Collaborative Research: Expedition 317 Objective Research - Linking Sediment Provenance to Supply and Lithofacies Formation on the Canterbury Margin

合作研究：317 号探险队目标研究 - 将坎特伯雷边缘的沉积物来源与供应和岩相形成联系起来

• 批准号: 1060703
• 负责人: Kathleen Marsaglia
• 金额: $ 5.8万
• 依托单位: The University Corporation, Northridge
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-05-01 至 2014-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1060703&HistoricalAwards=false
• 关键词: Collaborative; Research; Expedition; 317; Objective

Longstanding goals of scientific ocean drilling include determining the timing and amplitudes of global sea-level change, as well as the role of eustacy in the generation and preservation of continental margin stratigraphy. However, continental margin sedimentation is a function of both allogenic and autogenic processes, and extracting a eustatic record requires an understanding of local sedimentary processes and their influence on strata formation. IODP Expedition 317 to Canterbury Basin, New Zealand provides an opportunity to identify the regional processes involved in the formation of sedimentary sequences where temporally evolving across-shelf and along-margin sediment sources potentially interact with both eustasy and tectonics to generate margin stratigraphy. This study defines sedimentary petrofacies using petrographic and X-ray diffraction techniques and combines them with lithofacies to characterize sedimentation within unconformity-bounded sequences. Differentiating the relative influence of each sediment source is made possible by the unique aspects of the onshore geology and sediment supplied by the rivers of South Island, New Zealand: in this system sediment composition is a proxy for transport mode/direction, with mica-rich schist detritus being brought in from the south, and graywacke Torlesse detritus from the west. Higher-resolution analyses will target specific seismic sequences from the Pliocene to Recent that represent changing climatic and eustatic conditions. A primary hypothesis tested is that recurring lithofacies motifs that likely formed during high-amplitude Pleistocene sea-level cycles can be linked to sediment provenance, and even where less lithologically distinct, a recognizable signal may remain in the detrital fraction. Another hypothesis is that the formation of Plio- Pleistocene sequences along the Canterbury Margin is strongly influenced by the relative sediment supply from alongshore/shelf (Clutha/Waitaki rivers) versus cross-margin (Rangitata-Ashburton-Rakaia braided system) transport, with the latter becoming more dominant in the later Pleistocene, potentially leading to an autogenic increase in accommodation space that lead to increased sequence preservation. A holistic approach is used to test these hypotheses, similar to that applied in the MARGINS Source-to-Sink focus site on North Island, New Zealand. This methodology links newly acquired data from onshore outcrops, stream and coastal deposits (collected in conjunction with New Zealand colleagues) to Expedition 317 results in order to evaluate potential basin-wide changes in sediment supply and distribution. Temporal changes in the relative timing and routing of sediment to the Canterbury margin are determined from comparisons between the cross-shelf (U1351, U1353, U1354) and the two Canterbury slope sites (ODP Site 1119 and U1352). Discrete mineralogical observations from this study eventually will be compared to and combined with high-resolution elemental and carbonate analyses proposed by Fulthorpe et al. to provide key petrologic and mineralogic constraints on core and seismic data interpretation for the margin, including distinguishing lithologic changes that might correspond to Milankovitch cyclicity. The history of global sea level change and the impact of future sea-level rise related to global warming are one of the foremost issues facing society. Drilling results from the Canterbury Margin represent a key global component of a comprehensive IODP program to extract sea-level information from continental margin stratigraphy. Our data and results will be made publically available through the IODP portal as part of the IODP Sample, Data, and Obligations Policy and through presentations at meetings and publications. This study will provide educational opportunities for a number of high school, undergraduate and graduate students at CSU Northridge and the University of Florida. One high school student from Florida will participate as part of the UF Student Science Training Program (UF-SSTP), a seven-week residential research program for junior and senior-level high schools students considering science careers. Two undergraduate and two graduate students will participate in this project from CSUN and UF, including students from underrepresented groups and it is expected this participation will form the basis for their theses (BS/MS) or dissertation. The project includes an educational outreach program at UF as part of the UF Geogator program that provides presentations to local K-12 programs about Earth and our environment. The program will make the research on global sea-level change accessible to the local Florida community, where rising sea level and the hazards associated with it are a growing societal concern.

科学大洋钻探的长期目标包括确定全球海平面变化的时间和幅度，以及海平面上升在大陆边缘地层的形成和保存中的作用。然而，大陆边缘沉积既是异生作用又是自生作用的函数，提取海平面记录需要了解当地的沉积过程及其对地层形成的影响。新西兰坎特伯雷盆地IODP考察队的317次考察提供了一个机会，以确定在形成沉积层序时所涉及的区域过程，在这些过程中，跨陆架和沿边缘的沉积物源可能与海平面和构造相互作用，从而产生边缘地层学。本研究利用岩相学和X射线衍射技术确定了沉积岩相，并将其与岩相相结合，以表征不整合面层序中的沉积作用。新西兰南岛河流提供的岸上地质和沉积物的独特方面使区分每一种沉积物来源的相对影响成为可能：在这个系统中，沉积物组成代表了运输方式/方向，富含云母的片岩碎屑来自南部，Graywacke Torlesse碎屑来自西部。更高分辨率的分析将针对从上新世到最近代表气候和海平面变化条件的特定地震序列。验证的一个基本假设是，可能在更新世高幅度海平面旋回期间形成的反复出现的岩相图案可能与沉积物来源有关，即使在岩性不太明显的地方，碎屑组分中也可能保留可识别的信号。另一种假说是，坎特伯雷边缘上更新世层序的形成受到沿岸/陆架(Clutha/Waitaki河)和跨缘(Rangitata-Ashburton-Rakaia辫状体系)输运的相对沉积物供应的强烈影响，后者在晚更新世变得更加主导，可能导致可容纳空间的自生增加，从而增加了层序保存。一种整体的方法被用来检验这些假设，类似于新西兰北岛边际源汇焦点网站的应用。这一方法将新获得的陆上露头、河流和沿海沉积物(与新西兰同事共同收集)的数据与317次勘探的结果联系起来，以评估整个盆地沉积物供应和分布的潜在变化。通过对跨陆架(U1351、U1353、U1354)和坎特伯雷两个斜坡点(ODP1119和U1352)的比较，确定了坎特伯雷边缘沉积物的相对时间和路线的时间变化。这项研究的离散矿物学观察最终将与Fulthorpe等人提出的高分辨率元素和碳酸盐分析进行比较和结合。为边缘岩心和地震资料解释提供关键的岩石学和矿物学约束，包括区分可能与米兰科维奇旋回性相对应的岩性变化。全球海平面变化的历史和未来海平面上升对全球变暖的影响是社会面临的首要问题之一。坎特伯雷边缘的钻探结果是从大陆边缘地层中提取海平面信息的综合IODP计划的关键全球组成部分。我们的数据和结果将通过IODP门户网站作为IODP样本、数据和义务政策的一部分以及通过在会议和出版物上的介绍向公众公布。这项研究将为加州大学北岭分校和佛罗里达大学的一些高中生、本科生和研究生提供教育机会。来自佛罗里达州的一名高中生将参加UF学生科学培训计划(UF-SSTP)，这是一个为期七周的寄宿研究计划，面向考虑科学职业的初中和高中学生。来自CSUN和UF的两名本科生和两名研究生将参与这一项目，其中包括来自代表性不足群体的学生，预计这种参与将成为他们论文(BS/MS)或论文的基础。该项目包括UF的一个教育推广计划，作为UF Geogator计划的一部分，该计划向当地的K-12计划提供关于地球和我们环境的演示。该计划将使佛罗里达州当地社区能够获得有关全球海平面变化的研究，在那里，海平面上升及其相关的危险日益成为社会关注的问题。