Evolution of the Greater Caucasus Basement and Formation of the Main Caucasus Thrust, Georgia

Along the northern margin of the Arabia‐Eurasia collision zone in the western Greater Caucasus, the Main Caucasus Thrust (MCT) juxtaposes Paleozoic crystalline basement to the north against Mesozoic metasedimentary and volcaniclastic rocks to the south. The MCT is commonly assumed to be the trace of an active plate‐boundary scale structure that accommodates Arabia‐Eurasia convergence, but field data supporting this interpretation are equivocal. Here we investigate the deformation history of the rocks juxtaposed across the MCT in Georgia using field observations, microstructural analysis, U‐Pb and 40Ar/39Ar geochronology, and 40Ar/39Ar and (U‐Th)/He thermochronology. Zircon U‐Pb analyses show that Greater Caucasus crystalline rocks formed in the Early Paleozoic on the margin of Gondwana. Low‐pressure/temperature amphibolite‐facies metamorphism of these metasedimentary rocks and associated plutonism likely took place during Carboniferous accretion onto the Laurussian margin, as indicated by igneous and metamorphic zircon U‐Pb ages of ~330–310 Ma. 40Ar/39Ar ages of ~190–135 Ma from muscovite in a greenschist‐facies shear zone indicate that the MCT likely developed during Mesozoic inversion and/or rifting of the Caucasus Basin. A Mesozoic 40Ar/39Ar biotite age with release spectra indicating partial resetting and Cenozoic (<40 Ma) apatite and zircon (U‐Th)/He ages imply at least ~5–8 km of Greater Caucasus basement exhumation since ~10 Ma in response to Arabia‐Eurasia collision. Cenozoic reactivation of the MCT may have accommodated a fraction of this exhumation. However, Cenozoic zircon (U‐Th)/He ages in both the hanging wall and footwall of the MCT require partitioning a substantial component of this deformation onto structures to the south.Plain Language SummaryCollisions between continents cause deformation of the Earth’s crust and the uplift of large mountain ranges like the Himalayas. Large faults often form to accommodate this deformation and may help bring rocks once buried at great depths up to the surface of the Earth. The Greater Caucasus Mountains form the northernmost part of a zone of deformation due to the ongoing collision between the Arabian and Eurasian continents. The Main Caucasus Thrust (MCT) is a fault juxtaposing old igneous and metamorphic (crystalline) rocks against younger rocks that has often been assumed to be a major means of accommodating Arabia‐Eurasia collision. This study examines the history of rocks along the MCT with a combination of field work, study of microscopic deformation in rocks, and dating of rock formation and cooling. The crystalline rocks were added to the margins of present‐day Eurasia about 330–310 million years ago, and the MCT first formed about 190–135 million years ago. The MCT is likely at most one of many structures accommodating present‐day Arabia‐Eurasia collision.Key PointsAmphibolite‐facies metamorphism and plutonism in the Greater Caucasus basement took place ~330–310 MaThe Main Caucasus Thrust formed as a greenschist‐facies shear zone during Caucasus Basin inversion and/or rifting (~190–135 Ma)The Main Caucasus Thrust may have helped facilitate a portion of at least 5–8 km of basement exhumation during Arabia‐Eurasia collisionPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154626/1/tect21292-sup-0002-2019TC005828-ts01.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154626/2/tect21292-sup-0006-2019TC005828-ts05.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154626/3/tect21292_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154626/4/tect21292-sup-0003-2019TC005828-ts02.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154626/5/tect21292-sup-0005-2019TC005828-ts04.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154626/6/tect21292.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154626/7/tect21292-sup-0004-2019TC005828-ts03.pd

Pass a Law, Any Law, Fast! State Legislative Responses to the Kelo Backlash

The Supreme Court in Kelo v. City of New London left protection of property against takings for economic development to the states. Since Kelo, thirty-seven states have enacted legislation to update their eminent domain laws. This paper is the first to theoretically and empirically analyze the factors that influence whether, in what manner, and how quickly states change their laws through new legislation. Fourteen of the thirty-seven new laws offer only weak protections against development takings. The legislative response to Kelo was responsive to measures of the backlash but only in the binary decision whether to pass any new law. The decision to enact a meaningful restriction was more a function of relevant political economy measures. States with more economic freedom, greater value of new housing construction, and less racial and income inequality are more likely to have enacted stronger restrictions, and sooner. Of the thirteen states that have not updated, Arkansas, Oklahoma and Mississippi are highly likely to do so in the future. Hawaii, Massachusetts and New York are unlikely to update ever if at all

The choice of efficiencies and the necessity of politics

Efficiency requires legislative political institutions. There are many ways efficiency can be promoted, and so an ongoing legislative institution is necessary to resolve this choice in a politically sustainable and economically flexible way. This poses serious problems for classical liberal proposals to constitutionally protect markets from government intervention, as seen in the work of Ilya Somin, Guido Pincione & Fernando Tesón and others. The argument for the political nature of efficiency is set out in terms of both Pareto optimality and aggregate welfare maximisation, and similar arguments can be generalised to other social values

Applying the Theory of Affective Intelligence to Support for Authoritarian Policies and Parties

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/148346/1/pops12571.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/148346/2/pops12571_am.pd