Chicxulub impact structure, IODP‐ICDP Expedition 364 drill core: Geochemistry of the granite basement

The IODP-ICDP Expedition 364 drilling recovered a 829 m core from Hole M0077A, sampling ˜600 of near continuous crystalline basement within the peak ring Chicxulub impact structure. bulk consists pervasively deformed, fractured, and shocked granite. Detailed geochemical investigations 41 granitoid samples, that is, major trace element contents, Sr–Nd isotopic ratios are presented here, providing broad overview composition granitic basement. Mainly granite but also clasts (in melt rock), breccias, aplite were analyzed, yielding relatively homogeneous compositions between all samples. is part high-K, calc-alkaline metaluminous series. Additionally, they characterized by high Sr/Y (La/Yb)N ratios, low Y Yb which typical for adakitic rocks. However, other criteria (such as Al2O3 MgO Mg#, K2O/Na2O ratio, Ni concentrations, etc.) do not match adakite definition. Rubidium–Sr errorchron initial 87Sr/86Srt=326Ma suggest hydrothermal fluid metasomatic event occurred shortly after formation, in addition to postimpact alteration, mainly affected samples crosscut shear fractures or contact with aplite, where circulation was enhanced, would have preferentially fluid-mobile concentrations. (ɛNd)t=326Ma values range −4.0 3.2 indicate minor Grenville component may been involved genesis. Our results consistent previous studies, further supporting cored unit intruded Maya block during Carboniferous, an arc setting crustal melting related closure Rheic Ocean associated assembly Pangea. likely two distinct alteration events, both influencing chemistry: (1) event, possibly first stages Pangea breakup, approximately 50 Myr crystallization, (2) linked long-lived system Importantly, granites sampled M0077A unique when compared gneiss drill cores This marks them valuable lithologies provide new insights into Yucatán