Roberto Molina Garza

• PhD
• Investigador Titular at National Autonomous University of Mexico

We report paleomagnetic data for the Lower to Middle Jurassic La Silla and Todos Santos formations of southern Mexico, in west-central Chiapas and the Tehuantepec Isthmus region. Volcanic rocks and red beds of these formations were deposited prior to or during the early stages of Gulf of Mexico opening. Dual-polarity characteristic magnetizations r...

Stratigraphic relationships, detrital zircon provenance, U-Pb and Ar-40/Ar-39 geochronology, and trace element geochemistry in volcanic and sedimentary rocks of the Sierra homocline of central Chiapas near La Angostura reservoir in Mexico document an extensive pulse of Early-Middle Jurassic arc magmatism in rocks that overlie and intrude the Permia...

Twenty-eight selected sites (individual beds) in the Moenave Formation at the Echo Cliffs, northern Arizona, strata give a Hettangian paleomagnetic pole at 63.7°N, 59.7°E (dp = 2.6°, dm = 5.1°). The Wingate Sandstone and Rock Point Formation at Comb Ridge, southeast Utah, provide a Rhaetian paleopole at 57.4°N, 56.6°E (N = 16 sites; dp = 3.4, dm =...

The Zicapa Formation of Early Cretaceous is characterized by the presence of clastic rocks interbeded with layers of limestones and calcareous sandstones, deposited in continental to marine transitional environment, with an important income of primary volcanic material contemporaneous with de dated in the locality with an age between 151-131 My in...

El límite oriental del rift Golfo de California está pobremente definido, especialmente en su extremo septentrional en el área transfronteriza de México-EUA. Con el objetivo de precisar su localización en esta región, hemos realizado un modelo 2D de resistividad eléctrica a partir de datos magnetotelúricos adquiridos en 16 sondeos a lo largo de un...

An extensive dataset of existing and new geo/thermochronological data from several areas in Southern Mexico constrains the tectonic history of the region, as well as various source-to-sink relationships and local burial histories. Our interpretation acknowledges that not all cooling/heating observed in the source areas is due to erosional exhumatio...

An extensive dataset of existing and new geo/thermochronological data from several areas in Southern Mexico constrains the tectonic history of the region, as well as various source-to-sink relationships and local burial histories. Our interpretation acknowledges that not all cooling/heating observed in the source areas is due to erosional exhumatio...

An extensive dataset of existing and new geo/thermochronological data from several areas in Southern Mexico constrains the tectonic history of the region, as well as various source-to-sink relationships and local burial histories. Our interpretation acknowledges that not all cooling/heating observed in the source areas is due to erosional exhumatio...

We report results of a study of the Chicontepec Formation magnetic fabric in the central and southern region of the Tampico-Misantla basin in the state border region between Veracruz and Hidalgo. Samples were collected at 16 sites corresponding to two main facies associations: channel-fill facies and channel overbank facies. The channel facies domi...

Three successive strain regimes spanning up to ~16 million years were identified from the field, structural and geochronological analyses in Upper Eocene-Oligocene migmatites of the Xolapa Complex around the Puerto Escondido longitude (~97°W), in southern Mexico. A west-facing asymmetric folding affecting diatexites at ca. 38–31 Ma defines Regime A...

In this study 3D inversion of satellite gravimetric data with 3DINVER.M program is applied to model the depth of the crust in the Gulf of California rift. This rift dextrally separates Baja California Peninsula from the North American continent since Miocene, period in which the change occurred from ajundamentally extensional tectonic regime to the...

We studied the structure, paleomagnetism, and magnetic fabric of Miocene granitoids intruded along the left‐lateral, transpressional, Tonalá shear zone in Chiapas, southern Mexico. Magmatic fabrics delineate patterns of regional folding striking parallel to the shear zone, suggesting syn‐magmatic shortening. Magnetic susceptibility fabrics are well...

Dual-polarity characteristic magnetizations in red sandstones of the Early and Middle Eocene El Bosque Formation in central Chiapas, Mexico (D = 9.3° I = 23.6°; N = 19 selected sites, k = 32.6, α95 = 6.0°) indicate about 20° of clockwise rotation when compared with a coeval paleomagnetic reference pole in the North America craton. We interpret the...

We redefine the "Chontal arc" of the southern Isthmus of Tehuantepec, Mexico, as the Chontal allochthon. The Chontal assemblage is composed of Upper Creta-ceous low-grade metavolcanic and metasedimentary rocks included in the Chivela lithodeme. By means of field observations, laser-ablation detrital zircon geochronol-ogy, and trace-element geochemi...

New and existing strontium isotope data are given for several widespread evapo-rites from western equatorial Pangea. The data indicate evaporite deposition occurred on proximal margins of the Gulf of Mexico at ca. 169 Ma (Bajocian, not Callovian as commonly thought) and 166 Ma in Trinidad (Bathonian-Callovian boundary). The 166 Ma age may also appl...

This volume furthers our understanding of key basins in central and southern Mexico, and establishes links to exhumed sediment source areas in a plausible paleogeographic framework. Authors present new data and models on the relations between Mexican terranes and the assembly and breakup of western equatorial Pangea, plate-tectonic and terrane reco...

This volume furthers our understanding of key basins in central and southern Mexico, and establishes links to exhumed sediment source areas in a plausible paleogeographic framework. Authors present new data and models on the relations between Mexican terranes and the assembly and breakup of western equatorial Pangea, plate-tectonic and terrane reco...

This volume furthers our understanding of key basins in central and southern Mexico, and establishes links to exhumed sediment source areas in a plausible paleogeographic framework. Authors present new data and models on the relations between Mexican terranes and the assembly and breakup of western equatorial Pangea, plate-tectonic and terrane reco...

We present an updated, internally consistent synthesis of the Permo-Triassic assembly and Mesozoic evolution of the Gulf of Mexico, Mexico, Florida-Bahamas, northern South America (Guiana margin and northern Andes) incorporating advances at regional, field and geochronological levels. The recently determined Bajocian age for salt deposition (using...

Jurassic northward migration of Mexico, which lay on the southern part of the North America plate, resulted in temporal evolution of climate-sensitive depositional environments. Lower–Middle Jurassic rocks in central Mexico contain a record of warm-humid conditions, indicated by coal, plant fossils, and compositionally mature sandstone deposited in...

The Miocene Nanchital conglomerate of the western Chiapas Foldbelt is the coarsest terrigenous clastic depositional Cenozoic unit of the region, probably comprising more proximal sections of hydrocarbon-rich slope-fan reservoirs found in the more distal Sureste Basin of the southern Gulf of Mexico fringe. Traditionally, the felsic igneous and metam...

A database of 134 apatite fission track (AFT), and apatite and zircon (U–Th)/He analyses has been assembled for eastern Mexico. Most of these samples have reset ages and track lengths reflecting rapid cooling. Time–temperature histories were modelled for 99 localities, and were converted to depth using a constant gradient of 30°C km−1. Maps of thes...

Jurassic reconstruction of Mexico, as western margen of equatorial Pangea, has been under debate since the application of paleomagnetism to adjust the original model of Wegener. This due to part of Mexico causes conflict in the adjustment of global and regional reconstructions, causing the well-known overlap between southern part of Mexico and the...

The southern extension of the Western Cordillera of North America, in western Mexico, is integrated by accreted terranes of oceanic affinity, conforming the Guerrero superterrane. This tectonic elements are composed of volcanic and volcano-sedimentary rocks from the Upper Jurassic to the Cretaceous, resting on a meta-sedimentary basement of suppose...

Recent Bajocian Sr87/86 ages (169 Ma) for Louann, Campeche, and other evaporite samples in the northern, southern, and western proximal rims of the Gulf of Mexico Basin (GoM) suggest that new perspectives on the basin’s rift and drift history are warranted. Presently, sea-floor spreading is believed to have started in the Oxfordian because (1) salt...

Paleogeographic reconstructions place the Chortis block adjacent to southern Mexico in the Late Cretaceous and earlier time, forming the tectonically disturbed southwestern tip of the North American plate. This study assesses the relative motion between Chortis and North America during the Laramide orogeny, later development of the North America-Ca...

We discuss the 2018 publication that reports petrographic, heavy mineral data, mineral chemistry, and zircon geochronology for Oligocene sandstones in the Cerro Pelón area in southern Mexico Sureste basin. As the title of their paper says, the goal of their study is to establish the source (s) of the voluminous Cenozoic section in this region, reac...

In this article we present a compilation of U–Pb zircon ages of the whole Xolapa terrane in coastal southern Mexico (dataset 1) as a curved line, obtained from plotting individual zircon grains versus its corresponding age. We identified five low-slope segments of the curved line, each one assigned to a high zircon-production (or preservation) even...

Zepeda et al. (2018) present the sandstone petrography of Lower-Middle Jurassic sedimentary rocks of the Tezoatlán basin, in Oaxaca, southern Mexico. These data are for a well-known locality, historically know for its plant and ammonite fossil content. They also present detrital zircon geochronology for two samples in a measured section about 200 m...

Phase 1 of the Colorado Plateau Coring Project (CPCP-I) recovered a total of over 850 m of stratigraphically overlapping core from three coreholes at two sites in the Early to Middle and Late Triassic age largely fluvial Moenkopi and Chinle formations in Petrified Forest National Park (PFNP), northeastern Arizona, USA. Coring took place during Nove...

Structural data and cross-cutting relationships in the Xolapa Complex around Puerto Escondido, southern Mexico, indicate the development of two pre-Cenozoic folding systems recorded, in part, by migmatites. The older system is defined by gently SW-plunging, vertical open folds (FS1), related to a southwestward extension. A subsequent FS2 folding sy...

Poles from continental redbeds are a large fraction of the world's palaeomagnetic database. Nonetheless, the time of acquisition and origin of the remanent magnetization of redbeds has been long debated. We report palaeomagnetic data, rock magnetic data, and microscope observations for Lower Cretaceous redbeds in southern Mexico. These data allow u...

The North American Cordillera has been shaped by a long history of accretion of arcs and other buoyant crustal fragments to the western margin of the North American plate since early Mesozoic time. The southernmost accreted terrane is the Guerrero terrane of southwestern Mexico, a latest Jurassic-Cretaceous volcanic arc built on a Triassic accretio...

We show new data regarding the rock magnetic signature of chemical vs. depositional remanence of the Zicapa Formation, a continental to transitional marine sedimentary sequence from southern Mexico. Thermal demagnetization shows a multivectorial behavior with a north-directed low unblocking-temperature component (<200° C) interpreted as a viscous r...

Mio-Pliocene hypabyssal rocks of the Combia event in the Amagá basin (NW Andes- Colombia), contain a deformational record of the activity of the Cauca-Romeral fault system, and the interaction of terranes within the Choco and northern Andean blocks. Previous paleomagnetic studies interpreted coherent counterclockwise rotations and non- coherent mod...

We present the electrical resistivity model along a profile perpendicular to the Middle America trench in southern Mexico that reveals previously unrecognized tectonic features at upper to mid-crustal depths. Our results support the hypotheses that the upper crust of the Oaxaca terrane is a residual ~20 km thick crust composed by an ~10 km thick fa...

Lower Cretaceous depositional systems of southwestern Oaxaquia, in south-central Mexico, were influenced by initiation of a continental arc on mainland Mexico and subsequent accretion of the Guerrero composite arc terrane to mainland Mexico. The Atzompa Formation, defined herein, which crops out in the Sierra de Tentzo, constitutes a succession of...

We present the electrical resistivity model along a profile perpendicular to the Middle America trench in southern Mexico that reveals previously unrecognized tectonic features at upper to mid-crustal depths. Our results support the hypotheses that the upper crust of the Oaxaca terrane is a residual ~20 km thick crust composed by an ~10 km thick fa...

The Lower Cretaceous depositional systems of southwestern Oaxaquia, in south-central Mexico, were controlled by tectonic processes related to the instauration of a continental arc and the accretion of the Guerrero arc to mainland Mexico. The Atzompa Formation refers to a succession of conglomerate, sandstone, siltstone, and limestone that crop out...

We report geological and palaeomagnetic data from five discrete plutons in the southern part of the Peninsular Ranges batholith (PRB) and one pluton that is part of the Jurassic plutonic suite in the Vizcaíno peninsula. The PRB plutons are Cretaceous and belong to the Alisitos island arc. The Jurassic pluton intrudes a Triassic-Jurassic ophiolite....

Late Miocene plutons in coastal Chiapas, Mexico, represent the roots of an extinct magmatic arc. Miocene granitoids of calc-alkaline composition and arc chemistry intruded into and were deformed within the Tonalá mylonite belt in the middle to upper crust. The mylonite belt is a crustal-scale shear zone extending along the western margin of the Chi...

El Chichón and Tacaná, two active volcanoes in the southeastern Mexico Chiapas state, illustrate the complexity of the magmatic systems in the Middle America Trench. Tacaná represents the northwestern end of the Central American Volcanic Arc, whilst El Chichón is the northernmost volcano of the Modern Chiapanecan Volcanic Arc. Tacaná was built on M...

The Rancho Nuevo semi-circular structure is a geomorphological structure defined by drainage patterns in coastal Sonora, about 160 km NW of Hermosillo. The structure is about 15 by 30 km, and it is cored by felsic to intermediate plutons (granodiorite, monzogranite, quartz-porphyry) covered by Miocene volcanic rocks. This work is focused on the def...

The La Union volcanic-plutonic complex is located near the southwestern margin of the Peninsular Ranges batholith (PRb). La Union complex rocks are grouped into prebatholithic and batholithic rock units. Batholithic rocks are assigned to the Cretaceous western zone of the PRb, which is associated with the Alisitos island arc. Prebatholithic rocks a...

El Macizo de Chiapas (MC) es un complejo plutónico y metamórfico del Pérmico-Triásico que está regionalmente ubicado en el extremo occidental del Bloque Maya. Un cinturón de pliegues y cabalgaduras ubicado a lo largo del margen norte del MC, y vigente hace 12-10 Ma, exhumó rocas sedimentarias suprayacentes del Jurásico-Mioceno. Asimismo, a lo largo...

U-Pb ages of ignimbrites and detrital-zircon analyses from Middle Jurassic through lowermost Cretaceous strata in northeastern Durango, Mexico, indicate the age of local volcanism and the age range, respectively, of the Jurassic continental-margin arc in north-central Mexico, where it is termed the Nazas arc. The type Nazas Formation along the Rio...

The Lower Cretaceous of western Mexico has been interpreted as the record of magmatism and sedimentation in an island arc system, separated of the continental margin by a marginal basin, east of which a system of carbonate platforms was developed on the pre-Mesozoic basement. The sedimentological characteristics and facies relations of the Zicapa F...

The Lower Cretaceous of western Mexico has been interpreted as the record of magmatism and sedimentation in an island arc system, separated of the continental margin by a marginal basin, east of which a system of carbonate platforms was developed on the pre-Mesozoic basement. The sedimentological characteristics and facies relations of the Zicapa F...

We report structural, paleomagnetic, and magnetic fabric data for mid- Cretaceous plutons of the Peninsular Ranges batholith along a transect at ∼30°N latitude. Four plutons in the western sector are characterized by characteristic magnetizations residing in magnetite. In this sector, El Milagro, Aguaje del Burro, La Zarza, and San Telmo plutons yi...

We report structural and paleomagnetic data for five mid-Cretaceous plutons along the southwestern margin of the Peninsular Ranges batholith (PRb). With the exception of the Punta Prieta pluton area in the Pacific coast, where Aptian Alisitos Fm. is well identified, the plutons of the studied region intruded arc related Jurassic-Early Cretaceous vo...

The Oligocene Upper Panalillo Ignimbrite is widely distributed in the San Luis Potosí Volcanic Field, in the southeastern portion of the Mesa Central province of Mexico. It crops out sporadically over a ~15,000 km2 area. The best exposures of the ignimbrite were sampled for paleomagnetic and geochronological studies, with sites grouped in five zone...

http://www.ugm.org.mx/bak/raugm/2012/docs/GEOS32-1_PRELIMINAR.pdf

In this work we report the preliminary results of a study that includes geological mapping, stratigraphy, sedimentology, paleomagnetism and detrital geocronology of the Sierra Madre del Sur in the states of Guerrero and Puebla, southern Mexico. The Lower Cretaceous Zicapa Formation is characterized by the presence of clastic rocks interbeded with l...

The Sierra de Catorce in northern San Luis Potosí, Mexico, represents an uplifted block with exposures of the oldest rocks of the region which include Upper Trias-sic turbidites interpreted as deposits of a submarine fan system (" Potosí Fan ") and overlying Lower Jurassic volcanic and volcaniclastic strata interpreted as a record of the Early-Midd...

The Oligocene Upper Panalillo Ignimbrite is widely distributed in the San Luis Potosí Volcanic Field, in the southeastern portion of the Mesa Central province of Mexico. It crops out sporadically over a ~15,000 km2 area. The best exposures of the ignimbrite were sampled for paleomagnetic and geochronological studies, with sites grouped in five zone...

La Formación Zicapa (De Cserna et al, 1980) corresponde a una unidad volcanosedimentaria compuesta por capas rojas, conglomerados polímicticos, areniscas, lutitas, calizas y rocas volcánicas intercaladas, contemporáneas con evaporitas, dicha formación registra un ambiente de sedimentación continental cercano a la costa que es afectado por cambios e...

We report the results of a magnetostratigraphic study of the San Marcos Formation in central Coahuila, at two localities along the San Marcos Fault. These localities are characterized by outcrops of a sequence of conglomerates, immature sandstone and red mudstone, cemented by hematite; the sequence was deposited in a continental environment, and ha...

We report the results of a magnetostratigraphic study of the San Marcos Formation in central Coahuila, at two localities along the San Marcos Fault. These localities are characterized by outcrops of a sequence of conglomerates, immature sandstone and red mudstone, cemented by hematite; the sequence was deposited in a continental environment, and ha...

Cartografía geológica-estructural en la sierra Cuesta El Infierno (SCI), ubicada en el borde occidental del levantamiento de Plomosas, permitió identificar dos sucesiones volcánicas del Paleógeno que descansan discordantemente sobre rocas sedimentarias del cinturón plegado de Chihuahua. Las sucesiones volcánicas, a las que llamamos informalmente su...

Scholars attribute the growth and decline of Classic period (AD 200–900) settlements in the semi-arid northern frontier zone of Mesoamerica to rainfall cycles that controlled the extent of arable land. However, there is little empirical evidence to support this claim. We present phytolith, organic carbon, and magnetic susceptibility analyses of a 4...

This paper presents multiproxy (pollen, magnetic susceptibility, sediment chemistry) records from two maar crater lakes in the Valle de Santiago of Guanajuato, Mexico: Hoya San Nicolás and Hoya Rincon de Parangueo. Sediment cores from the two sites have basal dates of ca 11,600 and 9600 cal yr BP, respectively. The San Nicolás results show that the...

Geologic and structural mapping of volcanic rocks in sierra Cuesta El Infierno, located on the western flank of the Plomosas uplift, allowed us to divide the Paleogene volcanic section into two succesions. The volcanic rocks unconformably overlie sedimentary rocks of the Chihuahua fold belt. The lower volcanic succession (felsic ash flow tuffs and...

The Permian age Chiapas Massif in southeast Mexico is locally host to well-exposed pseu-dotachylyte vein networks. The veins are black to dark grey and aphanitic in appearance, and consist mostly of microbreccia of angular fragments of plagioclase, K-feldspar, biotite and quartz, in a cryptocrystalline (microscopically irresolvable) matrix. Evidenc...

http://www.biblioteca.juriquilla.unam.mx/WONDERLAND/CGEO/ProductividadCGEO09/Geoguerrero_resumenes2009.pdf

The stratigraphic and geochemical record of the mid-Cretaceous (Cenomanian–Turonian) Oceanic Anoxic Event 2 (OAE2) has been studied in numerous Tethyan and proto-Atlantic hemi-pelagic/pelagic successions, but little data comes from nearshore carbonate successions from the proto-Pacific region. Here we present the results of a combined stratigraphic...

Preliminary results of a paleomagnetic study on jurassic volcanic rocks (U-Pb 188.8 +/- 3.2Ma) locally interbedded with red beds assigned to the Todos Santos Formation, sampled in the Homoclinal Tectonic Province of the Neogene Fold Belt, Chiapas-Mexico, reveal multi component magnetizations acquired during pre- and post- folding of these rocks. Th...

Three up to 520-cm-long sediment cores from Hoya San Nicolas in Guanajuato, Mexico, were analysed for various magnetic properties in order to better define a palaeomagnetic secular curve for Central Mexico. The results—magnetic susceptibility, hysteresis cycles, anhysteretic and isothermal remanent magnetization—suggest that the remanent magnetizat...

The Cerro Mercado pluton, emplaced in the Coahuila fold belt, contains magmatic, ductile, and brittle fabrics that suggest local and regional deformation during igneous emplacement, later affected by regional deformation in the area. The Cerro Mercado pluton intruded, deformed and uplifted Upper Cretaceous strata in the southern edge of the central...

The Cerro Mercado pluton, emplaced in the Coahuila fold belt, contains magmatic, ductile, and brittle fabrics that suggest local and regional deformation during igneous emplacement, later affected by regional deformation in the area. The Cerro Mercado pluton intruded, deformed and uplifted Upper Cretaceous strata in the southern edge of the central...

The Cerro Mercado pluton, emplaced in the Coahuila fold belt, contains magmatic, ductile, and brittle fabrics that suggest local and regional deformation during igneous emplacement, later affected by regional deformation in the area. The Cerro Mercado pluton intruded, deformed and uplifted Upper Cretaceous strata in the southern edge of the central...

Joya Honda (JH) is a Quaternary maar excavated in Mesozoic limestone. It is located in central Mexico and belongs to the Ventura volcanic field (VVF), which is composed by cinder cones and maars made of intraplate-type mafic alkalic rocks. Volcanoes in the region form ∼ N20W lineaments, roughly parallel to a regional set of normal faults, but there...

Pinos volcanic complex is an uplifted area that exposes Mesozoic strata and mid-Tertiary volcanic and sedimentary rocks. Its stratigraphy, deformation style, and volcanism are characteristic of the Mesa Central region of central Mexico and the southeastern segment of the Sierra Madre Occidental (SMO) volcanic province. The oldest rocks in Pinos are...

http://www.ugm.org.mx/bak/raugm/2007/docs/geos27-1b.pdf GET-24

Pinos volcanic complex is an uplifted area that exposes Mesozoic strata and mid–Tertiary volcanic and sedimentary rocks. Its stratigraphy, deformation style, and volcanism are characteristic of the Mesa Central region of central Mexico and the southeastern segment of the Sierra Madre Occidental (SMO) volcanic province. The oldest rocks in Pinos are...

Pinos volcanic complex is an uplifted area that exposes Mesozoic strata and mid-Tertiary volcanic and sedimentary rocks. Its stratigraphy, deformation style, and volcanism are characteristic of the Mesa Central region of central Mexico and the southeastern segment of the Sierra Madre Occidental (SMO) volcanic province. The oldest rocks in Pinos are...

Continental hematitic strata of the Lower Cretaceous San Marcos Formation, in central Coahuila, were deposited on and along the margins of the Coahuila Island, a prominent paleogeographic element in NE Mexico. It contains the stratigraphic record of activity along the San Marcos fault, the southern margin of the Sabinas basin. It is overlain by mar...

According with the premise that all plutons are nearly circular in plan view in almost any environment, we interpret pluton-related structures (PRS) from LandsatTM images in Baja California, between latitudes 28 and 29N. In this region the NW regional trending of the Peninsular Ranges Batholith changes to be E-W. The presence and shape of the pluto...

Upper Jurassic and Lower Cretaceous continental strata at Potrero Colorado, in the core of Sierra La Fragua anticline in central Coahuila, carry dual-polarity characteristic magnetizations that we interpret as near primary chemical remanent magnetizations. Upper Jurassic fluvial and eolian sandstones of the Colorado beds yield a tilt-corrected mean...

The San Marcos fault is a regional structure in northeast México with a minimum length of 300 km, which separates the Coahuila block from the Coahuila fold belt; the fault dips north-northeast and its trend is west-northwest. The San Marcos fault is a basement structure that has been reactivated multiple times, and along its trace there is stratigr...

The Mojave-Sonora megashear model, which implies left-lateral strike-slip motion of northern México in Jurassic time, remains one of the most influential ideas concerning the geology of México. A comprehensive review of the literature related to this topic does not yet allow resolution of the controversy over the validity of this hypothesis. A clea...

El relleno Cenozoico de la cuenca the Tuzantlán-Copalillo, en el noreste de Guerrero, México, se asigna a dos unidades estratigráfi cas distintas. La primera unidad consiste de conglomerado de guijas y guijarros que gradúan hacia el este a areniscas gruesas conglomeráticas interestratifi cadas con areniscas y lodolitas. La secuencia de areniscas y...

http://www.ugm.org.mx/bak/raugm/2006/docs/geos26-1.pdf GET-15

discordance may be explained by tilt down-to-the-northeast of the structural block that contains the intrusive suite of about 40◦ about a NW-SE trending axis, or perhaps more likely and based on additional geological evidence, by a combination of ∼20◦ of counterclockwise rotation about a vertical axis and a smaller amount of tilt. Vertical- axis-ro...

Ocean Drilling Program (ODP) Leg 182, to the Great Australian Bight (GAB), Leg 189 around Tasmania, and Leg 194 off the Great Barrier Reef on the Marion Plateau, all sampled thick carbonate sections that tested the coring techniques and the magnetics instrumentation on the JOIDES Resolution. Coring overprints were demonstrated due to: (1) sediment...