Acta Botanica Brasilica - 31(4): 720-735
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Acta Botanica Brasilica - 31(4): 720-735. October-December 2017. doi: 10.1590/0102-33062017abb0160 Miocene fern spores and pollen grains from the Solimões Basin, Amazon Region, Brazil Natália de Paula Sá1*and Marcelo de Araujo Carvalho1 Received: April 27, 2017 Accepted: July 11, 2017 . ABSTRACT is work documents fern spores and pollen grains (miospores) recovered from rocks of the Solimões Formation (Solimões Basin), their botanical a nities, ecology and distribution in the Miocene of the Amazon Region. e assemblage of miospores is well preserved and diverse. ey are identi ed, illustrated and assigned to the ten families of ferns and 22 families of spermatophytes. All miospores were identi ed to the taxonomic level of species except for two taxa (Perinomonoletes and Podocarpidites). e families Pteridaceae and Arecaceae were most representative of ferns and spermatophytes, respectively. is work contributes to the knowledge of the paleo ora and will aid in paleoenvironmental, paleoecological and biostratigraphic interpretations of the Miocene of the Amazon Region. Keywords: Miocene, miospores, Neogene, palynology, Solimões, vegetation a large part of this material allows establishing botanical Introduction a nities. For Miocene age, the palynology has been the most used technique to understand the past of the Amazon, e Amazon is the largest tropical rainforest ecosystem especially miospores, which inform about the diversity and and its high diversity can be explained by ecological, richness of the paleo ora. Several studies (e.g. Lorente 1986; environmental and paleontological models. Climate changes Hoorn 1993; 1994a; b; c; Hoorn et al. 1995; Silva-Caminha in the Pleistocene caused the expansion and retraction of the rainforest cycles. e changes were considered the triggers et al. 2010; Hoorn et al. 2010b; Silveira & Souza 2015; 2016; for the speciation and accumulation of species (Ha er 1969) Leite et al. 2016; D’Apolito 2016) show a paleo ora rich in and this theory has long been the basis for interpreting pteridophytes (Anemiaceae, Cyatheaceae, Polypodiaceae, the current diversity patterns. However, numerous studies Pteridaceae) and gymnosperms (Araucariaceae and (e.g., Gentry 1982; Frailey 1986; Hooghiemstra & Hammen Podocarpaceae). Angiosperms are a separate case because it 1998; Monsch 1998; Jaramillo et al. 2006; Cozzuol 2006; is currently the most important ora in the Amazon region. Hoorn et al. 2010a) have shown that the diversi cation of Since the Miocene, almost all the families (e.g. Annonaceae, biota is pre-Quaternary, reassembling to the last 60 Ma Arecaceae, Asteraceae, Bombacaceae, Euphorbiaceae, (million years). Fabaceae, Malvaceae, Melastomataceae, Malpighiaceae, e Neogene of Amazon region shows a very diversi ed Sapotaceae) were already present in the region (Gentry ora. e records of this ora are based mainly on fossil 1982; Burnham & Graham 1999; Jaramillo et al. 2010; woods and palynomorphs (e.g., spores, pollen grains) and Hoorn et al. 2010c; 2017). 1 Laboratório de Paleoecologia Vegetal, Departamento de Geologia e Paleontologia, Museu Nacional, Universidade Federal do Rio de Janeiro, 20940-040, Rio de Janeiro, RJ, Brazil * Corresponding author: [email protected] Diagramação e XML SciELO Publishing Schema: www.editoraletra1.com.br Miocene fern spores and pollen grains from the Solimões Basin, Amazon Region, Brazil The recognition of the Miocene flora also allows the sediments in the basin, called the Carauari Arch. is paleoecological and paleoenvironmental inferences, as subdivides the depression into the Juruá sub-basin to the well as support the biostratigraphy framework the region east and the Jandiatuba sub-basin to the west (Wanderley- (Lorente 1986; Hoorn 1993; 1994c; Silva-Caminha et al. Filho et al. 2007, Fig. 1). 2010; Leandro 2012; Silveira & Souza 2015; 2016; Leite According to Eiras et al. (1994), the Solimões Basin et al. 2016). covers six depositional sequences: ordovician, siluro- erefore, this work seeks to inventory fern spores devonian, devonian-carboniferous, carboniferous-permian, and pollen grains found in the Miocene rocks (Solimões cretaceous and cenozoic. In the last sequence are recognizing Formation), their anities and ecology in order to facilitate the Solimões and Içá formations. taxonomic identication and to support paleoenvironmental, e Solimões Formation extends for about 500,000 km2, paleoecological and biostratigraphic studies of the Miocene with sedimentary thickness ranging from 300 to 400 m, in the Amazon. and can reach up to 1000 m near the Iquitos Arch. It covers Acre and west Amazonas, as well as the territories of Peru (Marañon and Putumayo basins) and Colombia (Caquetá Materials and methods and Putumayo basins) (Maia et al. 1977; Hoorn et al. 2010a). e Solimões Formation rocks comprise shales, siltstones Study area and sandy shales, clayey silts and medium to ne-grained sands, lignites, carbonaceous clays and limestones (Maia e Solimões Basin is located in the western portion of et al. 1977). the Amazon, bordered to the west by the Iquitos Arch and In relation to the paleoenvironments during the to the east by the Purus Arch. It is Paleozoic intracratonic Miocene, several studies indicate a heterogeneous and depression, covering about 950,000 km2 (Barata & Caputo dynamic environment composed of rivers, lakes, ood 2007) is between 2°-8°S 62°-72°W (Fig. 1). Internally, there plains, mangroves and coastal plains. It is also found is a north-south regional control characterized to distribute elements of transitional and / or marine environments such Figure 1. Solimões Basin location. A. Juruá sub-basin. B. Jandiatuba sub-basin. C. Carauari High. Legends: black dots 1-AS-37-AM (1) e 1-AS-46-AM (2); red dot: 1-AS-4a-AM (11); green dot: 1-AS-32-AM (10); yellow dots: 1-AS-19-AM (6) and 1-AS-27-AM (5); white dots: 1-AS-51-AM (4) and 1-AS-52-AM (3); blue dots: 1-AS-31-AM (7) and 1-AS-34-AM (8); pink dot: 1-AS-33-AM (9); brown dot: 1-AS-105-AM (12) and orange dot: Coari and Alto Solimões outcrops (13). Please see the PDF version for color reference. Acta Botanica Brasilica - 31(4): 720-735. October-December 2017 721 Diagramação e XML SciELO Publishing Schema: www.editoraletra1.com.br Natália de Paula Sá and Marcelo de Araujo Carvalho as microforaminifera linings, molluscs and dinoagellate slides. e slides were deposited in the Laboratory of Plant cysts (e.g. Hoorn 1993; 1994a; Räsänen et al. 1995; Paleoecology of the Department of Geology and Paleontology Latrubesse et al. 1997; 2007; 2010; Lovejoy 1998; Vonhof of the National Museum of the Federal University of Rio et al. 1998; 2003; Wesselingh et al. 2002; 2006; Wesselingh de Janeiro. 2006; Wesselingh & Salo 2006; Ramos 2006; Hoorn et al. 2010a; Gross et al. 2011; 2013; Linhares et al. 2011; Results Nogueira et al. 2013; Boonstra et al. 2015). Sixty miospores were selected for this work, which Metodology include 19 fern spores and 41 pollen grains. e spores are distributed into 10 families, being the family Pteridaceae In Solimões Basin investigations for energy resources the most frequent. e pollen grains are distributed into were conducted by the federal government in the 1970s by 22 families (according to Cronquist 1988), with emphasis the Geological Survey of Brazil (CPRM) and the National on the family Arecaceae. e miospores were systematized Department of Mineral Production (DNPM). e project in two categories: spores and pollen grains, following entitled “Coal Alto Solimões” did a survey of areas with the alphabetical order. Botanical anity, ecology and coal mining potential. A total of 84 wells was drilled in an distribution in the Solimões Formation (Tab. 1, Fig. 1) area of 320,000 km2 in northwest Brazil and this material were attributed based on the literature. was deposited at CPRM/DNPM - Manaus - AM (Maia et al. 1977). e wells 1-AS-37-AM and 1-AS-46-AM were chosen Anteturma SPORITES Potonié 1893 for palynological analysis considering its position in the Genus Cingulatisporites omson emend. Potonié 1956 Solimões Basin and the state of conservation. Cingulatisporites laevigatus Silva-Caminha et al. 2010 e well 1-AS-37-AM is at an altimetric elevation of 60 m (Fig. 2A) and coordinates 03°30’S 68°51’W near the Jandiatuba River. Botanical anity: unknown Its thickness is 242.60 m, and the initial 12 m corresponds Ecology: unknown to Holocene deposits in contact with the top of the Solimões Formation. e lithology is predominantly pelitic with Genus Crassoretitriletes Germeraad et al, 1968 higher occurrence of lignite layers (Maia et al. 1977). Crassoretitriletes vanraadshoovenii Germeraad et al. 1968 e well 1-AS-46-AM is located in the northwestern (Fig. 2B) portion of the Solimões Basin, coordinates 02°23’S 68°28’W, Ecology: pantropical, it occurs throughout South America altimetry 101 m and thickness of 200.90 m. In this well, the (Tryon & Lugardon 1991), wetlands and swamps. Içá Formation represents the initial 6.0 m in erosive contact with the Solimões Formation. e lithology is pelitic and Genus Deltoidospora Miner 1935 there are fewer layers of lignite (Maia et al. 1977). Deltoidospora adriennis (Potonié & Gelletich 1933) For the study were selected 100 core samples from each Fredericksen 1983 (Fig. 2C) well, from which 10g/sample was processed by standard Botanical affinity: family Pteridaceae, Acrostichum technique in palynology to eliminate the inorganic material aureum by means of acidic attacks (see Uesugui 1979; Erdtman Ecology: pantropical, it occurs in coastal environments 1969; Faegri & Iversen 1966). on all continents (Tryon & Lugardon 1991), mangrove e miospores recovered from the cores were identied (Jaramillo et al. 2010) by comparison with works of Germeraad et al. (1968); Regali et al. (1974a; b); Lorente (1986); Hoorn (1993; 1994c); Genus Distaverrusporites Muller 1968 Silva-Caminha et al. (2010); Jaramillo et al. (2011); D’Apolito Distaverrusporites margaritatus Muller 1968 (Fig. 2D) (2016) and the website http://biogeodb.stri.si.edu/jaramillo/ Botanical anity: unknown palynomorph/pollen, which hosts an atlas with images of Ecology: unknown several publications of palynomorphs from North of South America.