Dickinson Medal recipient 2022
This Medal Award is for recognition of a mid-career research geoscientist who is significantly influencing the sedimentary geology community with innovative work; with a track record of impactful publications, pioneering approaches and the establishment of an influential research program.
ANSWERING GEOSCIENCES RESEARCH QUESTIONS AT A GLOBAL SCALE VIA A HYBRID MACHINE-HUMAN LEARNING APPROACH: A CASE STUDY OF THE LINK BETWEEN CLIMATE AND VOLCANISM
PARK, S., CARRAPA, B., DUCEA, M.N., SURDEANU, M., HAYES, R., COLLINS, D.
A common challenge in science is the human capability to evaluate the real impact of an observation and a data set. This is a complex task due to having only partial information and/or to the complexity of the problem, requiring different fields to be combined. In order to overcome these important limitations, we need to be able to review all the available data and interpretations. This would allow us to evaluate the global distribution of a specific process or phenomenon of interest. The increasing number of scientific publications prevents scientists from being able to keep up with all the available literature especially when scientific papers cross disciplines. These challenges prevent us from evaluating the global impact of a certain process and are particularly relevant today given the impact of our scientific assessment on one of the most pressing issues of our time, which is climate change and its impact on society. We present here an application of artificial intelligence to geosciences: We conduct a systematic analysis of geoscience literature through a hybrid machine-human approach.
ESTIMATES OF PALEO-CRUSTAL THICKNESS AT CERRO ACONCAGUA (SOUTHERN CENTRAL ANDES) FROM DETRITAL PROXY-RECORDS: IMPLICATIONS FOR MODELS OF CONTINENTAL ARC EVOLUTION
The Central Andes represent the archetypical Cordilleran orogenic system, with a well-developed continental volcanic arc and some of the thickest crust on Earth. Yet the relative contributions of shortening and magmatic additions to crustal thickening remain difficult to quantify, which hinders understanding processes of crustal evolution in continental arcs. Cerro Aconcagua, the highest mountain in the Americas and a relict Miocene stratovolcano resting on 55 km-thick crust, is the ideal natural laboratory to address this issue in subduction-related magmatic arcs because it preserves a multi-million year record of magmatism and deformation within the Aconcagua fold-thrust belt. Estimates of paleo-crustal thickness in the Andes can be made using the geochemistry of subduction-related magmatic rocks, or minerals crystallized within them. This study applies a geochemical proxy approach for crustal thickness estimates to detrital syntectonic deposits of the Santa Maria Conglomerate derived from the Aconcagua stratovolcano to reconstruct paleo-crustal thickness of the Andes at this latitude. Detrital zircon trace-element data from ashes intercalated in the conglomerate, combined with previously published paleo-crustal thickness data, indicate crustal thicknesses of ∼35 km ca. 38 Ma and ∼44 km ca. 12 Ma, requiring ∼11 km of crustal thickening after ca. 12 Ma to achieve present-day crustal thickness of ∼55 km. In the absence of significant magmatism since ca. 10 Ma at this location, we show that more than half of the crustal thickening after 12 Ma, corresponding to 2 km of uplift, was achieved by Miocene shortening. Our study also reveals significant differences in crustal thicknesses between the Central Andes and the southern Central Andes which we speculate may be due to southward crustal flow during the last ∼20 My.
WHERE DID THE ARIZONA-PLANO GO? PROTRACTED THINNING VIA UPPER- TO LOWER-CRUSTAL PROCESSES
Mesozoic-Cenozoic subduction of the Farallon slab beneath North America generated a regionally extensive orogenic plateau in the southwestern US during the latest Cretaceous, similar to the modern Central Andean Plateau. In Nevada and southern Arizona, estimates from whole-rock geochemistry suggest crustal thicknesses reached ∼60–55 km by the Late Cretaceous. Modern crustal thicknesses are ∼28 km, requiring significant Cenozoic crustal thinning. Here, we compare detailed low-temperature thermochronology from the Catalina metamorphic core complex (MCC) to whole rock Sr/Y crustal thickness estimates across southern Arizona. We identify three periods of cooling. A minor cooling phase occurred prior to ∼40 Ma with limited evidence of denudation and ∼10 km of crustal thinning. Major cooling occurred during detachment faulting and MCC formation at 26–19 Ma, corresponding to ∼8 km of denudation and ∼8 km of crustal thinning. Finally, we document a cooling phase at 17–11 Ma related to Basin and Range extension that corresponds with ∼5 km of denudation and ∼9 km of crustal thinning. During the MCC and Basin and Range extension events, the amount of denudation recorded by low-temperature thermochronology can be explained by corresponding decreases in the crustal thickness. However, the relatively limited exhumation prior to detachment faulting at ∼26 Ma recorded by thermochronology is insufficient to explain the magnitude of crustal thinning (∼10 km) observed in the whole rock crustal thickness record. Therefore, we suggest that crustal thinning of the Arizona-plano was facilitated via ductile mid- to lower-crustal ﬂow, and limited upper-crustal extension at 50–30 Ma prior to detachment faulting and Basin and Range extension.
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