Collaborative Research: (GRGC) Testing the Hypothesis of a Cretaceous Supertropical Climate Zone in the Caribbean Province

9418704考夫曼这一建议侧重于通过分析综合的高分辨率地层学、沉积学、古生物学和地球化学数据，结合气候模拟，测试加勒比省白垩纪气候的稳定性，以检验更温暖和更盐分的核心热带气候带--Supertethys的假设(Kauffman和Johnson，1988年)--并确定其时间和空间特征。测试将沿着横跨整个白垩纪古热带及其边缘的两个南北断面进行，绘制在重建Pindell和Barrett(1990)的加勒比海板块上，并将利用一系列代表白垩纪气候-海洋历史不同阶段(阿尔卑斯晚期、图罗纪早期、马斯特里赫特早期)的三个时间片。这些时间片将跨越古生物地理和珊瑚礁多样性数据(Johnson，1993；1994，正在出版)提出的两个发展阶段和Supertethys崩溃的间隔期。一个样带将从新墨西哥州延伸到德克萨斯州西部、墨西哥、中美洲和委内瑞拉西部(图1)；第二个样带将从俄克拉何马州延伸到德克萨斯州中部、大安的列斯群岛、特立尼达、荷兰、西印度群岛和委内瑞拉东部直到巴西北部(图1)。对于每个时间片，将使用浅水平台层序的详细相分析来独立确定净蒸发、上升流等区域。对未改变的生锈双壳类贝壳材料、早期海洋水泥和有孔虫测试进行稳定同位素分析，将能够定义相对海面(光化带)温度/盐度，并描述从北到南的温度梯度。沿样带的古生物数据将包括物种和属的分散图、群落组成和结构的分类学和生态学分析、统计预测的纬度多样性梯度、古生物地理扩散、扩散路径以及古生物地理单元的分类组成和边界特征的分析。每个样带和时间片都有一个部分地层和古生物数据库，提高了拟议研究的效率。将每个时间片的这些数据集合并，将能够查明并在存在的情况下描述超热带加勒比气候带(Supertethys)、其在白垩纪温室间期的动态演变、其对热带生物/生态系统的演变、多样化和灭绝的影响、热带白垩纪海洋的结构和化学以及白垩纪古气候的演变。这些数据将直接用于测试和修改使用Semtner-Chervin涡旋分辨海洋环流模式(Semtner和Chervin，1988)和Genesis大气环流模式(Pollard和Thompson 1993a，b)为这些相同时间间隔产生的白垩纪气候模拟。

9418704 Kauffman This proposal focuses on testing the stability of cretaceous climates in the Caribbean Province by analyzing integrated high- resolution stratigraphic, sedimentologic , paleobiologic and geochemical data, in conjunction with climate simulations, to test the hypothesis of a warmer and more saline core tropical climate zone - Supertethys (Kauffman and Johnson, 1988) - and to define its temporal and spatial characteristics. Tests will be made along two north-south transects spanning the entire cretaceous paleotropics and its margins, plotted on the Caribbean plate reconstructions of Pindell and Barrett (1990), and will utilize a series of three time slices representing different stages of Cretaceous climate-ocean history (Late Albian, Early Turonian, Early Maastrichtian). These time slices will span the interval for which paleobiogeographic and reef diversity data (Johnson, 1993; 1994, in press) propose two episodes of development and an intervening period of collapse of Supertethys. One transect will extend from New Mexico through west Texas, Mexico, Central American and western Venezuela (Fig.1); the second will extend from Oklahoma through central Texas, and Greater Antilles, Trinidad, the Dutch, West Indies, and eastern Venezuela to northern Brazil (Fig.1). For each time slice, detailed facies analyses of shallow water platform sequences will be used to independently determine areas of net evaporation, upwelling , etc. Stable isotope analyses of unaltered rudisted bivalve shell material, early marine cements, and foraminifer tests where available, will allow definition of relative sea surface (photic zone) temperature/salinity, and characterization of north to south thermal gradients. Paleobiological data along the transects will include species and generic dispersion maps, taxonomic and ecologic analyses of community composition and structure, statistically predicted latitudinal diversity gradients, and ana lyses of paleobiogeographic dispersion, dispersal pathways, and the taxonomic composition and boundary characteristics of paleobiogeographic units. A partial stratigraphic and paleobiologic data base exists for each transect and time slice, enhancing the efficiency of the proposed research. Integration of these data sets for each time slice will allow identification, and where present, characterization of the supertropical Caribbean climate zone (Supertethys), its dynamic evolution during the Cretaceous greenhouse interval, its effect on the evolution, diversification, and extinction of tropical organisms/ecosystems, the structure and chemistry of tropical Cretaceous seas, and the evolution of Cretaceous paleoclimates. These data will be directly applied to testing and modifying Cretaceous climate simulations generated using the Semtner-Chervin eddy-resolving ocean general circulation model (Semtner and Chervin, 1988) and the GENESIS atmospheric general circulation model (Pollard and Thompson 1993a,b) for these same time intervals.