SGER: Triassic-Jurassic Mass Extinction Caused by Volcanism? Bio- and Magnetostratigraphic Tests in Eastern North America and Morocco

火山作用导致三叠纪-侏罗纪大规模灭绝？北美东部和摩洛哥的生物和岩石地层测试Paul Olsen，Dennis Olsen-0753496，哥伦比亚大学摘要三叠纪-侏罗纪（Tr-J）边界的岩石圈是中生代最严重的岩石圈构造之一，其规模与K-T相当。虽然它明显地减少了至少一半的现存陆地多样性，但它为恐龙占主导地位的生态系统的崛起奠定了生态舞台。与K-T和P-Tr大灭绝一样，Tr-J大灭绝在时间上与火成岩事件有关，在这种情况下，是中大西洋岩浆区（CAMP）-地球上已知的最广泛的洪水钡盐。以前在北美东部纽瓦克和芬迪裂谷盆地的Tr-J边界的工作以及其他人在海洋和大陆沉积物中的工作表明，与K-T边界有额外的相似之处，包括一个显著的（尽管是适度的）Ir异常，一个“蕨类植物穗”，一个气孔（CO2）异常，以及一个或多个负13 C偏移。虽然与外星撞击一致，但这些证据中的大部分（如果不是全部）也可以解释为CAMP的影响。来自北美东部的数据表明，所有CAMP流量都比灭绝水平晚了数万年。尽管如此，一些证据从流动的摩洛哥CAMP，包括存在至少一个区域的反极性，已被解释为表明，熔岩早于或与Tr-J边界同步，使因果关系成为可能。我们将使用一个三管齐下的方法来探讨假设，CAMP喷发可能是同步的大灭绝。首先，我们将在Jacksonwald向斜中取125 m的剖面，在最低的CAMP流量中进行钻探，并获得灭绝间隔的扩展剖面和周围400 ky的最新三叠纪和早侏罗世地层。这一核心将是对大陆领域事件序列进行独特详细描述的基础。第二，我们将制作一个磁性地层学Fundy盆地的北山玄武岩（根据现有岩心），在Fundy盆地附近的沉积物中已经发现了孢粉学灭绝事件、13 C和Ir异常，这是因为Fundy盆地比其他北美东部CAMP地层具有更多的流动，并且具有与最古老的摩洛哥流动相匹配的化学成分，可以更好地捕捉到在摩洛哥看到的短暂的反转间隔。第三，与我们的摩洛哥同事合作，我们将在摩洛哥CAMP流动以下的地层中寻找Tr-J边界以下纽瓦克盆地的反极性区。这种方法应该让我们深入了解地球历史上最大的大规模喷发和最大的喷发事件之一之间的关系。该奖项由地球科学司和国际科学与工程办公室共同资助。

SGER: TRIASSIC-JURASSIC MASS EXTINCTION CAUSED BY VOLCANISM? BIO-, AND MAGNETOSTRATIGRAPHIC TESTS IN EASTERN NORTH AMERICA AND MOROCCOPaul Olsen, Dennis KentEAR-0753496, Columbia UniversityABSTRACTMarking one of the most severe Phanerozoic mass extinctions, that at the Triassic-Jurassic (Tr-J) boundary is comparable in magnitude to that of the K-T. While appar-ently decimating at least half of then-extant terrestrial diversity, it set the ecological stage for the ascent of dinosaur-dominated ecosystems. As with the K-T and P-Tr mass extinctions, the Tr-J mass extinction is temporally linked to igneous event, in this case, the Central Atlantic Magmatic Province (CAMP) - the most areally extensive flood ba-salt known on Earth. Previous work on the Tr-J boundary in the Newark and Fundy rift basins of eastern North America and work by others in marine and continental deposits demonstrate additional parallels to the K-T boundary including a significant (albeit modest) Ir anomaly, a "fern spike," a stomatal (CO2) anomaly, and one or more nega-tive 13C excursions. While consistent with an extraterrestrial impact, much if not all of this evidence could also be explained as an effect of the CAMP. Data from eastern North America suggest that all CAMP flows post-date the extinction level by tens of thousands of years. Nonetheless, some evidence from flows of the Moroccan CAMP, including the presence of at least one zone of reverse polarity, has been interpreted as indicating that the lavas predate or were synchronous with the Tr-J boundary, making causation possible.We will use a three-pronged approach to explore the hypothesis that CAMP erup-tions could be synchronous with the mass extinction. First, we will core a 125 m section in the Jacksonwald syncline, spudding in the lowest CAMP flow and obtaining an ex-panded section of the extinction interval and surrounding 400 ky of latest Triassic and Early Jurassic strata. This core will be the basis of a uniquely detailed characterization of the sequence of events in the continental realm. Second, we will produce a magnetic stratigraphy (based on available core) for the North Mountain Basalt of the Fundy ba-sin, which is where the palynological extinction event, 13C and Ir anomalies have al-ready been recognized in the immediately underlying sediments, which because it has many more flows than other eastern North American CAMP formations and has a chemistry matching that of the oldest Moroccan flows, may better capture the brief re-verse interval seen in Morocco. Third, working with our Moroccan colleagues we will look in strata below the CAMP flows of Morocco for the reverse polarity zone in the Newark basin just below the Tr-J boundary. This approach should allow insight into our knowledge of the relationship between one of the largest mass extinctions and one of the largest eruptive events in Earth history. This award is co-funded by the Division of Earth Sciences and Office of International Science and Engineering.