Stratigraphic data and ^Ar-39Ar ages for the Early Cretaceous ParaniEtendeka flood basalts indicate that the main magmatic episode lasted for several m.y. (129-134 Ma) and was linked to the northward opening of the South Atlantic Ocean, but with some earlier magmatism (135-138 Ma) found inland far from the eventual oceanic rift. The regional distribution of distinct high-TiN (Urubici, Pitanga, ...

Introduction: Basaltic volcanism is a fundamental process that has occurred on most terrestrial planets like Earth, Moon, and Mars. As partial melts of planetary interiors, basalts have compositions that reflect the planet’s bulk composition, its oxidation state, and the size and composition of its core. Several previous studies have compared bulk-rock major-, minor-, and traceelement compositi...

The Cenozoic Mormon Mountain Volcanic Field (MMVF) of northern Arizona is situated in the transition zone between the Basin and Range and the Colorado Plateau. It is composed of alkalic to sub-alkalic basalts and calcalkalic andesites, dacites, and rhyodacites. Despite their spatial and temporal association, the basalts and the calcalkalic suite do not seem to be co-genetic. The petrogenesis of...

To constrain further the Mg isotopic composition of the Earth and chondrites, and investigate the behavior of Mg isotopes during planetary formation and magmatic processes, we report high-precision (±0.06& on dMg and ±0.07& on dMg, 2SD) analyses of Mg isotopes for (1) 47 mid-ocean ridge basalts covering global major ridge segments and spanning a broad range in latitudes, geochemical and radioge...

Continental flood basalts and mid-ocean ridge (MOR) tholeiitic basalts have distinctly different 14 3 Ndf1 44 Nd which may permit a priori distinctwn between '"continental" and "oceanic" igneous rocks. Initial 14 3 NdJI 4 4 Nd of continental igneous rocks through time fall on a Sm/Nd evolution curve with chondritic REE abundance ratio. These observations indicate that many continental igneous r...

The basalts within Oceanus Procellarum have been named the Oceanus Procellarum Group and subdivided into four major geologic units on the basis of morphology, spectral reflectance, and other remote sensing information in order to develop a framework of regional stratigraphy for the largest lunar mare. The oldest mare basalt unit identified, the Repsold Formation (blue color, low albedo, high cr...

The Izu-Bonin-Mariana (IBM) island arc formed following initiation of subduction of the Pacific plate beneath the Philippine Sea plate at about 52 Ma. Site U1438 of IODP Expedition 351 was drilled to sample the oceanic basement on which the IBM arc was constructed, to better understand magmatism prior to and during the subduction initiation event. Site U1438 igneous basement Unit 1 (150 m) was ...

Introduction: The A16 (Apollo16) site in the lunar nearside highlands is 220 km from the nearest mare. Thus it is no surprise that mare basalt samples are uncommon at the site. Here, we present the petrography and geochemistry of 5 new mare basalt samples found at the A16 site. We also discuss possible provenances of all A16 mare basalt samples using high-resolution global data for the distribu...