Collaborative Research: In Pursuit of Missing Andean Lithosphere: Constraining Late Cenozoic Crust-mantle Processes in the Puna Plateau, Central Andes

合作研究：寻找失踪的安第斯岩石圈：限制安第斯山脉中部普纳高原的晚新生代壳幔过程

• 批准号: 0911577
• 负责人: Barbara Carrapa
• 金额: $ 32.61万
• 依托单位: University of Wyoming
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0911577&HistoricalAwards=false
• 关键词: Collaborative; Research; Pursuit; Missing; Andean

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The Puna Plateau, northwestern Argentina, together with the Altiplano of Bolivia, is the second largest plateau on Earth. One popular model often invoked to explain the present day crustal structure and elevation of the Central Andean Plateau, including the Argentinean Puna and the Bolivian Altiplano, is lithospheric delamination. Full, convective removal of eclogitized lower crust and lithospheric root and subsequent rebound in the Altiplano of Bolivia is proposed to explain paleoaltimetric evidence for high magnitude (greater than 2 kilometers) surface uplift. However, the region of thin crust and lithosphere and of basaltic volcanism originally argued to be the site of lithospheric removal is located to the south in the Puna Plateau of Argentina. Moreover, geochemical data suggest the presence of Ordovician lithosphere beneath the Puna, arguing against complete lithospheric removal. The objective of this research project is to reconcile the geological observations with geophysical data in the area of thin crust and mantle lithosphere in the Puna Plateau. This international effort, lead by researchers at the University of Wyoming and University of Arizona, is a multidisciplinary investigation utilizing structural geology, sedimentology and stratigraphy, geochronology, thermochronology, geochemistry and paleontology, targeting the thinned region in order to constrain: 1) the history of horizontal shortening and extension; 2) basin evolution and incision; 3) magma geochemistry; and 4) paleo-environment in the mid-late Cenozoic. These comprehensive new data are being used as input parameters to a combined numerical-analog model that will test a set of hypotheses to explain the present crustal configuration of the Plateau including: 1) full removal of mantle lithosphere and possibly lower crust through viscous Rayleigh-Taylor type convective instability; 2) partial removal of mantle lithosphere and possibly lower crust plateau-wide, leaving a horizon of uppermost mantle lithosphere intact following viscous convective instability; 3) partial removal of mantle lithosphere and possibly lower crust via small-scale viscous convective instability; 4) full removal of mantle lithosphere through; 5) lithospheric extension in a continental back-arc type environment.The tectonic explanations for the uplift of large plateaus in orogenic belts, such as the Altiplano in the Andes and the Tibet plateau, are numerous and controversial. The objective of this project is to test these models by using geological observations as constraints on numerical and physical models of the processes. This research will ultimately constrain the connection between mantle processes on deformation, uplift, subsidence and magmatism within the Puna Plateau, a natural laboratory that will serve as an example for other geodynamically similar regions on Earth.

该奖项是根据2009年的《美国复苏与再投资法》（公法111-5）进行的。一个流行的模型通常被解释以解释当今的地壳结构和中央高原的抬高，包括阿根廷Puna和玻利维亚的Altiplano，是岩石圈分层的。提出了对玻利维亚山地山脉的截止性下地壳和岩石圈根的全面去除，以解释高幅度（大于2公里）地表上升的古级证据。然而，薄皮和岩石圈以及最初被认为是岩石圈去除部位的玄武岩的区域位于阿根廷Puna Plateau的南部。此外，地球化学数据表明，在Puna下面存在奥陶纪岩石圈，反对完全岩石圈的去除。该研究项目的目的是将地质观察结果与puna高原薄皮和地幔岩石圈区域的地质数据调解。怀俄明大学和亚利桑那大学的研究人员领导的这项国际努力是一项多学科的研究，利用结构地质学，沉积学和地层，地球人工学，热量学，地球化学和古生物学，针对稀薄的地区，以限制水平缩短和扩展的历史； 2）盆地进化和切口； 3）岩浆地球化学； 4）中期新生代中的古环境。这些综合的新数据被用作组合数值 - 分析模型的输入参数，该参数将测试一组假​​设，以解释高原的当前地壳配置，包括：1）完全去除地幔岩石圈以及可能通过粘性雷利 - 泰勒类型对流的对流不稳定性降低地壳； 2）部分去除地幔岩石圈，并可能较低的地壳高原，在粘性对流不稳定性后，使最上面的地幔岩石圈完好无损； 3）部分去除地幔岩石圈，并可能通过小规模的粘性对流不稳定性降低地壳； 4）完全去除地幔岩石圈； 5）岩石圈在大陆后弧形环境中的延伸。造山带中大型高原的隆起的构造解释，例如安第斯山脉和西藏高原的altiplano，众多且有争议。该项目的目的是通过将地质观测作为对过程的数值和物理模型的约束来测试这些模型。这项研究最终将限制地幔过程对Puna Plateau内部变形，隆升，沉降和岩浆作用之间的联系，Puna Plateau是一个自然实验室，将作为地球上其他地球动力学区域的其他地球动力学区域的例子。