozoic conifer-like woods[J]. Review of Palaeobotany and Palynology, 2008, 148(2/3/4): 184-207. DOI URL
[42]	PUJANA R R, RAFFI M E, OLIVERO E B. Conifer fossil woods from the Santa Marta Formation (Upper Cretaceous), Brandy Bay, James Ross Island, Antarctica[J]. Cretaceous Research, 2017, 77: 28-38. DOI URL
[43]	PUJANA R R, MARENSSI S A, SANTILLANA S N. Fossil woods from the Cross Valley Formation (Paleocene of Western Antarctica): Araucariaceae-dominated forests[J]. Review of Palaeobotany and Palynology, 2015, 222: 56-66. DOI URL
[44]	PUJANA R R, SANTILLANA S N, MARENSSI S A. Conifer fossil woods from the La Meseta Formation (Eocene of Western Antarctica): evidence of Podocarpaceae-dominated forests[J]. Review of Palaeobotany and Palynology, 2014, 200: 122-137. DOI URL
[45]	OH C, PHILIPPE M, MCLOUGHLIN S, et al. New fossil woods from lower Cenozoic volcano-sedimentary rocks of the Fildes Peninsula, King George Island, and the implications for the trans-Antarctic Peninsula Eocene climatic gradient[J]. Papers in Palaeontology, 2020, 6(1): 1-29. DOI URL
[46]	YAMADA S, NANJO J, NOMURA S, et al. Morphology of iron pyrite crystals[J]. Journal of Crystal Growth, 1979, 46(1): 10-14. DOI URL
[47]	RICKARD D T. The origin of framboids[J]. Lithos, 1970, 3(3): 269-293. DOI URL
[48]	WILKIN R T, BARNES H L. Formation processes of framboidal pyrite[J]. Geochimica et Cosmochimica Acta, 1997, 61(2): 323-339. DOI URL
[49]	WIGNALL P B, NEWTON R, BROOKFIELD M E. Pyrite framboid evidence for oxygen-poor deposition during the Permian-Triassic crisis in Kashmir[J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 2005, 216(3/4): 183-188. DOI URL
[50]	WEI H Y, ALGEO T J, YU H, et al. Episodic euxinia in the Changhsingian (late Permian) of South China: evidence from framboidal pyrite and geochemical data[J]. Sedimentary Geology, 2015, 319: 78-97. DOI URL
[51]	常华进, 储雪蕾. 草莓状黄铁矿与古海洋环境恢复[J]. 地球科学进展, 2011, 26(5): 475-481.
[52]	WILKIN R T, BARNES H L, BRANTLEY S L. The size distribution of framboidal pyrite in modern sediments: an indicator of redox conditions[J]. Geochimica et Cosmochimica Acta, 1996, 60(20): 3897-3912. DOI URL
[53]	WEI H Y, WEI X M, QIU Z, et al. Redox conditions across the G-L boundary in South China: evidence from pyrite morphology and sulfur isotopic compositions[J]. Chemical Geology, 2016, 440: 1-14. DOI URL