Coexisting hornblende and cummingtonite in an amphibolite near Peliwali have been analysed. The rock formed by Fe-Mg addition and Ca removal from pre-existing amphibole quartzites within the altered wall rocks surrounding sulphide lodes. The amphibole compositions are controlled by the bulk composition of the rock. The Mg/(Mg+Fe 2+) ratio of the hornblende (o.66) is only slightly higher than th...

NWA 2700 and NWA 2977 Paired With NWA 773: NWA 2700 is a 31.7 gram stone consisting of small gabbro clasts plus regolith breccia matrix (see Figure 1). The olivine gabbro contains ~50 vol.% olivine (Fa29.3-34.7; FeO/MnO = 94), pigeonite (Fs2228.3Wo5.6-10; FeO/MnO = 52), augite (Fs13.2Wo38.5), plagioclase and minor maskelynite (An89), Ba-rich alkali feldspar (Or92An4, BaO up to 8.9 wt.%), Crspin...

Abstract The Abu Ghalaga pluton in the southern eastern desert of Egypt (SED) consists undeformed norite and hornblende gabbro intruding island arc metavolcanics, ophiolitic rocks, syn-tectonic older granitic rocks. Fe-Ti ore (mainly ilmenite) occurs form lenses at base norite. Based on microtextures, mineralogy, chemical composition, three types ilmenites are recognized: massive high-Mg type, ...

Zoned plutons, composed of dunites, pyroxenites, and gabbroic rocks, have been referred to as the Ural-Alaskan type complexes (UA-complexes) occur in numerous paleo-arc settings worldwide. Many these are source rocks for economic placers platinum-group metals. Thus, it is important understand how UA-complexes form origin behavior elements (PGEs). It widely assumed that result from differentiati...

The Omai intrusion-centred Au-quartz vein system, the largest Au producer presently operating in the Guyana Shield, was sampled for detailed U-Pb and Pb-Pb geochronology and petrological investigation. The age of a metavolcanic/sub-volcanic unit in the host rock sequence is 212092 Ma. Zircon analyses from the main body dioritic rocks give U-Pb ages of 209496, 2092911 and 2096+11/−10 Ma. Magmati...

The Sangiran dome is the primary stratigraphic window for the Plio-Pleistocene deposits of the Solo basin of Central Jawa. The dome has yielded nearly 80 Homo erectus fossils, around 50 of which have known findspots. With a hornblende (40)Ar/(39)Ar plateau age of 1.66 +/- 0.04 mega-annum (Ma) reportedly associated with two fossils [Swisher, C.C., III, Curtis, G. H., Jacob, T., Getty, A. G., Sup...

the arghash area is located 45 km to southwest of neyshabour. the subvolcanic rocks in the area consist of biotite hornblende quartz monzodiorite porphyry, hornblende biotite quartz monzodiorite porphyry, hornblende monzonite porphyry, biotite hornblende monzonite porphyry, monzodiorite porphyry and biotite quartz monzodiorite porphyry units. the volcanic rocks consist of hornblende biotite dac...

Karapınar-Karacadağ Volcanic Rocks (KKVR) have very complex magmatic history and outcropped the southwestern part of Cappadocia Province (Central Anatolia). Here we present petrography whole-rock chemistry enclave-bearing rocks to constrain their source evolution history. These petrographic observation geochemical data reveal that enclaves in volcanic are magma mixing/mingling (MME), segregatio...

In the mountainous Rio Icacos watershed in northeastern Puerto Rico, quartz diorite bedrock weathers spheroidally, producing a 0.2–2 m thick zone of partially weathered rock layers ( 2.5 cm thickness each) called rindlets, which form concentric layers around corestones. Spheroidal fracturing has been modeled to occur when a weathering reaction with a positive DV of reaction builds up elastic st...