MODERN FORAMINIFERAL FACIES IN A SUBTROPICAL ESTUARINE CHANNEL, BERTIOGA, SAO PAULO, BRAZIL
MODERN FORAMINIFERAL FACIES IN A SUBTROPICAL ESTUARINE CHANNEL, BERTIOGA, SAO PAULO, BRAZIL
复制标题
巴西圣保罗伯蒂奥加亚热带河口水道的现代有孔虫相
DOI：
--
复制
发表时间：
2007
期刊：
影响因子：
--
通讯作者：
A. R. Rodrigues
中科院分区：
文献类型：
--
作者：
P. Eichler;B. B. Eichler;L. B. Miranda;A. R. Rodrigues
对巴西圣保罗贝尔蒂奥加海峡现代有孔虫丰度和环境数据的数值分析揭示了一个整体海洋环境中的多种生物相。尽管贝尔蒂奥加的渔业、海水养殖业和对游客的吸引力很大，但对其环境状况的研究仍然很少。本次调查试图部分填补这一空白;检查的参数包括深度，盐度，温度，有机碳，硫含量和底质类型。在海峡的东部入口处，桑迪沉积物中含有来自第1相的多种Rotalida（包括Elphidium discoidale、Elphidium poeyanum、Hanzawaia boueana、Para-rotalia cananeiaensis和Nonionella atlantica），反映了正常的海洋盐度。在东部和Itapanhau河的多盐和广盐环境中，粉砂和粘土含量较高的沉积物包含相2，其中包括Ammonia beccarii和Pararotalia cananeiaensis。在西部入口和中部，西部和东部，盐度变化在18 - 30 psu之间，沉积物含有低和高有机碳，相3的有孔虫以Quinqueloculina milletti为主，Arenoparrella mexicana，Pararotalia cananeiaensis，Ammo-nia beccarii，Buliminella elegantissima，Elphidium sp.，凹叶Elphidium，冈氏Elphidium gunteri和波叶Elphidiumpoeyanum。在中部的中盐和多盐沃茨中，富含有机碳的粉砂和粘土包含相4，其中包括Ammonia beccarii，Pararotalia cananeiaensis，Elphidium unculatum和Elphidium sp.。大多数富含有机碳的粉砂-粘土基质受到最高淡水流量和高底部温度的影响，支持两种不同的组合：一个主要是Rotaliina，另一个主要是Textulariida（相5和6）。相5包括Beccarii、Elphidium unculatum、Areno-parrella mexicana、Haplophragmoides wilberti、Siphotro-chammina lobata、Trochammina inflata和Trochamminasp.，所有这些都是典型的中盐地区（主要是Crumau '河和特林达德河），相6包括Bolivinasp.，盐地砂甲（Ammoastuta salsa）、墨西哥砂甲藻（Arenoparrella mexicana）、单脉藻（Haplo-phragmoides wilberti）和轮藻（Trochammina sp.），它们都是典型的寡盐和中盐红树林边缘。TheForaminiferal物种从目前的研究中经常发现在巴西，西非和其他河口世界各地的环境中的环境变化的背景下，巴西海岸线，其中有许多河口，有孔虫记录在沉积物中没有得到广泛或深入的研究。过去的一些研究（Tinoco，1965，1971，1972; Bronnimann，1979）的有孔虫化石覆盖大陆架，但大部分与河口、泻湖和沼泽有孔虫有关。（Closs，1963）;（2）Parana ′（Scott andothers，1990年;巴博萨，1995年;巴博萨等人，2005年）;（3）圣卡塔里纳、圣保罗和巴伊亚（Zaninetti等人，1977年，1979年; Eichler等人，1995年; Eichler，1996年; Duleba，1997年; Debenay等人，1997年，2001年a; Debenay，2000年;Duleba和Debenay，2003年）;里约热内卢，瓜纳巴拉湾（Eichler等人，2001年，2003年; Vilela等人，2003年，2004年）。与大多数这些研究中，其中掩盖了广泛的分布模式的巴西Aromicforaminifera，本调查的重点是在一个河口地区的有孔虫相的区别和这种相与测量的海洋环境变量的关系。研究区域是贝尔蒂奥加海峡，这是桑托斯河口系统的一个25公里长的二级分支（图1），位于圣保罗中部的沿海平原。它主要伊萨半咸水，部分混合，亚热带河口，直接与大西洋在贝尔蒂奥加酒吧（23 u 519 S，46 u 089 W）和间接通过桑托斯河口（23 u 569 S，46 u209 W;图1）。尽管它的渔业，海产养殖和旅游吸引力，贝尔蒂奥加海峡的环境状况尚未令人满意的研究。本次调查试图部分填补这一空白，所考察的参数包括有孔虫普查、深度、盐度、温度、有机碳、硫含量和底质类型。我们的目标是使用有孔虫的分布，是相关的环境变量作为基线研究，以监测未来的变化，在健康的河口。研究区域Bertioga海峡范围从200-700米宽，通常3-6米深，但高达10米的凹陷主要记录在最陡峭的渠道曲线。该水道在其中部（Largo do Candinho）、与桑托斯河口的汇合处（西入口）和贝尔蒂奥加酒吧（东入口）最宽，在那里可以找到10 -12米的深度（Harari和Camargo，1998年）。它在Largo do Candinho和Santos河口之间相当狭窄，抑制了沃茨这一段的交换（米兰达等人，1998年）。
ABSTRACT Numerical analyses of modern foraminiferal abundanceand environmental data from the Bertioga Channel (Sa˜oPaulo, Brazil) reveal multiple biofacies within an overallparalic setting. Despite its fisheries, mariculture and attrac-tion to tourists, the environmental state of Bertioga Channelremains poorly studied. The present investigation is anattempt to partly fill this gap; the parameters examinedinclude depth, salinity, temperature, organic carbon, sulfurcontent and bottom sediment type. Muddy sediments withhigh organic carbon content derived from land drainage arefound in the inner parts of the channel, whereas sandysediment dominates the areas adjacent to the Atlantic Ocean.In the eastern entrance to the channel, sandy sediment containspecies of Rotaliida from Facies 1 (including Elphidiumdiscoidale, Elphidium poeyanum, Hanzawaia boueana, Para-rotalia cananeiaensis and Nonionella atlantica), reflectingnormal marine salinity. Sediments with high percentages ofsilt and clay in polyhaline and euryhaline environments of theeastern part and Itapanhau´ River contain Facies 2, whichincludes Ammonia beccarii and Pararotalia cananeiaensis.Inthe western entrance and central, western and eastern parts,where salinities vary from 18 to 30 psu and the sedimentscontain both low and high organic carbon, the foraminiferafrom Facies 3 are dominated by Quinqueloculina milletti,Arenoparrella mexicana, Pararotalia cananeiaensis, Ammo-nia beccarii, Buliminella elegantissima, Elphidium sp.,Elphidium excavatum, Elphidium gunteri and Elphidiumpoeyanum. In mesohaline and polyhaline waters of the centralpart, the organic-carbon-rich silt and clay contain Facies 4,which includes Ammonia beccarii, Pararotalia cananeiaensis,Elphidium excavatum and Elphidium sp. Most of organic-carbon-enriched, silty-clay substrates that are subject to thehighest fresh-water discharge and high bottom temperaturessupport two different assemblages: one of mostly Rotaliinaand the other mostly of Textulariida (Facies 5 and 6). Facies5 includes Ammonia beccarii, Elphidium excavatum, Areno-parrella mexicana, Haplophragmoides wilberti, Siphotro-chammina lobata, Trochammina inflata and Trochamminasp., all of which are typical of mesohaline sites (mainlyCrumau´ and Trindade rivers), and Facies 6 includes Bolivinasp., Ammoastuta salsa, Arenoparrella mexicana, Haplo-phragmoides wilberti and Trochammina sp., all of which aretypical of oligohaline and mesohaline mangrove fringes. Theforaminiferal species from the present study are frequentlyfound in paralic environments in Brazil, western Africa andother estuaries around the world.INTRODUCTIONIn the context of the environmental variability of theBrazilian coastline, which has many estuaries, the foraminif-eral record in the sediment has not been extensively orintensively studied. Some past studies (Tinoco, 1965, 1971,1972; Bro¨nnimann, 1979) cover the continental shelf, but themajority relate to estuarine, lagoonal and marsh foraminifera.Examples from various coastal states include (1) Rio Grandedo Sul, Patos Lagoon (Closs, 1963); (2) Parana´ (Scott andothers, 1990; Barbosa, 1995; Barbosa and others, 2005); (3)Santa Catarina, Sa˜o Paulo and Bahia (Zaninetti and others,1977, 1979; Eichler and others, 1995; Eichler, 1996; Duleba,1997; Debenay and others, 1997, 2001a; Debenay, 2000;Duleba and Debenay, 2003); and (4) Rio de Janeiro,Guanabara Bay (Eichler and others, 2001, 2003; Vilela andothers, 2003, 2004). In contrast to most of these studies, whichunveiled broad distribution patterns of Brazilian paralicforaminifera, the present investigation is focused on thedistinction of foraminiferal facies within one estuarine areaand the relationship of such facies with measured environ-mental variables. The study area is the Bertioga Channel, a 25-km-long, secondary branch of the Santos estuarine system(Fig. 1), located in the coastal plain of central Sa˜o Paulo. It isa predominantly brackish-water, partially-mixed, subtropicalestuary, directly connected with the Atlantic Ocean at theBertioga Bar (23u519S, 46u089W) and indirectly through theSantos estuary (23u569S, 46u209W; Fig. 1).Despite its fisheries, mariculture and attraction to tourists,the environmental state of Bertioga Channel remainsunsatisfactorily studied. The present investigation is anattempt to partly fill this gap; the parameters examinedinclude a census of foraminifera, depth, salinity, tempera-ture, organic carbon, sulfur content and bottom sedimenttype. Our goal is to use the foraminiferal distributions thatare related to environmental variables as a baseline study tomonitor future changes in the health of the estuary.STUDY AREABertioga Channel ranges from 200–700 m wide andusually 3–6 m deep, but depressions of up to 10 m arerecorded mainly at the most abrupt channel curves. Thechannel is widest at its central part (Largo do Candinho), atthe confluence with the Santos estuary (western entrance)and at Bertioga Bar (eastern entrance), where depths up to10–12 m can be found (Harari and Camargo, 1998). Itnarrows considerably between the Largo do Candinho andSantos estuary, inhibiting exchange of saline waters acrossthis segment (Miranda and others, 1998).