A Faixa Araçuaí, localizada na porção setentrional da Província Mantiqueira, pode ser dividida em três domínios estruturais os quais estão envolvidos em um sistema de empurrões com vergência tanto oeste quanto para leste. A porção ocidental corresponde ao Domínio Milonítico constituido por gnaisses miloníticos de alta temperatura ~750ºC, o Domínio Central é caracterizado por intenso magmatismo tonalítico, granodiorítico e granítico de idade aproximada de 580 Ma e o setor oriental, denominado de Domínio Anatético, formado pelo Leucogranito Carlos Chagas (CC), um granito tipo S de idades compreendidas entre 572 ± 4 Ma a 597 ± 3 Ma. O Domínio Central, formado pelas Suítes Galiléia e Aimorés, são constituídas respectivamente pelos tonalitos São Vitor, e Galiléia e pelo Granito Caladão e o Charnockito Padre Paraíso. A Suíte Aimorés e a borda oeste do Leucogranito Carlos Chagas, constituem-se no foco desta dissertação, a qual teve por meta um estudo estrutural, baseado em Anisotropia de Suscetibilidade Magnética (ASM) e datações através dos métodos U/Pb em zircões e monazitas e Lu/Hf em zircões. Petrograficamente o Granito Caladão tem como característica uma textura porfirítica, com matriz de granulação grossa, composta por quartzo, feldspato, hornblenda e biotita, com cristais de feldspatos de 2 a 5 centímetros. O Charnockito Padre Paraíso é um hiperstênio granito, de cor esverdeada, de matriz de granulação grossa composta de quartzo, feldspato, hiperstênio, biotita e hornblenda, com cristais de feldspato de até 6 centímetros. O Leucogranito Carlos Chagas possui granulação media a grossa e apresenta em sua constituição, quartzo, feldspato, biotita sillimanita, cordierita e granada. Um granito tipo S. Os resultados da análise estrutural através da ASM apresentaram orientações variáveis da foliação magnética em setores distintos dos corpos magmáticos, compatível com a orientação espacial do plúton, indicando assim sua colocação, porém a orientações das lineações magnéticas sugerem uma direção predominantemente NNE-SSW, aventando um fluxo magmático nessa direção. Investigações sobre a mineralogia magnética através de curvas termomagnéticas evidenciaram ocorrências de óxidos de ferro, magnetita e hematita, tanto no Granito Caladão como no Charnockito Padre Paraíso. Os baixos valores de suscetibilidade magnética, da ordem de 10-4 a 10-5 SI sugerem que a ASM, para esses corpos ígneos, é controlada essencialmente pelos minerais paramagnéticos. Os elipsoides de ASM são dominantemente oblatos, caracterizando uma forte deformação por achatamento, apenas localmente foram identificados elipsoides prolato. As análises isotópicas forneceram idades de 500.7 ± 1.5 Ma a 512.1 ± 1.5 Ma (zircão) e 445.0 ± 9.5 Ma (monazita) para o Granito Caladão e de 498 ± 2.4 Ma a 502.7 ± 1.9 Ma (zircão) para o Charnockito Padre Paraíso. Idades obtidas como sendo mais antigas para o Granito Caladão e o Charnockito Padre Paraíso, respectivamente de 556.8 ± 3.7 Ma (zircão) e 576.0 ± 2.2 Ma (zircão) foram interpretadas como zircões herdados das rochas encaixantes quando do emplacement dos plutons. A idade de 570.1 ± 1.7 Ma para o CC na porção norte é compatível com as idades obtidas na literatura, entretanto na porção sul, as idades obtidas são da ordem de 510.8 ± 1.7 Ma e 520.5 ± 2.5 Ma para o CC, indicando pulsos magmáticos diacronicos. As determinações Lu/Hf revelaram valores de ?Hf negativos para todos os plutons estudados, mostrando que são provenientes de retrabalhamento crustal, de uma crosta arqueana e paleoproterozoica. / The Araçuaí Orogen corresponds the northern part of the Mantiqueira Province, which can be divided into three different structural domains. These areas are involved in thrust systems towards the west and east. The western part corresponds to the Mylonites Domain, constituted by high temperature mylonitic gneisses, the Central Domain is characterized by a huge tonalitic, granodioritic and granitic magmatism dated around 580 Ma, and, the eastern area, described as Anatexis Domain where the Carlos Chagas Leucogranite (CC) is the predominant lithology. The Galiléia Suite constituting by the St. Vitor and Galiléia tonalites, Aimorés Suites, by the Caladão Granite and the Padre Paraíso Charnockite, all theses suites belong to the Central Domain. The Aimorés Suite and the western border of the Carlos Chagas Leucogranite are the focus of this Master thesis, which the goals are a structural study based on Anisotropy of Magnetic Susceptibility (AMS) and a geochronological analysis using U/Pb in zircon and monazite and Lu/Hf in zircon methodologies. The petrographic analysis shows the Caladão Granite as porphyritic granite, with a thick granulation matrix composed of quartz, feldspar, hornblende and biotite. The feldspar crystals can reach 2 to 5 centimeters in size. The Padre Paraíso Charnockite is hypersthene granite; greenish-colored matrix with a coarse granulation composed of quartz, feldspar, hypersthene, biotite and hornblende, the feldspar crystals size can be bigger than 5 centimeters. The Carlos Chagas Leucogranite has medium to coarse granulation that is constituted by quartz, feldspar, biotite, sillimanite, cordierite and garnet, the mineralogy typical of type S granite. Structural analysis using the AMS showed variable magnetic foliation orientations in distinct sectors of the magmatic bodies, compatible with the spatial trend of the pluton, your emplacement, but the orientations of the magnetic lines suggest a predominantly NNE-SSW direction, suggesting a magmatic flow in this direction. Investigations on magnetic mineralogy through thermomagnetic curves showed evidence of iron magnetite and hematite oxides in both the Caladão Granite and the Padre Paraíso Charnockite. The low values of magnetic susceptibility, on the order of 10-4 to 10-5 SI, suggest that paramagnetic minerals essentially control the ASM for these igneous bodies. The AMS ellipsoids are predominantly oblate, characterizing a strong flattening deformation; only locally prolate ellipsoids have been identified. Isotopic analyzes performed at Caladão Granite provided ages ranging from 500.7 ± 1.5 Ma to 512.1 ± 1.5 Ma (zircon) and 445.0 ± 9.5 Ma (monazite), and zircon ages from 498 ± 2.4 Ma to 502.7 ± 1.9 Ma obtained in the Padre Paraíso Charnockite. Older zircon ages determined in the Caladão Granite and Padre Paraíso Charnockite are, respectively, 556.8 ± 3.7 Ma and 576.0 ± 2.2Ma, whose ages were interpreted as inherited zircons that were captured from the host rocks during the plutons emplacement. In the northern sector of the studied area, the CC age of 570.1 ± 1.7 Ma is compatible with the ages that were obtained in the literature, ranging from 572 ± 4 Ma to 597 ± 3 Ma, however in the south of the area some surprisingly younger ages (510.8 ± 1.7 Ma and 520.5 ± 2.5 Ma) in the CC, suggesting diachronic magmatic pulses. The Lu/Hf determinations revealed negative ?Hf values for all studied plutons, showing that they are derived from crustal reworking, from an Archaean and Paleoproterozoic crust. The most Hf model age are 2,0 Ga, however there are some Archean ages ranging from 3.0 to 3.8 Ga. The presence of highly negative values of -20 and -30 for the Caladão Granite are interpreted as largely crustal-derived melts.

O sistema pórfiro Yarumalito, caracterizado por concentrar minério em veios controlados por estruturas e stockworks encontra-se localizado no distrito mineiro de Marmato, que é considerado um dos mais antigos distritos de ouro da Colômbia, com atividades de extração que remontam da época dos Incas. O sistema ígneo da região é relacionado ao magmatismo Miocênico da Formação Combia. Neste trabalho foram descritas as rochas subvulcânicas diretamente relacionadas às zonas mineralizadas do sistema pórfiro Yarumalito com o objetivo de, após caracterizar as intrusões, realizar datação através do método U-Pb em zircão. Amostras selecionadas de duas intrusões férteis, uma andesítica mais abundante na área e outra diorítica com características intrusivas na primeira e de ocorrência mais restrita, foram criteriosamente descritas e tiveram zircões separados e posteriormente analisados por SHRIMP na Universidade de São Paulo. Os resultados apontaram para um intervalo bastante restrito para as idades, com médias ponderadas das idades 206Pb/238U variando de 7 ± 0.15 Ma para o andesito pórfiro a 6.95 ± 0.16 Ma para o diorito pórfiro. Estes resultados sugerem um período restrito no tempo para a cristalização das intrusivas portadoras de mineralizações na área do projeto e posicionam o sistema Yarumalito para o final do magmatismo Combia. / The Yarumalito porphyry system, characterized to concentrate ore in structure related veins and stockworks is located in the mining district of Marmato, that is considered one of the oldest gold mining districts of Colombia, with exploration activities since the Inca Empire. The igneous system of the region is related to the miocenic magmatism of the Combia formation. In this paper, the subvolcanic rocks directly related with the mineralized zones of the Yarumalito porphyry were described in order to, after characterization, obtain UPb ages in zircon to the intrusions. Selected samples of the two fertile intrusions, one andesitic more abundant in the area and one dioritic more restricted, were carefully described and had their zircon grains separated and analyzed by SHRIMP in the University of São Paulo. The results points to a very restricted interval for the ages, with weighted average 206Pb/238U varying from 7 ± 0.15 Ma for the andesitic porphyry and 6.95 ± 0.16 Ma for the dioritic porphyry. These results suggest a brief period for the crystallization of the mineralized subvolcanic rocks in the area and constrain the Yarumalito system to the final stages of the Combia magmatism.

No description available.

The Wrangellia composite terrane is one of the largest fragments of juvenile crust added to the North American continent since Mesozoic time, and refining its accretionary history has important implications for understanding how continents grow. New U-Pb geochronology and Hf isotopes of detrital zircons from Late Jurassic-Late Cretaceous strata from the forearc of the Wrangellia composite terrane allows more insight on the tectonic and paleogeographic history of the terrane. Our stratigraphically oldest samples from the Late Jurassic Naknek Formation have a detrital zircon U-Pb signature dominated by Early and Late Jurassic grains (195-190 Ma; 153-147 Ma). Hf isotopic compositions of these grains are juvenile to intermediate (εHf(t)=4.5-14.7). Disconformably above the Naknek Formation are two poorly understood units Ks and Kc. The Ks unit is dominated by Early to Late Jurassic grains (159-154 Ma) with a few Paleozoic grains (347-340 Ma). Hf isotopic compositions of Carboniferous-Jurassic grains are juvenile to intermediate (εHf(t)=6.0-18.8). The overlying Kc unit has Late to Early Jurassic zircons (198-161 Ma), and an increase in Paleozoic ages (374-323 Ma). Hf isotopic compositions of these grains are juvenile to intermediate (εHf(t)=4.5-14.7). Samples from the Matanuska Formation have major Late Cretaceous grains (90-71 Ma), and minor Early Cretaceous (137-106 Ma), Late to Early Jurassic (200-153 Ma), Paleozoic (367-277 Ma), and Precambrian grains (2597-1037 Ma). Hf compositions have a wider range from both the Late Cretaceous grains (εHf(t)=-1.5-14.9) and Paleozoic-Precambrian grains (εHf(t)=-23.7-16.3). Our results suggest an evolving provenance from Late Jurassic to Late Cretaceous time for the Wrangellia composite terrane forearc basin. The Late Jurassic Naknek Formation samples were dominantly derived from a juvenile to intermediate Jurassic igneous sediment source. During Early Cretaceous time, there is a slight increase in the number of Paleozoic grains in the Ks and Kc unit samples. The Early Cretaceous sediments have a mostly positive Hf isotopic compositions suggesting exhumation of Jurassic and Paleozoic juvenile igneous sediment sources. By Late Cretaceous time, our data illustrates another increase in Paleozoic grain abundances, in addition to the introduction of Precambrian grains, all with widely variable Hf isotopic compositions. We interpret this to reflect a larger sediment flux from the interior of Alaska where more evolved igneous rocks of that age are found.

The 87Rb-86Sr system is a widely used long-lived isotope geochronometer. 87Rb, the naturally occurring radioactive isotope of Rb, undergoes beta-decay to stable 87Sr with a half-life of approximately 50 Ga. Decay of 87Rb to 87Sr results in variable 87Sr/86Sr in minerals with different Rb/Sr, and measurement of 87Rb/86Sr and 87Sr/86Sr allows for the determination of the age of the rock. Accurate ages depend both on the quality of the isotopic analysis and on the accuracy of the 87Rb decay constant, lambda87. Although the currently accepted value for lambda87 of 1.42 × 10-11a-1 has been in use for over 30 years, there is growing evidence that it is not accurate. Recent attempts to refine lambda87 and its precision have not reached a consensus. This thesis describes a new experiment to measure lambda87 by 87Sr accumulation over a period of about 30 years, and the preparation of a 84-86Sr double-spike in conjunction with that experiment. Radiogenic 87Sr produced in aliquots of a RbClO4 salt was measured by isotope dilution thermal ionization mass spectrometry. An average of 31 measurements yields a value of 1.398 ± 0.003 × 10-11a-1 . This requires a substantial revision from the previously accepted decay constant and makes Rb-Sr ages calculated with it 1.5% older. A Rb-Sr and U-Pb isotopic chronometry study was carried out on thirteen ordinary chondrites – the most common type of meteorite, the origin and history of which are still unclear. Some meteorites appear disturbed, possibly by recent shock during breakup of the parent body, whereas others yielded accurate and precise U-Pb and Pb-Pb ages. For example, L5 Elenovka yielded distinct ages for silicates (4555 Ma) and phosphates (4535 Ma), allowing the cooling rate of this meteorite from approximately 1055 K to 759 K to be constrained to 15 ± 3 K/Ma. Rb-Sr yielded less precise ages than U-Pb, but using the new decay constant allows accurate comparison between the two methods. This study creates a firm foundation for future studies in thermal history of chondrites and terrestrial metamorphic complexes using Rb-Sr together with other isotopic chronometers.

The 87Rb-86Sr system is a widely used long-lived isotope geochronometer. 87Rb, the naturally occurring radioactive isotope of Rb, undergoes beta-decay to stable 87Sr with a half-life of approximately 50 Ga. Decay of 87Rb to 87Sr results in variable 87Sr/86Sr in minerals with different Rb/Sr, and measurement of 87Rb/86Sr and 87Sr/86Sr allows for the determination of the age of the rock. Accurate ages depend both on the quality of the isotopic analysis and on the accuracy of the 87Rb decay constant, lambda87. Although the currently accepted value for lambda87 of 1.42 × 10-11a-1 has been in use for over 30 years, there is growing evidence that it is not accurate. Recent attempts to refine lambda87 and its precision have not reached a consensus. This thesis describes a new experiment to measure lambda87 by 87Sr accumulation over a period of about 30 years, and the preparation of a 84-86Sr double-spike in conjunction with that experiment. Radiogenic 87Sr produced in aliquots of a RbClO4 salt was measured by isotope dilution thermal ionization mass spectrometry. An average of 31 measurements yields a value of 1.398 ± 0.003 × 10-11a-1 . This requires a substantial revision from the previously accepted decay constant and makes Rb-Sr ages calculated with it 1.5% older. A Rb-Sr and U-Pb isotopic chronometry study was carried out on thirteen ordinary chondrites – the most common type of meteorite, the origin and history of which are still unclear. Some meteorites appear disturbed, possibly by recent shock during breakup of the parent body, whereas others yielded accurate and precise U-Pb and Pb-Pb ages. For example, L5 Elenovka yielded distinct ages for silicates (4555 Ma) and phosphates (4535 Ma), allowing the cooling rate of this meteorite from approximately 1055 K to 759 K to be constrained to 15 ± 3 K/Ma. Rb-Sr yielded less precise ages than U-Pb, but using the new decay constant allows accurate comparison between the two methods. This study creates a firm foundation for future studies in thermal history of chondrites and terrestrial metamorphic complexes using Rb-Sr together with other isotopic chronometers.

The Ertsberg-Grasberg Mining District of Papua, Indonesia (Western New Guinea) hosts the Ertsberg Cu-Au Skarn, the giant Grasberg Porphyry Cu-Au deposit, and several other orebodies. Two 1700-meter-long cores beneath the Kucing Liar ore skarn (KL98-10-22) and the Grasberg Igneous Complex (KL98-10-21) contain high concentrations of vein and disseminated molybdenite. KL98-10-22, the focus of this study, intersects two previously unencountered intrusions, the “Tertiary intrusion Kucing Liar” (Tikl) and “Tertiary Pliocene intrusion” (Tpi). An intense dilatational quartz vein stockwork cuts Tikl and Ekmai Sandstone (Kkes) units, predating Tpi intrusion. Prior to these ultradeep cores, which extend almost 3 km below pre-mining surface, molybdenite was rarely observed in the district. Geochemistry and isotopic data indicate that Tikl and Tpi intrusions originated from the same large magmatic system that emplaced other ore-forming Ertsberg-Grasberg district intrusions. Magma in a lower crustal chamber was recharged at least twice, according to Sr-Nd data. Laser-ablation inductively-coupled plasma mass spectrometry of magmatic zircons yields 238U-206Pb ages between 3.40 ± 0.12 Ma (Dalam Andesite) and 2.77 ± 0.15 Ma (Ertsberg intrusion), revealing a shorter period of igneous activity than previously measured by K-Ar and Ar-Ar dating. Analyses include composite ages of 3.28 ± 0.08 Ma for Tikl and 3.18 ± 0.11 Ma for Tpi. Inherited zircon cores indicate Precambrian (mostly Proterozoic) basement. Molybdenite veining beneath the Kucing Liar Skarn and Grasberg Igneous Complex postdates stockwork veining and occurred before the 2.99 ± 0.11 Ma Kali dikes. Only one molybdenite vein was observed cutting Tpi. Molybdenites yielded ~3 Ma Re-Os ages and anomalous >4 Ma and <0.5 Ma ages; anomalous ages were not reproducible in follow-up analyses (this study). Smearing deformation of molybdenite (through fault activity) causes crystal strain, likely leading to annealing recrystallization. Recrystallization possibly redistributes daughter-product Os, resulting in anomalous ages from annealed material. Fluids with high Mo/Cu ratios (which were likely supercritical) precipitated late-stage molybdenite deep in the system. These fluids developed through magma chamber crystallization, which concentrated molybdenum in the melt as an incompatible element, and stripping of Cu from the magma chamber during hydrothermal activity. / text

The Ertsberg-Grasberg Mining District of Papua, Indonesia (Western New Guinea) hosts the Ertsberg Cu-Au Skarn, the giant Grasberg Porphyry Cu-Au deposit, and several other orebodies. Two 1700-meter-long cores beneath the Kucing Liar ore skarn (KL98-10-22) and the Grasberg Igneous Complex (KL98-10-21) contain high concentrations of vein and disseminated molybdenite. KL98-10-22, the focus of this study, intersects two previously unencountered intrusions, the “Tertiary intrusion Kucing Liar” (Tikl) and “Tertiary Pliocene intrusion” (Tpi). An intense dilatational quartz vein stockwork cuts Tikl and Ekmai Sandstone (Kkes) units, predating Tpi intrusion. Prior to these ultradeep cores, which extend almost 3 km below pre-mining surface, molybdenite was rarely observed in the district. Geochemistry and isotopic data indicate that Tikl and Tpi intrusions originated from the same large magmatic system that emplaced other ore-forming Ertsberg-Grasberg district intrusions. Magma in a lower crustal chamber was recharged at least twice, according to Sr-Nd data. Laser-ablation inductively-coupled plasma mass spectrometry of magmatic zircons yields 238U-206Pb ages between 3.40 ± 0.12 Ma (Dalam Andesite) and 2.77 ± 0.15 Ma (Ertsberg intrusion), revealing a shorter period of igneous activity than previously measured by K-Ar and Ar-Ar dating. Analyses include composite ages of 3.28 ± 0.08 Ma for Tikl and 3.18 ± 0.11 Ma for Tpi. Inherited zircon cores indicate Precambrian (mostly Proterozoic) basement. Molybdenite veining beneath the Kucing Liar Skarn and Grasberg Igneous Complex postdates stockwork veining and occurred before the 2.99 ± 0.11 Ma Kali dikes. Only one molybdenite vein was observed cutting Tpi. Molybdenites yielded ~3 Ma Re-Os ages and anomalous >4 Ma and <0.5 Ma ages; anomalous ages were not reproducible in follow-up analyses (this study). Smearing deformation of molybdenite (through fault activity) causes crystal strain, likely leading to annealing recrystallization. Recrystallization possibly redistributes daughter-product Os, resulting in anomalous ages from annealed material. Fluids with high Mo/Cu ratios (which were likely supercritical) precipitated late-stage molybdenite deep in the system. These fluids developed through magma chamber crystallization, which concentrated molybdenum in the melt as an incompatible element, and stripping of Cu from the magma chamber during hydrothermal activity. / text

The Ertsberg-Grasberg Mining District of Papua, Indonesia (Western New Guinea) hosts the Ertsberg Cu-Au Skarn, the giant Grasberg Porphyry Cu-Au deposit, and several other orebodies. Two 1700-meter-long cores beneath the Kucing Liar ore skarn (KL98-10-22) and the Grasberg Igneous Complex (KL98-10-21) contain high concentrations of vein and disseminated molybdenite. KL98-10-22, the focus of this study, intersects two previously unencountered intrusions, the “Tertiary intrusion Kucing Liar” (Tikl) and “Tertiary Pliocene intrusion” (Tpi). An intense dilatational quartz vein stockwork cuts Tikl and Ekmai Sandstone (Kkes) units, predating Tpi intrusion. Prior to these ultradeep cores, which extend almost 3 km below pre-mining surface, molybdenite was rarely observed in the district. Geochemistry and isotopic data indicate that Tikl and Tpi intrusions originated from the same large magmatic system that emplaced other ore-forming Ertsberg-Grasberg district intrusions. Magma in a lower crustal chamber was recharged at least twice, according to Sr-Nd data. Laser-ablation inductively-coupled plasma mass spectrometry of magmatic zircons yields 238U-206Pb ages between 3.40 ± 0.12 Ma (Dalam Andesite) and 2.77 ± 0.15 Ma (Ertsberg intrusion), revealing a shorter period of igneous activity than previously measured by K-Ar and Ar-Ar dating. Analyses include composite ages of 3.28 ± 0.08 Ma for Tikl and 3.18 ± 0.11 Ma for Tpi. Inherited zircon cores indicate Precambrian (mostly Proterozoic) basement. Molybdenite veining beneath the Kucing Liar Skarn and Grasberg Igneous Complex postdates stockwork veining and occurred before the 2.99 ± 0.11 Ma Kali dikes. Only one molybdenite vein was observed cutting Tpi. Molybdenites yielded ~3 Ma Re-Os ages and anomalous >4 Ma and <0.5 Ma ages; anomalous ages were not reproducible in follow-up analyses (this study). Smearing deformation of molybdenite (through fault activity) causes crystal strain, likely leading to annealing recrystallization. Recrystallization possibly redistributes daughter-product Os, resulting in anomalous ages from annealed material. Fluids with high Mo/Cu ratios (which were likely supercritical) precipitated late-stage molybdenite deep in the system. These fluids developed through magma chamber crystallization, which concentrated molybdenum in the melt as an incompatible element, and stripping of Cu from the magma chamber during hydrothermal activity. / text

This dissertation research addresses the tectonism of continental crust during ocean basin closure, suturing between continental landmasses, and collisional orogenesis. The new data and insights presented here were gathered through localized geologic investigations of the Tibetan Plateau of central Asia. This area of central Asia is an ideal location to study these fundamental tectonic processes because it has been the locus of numerous Tethyan ocean basins and terminal collisions between continents during Phanerozoic accretion of Gondwana-derived landmasses onto the southern margin of Eurasia. In this work, I propose, in many orogens, that high-pressure (HP) metamorphism of continental rocks may mark the early stages of the suturing process between continental landmasses rather than the culmination of suturing. This insight has been acquired from a geologic-, geochronologic-, and thermochronologic-based investigation of the HP-near ultrahigh-pressure bearing Triassic metasedimentary metamorphic belt in central Tibet. This work shows near synchronous continent-continent collisions between landmass adjacent to the Paleo-Tethys ocean prior to its final closure in Late Triassic time. In addition, this work shows that Mediterranean-style tectonics may be more widespread during accretionary tectonics than previously thought. A comparison between the distribution of the HP bearing metamorphic belt, autochthonous crystalline basement, and geophysical images of Tibet suggests that a Mesozoic tectonic feature may be controlling the structure and distribution of melt within the middle crust of the Tibetan Plateau. This concept underscores the importance of inherited tectonic frameworks on the evolution of orogenic plateaus. Work in southwest Tibet, along the India-Asia suture zone, highlights the complex behavior of continental crust during collisional orogenesis. This work identifies previously undocumented magmatism, crustal antexis, and high-grade metamorphism along the India-Asia suture. In this work I attribute these observations to the initial interactions between Indian, Asian, and subducting Neo-Tethys oceanic lithosphere.