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Review of Fossil Floras and Nonmarine Deposits of West Greenland

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Review of Fossil Floras and Nonmarine Deposits of West Greenland B. ESKE KOCH Dept. Geology, Aarhus University, Aarhus, Denmar^ Review of Fossil Floras and Nonmarine Deposits of West Greenland Abstract: The sedimentary area of central West Pautut flora sensu stricto. Furthermore, the Atane Greenland comprises, besides marine sediments, a formation (ordinarily accepted as Cenomanian, al- number of plant-bearing, nonmarine, and transi- though this has never been convincingly proven) tional-facies formations. Mainly because of insuf- and the Pautut formation (Senonian) may be ex- ficient field studies and conclusions based on scanty posures of a continuous Senonian sequence along geological information, the generally accepted the south coast of the Nugssuaq Peninsula. The ideas about these formations and their floras have Kmgigtoq constituent of the Pautut flora is a been affected by severe misunderstandings. How- mixture of Cretaceous and Tertiary fossils, which ever, recent geological investigations under the were collected from a landslide. auspices of The Geological Survey of Greenland Recent paleontologic and stratigraphic studies have provided a sounder basis for the stratigraphic are attempts to solve the remaining problems. In interpretations and exposed a number of mistakes, Tertiary stratigraphy, such positive results as de- e.g.: in the Lower Cretaceous Kome formation the fining the age of the classic Upper Atanikerdluk often-cited "oldest" angiosperms are dubious, and floras as early Paleocene have been achieved. Study those of the Upernivik Nses formation may be of the Cretaceous formations has been advanced, younger than assumed by Seward; the Atane flora, especially through the investigation of spores and ordinarily cited as Cenomanian, consists of fossils pollen. These studies have been facilitated by dis- from localities the beds of which are not exactly of coveries of marine zones and new faunal localities. the same age—one collection (Alianaitsunguaq) be- This paper attempts to clarify present knowledge longs to the Coniacian (marine evidence), whereas of the formations mentioned and to correct the another (Pautut: Lower Pautut flora) is at the misinterpretations and possible mistakes that have Santonian-Campaman boundary (marine evidence) been widely accepted. It is not intended to give a and comes from exactly the same level as the complete survey of the formations in question. CONTENTS Introduction 535 Conclusions . 547 Acknowledgments 537 References cited 547 Cretaceous 538 Kome formation 538 Figure Upernivik Naes formation 539 1. Map section of Northwest Greenland .... 536 Pautut formation 540 2. Sketch of the Pautut locality and surroundings 541 Atane formation 542 3. Rough sketch of the south coast of Nugssuaq Tertiary 545 Peninsula 543 General statement 545 Agatdal formation 545 Plate Facing Upper Atanikerdluk formation 545 1. Relief model of Greenland with the inland ice Ifsorisok formation 546 removed 544 was based on observations gathered on oc- INTRODUCTION casional reconnaissance trips. Such observa- Before the great technical developments of tions often have been used in formulating our time, the arctic explorer was confronted theories and speculations of a wider scope than with such difficulties that no geological map- evidence permitted. Much poorly documented ping, in the modern sense, was possible. Knowl- information on the Cretaceous and Tertiary edge of the geology of the huge arctic regions floras of Greenland and their geological setting Geological Society of America Bulletin, v. 75, p. 535-548, 3 figs., 1 pi., June 1964 535 Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/75/6/535/3417068/i0016-7606-75-6-535.pdf by guest on 25 September 2021 536 B. E. KOCH—FOSSIL FLORAS AND NONMARINE DEPOSITS OF WEST GREENLAND 56' 55' 54' S3' 52' 51° 50' 49' EGEDESMINDE: 100 20 40 60 80 100km Figure 1. Map section of Northwest Greenland in question. Numbers refer to geological localities mentioned in the text: 1, Itsako peninsula; 2, Qeqertarssuaq island; 3, Upernivik Naes; 4, Kuk; 5, Pagtorfik; 6, Angiarssuit-Ujarartorssuaq; 7, Agatdalen valley; 8, Qernertuarssuit; 9, Puiagtiinguaq; 10, Qissugssarigsup qorua; 11, Kugssininguaq; 12, Hare0; 13, Alianaitsunguaq; 14, Ata; 15, Pautut; 16, Kingigtoq; 17, Qutdligssat; 18, Atanikerdluk; 19, Ikorfat Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/75/6/535/3417068/i0016-7606-75-6-535.pdf by guest on 25 September 2021 INTRODUCTION 537 has thus been incorporated into geologic litera- We can thus visualize a huge source area with ture and is a serious source of error in syn- a drainage outlet near the area of late Mesozoic thesizing studies. and early Tertiary sedimentary rocks. This The author presents here a summary of the view is supported by the presence of a "fossil" present geological knowledge of the nonmarine channel several hundred meters deep, eroded formations of central West Greenland and their into older deposits in the area of sedimentation floras based on studies and investigations under- during the regression between Danian and taken in recent years by the Geological Survey Paleocene, which winds its way along the south of Greenland. coast of the Nugssuaq Peninsula. During the The sedimentary area of central West Green- early Paleocene this channel was filled with land includes parts of Disko island, Nugssuaq fluviatile sediments (see section on Upper and Svartenhuk peninsulas (Fig. 1), and some Atanikerdluk formation), and may have formed smaller patches on neighboring islands. Cre- a part of the same drainage system as the sup- taceous and Tertiary sedimentary rocks, ex- posed Disko Bay outlet; upstream its direction clusively clastic and mostly continental or points at the region of this outlet. This transitional facies, rest upon strongly weathered hypothesis affords an explanation for the for- crystalline rocks. Marine deposits show that mation of the sedimentary area of central west the Coniacian, Senonian, Danian, and Paleo- Greenland. cene transgressions advanced over the borders The Cretaceous and Tertiary formations, of central West Greenland. The geological his- considered chiefly nonmarine, are: tory of these sedimentary rocks has been es- sentially explained by investigations done in Ifsorisoq formation these areas between 1938 and 1958 (except Upper Atanikerdluk formation during World War II) under the direction of (lower Paleocene) Prof. A. Rosenkrantz of the University of Tertiary: < Agatdalen formation (lower Copenhagen. Paleocene) (contains transi- The great thickness of the clastic sedimen- tional facies with fossil plants tary rocks, as well as paleontologic and other and marine zoo-fossils) geologic evidence, shows that the relevant area Atane formation (Upper Cre- of central West Greenland during the late taceous) Mesozoic and at the beginning of the Tertiary Pautut formation (at least partly was a coastal zone adjacent to a high potential Cretaceous: ( Senonian) source area of erosional debris. Recent in- Upernivik Nass formation vestigation of the inland ice (Bauer and Korne formation (Lower Cre- Holtzscherer, 1954) has revealed, in broadest taceous) outline, the great relief of the ice-covered land. The dominant topographical feature is an Plant fossils, i.e. fossil woods (Danian), from enormous, central depression rimmed by almost the Nugssuaq Peninsula (Mathiesen, 1961) and continuous mountain chains and highlands in leaf impressions from Umivik, Svartenhuk which the most distinctive gap is in the central Peninsula (Coniacian) (Unpub. ms., Mineral- west coast facing Disko Bay. The central part ogical Museum coll., Copenhagen), have also of this basin, divided into a northern and a been found in other facies (i.e. marine shales). southern second-order basin by high, distinc- tive east-west ridges pointing toward Disko ACKNOWLEDGMENTS Bay (PI. 1), attains extraordinary depths. The author wishes to express his gratitude to These basins reach Disko Bay and join into a the Mineralogical Museum, University of common outlet. A valley between the two main Copenhagen, for economic support; to Prof. east-west ridges points to the same outlet. A. Rosenkrantz and Mr. K. Raunsgaard Hence, some primary geomorphological fea- Pedersen for information on their field work tures, at present concealed by ice, converge at and for stimulating discussions; to Prof. Erling this outlet and may have carried pre-Quater- Dorf (Princeton University), Mr. Brian nary drainage from the basins. Independent of Whindley (Geol. Surv. Greenland), and Mr. the rate of isostatic movements of the Central Ivan Madirazza (University of Aarhus) for aid Greenland shield caused by the inland ice, in translation; and to Mr. F. H. R0hling (Geol. these secondary basins with their common out- Surv. Greenland) for cartographic and Mrs. let may have acted as source areas for the sedi- Bente Soltau (Mineralogical Museum, Copen- ments deposited in Central West Greenland. hagen) for photographic contributions. Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/75/6/535/3417068/i0016-7606-75-6-535.pdf by guest on 25 September 2021 538 B. E. KOCH—FOSSIL FLORAS AND NONMARINE DEPOSITS OF WEST GREENLAND specimen is truly of dicotyledonous affinities. CRETACEOUS So far, we cannot rule out the possibility that Kome formation (Nordenskjold, 1870) it may derive from a nonangiospermous species with similar leaves. The existence of plants like Tvpelocality: Ku\ (syn: Koo\, Kome), Nugssuaq the recent Gnetum justifies this hesitation. Peninsula (north coast opposite
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